Urban Flood Risk Insurance Models as a Strategy for Proactive Water Management Policies

NASA Astrophysics Data System (ADS)

Graciosa, M. C.; Mendiondo, E. M.

2006-12-01

To improve the water management through hydrological sciences, novel integration strategies could be underpinned to bridge up both engineering and economics. This is especially significant in developing nations where hydrologic extremes are expressive while the financial resources to mitigate that variability are scarce. One example of this problem is related to floods and their global and regional consequences. Floods mainly cause disasters in terms of human and material losses. In 2002, more than 30% of extreme climatic events occurred worldwide were floods, representing 42% of fatalities and 66% of material losses, mostly related to reactive policies. Throughout the last century, hydrological variability and rapidly growing of urban areas have developed new environmental problems in Brazilian cities, such as inundation occurrences on non-planned river basins. One of the causes of flood impacts is that public funds (national, state or municipal) have barely introduced wise proactive polices to follow up rapidly growing urban areas. Inexistent flood-risk-transfer mechanisms have caused the so-called `flood poverty cycle' due to reactive polices that have been increasing flood losses and, sometimes, became flood disasters. Flood risk management (FRM) is part of pro-active policies to mitigate inundation losses, in order to sustain environmental, social and economic aspects. Concepts and principles of FRM are part of a process that encompasses three phases: (1) preparedness stage, that consists in structural and non-structural actions to prevent and protect potential risk areas, such as early warning systems and scenarios development; (2) control stage, that refers to help actions and protection facilities during the event, and (3) restoration stage, that is related to rebuild affected areas, restore the river dynamics and transfer the socio-economic risks through flood insurances. Flood risk insurances agree to the goals of losses mitigation programs. Their use is more common in basins affected by alluvial floods. However, most of losses occur in urban areas, as a consequence of flash floods. Quantification of losses is an important basis of flood mitigation programs. It is also a complex task, which involves setting values on not easily quantifiable goods and determining risk and damage curves. This work proposes a flood insurance risk model coupled with a hydrological model as an incentive-based mechanism for achieving economically efficient flood management to be applied in Brazilian urban basins. It consists of integrating an insurance model and hydrological modeling of peak discharge warnings. It sets up curves, such as: water level versus discharge, water level versus inundation areas, and inundation area versus damage. It considers the prediction of future scenarios in order to evaluate the behavior of the insurance fund under climate variability. By using different probability distribution is compared the solvency and efficiency of the flood insurance fund for each premium-covered situation. The methodology is outlined to provide resources for the FRM restoration phase. Results are depicted from an experimental river basin sited on a rapid growing urban area, with some lessons learned valid to approach in other urban basins. This example is envisaged to foster resilience in the integration of hydrological science with policy and economic approaches. KEY WORDS: Flood risks management; flood insurance; hydrological modeling.

Quantification of increased flood risk due to global climate change for urban river management planning.

PubMed

Morita, M

2011-01-01

Global climate change is expected to affect future rainfall patterns. These changes should be taken into account when assessing future flooding risks. This study presents a method for quantifying the increase in flood risk caused by global climate change for use in urban flood risk management. Flood risk in this context is defined as the product of flood damage potential and the probability of its occurrence. The study uses a geographic information system-based flood damage prediction model to calculate the flood damage caused by design storms with different return periods. Estimation of the monetary damages these storms produce and their return periods are precursors to flood risk calculations. The design storms are developed from modified intensity-duration-frequency relationships generated by simulations of global climate change scenarios (e.g. CGCM2A2). The risk assessment method is applied to the Kanda River basin in Tokyo, Japan. The assessment provides insights not only into the flood risk cost increase due to global warming, and the impact that increase may have on flood control infrastructure planning.

"Flooding Risk Analysis and the Understanding of Hydrological Disturbance due to the Rapid Urbanization in a Low-Scale Subwatershed in Houston Area". ( The project develops a relavant Model of flooding risk assessment to define the connection between increased streamflow/flooding and the rapid urban land development).

NASA Astrophysics Data System (ADS)

Geldiyev, P.

2017-12-01

Rapid urban development and changing climate influences the frequency and magnitude of flooding in Houston area. This proposed project aims to evaluate the flooding risks with the current and future land use changes by 2040 for one subbasin of the San Jacinto Brazos/Neches-Trinity Coastal basin. Surface environments and streamflow data of the Clear Creek are analyzed and stimulated to discuss the possible impact of urbanization on the occurrence of floods. The streamflow data is analyzed and simulated with the application of the Geographic Information Systems and its extensions. Both hydrologic and hydraulic models of the Clear Creek are created with the use of HEC-HMS and HEC-RAS software. Both models are duplicated for the year 2040, based on projected 2040 Landcover Maps developed by Houston and Galveston Area Council. This project examines a type of contemporary hydrologic disturbance and the interaction between land cover and changes in hydrological processes. Expected results will be very significant for urban development and flooding management.

Microbial Risk Assessment of Tidal-Induced Urban Flooding in Can Tho City (Mekong Delta, Vietnam).

PubMed

Nguyen, Hong Quan; Huynh, Thi Thao Nguyen; Pathirana, Assela; Van der Steen, Peter

2017-11-30

Public health risks from urban flooding are a global concern. Contaminated floodwater may expose residents living in cities as they are in direct contact with the water. However, the recent literature does not provide much information about this issue, especially for developing countries. In this paper, the health risk due to a flood event occurred in Can Tho City (Mekong Delta, Vietnam) on 7 October 2013 was investigated. The Quantitative Microbial Risk Assessment method was used in this study. The data showed that the pathogen concentrations were highly variable during the flood event and exceeded water standards for surface water. Per 10,000 people in contact with the floodwater, we found Salmonella caused the highest number of infections to adults and children (137 and 374, respectively), while E. coli caused 4 and 12 cases, per single event, respectively. The results show that further investigations on health risk related to flood issues in Can Tho City are required, especially because of climate change and urbanization. In addition, activities to raise awareness- about floods, e.g., "living with floods", in the Mekong Delta should also consider health risk issues.

Lessons learned from Khartoum flash flood impacts: An integrated assessment.

PubMed

Mahmood, Mohamad Ibrahim; Elagib, Nadir Ahmed; Horn, Finlay; Saad, Suhair A G

2017-12-01

This study aims at enabling the compilation of key lessons for decision makers and urban planners in rapidly urbanizing cities regarding the identification of representative, chief causal natural and human factors for the increased level of flash flood risk. To achieve this, the impacts of flash flood events of 2013 and 2014 in the capital of Sudan, Khartoum, were assessed using seven integrated approaches, i.e. rainfall data analysis, document analysis of affected people and houses, observational fieldwork in the worst flood affected areas, people's perception of causes and mitigation measures through household interviews, reported drinking water quality, reported water-related diseases and social risk assessment. Several lessons have been developed as follows. Urban planners must recognize the devastating risks of building within natural pathways of ephemeral watercourses. They must also ensure effective drainage infrastructures and physio-geographical investigations prior to developing urban areas. The existing urban drainage systems become ineffective due to blockage by urban waste. Building of unauthorized drainage and embankment structures by locals often cause greater flood problems than normal. The urban runoff is especially problematic for residential areas built within low-lying areas having naturally low infiltration capacity, as surface water can rapidly collect within hollows and depressions, or beside elevated roads that preclude the free flow of floodwater. Weak housing and infrastructure quality are especially vulnerable to flash flooding and even to rainfall directly. Establishment of services infrastructure is imperative for flash flood disaster risk reduction. Water supply should be from lower aquifers to avoid contaminant groundwater. Regular monitoring of water quality and archiving of its indicators help identify water-related diseases and sources of water contamination in the event of environmental disasters such as floods. Though the understanding of risk perception by the locals is an important aspect of the decision making and planning processes, it should be advanced enough for proper awareness. Copyright © 2017 Elsevier B.V. All rights reserved.

An Integrated Urban Flood Analysis System in South Korea

NASA Astrophysics Data System (ADS)

Moon, Young-Il; Kim, Min-Seok; Yoon, Tae-Hyung; Choi, Ji-Hyeok

2017-04-01

Due to climate change and the rapid growth of urbanization, the frequency of concentrated heavy rainfall has caused urban floods. As a result, we studied climate change in Korea and developed an integrated flood analysis system that systematized technology to quantify flood risk and flood forecasting in urban areas. This system supports synthetic decision-making through real-time monitoring and prediction on flash rain or short-term rainfall by using radar and satellite information. As part of the measures to deal with the increase of inland flood damage, we have found it necessary to build a systematic city flood prevention system that systematizes technology to quantify flood risk as well as flood forecast, taking into consideration both inland and river water. This combined inland-river flood analysis system conducts prediction on flash rain or short-term rainfall by using radar and satellite information and performs prompt and accurate prediction on the inland flooded area. In addition, flood forecasts should be accurate and immediate. Accurate flood forecasts signify that the prediction of the watch, warning time and water level is precise. Immediate flood forecasts represent the forecasts lead time which is the time needed to evacuate. Therefore, in this study, in order to apply rainfall-runoff method to medium and small urban stream for flood forecasts, short-term rainfall forecasting using radar is applied to improve immediacy. Finally, it supports synthetic decision-making for prevention of flood disaster through real-time monitoring. Keywords: Urban Flood, Integrated flood analysis system, Rainfall forecasting, Korea Acknowledgments This research was supported by a grant (16AWMP-B066744-04) from Advanced Water Management Research Program (AWMP) funded by Ministry of Land, Infrastructure and Transport of Korean government.

Exploring the Linkage between Urban Flood Risk and Spatial Patterns in Small Urbanized Catchments of Beijing, China

PubMed Central

Yao, Lei; Chen, Liding; Wei, Wei

2017-01-01

In the context of global urbanization, urban flood risk in many cities has become a serious environmental issue, threatening the health of residents and the environment. A number of hydrological studies have linked urban flooding issues closely to the spectrum of spatial patterns of urbanization, but relatively little attention has been given to small-scale catchments within the realm of urban systems. This study aims to explore the hydrological effects of small-scaled urbanized catchments assigned with various landscape patterns. Twelve typical residential catchments in Beijing were selected as the study areas. Total Impervious Area (TIA), Directly Connected Impervious Area (DCIA), and a drainage index were used as the catchment spatial metrics. Three scenarios were designed as different spatial arrangement of catchment imperviousness. Runoff variables including total and peak runoff depth (Qt and Qp) were simulated by using Strom Water Management Model (SWMM). The relationship between catchment spatial patterns and runoff variables were determined, and the results demonstrated that, spatial patterns have inherent influences on flood risks in small urbanized catchments. Specifically: (1) imperviousness acts as an effective indicator in affecting both Qt and Qp; (2) reducing the number of rainwater inlets appropriately will benefit the catchment peak flow mitigation; (3) different spatial concentrations of impervious surfaces have inherent influences on Qp. These findings provide insights into the role of urban spatial patterns in driving rainfall-runoff processes in small urbanized catchments, which is essential for urban planning and flood management. PMID:28264521

Exploring the Linkage between Urban Flood Risk and Spatial Patterns in Small Urbanized Catchments of Beijing, China.

PubMed

Yao, Lei; Chen, Liding; Wei, Wei

2017-02-28

In the context of global urbanization, urban flood risk in many cities has become a serious environmental issue, threatening the health of residents and the environment. A number of hydrological studies have linked urban flooding issues closely to the spectrum of spatial patterns of urbanization, but relatively little attention has been given to small-scale catchments within the realm of urban systems. This study aims to explore the hydrological effects of small-scaled urbanized catchments assigned with various landscape patterns. Twelve typical residential catchments in Beijing were selected as the study areas. Total Impervious Area ( TIA ), Directly Connected Impervious Area ( DCIA ), and a drainage index were used as the catchment spatial metrics. Three scenarios were designed as different spatial arrangement of catchment imperviousness. Runoff variables including total and peak runoff depth ( Q t and Q p ) were simulated by using Strom Water Management Model (SWMM). The relationship between catchment spatial patterns and runoff variables were determined, and the results demonstrated that, spatial patterns have inherent influences on flood risks in small urbanized catchments. Specifically: (1) imperviousness acts as an effective indicator in affecting both Q t and Q p ; (2) reducing the number of rainwater inlets appropriately will benefit the catchment peak flow mitigation; (3) different spatial concentrations of impervious surfaces have inherent influences on Q p . These findings provide insights into the role of urban spatial patterns in driving rainfall-runoff processes in small urbanized catchments, which is essential for urban planning and flood management.

Exploring public databases to characterize urban flood risks in Amsterdam

NASA Astrophysics Data System (ADS)

Gaitan, Santiago; ten Veldhuis, Marie-claire; van de Giesen, Nick

2015-04-01

Cities worldwide are challenged by increasing urban flood risks. Precise and realistic measures are required to decide upon investment to reduce their impacts. Obvious flooding factors affecting flood risk include sewer systems performance and urban topography. However, currently implemented sewer and topographic models do not provide realistic predictions of local flooding occurrence during heavy rain events. Assessing other factors such as spatially distributed rainfall and socioeconomic characteristics may help to explain probability and impacts of urban flooding. Several public databases were analyzed: complaints about flooding made by citizens, rainfall depths (15 min and 100 Ha spatio-temporal resolution), grids describing number of inhabitants, income, and housing price (1Ha and 25Ha resolution); and buildings age. Data analysis was done using Python and GIS programming, and included spatial indexing of data, cluster analysis, and multivariate regression on the complaints. Complaints were used as a proxy to characterize flooding impacts. The cluster analysis, run for all the variables except the complaints, grouped part of the grid-cells of central Amsterdam into a highly differentiated group, covering 10% of the analyzed area, and accounting for 25% of registered complaints. The configuration of the analyzed variables in central Amsterdam coincides with a high complaint count. Remaining complaints were evenly dispersed along other groups. An adjusted R2 of 0.38 in the multivariate regression suggests that explaining power can improve if additional variables are considered. While rainfall intensity explained 4% of the incidence of complaints, population density and building age significantly explained around 20% each. Data mining of public databases proved to be a valuable tool to identify factors explaining variability in occurrence of urban pluvial flooding, though additional variables must be considered to fully explain flood risk variability.

Risk-based zoning for urbanizing floodplains.

PubMed

Porse, Erik

2014-01-01

Urban floodplain development brings economic benefits and enhanced flood risks. Rapidly growing cities must often balance the economic benefits and increased risks of floodplain settlement. Planning can provide multiple flood mitigation and environmental benefits by combining traditional structural measures such as levees, increasingly popular landscape and design features (green infrastructure), and non-structural measures such as zoning. Flexibility in both structural and non-structural options, including zoning procedures, can reduce flood risks. This paper presents a linear programming formulation to assess cost-effective urban floodplain development decisions that consider benefits and costs of development along with expected flood damages. It uses a probabilistic approach to identify combinations of land-use allocations (residential and commercial development, flood channels, distributed runoff management) and zoning regulations (development zones in channel) to maximize benefits. The model is applied to a floodplain planning analysis for an urbanizing region in the Baja Sur peninsula of Mexico. The analysis demonstrates how (1) economic benefits drive floodplain development, (2) flexible zoning can improve economic returns, and (3) cities can use landscapes, enhanced by technology and design, to manage floods. The framework can incorporate additional green infrastructure benefits, and bridges typical disciplinary gaps for planning and engineering.

A global framework for future costs and benefits of river-flood protection in urban areas

NASA Astrophysics Data System (ADS)

Ward, Philip J.; Jongman, Brenden; Aerts, Jeroen C. J. H.; Bates, Paul D.; Botzen, Wouter J. W.; Diaz Loaiza, Andres; Hallegatte, Stephane; Kind, Jarl M.; Kwadijk, Jaap; Scussolini, Paolo; Winsemius, Hessel C.

2017-09-01

Floods cause billions of dollars of damage each year, and flood risks are expected to increase due to socio-economic development, subsidence, and climate change. Implementing additional flood risk management measures can limit losses, protecting people and livelihoods. Whilst several models have been developed to assess global-scale river-flood risk, methods for evaluating flood risk management investments globally are lacking. Here, we present a framework for assessing costs and benefits of structural flood protection measures in urban areas around the world. We demonstrate its use under different assumptions of current and future climate change and socio-economic development. Under these assumptions, investments in dykes may be economically attractive for reducing risk in large parts of the world, but not everywhere. In some regions, economically efficient investments could reduce future flood risk below today’s levels, in spite of climate change and economic growth. We also demonstrate the sensitivity of the results to different assumptions and parameters. The framework can be used to identify regions where river-flood protection investments should be prioritized, or where other risk-reducing strategies should be emphasized.

Health Co-Benefits of Green Building Design Strategies and Community Resilience to Urban Flooding: A Systematic Review of the Evidence.

PubMed

Houghton, Adele; Castillo-Salgado, Carlos

2017-12-06

Climate change is increasingly exacerbating existing population health hazards, as well as resulting in new negative health effects. Flooding is one particularly deadly example of its amplifying and expanding effect on public health. This systematic review considered evidence linking green building strategies in the Leadership in Energy and Environmental Design ® (LEED) Rating System with the potential to reduce negative health outcomes following exposure to urban flooding events. Queries evaluated links between LEED credit requirements and risk of exposure to urban flooding, environmental determinants of health, co-benefits to public health outcomes, and co-benefits to built environment outcomes. Public health co-benefits to leveraging green building design to enhance flooding resilience included: improving the interface between humans and wildlife and reducing the risk of waterborne disease, flood-related morbidity and mortality, and psychological harm. We conclude that collaborations among the public health, climate change, civil society, and green building sectors to enhance community resilience to urban flooding could benefit population health.

Opportunities for multivariate analysis of open spatial datasets to characterize urban flooding risks

NASA Astrophysics Data System (ADS)

Gaitan, S.; ten Veldhuis, J. A. E.

2015-06-01

Cities worldwide are challenged by increasing urban flood risks. Precise and realistic measures are required to reduce flooding impacts. However, currently implemented sewer and topographic models do not provide realistic predictions of local flooding occurrence during heavy rain events. Assessing other factors such as spatially distributed rainfall, socioeconomic characteristics, and social sensing, may help to explain probability and impacts of urban flooding. Several spatial datasets have been recently made available in the Netherlands, including rainfall-related incident reports made by citizens, spatially distributed rain depths, semidistributed socioeconomic information, and buildings age. Inspecting the potential of this data to explain the occurrence of rainfall related incidents has not been done yet. Multivariate analysis tools for describing communities and environmental patterns have been previously developed and used in the field of study of ecology. The objective of this paper is to outline opportunities for these tools to explore urban flooding risks patterns in the mentioned datasets. To that end, a cluster analysis is performed. Results indicate that incidence of rainfall-related impacts is higher in areas characterized by older infrastructure and higher population density.

Virtual reality in urban water management: communicating urban flooding with particle-based CFD simulations.

PubMed

Winkler, Daniel; Zischg, Jonatan; Rauch, Wolfgang

2018-01-01

For communicating urban flood risk to authorities and the public, a realistic three-dimensional visual display is frequently more suitable than detailed flood maps. Virtual reality could also serve to plan short-term flooding interventions. We introduce here an alternative approach for simulating three-dimensional flooding dynamics in large- and small-scale urban scenes by reaching out to computer graphics. This approach, denoted 'particle in cell', is a particle-based CFD method that is used to predict physically plausible results instead of accurate flow dynamics. We exemplify the approach for the real flooding event in July 2016 in Innsbruck.

Systematic testing of flood adaptation options in urban areas through simulations

NASA Astrophysics Data System (ADS)

Löwe, Roland; Urich, Christian; Sto. Domingo, Nina; Mark, Ole; Deletic, Ana; Arnbjerg-Nielsen, Karsten

2016-04-01

While models can quantify flood risk in great detail, the results are subject to a number of deep uncertainties. Climate dependent drivers such as sea level and rainfall intensities, population growth and economic development all have a strong influence on future flood risk, but future developments can only be estimated coarsely. In such a situation, robust decision making frameworks call for the systematic evaluation of mitigation measures against ensembles of potential futures. We have coupled the urban development software DAnCE4Water and the 1D-2D hydraulic simulation package MIKE FLOOD to create a framework that allows for such systematic evaluations, considering mitigation measures under a variety of climate futures and urban development scenarios. A wide spectrum of mitigation measures can be considered in this setup, ranging from structural measures such as modifications of the sewer network over local retention of rainwater and the modification of surface flow paths to policy measures such as restrictions on urban development in flood prone areas or master plans that encourage compact development. The setup was tested in a 300 ha residential catchment in Melbourne, Australia. The results clearly demonstrate the importance of considering a range of potential futures in the planning process. For example, local rainwater retention measures strongly reduce flood risk a scenario with moderate increase of rain intensities and moderate urban growth, but their performance strongly varies, yielding very little improvement in situations with pronounced climate change. The systematic testing of adaptation measures further allows for the identification of so-called adaptation tipping points, i.e. levels for the drivers of flood risk where the desired level of flood risk is exceeded despite the implementation of (a combination of) mitigation measures. Assuming a range of development rates for the drivers of flood risk, such tipping points can be translated into anticipated time spans over which a measure will be effective. While the new simulation setup is limited to situations where the planner is able to define realistic ranges for the development of drivers of flood risk, it certainly contributes to an improved consideration of deep uncertainties in the planning process. Future work will particularly focus on the application of the framework in a variety of urban development contexts.

Microbial Risk Assessment of Tidal−Induced Urban Flooding in Can Tho City (Mekong Delta, Vietnam)

PubMed Central

Huynh, Thi Thao Nguyen; Van der Steen, Peter

2017-01-01

Public health risks from urban flooding are a global concern. Contaminated floodwater may expose residents living in cities as they are in direct contact with the water. However, the recent literature does not provide much information about this issue, especially for developing countries. In this paper, the health risk due to a flood event occurred in Can Tho City (Mekong Delta, Vietnam) on 7 October 2013 was investigated. The Quantitative Microbial Risk Assessment method was used in this study. The data showed that the pathogen concentrations were highly variable during the flood event and exceeded water standards for surface water. Per 10,000 people in contact with the floodwater, we found Salmonella caused the highest number of infections to adults and children (137 and 374, respectively), while E. coli caused 4 and 12 cases, per single event, respectively. The results show that further investigations on health risk related to flood issues in Can Tho City are required, especially because of climate change and urbanization. In addition, activities to raise awareness- about floods, e.g., “living with floods”, in the Mekong Delta should also consider health risk issues. PMID:29189715

Hydrodynamics of flood impact on urban mobility: critical conditions for vehicles carry-off

NASA Astrophysics Data System (ADS)

Arrighi, Chiara; Alcèrreca Huerta, Juan Carlos; Oumeraci, Hocine; Castelli, Fabio

2015-04-01

The street networks are a critical infrastructure during flood events in urban areas, on one hand because they allow the flood propagation in the urban environment, on the other hand because they ensure capillary rescue activities during and after the event. At present, the vehicle instability during an urban flood is recognized as being one of the most exacerbating factor for flood risk. In fact roads can be clogged by vehicles debris, which is also particularly dangerous for people's safety. In this work the incipient motion conditions of flooded vehicles are investigated and discussed. A mobility parameter θV is introduced as a function of the Froude number of the flow. The flow for different regimes past a specific vehicle geometry is modelled using a 3-dimensional numerical approach. The results of the numerical model clarify the contribution of drag and lift forces to the incipient motion conditions. The numerical results are compared with recent experimental data found in literature on partially submerged scale 1:18 vehicle models. The estimated force coefficients and instability conditions may provide a useful tool for flood risk assessment and management in urban areas.

A GIS-based model to estimate flood consequences and the degree of accessibility and operability of strategic emergency response structures in urban areas

NASA Astrophysics Data System (ADS)

Albano, R.; Sole, A.; Adamowski, J.; Mancusi, L.

2014-11-01

Efficient decision-making regarding flood risk reduction has become a priority for authorities and stakeholders in many European countries. Risk analysis methods and techniques are a useful tool for evaluating costs and benefits of possible interventions. Within this context, a methodology to estimate flood consequences was developed in this paper that is based on GIS, and integrated with a model that estimates the degree of accessibility and operability of strategic emergency response structures in an urban area. The majority of the currently available approaches do not properly analyse road network connections and dependencies within systems, and as such a loss of roads could cause significant damages and problems to emergency services in cases of flooding. The proposed model is unique in that it provides a maximum-impact estimation of flood consequences on the basis of the operability of the strategic emergency structures in an urban area, their accessibility, and connection within the urban system of a city (i.e. connection between aid centres and buildings at risk), in the emergency phase. The results of a case study in the Puglia region in southern Italy are described to illustrate the practical applications of this newly proposed approach. The main advantage of the proposed approach is that it allows for defining a hierarchy between different infrastructure in the urban area through the identification of particular components whose operation and efficiency are critical for emergency management. This information can be used by decision-makers to prioritize risk reduction interventions in flood emergencies in urban areas, given limited financial resources.

The integration of the risk in the governance of urban projects: a key issue for a resilient city

NASA Astrophysics Data System (ADS)

Moulin, E.; Deroubaix, J.-F.

2012-04-01

Despite a severe regulation concerning the building in flooding areas, 80% of these areas are already built in the Greater Paris (Paris, Val-de-Marne, Hauts-de-Seine and Seine-Saint-Denis). The land use in flooding area is presented as one of the main solutions to solve the ongoing real estate pressure. For instance some of the industrial wastelands located along the river are currently in redevelopment and residential buildings are planned. So landuse in the flooding areas is currently a key issue in the development of the Greater Paris area. Tools and measures, structural or non-structural such as warning systems, barriers, etc do exist and could be a smart way to improve the resilience of the new urbanised areas. The technical solutions are available and efficient, but we notice that these tools are not much implemented. There is a lack of flood risk concern among the stakeholders and the inhabitants1. How landuse stakeholders could integrate the flood risk in the decision making process throughout the implementation of the urban project? Which type of governance favours an efficient development of good flood risk policy including prevention, protection and the management of the crisis? What is the "good" governance of the urban project e.g. enabling to take into account or not to forget the flood risk and to empower the (future) inhabitants? This inhabitants' empowerment includes the improvement of awareness (i.e. inhabitants being aware that they live in a flooded area) and the improvement of concern (i.e. inhabitants adopting the "right" behaviour when the risk occurs). In order to investigate how flood risk is or could be integrated in the project governance, we interviewed stakeholders (elected representatives, architects, property developers, etc.) and observed the integration or the vanishing of the risk throughout the project. In order to develop this topic we rely on a case study. The "Ardoines" is a project aiming at redeveloping an industrial site (South-East Paris), into a project including residential and office buildings and other amenities. In order to elaborate the master plan, the urban planning authority brought together some flood risk experts. With the remarks of the experts, the architect in charge of the landuse elaborated the master plan taking into account the flood risk; reducing vulnerability of the area and improving the resilience in case of floods, towards a threshold plan. How the experts' recommendations appear in the execution phase? We will show how the project completes or departs from the regulatory policy concerning the drawing up and the implementation of the prevention/protection against flood risk in France. How the vulnerability reduction or the resilience improvement reproduce the regulatory fragmentation, i.e.; on one hand the risk prevention plan and on the other hand the crisis management? We will demonstrate how a resilient approach should mix the several regulatory segments and put the inhabitant in the middle of the urban project thanks to suitable urban forms.

Health Co-Benefits of Green Building Design Strategies and Community Resilience to Urban Flooding: A Systematic Review of the Evidence

PubMed Central

Castillo-Salgado, Carlos

2017-01-01

Climate change is increasingly exacerbating existing population health hazards, as well as resulting in new negative health effects. Flooding is one particularly deadly example of its amplifying and expanding effect on public health. This systematic review considered evidence linking green building strategies in the Leadership in Energy and Environmental Design® (LEED) Rating System with the potential to reduce negative health outcomes following exposure to urban flooding events. Queries evaluated links between LEED credit requirements and risk of exposure to urban flooding, environmental determinants of health, co-benefits to public health outcomes, and co-benefits to built environment outcomes. Public health co-benefits to leveraging green building design to enhance flooding resilience included: improving the interface between humans and wildlife and reducing the risk of waterborne disease, flood-related morbidity and mortality, and psychological harm. We conclude that collaborations among the public health, climate change, civil society, and green building sectors to enhance community resilience to urban flooding could benefit population health. PMID:29210981

A Probabilistic Analysis of Surface Water Flood Risk in London.

PubMed

Jenkins, Katie; Hall, Jim; Glenis, Vassilis; Kilsby, Chris

2018-06-01

Flooding in urban areas during heavy rainfall, often characterized by short duration and high-intensity events, is known as "surface water flooding." Analyzing surface water flood risk is complex as it requires understanding of biophysical and human factors, such as the localized scale and nature of heavy precipitation events, characteristics of the urban area affected (including detailed topography and drainage networks), and the spatial distribution of economic and social vulnerability. Climate change is recognized as having the potential to enhance the intensity and frequency of heavy rainfall events. This study develops a methodology to link high spatial resolution probabilistic projections of hourly precipitation with detailed surface water flood depth maps and characterization of urban vulnerability to estimate surface water flood risk. It incorporates probabilistic information on the range of uncertainties in future precipitation in a changing climate. The method is applied to a case study of Greater London and highlights that both the frequency and spatial extent of surface water flood events are set to increase under future climate change. The expected annual damage from surface water flooding is estimated to be to be £171 million, £343 million, and £390 million/year under the baseline, 2030 high, and 2050 high climate change scenarios, respectively. © 2017 Society for Risk Analysis.

Long-term strategies of climate change adaptation to manage flooding events in urban areas

NASA Astrophysics Data System (ADS)

Pouget, Laurent; Russo, Beniamino; Redaño, Angel; Ribalaygua, Jaime

2010-05-01

Heavy and sudden rainfalls regularly affect the Mediterranean area, so a great number of people and buildings are exposed to the risk of rain-generated floods. Climate change is expected to modify this risk and, in the case that extreme rainfalls increase in frequencies and intensity, this could result in important damages, particularly in urban areas. This paper presents a project that aims to determine adaptation strategies to future flood risks in urban areas. It has been developed by a panel of water companies (R+i Alliance funding), and includes the evaluation of the climate change impact on the extreme rainfall, the use of innovative modelling tools to accurately forecast the flood risk and, finally, the definition of a pro-active and long-term planning against floods. This methodology has been applied in the city of Barcelona. Current climate models give some projections that are not directly applicable for flood risk studies, either because they do not have an adequate spatial and temporal resolution, or because they do not consider some important local factors, such as orography. These points have been considered within the project, when developing the design storms corresponding to future climatic conditions (e.g. years 2030 or 2050). The methodology uses statistical downscaling techniques based on global climate models predictions, including corrections for extreme events and convective storms, as well as temporal downscaling based on historical observations. The design storms created are used in combination with the predictions of sea level rise and land use evolutions to determine the future risk of flooding in the area of study. Once the boundary conditions are known, an accurate flood hazard assessment is done. It requires a local knowledge of the flow parameters in the whole analyzed domain. In urban catchments, in order to fulfill this requirement, powerful hydrological and hydraulic tools and detailed topographic data represent the unique way for a local estimation of the flow parameters (flow depth, flow velocity, flood duration, etc.). If urban floods are caused by heavy rainfall events and a quick hydrological response of the catchment, the approach to elaborate a flood hazard assessment study should take into account the drainage system capacity, too (in terms of effectiveness of surface drainage structures, as well as storm sewerages). In these cases, the hydrological modelling of the involved subcatchments should be linked to the runoff propagation 2D modelling on the urban surface and the hydraulics of the storm sewers (dual drainage modelling) through a coupled 2D/1D approach. The design storm created and the 2D/1D modelling approach have been used to simulate the future flood risk in the city of Barcelona. From the simulation results, it is possible to understand the flooding processes and the risk associated. It is therefore possible to develop some long-term adaptation strategies to reduce the flood risk for current and future climatic conditions, such as structural measures (e.g. improvement of the stormwater network) and non-structural measures (e.g. enhancement of the flood warning system).

Assessing urban strategies for reducing the impacts of extreme weather on infrastructure networks.

PubMed

Pregnolato, Maria; Ford, Alistair; Robson, Craig; Glenis, Vassilis; Barr, Stuart; Dawson, Richard

2016-05-01

Critical infrastructure networks, including transport, are crucial to the social and economic function of urban areas but are at increasing risk from natural hazards. Minimizing disruption to these networks should form part of a strategy to increase urban resilience. A framework for assessing the disruption from flood events to transport systems is presented that couples a high-resolution urban flood model with transport modelling and network analytics to assess the impacts of extreme rainfall events, and to quantify the resilience value of different adaptation options. A case study in Newcastle upon Tyne in the UK shows that both green roof infrastructure and traditional engineering interventions such as culverts or flood walls can reduce transport disruption from flooding. The magnitude of these benefits depends on the flood event and adaptation strategy, but for the scenarios considered here 3-22% improvements in city-wide travel times are achieved. The network metric of betweenness centrality, weighted by travel time, is shown to provide a rapid approach to identify and prioritize the most critical locations for flood risk management intervention. Protecting just the top ranked critical location from flooding provides an 11% reduction in person delays. A city-wide deployment of green roofs achieves a 26% reduction, and although key routes still flood, the benefits of this strategy are more evenly distributed across the transport network as flood depths are reduced across the model domain. Both options should form part of an urban flood risk management strategy, but this method can be used to optimize investment and target limited resources at critical locations, enabling green infrastructure strategies to be gradually implemented over the longer term to provide city-wide benefits. This framework provides a means of prioritizing limited financial resources to improve resilience. This is particularly important as flood management investments must typically exceed a far higher benefit-cost threshold than transport infrastructure investments. By capturing the value to the transport network from flood management interventions, it is possible to create new business models that provide benefits to, and enhance the resilience of, both transport and flood risk management infrastructures. Further work will develop the framework to consider other hazards and infrastructure networks.

Assessing urban strategies for reducing the impacts of extreme weather on infrastructure networks

PubMed Central

Pregnolato, Maria; Ford, Alistair; Robson, Craig; Glenis, Vassilis; Barr, Stuart; Dawson, Richard

2016-01-01

Critical infrastructure networks, including transport, are crucial to the social and economic function of urban areas but are at increasing risk from natural hazards. Minimizing disruption to these networks should form part of a strategy to increase urban resilience. A framework for assessing the disruption from flood events to transport systems is presented that couples a high-resolution urban flood model with transport modelling and network analytics to assess the impacts of extreme rainfall events, and to quantify the resilience value of different adaptation options. A case study in Newcastle upon Tyne in the UK shows that both green roof infrastructure and traditional engineering interventions such as culverts or flood walls can reduce transport disruption from flooding. The magnitude of these benefits depends on the flood event and adaptation strategy, but for the scenarios considered here 3–22% improvements in city-wide travel times are achieved. The network metric of betweenness centrality, weighted by travel time, is shown to provide a rapid approach to identify and prioritize the most critical locations for flood risk management intervention. Protecting just the top ranked critical location from flooding provides an 11% reduction in person delays. A city-wide deployment of green roofs achieves a 26% reduction, and although key routes still flood, the benefits of this strategy are more evenly distributed across the transport network as flood depths are reduced across the model domain. Both options should form part of an urban flood risk management strategy, but this method can be used to optimize investment and target limited resources at critical locations, enabling green infrastructure strategies to be gradually implemented over the longer term to provide city-wide benefits. This framework provides a means of prioritizing limited financial resources to improve resilience. This is particularly important as flood management investments must typically exceed a far higher benefit–cost threshold than transport infrastructure investments. By capturing the value to the transport network from flood management interventions, it is possible to create new business models that provide benefits to, and enhance the resilience of, both transport and flood risk management infrastructures. Further work will develop the framework to consider other hazards and infrastructure networks. PMID:27293781

A multi-disciplinary approach to evaluate vulnerability and risks of pluvial floods under changing climate: the case study of the municipality of Venice (Italy).

NASA Astrophysics Data System (ADS)

Sperotto, Anna; Torresan, Silvia; Gallina, Valentina; Coppola, Erika; Critto, Andrea; Marcomini, Antonio

2015-04-01

Global climate change is expected to affect the intensity and frequency of extreme events (e.g. heat waves, drought, heavy precipitations events) leading to increasing natural disasters and damaging events (e.g. storms, pluvial floods and coastal flooding) worldwide. Especially in urban areas, disasters risks can be exacerbated by changes in exposure and vulnerability patterns (i.e. urbanization, population growth) and should be addressed by adopting a multi-disciplinary approach. A Regional Risk Assessment (RRA) methodology integrating climate and environmental sciences with bottom-up participative processes was developed and applied to the urban territory of the municipality of Venice in order to evaluate the potential consequences of climate change on pluvial flood risk in urban areas. Based on the consecutive analysis of hazard, exposure, vulnerability and risks, the RRA methodology is a screening risk tool to identify and prioritize major elements at risk (e.g. residential, commercial areas and infrastructures) and to localize sub-areas that are more likely to be affected by flood risk due to heavy precipitation events, in the future scenario (2041-2050). From the early stages of its development and application, the RRA followed a bottom-up approach to select and score site-specific vulnerability factors (e.g. slope, permeability of the soil, past flooded areas) and to consider the requests and perspectives of local stakeholders of the North Adriatic region, by means of interactive workshops, surveys and discussions. The main outputs of the assessment are risk and vulnerability maps and statistics aimed at increasing awareness about the potential effect of climate change on pluvial flood risks and at identifying hot-spot areas where future adaptation actions should be required to decrease physical-environmental vulnerabilities or building resilience and coping capacity of human society to climate change. The overall risk assessment methodology and the results of its application to the territory of the municipality of Venice will be here presented and discussed.

General characteristics of causes of urban flood damage and flood forecasting/warning system in Seoul, Korea Young-Il Moon1, 2, Jong-Suk Kim1, 2 1 Department of Civil Engineering, University of Seoul, Seoul 130-743, South Korea 2 Urban Flood Research Inst

NASA Astrophysics Data System (ADS)

Moon, Young-Il; Kim, Jong-Suk

2015-04-01

Due to rapid urbanization and climate change, the frequency of concentrated heavy rainfall has increased, causing urban floods that result in casualties and property damage. As a consequence of natural disasters that occur annually, the cost of damage in Korea is estimated to be over two billion US dollars per year. As interest in natural disasters increase, demands for a safe national territory and efficient emergency plans are on the rise. In addition to this, as a part of the measures to cope with the increase of inland flood damage, it is necessary to build a systematic city flood prevention system that uses technology to quantify flood risk as well as flood forecast based on both rivers and inland water bodies. Despite the investment and efforts to prevent landside flood damage, research and studies of landside-river combined hydro-system is at its initial stage in Korea. Therefore, the purpose of this research introduces the causes of flood damage in Seoul and shows a flood forecasting and warning system in urban streams of Seoul. This urban flood forecasting and warning system conducts prediction on flash rain or short-term rainfall by using radar and satellite information and performs prompt and accurate prediction on the inland flooded area and also supports synthetic decision-making for prevention through real-time monitoring. Although we cannot prevent damage from typhoons or localized heavy rain, we can minimize that damage with accurate and timely forecast and a prevention system. To this end, we developed a flood forecasting and warning system, so in case of an emergency there is enough time for evacuation and disaster control. Keywords: urban flooding, flood risk, inland-river system, Korea Acknowledgments This research was supported by a grant (13AWMP-B066744-01) from Advanced Water Management Research Program (AWMP) funded by Ministry of Land, Infrastructure and Transport of Korean government.

Urban Flood Management with Integrated Inland-River System in Seoul

NASA Astrophysics Data System (ADS)

Moon, Y. I.; Kim, J. S.; Yuk, J. M.

2015-12-01

Global warming and climate change have caused significant damage and loss of life worldwide. The pattern of natural disasters has gradually diversified and their frequency is increasing. The impact of climate change on flood risk in urban rivers is of particular interest because these areas are typically densely populated. The occurrence of urban river flooding due to climate change not only causes significant loss of life and property but also causes health and social problems. It is therefore necessary to develop a scientific urban flood management system to cope with and reduce the impacts of climate change, including flood damage. In this study, we are going to introduce Integrated Inland-River Flood Analysis System in Seoul to conduct predictions on flash rain or short-term rainfall by using radar and satellite information and perform prompt and accurate prediction on the inland flooded areas. In addition, this urban flood management system can be used as a tool for decision making of systematic disaster prevention through real-time monitoring.

Increase in the exposition to floods in the Alicante coast (Valencia region, Spain)

NASA Astrophysics Data System (ADS)

Olcina, J.; Rico, A. M.; Hernandez, M.; Martínez, E.

2009-09-01

During the last two decades, Flood episodes along the Alicante coastline have caused important material losses and general disruptions of everyday life in the municipalities affected. We can speak of an increase in the vulnerability to floods chiefly as a result of an increase in exposition. In turn this increase is fundamentally linked to the nature of the recent urbanization process in this area and the corresponding occupation of flood prone land. The province of Alicante occupies one of the first positions in Europe regarding flood risk (ESPON 2006). Even counting with legislation that regulates land uses, processes leading to the occupation of flood risk areas have proven very difficult to manage. In this sense, the Valencia region has enacted legislation such as the Land Use Planning Law of 1989, the Law on Urban Growth Regulations of 1994, and the Planning Regulations of 1998. All these legal pieces attempted to prohibit development in flood prone land declaring this land as "non.urban". New laws such as the Law on Land Use Planning and Landscape protection of 2004, the Law on New Urban Land (2004), and the Decree on Landscape (2006) also consider the need to include the flood hazard in planning activities. Furthermore in 1997, the so-called "Cartography of the flood hazard at the regional level" was elaborated. This mapping exercise was the base for the "Territorial Plan for the Reduction of Flood Risks (PATRICOVA) approved in 2003 and currently the main planning tool for flood management in Valencia. On the other hand, the European Directive 60/2007 pointed towards the need to take into consideration the social perception of Flood risks in order to develop integrated actions of risk management. Accordingly we have undertaken 285 interviews in the coastal communities of Alicante, Calpe and Campello (95 interviews each). We have chosen these municipalities for two reasons: first their significance in population and economic activity terms, and second, their different approach in specific measures to reduce the impact of floods

floodX: urban flash flood experiments monitored with conventional and alternative sensors

NASA Astrophysics Data System (ADS)

Moy de Vitry, Matthew; Dicht, Simon; Leitão, João P.

2017-09-01

The data sets described in this paper provide a basis for developing and testing new methods for monitoring and modelling urban pluvial flash floods. Pluvial flash floods are a growing hazard to property and inhabitants' well-being in urban areas. However, the lack of appropriate data collection methods is often cited as an impediment for reliable flood modelling, thereby hindering the improvement of flood risk mapping and early warning systems. The potential of surveillance infrastructure and social media is starting to draw attention for this purpose. In the floodX project, 22 controlled urban flash floods were generated in a flood response training facility and monitored with state-of-the-art sensors as well as standard surveillance cameras. With these data, it is possible to explore the use of video data and computer vision for urban flood monitoring and modelling. The floodX project stands out as the largest documented flood experiment of its kind, providing both conventional measurements and video data in parallel and at high temporal resolution. The data set used in this paper is available at https://doi.org/10.5281/zenodo.830513.

Increase in flood risk resulting from climate change in a developed urban watershed - the role of storm temporal patterns

NASA Astrophysics Data System (ADS)

Hettiarachchi, Suresh; Wasko, Conrad; Sharma, Ashish

2018-03-01

The effects of climate change are causing more frequent extreme rainfall events and an increased risk of flooding in developed areas. Quantifying this increased risk is of critical importance for the protection of life and property as well as for infrastructure planning and design. The updated National Oceanic and Atmospheric Administration (NOAA) Atlas 14 intensity-duration-frequency (IDF) relationships and temporal patterns are widely used in hydrologic and hydraulic modeling for design and planning in the United States. Current literature shows that rising temperatures as a result of climate change will result in an intensification of rainfall. These impacts are not explicitly included in the NOAA temporal patterns, which can have consequences on the design and planning of adaptation and flood mitigation measures. In addition there is a lack of detailed hydraulic modeling when assessing climate change impacts on flooding. The study presented in this paper uses a comprehensive hydrologic and hydraulic model of a fully developed urban/suburban catchment to explore two primary questions related to climate change impacts on flood risk. (1) How do climate change effects on storm temporal patterns and rainfall volumes impact flooding in a developed complex watershed? (2) Is the storm temporal pattern as critical as the total volume of rainfall when evaluating urban flood risk? We use the NOAA Atlas 14 temporal patterns, along with the expected increase in temperature for the RCP8.5 scenario for 2081-2100, to project temporal patterns and rainfall volumes to reflect future climatic change. The model results show that different rainfall patterns cause variability in flood depths during a storm event. The changes in the projected temporal patterns alone increase the risk of flood magnitude up to 35 %, with the cumulative impacts of temperature rise on temporal patterns and the storm volume increasing flood risk from 10 to 170 %. The results also show that regional storage facilities are sensitive to rainfall patterns that are loaded in the latter part of the storm duration, while extremely intense short-duration storms will cause flooding at all locations. This study shows that changes in temporal patterns will have a significant impact on urban/suburban flooding and need to be carefully considered and adjusted to account for climate change when used for the design and planning of future storm water systems.

Assessing surface water flood risk and management strategies under future climate change: Insights from an Agent-Based Model.

PubMed

Jenkins, K; Surminski, S; Hall, J; Crick, F

2017-10-01

Climate change and increasing urbanization are projected to result in an increase in surface water flooding and consequential damages in the future. In this paper, we present insights from a novel Agent Based Model (ABM), applied to a London case study of surface water flood risk, designed to assess the interplay between different adaptation options; how risk reduction could be achieved by homeowners and government; and the role of flood insurance and the new flood insurance pool, Flood Re, in the context of climate change. The analysis highlights that while combined investment in property-level flood protection and sustainable urban drainage systems reduce surface water flood risk, the benefits can be outweighed by continued development in high risk areas and the effects of climate change. In our simulations, Flood Re is beneficial in its function to provide affordable insurance, even under climate change. However, the scheme does face increasing financial pressure due to rising surface water flood damages. If the intended transition to risk-based pricing is to take place then a determined and coordinated strategy will be needed to manage flood risk, which utilises insurance incentives, limits new development, and supports resilience measures. Our modelling approach and findings are highly relevant for the ongoing regulatory and political approval process for Flood Re as well as for wider discussions on the potential of insurance schemes to incentivise flood risk management and climate adaptation in the UK and internationally. Copyright © 2017 Elsevier B.V. All rights reserved.

Flood risk perception and adaptation capacity: a contribution to the socio-hydrology debate

NASA Astrophysics Data System (ADS)

Fuchs, Sven; Karagiorgos, Konstantinos; Kitikidou, Kyriaki; Maris, Fotios; Paparrizos, Spyridon; Thaler, Thomas

2017-04-01

Dealing with flood hazard and risk requires approaches rooted both in natural and social sciences, which provided the nexus for the ongoing debate on socio-hydrology. Various combinations of non-structural and structural flood risk reduction options are available to communities. Focusing on flood risk and the information associated with it, developing risk management plans is required but often overlooking public perception of a threat. The perception of risk varies in many different ways, especially between the authorities and the affected public. It is because of this disconnection that many risk management plans concerning floods have failed in the past. This paper examines the private adaptation capacity and willingness with respect to flooding in two different catchments in Greece prone to multiple flood events during the last 20 years. Two studies (East Attica and Evros) were carried out, comprised of a survey questionnaire of 155 and 157 individuals, from a peri-urban (East Attica) and a rural (Evros) area, respectively, and they focused on those vulnerable to periodical (rural area) and flash floods (peri-urban area). Based on the comparisons drawn from these responses, and identifying key issues to be addressed when flood risk management plans are implemented, improvements are being recommended for the social dimension surrounding such implementation. As such, the paper contributes to the ongoing discussion on human-environment interaction in socio-hydrology.

Flood risk perception and adaptation capacity: a contribution to the socio-hydrology debate

NASA Astrophysics Data System (ADS)

Fuchs, Sven; Karagiorgos, Konstantinos; Kitikidou, Kyriaki; Maris, Fotios; Paparrizos, Spyridon; Thaler, Thomas

2017-06-01

Dealing with flood hazard and risk requires approaches rooted in both natural and social sciences, which provided the nexus for the ongoing debate on socio-hydrology. Various combinations of non-structural and structural flood risk reduction options are available to communities. Focusing on flood risk and the information associated with it, developing risk management plans is required but often overlooks public perception of a threat. The perception of risk varies in many different ways, especially between the authorities and the affected public. It is because of this disconnection that many risk management plans concerning floods have failed in the past. This paper examines the private adaptation capacity and willingness with respect to flooding in two different catchments in Greece prone to multiple flood events during the last 20 years. Two studies (East Attica and Evros) were carried out, comprised of a survey questionnaire of 155 and 157 individuals, from a peri-urban (East Attica) and a rural (Evros) area, respectively, and they focused on those vulnerable to periodic (rural area) and flash floods (peri-urban area). Based on the comparisons drawn from these responses, and identifying key issues to be addressed when flood risk management plans are implemented, improvements are being recommended for the social dimension surrounding such implementation. As such, the paper contributes to the ongoing discussion on human-environment interaction in socio-hydrology.

Assessment of the landslide and flood risks in São Paulo City, Brazil

NASA Astrophysics Data System (ADS)

Vieira, Bianca; Listo, Fabrízio

2010-05-01

In Brazilian cities, especially during summer, the landslides and floods cause disaster and economic losses. Aricanduva basin is one of the most critical in the Metropolitan Region of São Paulo (RMSP), where many types of morphodynamic processes occur. This is the largest river basin in São Paulo City. The current situation is characterized by intense urbanization, soil sealing and consequent reduction of soil infiltration, increasing the frequency of flood events in this area. Thus, the main objective of this paper is to map risk areas of landslides and floods in the sub-basin Limoeiro, located in the head of the Aricanduva basin. For mapping the risk areas, we prepared a record field to floods and landslides, based on several studies. Initially, it were identified the natural indicators (vegetation, topography, surface cover and drainage) and anthropogenic (urban pattern, soil cover, building types, occupation density, road conditions, infrastructure, drainage systems, distance between houses and slope, at the top and base, and the drainage channel). On the second step of this research, we identified the evidences of mass movements (scars, cracks, subsidence, trees, poles and inclined walls). Thus, on the basis of this analysis it was possible to define the risk probability: R1 (low or no risk), R2 (moderate), R3 (high) and, R4 (very high). Subsequently, by means of oblique photographs (taken from helicopter flight) it was possible to define risk areas in the basin. In all the sectors identified, were recorded approximately 903 urban settlements. The results showed that from the 25 sectors of risk, 14 sectors (56%) presented landslide risk and 11 (44%), flood risk. Of the sectors that showed landslide risk areas, 21% have very high probability (R4), 21% high (R3), 29% moderate (R2) and 29% low (R1). The sectors at flood risk presented 45% of very high probability (R4), 10% high (R3), 18% moderate (R2) and 27% low (R1). There is large presence of sediments from landslides, debris and remnants of buildings. The drainage systems are precarious and there is runoff on the surface and sewage pipes on soil surface. Some houses were built without keeping safe distance from the top and bottom of the slope, increasing landslide risk. Others were built very close to the stream. There are cracks in the houses and walls and trees inclined by mass movements and riverbank erosion. In general, the urban occupation, after deforesting, characterized by land fragmentation and by settlements without urban infrastructure, occurred in the terrain less favorable to the occupation, where a natural susceptibility to landslides and flood processes exists. Thus, we believe that this mapping can help the identification of the active processes (landslides and floods) and the assessment of risk areas. Therefore, these maps can be used by public administration on identifying areas more appropriate to urban occupation.

A 2D simulation model for urban flood management

NASA Astrophysics Data System (ADS)

Price, Roland; van der Wielen, Jonathan; Velickov, Slavco; Galvao, Diogo

2014-05-01

The European Floods Directive, which came into force on 26 November 2007, requires member states to assess all their water courses and coast lines for risk of flooding, to map flood extents and assets and humans at risk, and to take adequate and coordinated measures to reduce the flood risk in consultation with the public. Flood Risk Management Plans are to be in place by 2015. There are a number of reasons for the promotion of this Directive, not least because there has been much urban and other infrastructural development in flood plains, which puts many at risk of flooding along with vital societal assets. In addition there is growing awareness that the changing climate appears to be inducing more frequent extremes of rainfall with a consequent increases in the frequency of flooding. Thirdly, the growing urban populations in Europe, and especially in the developing countries, means that more people are being put at risk from a greater frequency of urban flooding in particular. There are urgent needs therefore to assess flood risk accurately and consistently, to reduce this risk where it is important to do so or where the benefit is greater than the damage cost, to improve flood forecasting and warning, to provide where necessary (and possible) flood insurance cover, and to involve all stakeholders in decision making affecting flood protection and flood risk management plans. Key data for assessing risk are water levels achieved or forecasted during a flood. Such levels should of course be monitored, but they also need to be predicted, whether for design or simulation. A 2D simulation model (PriceXD) solving the shallow water wave equations is presented specifically for determining flood risk, assessing flood defense schemes and generating flood forecasts and warnings. The simulation model is required to have a number of important properties: -Solve the full shallow water wave equations using a range of possible solutions; -Automatically adjust the time step and keep it as large as possible while maintaining the stability of the flow calculations; -Operate on a square grid at any resolution while retaining at least some details of the ground topography of the basic grid, the storage, and the form roughness and conveyance of the ground surface; -Account for the overall average ground slope for particular coarse cells; -Have the facility to refine the grid locally; -Have the facility to treat ponds or lakes as single, irregular cells; -Permit prescribed inflows and arbitrary outflows across the boundaries of the model domain or internally, and sources and sinks at any interior cell; -Simulate runoff for spatial rainfall while permitting infiltration; -Use ground surface cover and soil type indices to determine surface roughness, interception and infiltration parameters; -Present results at the basic cell level; -Have the facility to begin a model run with monitored soil moisture data; -Have the facility to hot-start a simulation using dumped data from a previous simulation; -Operate with a graphics cards for parallel processing; -Have the facility to link directly to the urban drainage simulation software such as SWMM through an Open Modelling Interface; -Be linked to the Netherlands national rainfall database for continuous simulation of rainfall-runoff for particular polders and urban areas; -Make the engine available as Open Source together with benchmark datasets; PriceXD forms a key modelling component of an integrated urban water management system consisting of an on-line database and a number of complementary modelling systems for urban hydrology, groundwater, potable water distribution, wastewater and stormwater drainage (separate and combined sewerage), wastewater treatment, and surface channel networks. This will be a 'plug and play' system. By linking the models together, confidence in the accuracy of the above-ground damage and construction costs is comparable to the below-ground costs. What is more, PriceXD can be used to examine additional physical phenomenon such as the interaction between flood flows and flows to and from inlets distributed along the pipes of the underground network, and to optimize the removal of blockages and improve asset management. Finally, PriceXD is already an integral component on a number of operational projects and platforms, including the MyWater distributed platform and the HydroNET web portal, where it is already applied to realistic case studies on the Netherlands (namely the Rijnland area), facilitating the access to both the model execution and results, by abstracting most of the complexity out of the model setup and configuration.

Urban flood risk mitigation: from vulnerability assessment to resilient city

NASA Astrophysics Data System (ADS)

Serre, D.; Barroca, B.

2009-04-01

Urban flood risk mitigation: from vulnerability assessment to resilient city Bruno Barroca1, Damien Serre2 1Laboratory of Urban Engineering, Environment and Building (L G U E H) - Université de Marne-la-Vallée - Pôle Ville, 5, Bd Descartes - Bâtiment Lavoisier - 77454 Marne la Vallée Cedex 2 - France 2City of Paris Engineering School, Construction - Environment Department, 15 rue Fénelon, 75010 Paris, France In France, as in Europe and more generally throughout the world, river floods have been increasing in frequency and severity over the last ten years, and there are more instances of rivers bursting their banks, aggravating the impact of the flooding of areas supposedly protected by flood defenses. Despite efforts made to well maintain the flood defense assets, we often observe flood defense failures leading to finally increase flood risk in protected area during major flood events. Furthermore, flood forecasting models, although they benefit continuous improvements, remain partly inaccurate due to uncertainties populated all along data calculation processes. These circumstances obliged stakeholders and the scientific communities to manage flood risk by integrating new concepts like stakes management, vulnerability assessments and more recently urban resilience development. Definitively, the goal is to reduce flood risk by managing of course flood defenses and improving flood forecasting models, but also stakes and vulnerability of flooded areas to achieve urban resilience face to flood events. Vulnerability to flood is essentially concentrated in urban areas. Assessing vulnerability of a city is very difficult. Indeed, urban area is a complex system composed by a sum of technical sub-systems as complex as the urban area itself. Assessing city vulnerability consists in talking into account each sub system vulnerability and integrating all direct and indirect impacts generally depending from city shape and city spatial organization. At this time, although some research activities have been undertaken, there are no specific methods and tools to assess flood vulnerability at the scale of the city. Indeed, by studying literature we can list some vulnerability indicators and a few Geographic Information System (GIS) tools. But generally indicators and GIS are not developed specifically at the city scale: often a regional scale is used. Analyzing vulnerability at this scale needs more accurate and formalized indicators and GIS tools. The second limit of existing GIS is temporal: even if vulnerability could be assessed and localized through GIS, such tools cannot assist city managers in their decision to efficiency recover after a severe flood event. Due to scale and temporal limits, methods and tools available to assess urban vulnerability need large improvements. Talking into account all these considerations and limits, our research is focusing on: • vulnerability indicators design; • recovery scenarios design; • GIS for city vulnerability assessment and recovery scenarios. Dealing with vulnerability indicators, the goal is to design a set of indicators of city sub systems. Sub systems are seen like assets of high value and complex and interdependent infrastructure networks (i.e. power supplies, communications, water, transport etc.). The infrastructure networks are critical for the continuity of economic activities as well as for the people's basic living needs. Their availability is also required for fast and effective recovery after flood disasters. The severity of flood damage therefore largely depends on the degree that both high value assets and critical urban infrastructure are affected, either directly or indirectly. To face the challenge of designing indicators, a functional model of the city system (and sub systems) has to be built to analyze the system response to flood solicitation. Then, a coherent and an efficient set of vulnerability of indicators could be built up. With such methods city stakeholders will be informed on how and how much their systems are vulnerable. It is a first level of information that has to be completed to become a real decision making tool. Indeed, we have seen that major floods cause almost always failures in the flood defense system. So potentially the city could face a flood event and managers recovery works. Knowing the vulnerability of the city, direct and indirect impacts, how can managers optimize recovery actions? Our research will focus first on proposing recovery scenarios based on the city system and second on vulnerability indicators to first limit damages during floods and to speed up recovery actions. At last, a GIS will be developed to assist stakeholders to take spatial measures to reduce city system weakness before a flood event and to help them to decide on how to optimize recovery actions after a flood event. Dealing with these two temporal scales will allow obtaining more flood resilient cities.

Understanding high magnitude flood risk: evidence from the past

NASA Astrophysics Data System (ADS)

MacDonald, N.

2009-04-01

The average length of gauged river flow records in the UK is ~25 years, which presents a problem in determining flood risk for high-magnitude flood events. Severe floods have been recorded in many UK catchments during the past 10 years, increasing the uncertainty in conventional flood risk estimates based on river flow records. Current uncertainty in flood risk has implications for society (insurance costs), individuals (personal vulnerability) and water resource managers (flood/drought risk). An alternative approach is required which can improve current understanding of the flood frequency/magnitude relationship. Historical documentary accounts are now recognised as a valuable resource when considering the flood frequency/magnitude relationship, but little consideration has been given to the temporal and spatial distribution of these records. Building on previous research based on British rivers (urban centre): Ouse (York), Trent (Nottingham), Tay (Perth), Severn (Shrewsbury), Dee (Chester), Great Ouse (Cambridge), Sussex Ouse (Lewes), Thames (Oxford), Tweed (Kelso) and Tyne (Hexham), this work considers the spatial and temporal distribution of historical flooding. The selected sites provide a network covering many of the largest river catchments in Britain, based on urban centres with long detailed documentary flood histories. The chronologies offer an opportunity to assess long-term patterns of flooding, indirectly determining periods of climatic variability and potentially increased geomorphic activity. This research represents the first coherent large scale analysis undertaken of historical multi-catchment flood chronologies, providing an unparalleled network of sites, permitting analysis of the spatial and temporal distribution of historical flood patterns on a national scale.

Urbanisation and flood vulnerability in the peri-urban interface of Mexico City.

PubMed

Aragón-Durand, Fernando

2007-12-01

Chronic flooding in the Chalco valley, state of Mexico, Mexico, is the outcome of past and present socio-environmental changes which have taken place in Mexico City's south-eastern peri-urban interface. This flooding is the result of a complex interaction between urbanisation in an ex-lacustrine area, permanent ecological deterioration and ground subsidence, poor sanitation and inadequate policy responses. Far from solving the flooding problem, short-term policy responses have created increasingly unsafe conditions for current residents. A socio-historical analysis of disasters reveals the importance of taking into consideration particular social actors and institutions in hazard generation and flood vulnerability over time. This paper analyses three aspects of this flooding: first, the importance of approaching floods from a socio-historical perspective; second, the relation between urbanisation, former policies and flood risk generation; and third, current policy responses to and the failure in the risk management of La Compañía Canal.

Hyper-resolution monitoring of urban flooding with social media and crowdsourcing data

NASA Astrophysics Data System (ADS)

Wang, Ruo-Qian; Mao, Huina; Wang, Yuan; Rae, Chris; Shaw, Wesley

2018-02-01

Hyper-resolution datasets for urban flooding are rare. This problem prevents detailed flooding risk analysis, urban flooding control, and the validation of hyper-resolution numerical models. We employed social media and crowdsourcing data to address this issue. Natural Language Processing and Computer Vision techniques are applied to the data collected from Twitter and MyCoast (a crowdsourcing app). We found these big data based flood monitoring approaches can complement the existing means of flood data collection. The extracted information is validated against precipitation data and road closure reports to examine the data quality. The two data collection approaches are compared and the two data mining methods are discussed. A series of suggestions is given to improve the data collection strategy.

How do we best estimate fluvial flood risk in urban environments? : The case of the city of Eilenburg, Germany

NASA Astrophysics Data System (ADS)

Longo, Elisa; Tito Aronica, Giuseppe; Di Baldassarre, Giuliano; Mukolwe, Micah

2015-04-01

Flooding is one of the most impactful natural hazards. In particular, by looking at the data of damages from natural hazards in Europe collected in the International Disaster Database (EM-DAT) one can see a significant increase over the past four decades of both frequency of floods and associated economic damages. Similarly, dramatic trends are also found by analyzing other types of flood losses, such as the number of people affected by floods, homeless, injured or killed. To deal with the aforementioned increase of flood risk, more and more efforts are being made to promote integrated flood risk management, for instance, at the end of 2007, the European Community (EC) issued the Flood Directive (F.D.) 2007/60/EC. One of the major innovations was that the F.D. 2007/60/C requires Member State to carry out risk maps and then take appropriate measures to reduce the evaluated risk. The main goal of this research was to estimate flood damaging using a computer code based on a recently developed method (KULTURisk, www.kulturisk.eu) and to compare the estimated damage with the observed one. The study area was the municipality of Eilenburg, which in 2002 was subjected to a destructive flood event. Were produced flood damage maps with new procedures (e.g. KULTURisk) and compared the estimates with observed data. This study showed the possibility to extend the lesson learned with the Eilenburg case study in other similar contexts. The outcomes of this test provided interesting insights about the flood risk mapping, which are expected to contribute to raise awareness to the flooding issues,to plan (structural and/or non-structural) measures of flood risk reduction and to support better land-use and urban planning.

Flood risk governance arrangements in Europe

NASA Astrophysics Data System (ADS)

Matczak, P.; Lewandowski, J.; Choryński, A.; Szwed, M.; Kundzewicz, Z. W.

2015-06-01

The STAR-FLOOD (Strengthening and Redesigning European Flood Risk Practices Towards Appropriate and Resilient Flood Risk Governance Arrangements) project, funded by the European Commission, investigates strategies for dealing with flood risk in six European countries: Belgium, the UK, France, the Netherlands, Poland and Sweden and in 18 vulnerable urban regions in these countries. The project aims to describe, analyse, explain, and evaluate the main similarities and differences between the selected EU Member States in terms of development and performance of flood risk governance arrangements. It also discusses the scientific and societal importance of these similarities and differences. Attention is paid to identification and characterization of shifts in flood risk governance arrangements and in flood risk management strategies and to determination of triggering factors and restraining factors. An assessment of a change of resilience and appropriateness (legitimacy, effectiveness, efficiency) of flood risk governance arrangements in Poland is presented and comparison with other European countries is offered.

Aqueduct Global Flood Analyzer - bringing risk information to practice

NASA Astrophysics Data System (ADS)

Ward, Philip

2017-04-01

The economic losses associated with flooding are huge and rising. As a result, there is increasing attention for strategic flood risk assessments at the global scale. In response, the last few years have seen a large growth in the number of global flood models. At the same time, users and practitioners require flood risk information in a format that is easy to use, understandable, transparent, and actionable. In response, we have developed the Aqueduct Global Flood Analyzer (wri.org/floods). The Analyzer is a free, online, easy to use, tool for assessing global river flood risk at the scale of countries, states, and river basins, using data generated by the state of the art GLOFRIS global flood risk model. The Analyzer allows users to assess flood risk on-the-fly in terms of expected annual urban damage, and expected annual population and GDP affected by floods. Analyses can be carried out for current conditions and under future scenarios of climate change and socioeconomic development. We will demonstrate the tool, and discuss several of its applications in practice. In the past 15 months, the tool has been visited and used by more than 12,000 unique users from almost every country, including many users from the World Bank, Pacific Disaster Center, Red Cross Climate Centre, as well as many journalists from major international news outlets. Use cases will be presented from these user communities. We will also present ongoing research to improve the user functionality of the tool in the coming year. This includes the inclusion of coastal flood risk, assessing the costs and benefits of adaptation, and assessing the impacts of land subsidence and urban extension on risk.

Aqueduct Global Flood Analyzer - bringing risk information to practice

NASA Astrophysics Data System (ADS)

Ward, P.; Bierkens, M. F.; Bouwman, A.; Diaz Loaiza, A.; Eilander, D.; Englhardt, J.; Erkens, G.; Hofste, R.; Iceland, C.; Willem, L.; Luo, T.; Muis, S.; Scussolini, P.; Sutanudjaja, E.; Van Beek, L. P.; Van Bemmel, B.; Van Huijstee, J.; Van Wesenbeeck, B.; Vatvani, D.; Verlaan, M.; Winsemius, H.

2016-12-01

The economic losses associated with flooding are huge and rising. As a result, there is increasing attention for strategic flood risk assessments at the global scale. In response, the last few years have seen a large growth in the number of global flood models. At the same time, users and practitioners require flood risk information in a format that is easy to use, understandable, transparent, and actionable. In response, we have developed the Aqueduct Global Flood Analyzer (wri.org/floods). The Analyzer is a free, online, easy to use, tool for assessing global river flood risk at the scale of countries, states, and river basins, using data generated by the state of the art GLOFRIS global flood risk model. The Analyzer allows users to assess flood risk on-the-fly in terms of expected annual urban damage, and expected annual population and GDP affected by floods. Analyses can be carried out for current conditions and under future scenarios of climate change and socioeconomic development. We will demonstrate the tool, and discuss several of its applications in practice. In the past 15 months, the tool has been visited and used by more than 12,000 unique users from almost every country, including many users from the World Bank, Pacific Disaster Center, Red Cross Climate Centre, as well as many journalists from major international news outlets. Use cases will be presented from these user communities. We will also present ongoing research to improve the user functionality of the tool in the coming year. This includes the inclusion of coastal flood risk, assessing the costs and benefits of adaptation, and assessing the impacts of land subsidence and urban extension on risk.

Anthropogenic impact on flood-risk: a large-scale assessment for planning controlled inundation strategies along the River Po

NASA Astrophysics Data System (ADS)

Domeneghetti, Alessio; Castellarin, Attilio; Brath, Armando

2013-04-01

The European Flood Directive (2007/60/EC) has fostered the development of innovative and sustainable approaches and methodologies for flood-risk mitigation and management. Furthermore, concerning flood-risk mitigation, the increasing awareness of how the anthropogenic pressures (e.g. demographic and land-use dynamics, uncontrolled urban and industrial expansion on flood-prone area) could strongly increase potential flood damages and losses has triggered a paradigm shift from "defending the territory against flooding" (e.g. by means of levee system strengthening and heightening) to "living with floods" (e.g. promoting compatible land-uses or adopting controlled flooding strategies of areas located outside the main embankments). The assessment of how socio-economic dynamics may influence flood-risk represents a fundamental skill that should be considered for planning a sustainable industrial and urban development of flood-prone areas, reducing their vulnerability and therefore minimizing socio-economic and ecological losses due to large flood events. These aspects, which are of fundamental importance for Institutions and public bodies in charge of Flood Directive requirements, need to be considered through a holistic approach at river basin scale. This study focuses on the evaluation of large-scale flood-risk mitigation strategies for the middle-lower reach of River Po (~350km), the longest Italian river and the largest in terms of streamflow. Due to the social and economical importance of the Po River floodplain (almost 40% of the total national gross product results from this area), our study aims at investigating the potential of combining simplified vulnerability indices with a quasi-2D model for the definition of sustainable and robust flood-risk mitigation strategies. Referring to past (1954) and recent (2006) land-use data sets (e.g. CORINE) we propose simplified vulnerability indices for assessing potential flood-risk of industrial and urbanized flood prone areas taking into account altimetry and population density, and we analyze the modification of flood-risk occurred during last decades due to the demographic dynamics of the River Po floodplains. Flood hazard associated to a high magnitude event (i.e. return period of about 500 year) was estimated by means of a quasi-2D hydraulic model set up for the middle-lower portion of the Po River and for its major tributaries. The results of the study highlight how coupling a large-scale numerical model with the proposed flood-vulnerability indices could be a useful tool for decision-makers when they are called to define sustainable spatial development plans for the study area, or when they need to identify priorities in the organization of civil protection actions during a major flood event that could include the necessity of controlled flooding of flood-prone areas located outside the main embankment system.

Urbanization and climate change implications in flood risk management: Developing an efficient decision support system for flood susceptibility mapping.

PubMed

Mahmoud, Shereif H; Gan, Thian Yew

2018-04-26

The effects of urbanization and climate change impact to the flood risk of two governorates in Egypt were analyzed. Non-parametric change point and trend detection algorithms were applied to the annual rainfall, rainfall anomaly, and temperature anomaly of both study sites. Next, change points and trends of the annual and monthly surface runoff data generated by the Curve Number method over 1948-2014 were also analyzed to detect the effects of urbanization on the surface runoff. Lastly, a GIS decision support system was developed to delineate flood susceptibility zones for the two governorates. The significant decline in annual rainfall and rainfall anomaly after 1994 at 8.96 and 15.3 mm/decade respectively was likely due to climate change impact, especially significant warming trend since 1976 at 0.16 °C/decade, though that could partly be attributed to rapid urbanization. Since 1970, effects of urbanization to flood risk are clear, because despite a decline in rainfall, the annual surface runoff and runoff anomaly show positive trends of 12.7 and of 14.39 mm/decade, respectively. Eleven flood contributing factors have been identified and used in mapping flood susceptibility zones of both sites. In the El-Beheira governorate, 9.2%, 17.9%, 32.3%, 28.3% and 12.3% of its area are categorized as very high, high, moderate, low and very low susceptibility to flooding, respectively. Similarly, in Alexandria governorate, 15.9%, 33.5%, 41%, 8.8% and 0.8% of its area are categorized as very high, high, moderate, low and very low susceptibility to flooding, respectively. Very high and high susceptible zones are located in the northern, northwestern and northeastern parts of the Beheira governorates, and in the northeastern and northwestern parts of Alexandria. The flood related information obtained in this study will be useful to assist mitigating potential flood damages and future land use planning of both governorates of Egypt. Copyright © 2018 Elsevier B.V. All rights reserved.

One-dimensional modelling of the interactions between heavy rainfall-runoff in an urban area and flooding flows from sewer networks and rivers.

PubMed

Kouyi, G Lipeme; Fraisse, D; Rivière, N; Guinot, V; Chocat, B

2009-01-01

Many investigations have been carried out in order to develop models which allow the linking of complex physical processes involved in urban flooding. The modelling of the interactions between overland flows on streets and flooding flows from rivers and sewer networks is one of the main objectives of recent and current research programs in hydraulics and urban hydrology. This paper outlines the original one-dimensional linking of heavy rainfall-runoff in urban areas and flooding flows from rivers and sewer networks under the RIVES project framework (Estimation of Scenario and Risks of Urban Floods). The first part of the paper highlights the capacity of Canoe software to simulate the street flows. In the second part, we show the original method of connection which enables the modelling of interactions between processes in urban flooding. Comparisons between simulated results and the results of Despotovic et al. or Gomez & Mur show a good agreement for the calibrated one-dimensional connection model. The connection operates likes a manhole with the orifice/weir coefficients used as calibration parameters. The influence of flooding flows from river was taken into account as a variable water depth boundary condition.

Statistical analysis of the uncertainty related to flood hazard appraisal

NASA Astrophysics Data System (ADS)

Notaro, Vincenza; Freni, Gabriele

2015-12-01

The estimation of flood hazard frequency statistics for an urban catchment is of great interest in practice. It provides the evaluation of potential flood risk and related damage and supports decision making for flood risk management. Flood risk is usually defined as function of the probability, that a system deficiency can cause flooding (hazard), and the expected damage, due to the flooding magnitude (damage), taking into account both the exposure and the vulnerability of the goods at risk. The expected flood damage can be evaluated by an a priori estimation of potential damage caused by flooding or by interpolating real damage data. With regard to flood hazard appraisal several procedures propose to identify some hazard indicator (HI) such as flood depth or the combination of flood depth and velocity and to assess the flood hazard corresponding to the analyzed area comparing the HI variables with user-defined threshold values or curves (penalty curves or matrixes). However, flooding data are usually unavailable or piecemeal allowing for carrying out a reliable flood hazard analysis, therefore hazard analysis is often performed by means of mathematical simulations aimed at evaluating water levels and flow velocities over catchment surface. As results a great part of the uncertainties intrinsic to flood risk appraisal can be related to the hazard evaluation due to the uncertainty inherent to modeling results and to the subjectivity of the user defined hazard thresholds applied to link flood depth to a hazard level. In the present work, a statistical methodology was proposed for evaluating and reducing the uncertainties connected with hazard level estimation. The methodology has been applied to a real urban watershed as case study.

Upstream Structural Management Measures for an Urban Area Flooding in Turkey and their Consequences on Flood Risk Management

NASA Astrophysics Data System (ADS)

Akyurek, Z.; Bozoglu, B.; Girayhan, T.

2015-12-01

Flooding has the potential to cause significant impacts to economic activities as well as to disrupt or displace populations. Changing climate regimes such as extreme precipitation events increase flood vulnerability and put additional stresses on infrastructure. In this study the flood modelling in an urbanized area, namely Samsun-Terme in Blacksea region of Turkey is done. MIKE21 with flexible grid is used in 2- dimensional shallow water flow modelling. 1/1000 scaled maps with the buildings for the urbanized area and 1/5000 scaled maps for the rural parts are used to obtain DTM needed in the flood modelling. The bathymetry of the river is obtained from additional surveys. The main river passing through the urbanized area has a capacity of Q5 according to the design discharge obtained by simple ungauged discharge estimation depending on catchment area only. The effects of the available structures like bridges across the river on the flooding are presented. The upstream structural measures are studied on scenario basis. Four sub-catchments of Terme River are considered as contributing the downstream flooding. The existing circumstance of the Terme River states that the meanders of the river have a major effect on the flood situation and lead to approximately 35% reduction in the peak discharge between upstream and downstream of the river. It is observed that if the flow from the upstream catchments can be retarded through a detention pond constructed in at least two of the upstream catchments, estimated Q100 flood can be conveyed by the river without overtopping from the river channel. The operation of the upstream detention ponds and the scenarios to convey Q500 without causing flooding are also presented. Structural management measures to address changes in flood characteristics in water management planning are discussed. Flood risk is obtained by using the flood hazard maps and water depth-damage functions plotted for a variety of building types and occupancies. The estimated mean annual hazard for the area is calculated as $340 000 and it is estimated that the upstream structural management measures can decrease the direct economic risk 11% for the 500 return period flood.

Rapid Urbanization and Implications for Flood Risk Management in Hinterland of the Pearl River Delta, China: The Foshan Study.

PubMed

Zhang, Hao; Ma, Wei-Chun; Wang, Xiang-Rong

2008-03-28

The purpose of this paper is to examine the linkage between rapid urbanization and flood risk in the hinterlands of the Pearl River Delta, P.R. China. Foshan, a typical hinterland city in the Pearl River Delta region, was selected as a case study. Land use and cover change in Foshan during 1988-2003 was analyzed using remote sensing and geographic information system (GIS) techniques. Furthermore, analysis on historical hydrological data during 1962-2005 was performed. Results show that rapid urbanization has resulted in losses of farmland, forest and shrub since 1988. In addition, in order to compensate or offset the loss of farmland due to rapid urban expansion, more than 30 % of the forest and 20 % of the shrub areas were transformed into farmlands. Inevitably, both the urban and agricultural lands increased the pressure on the drainage systems. Furthermore, over the past decades human activities such as dredging up the floodways, excavating sand and building water facilities in the rivers, significantly changed the hydrological conditions, and therefore impaired the rivers' capacity to buffer floods. Lessons from the Foshan case implied that, in addition to natural processes, human activities driven by socio-economic factors should be considered responsible for the recently increasing level of flood risks. Both economically and environmentally, it is irrational and impractical to encourage encroachment of lands vulnerable to floods. It is also realistic and urgent to effectively prevent and control the adverse ecological consequences of urbanization and economic activities for building their wealth and prominence.

Rapid Urbanization and Implications for Flood Risk Management in Hinterland of the Pearl River Delta, China: The Foshan Study

PubMed Central

Zhang, Hao; Ma, Wei-chun; Wang, Xiang-rong

2008-01-01

The purpose of this paper is to examine the linkage between rapid urbanization and flood risk in the hinterlands of the Pearl River Delta, P.R. China. Foshan, a typical hinterland city in the Pearl River Delta region, was selected as a case study. Land use and cover change in Foshan during 1988-2003 was analyzed using remote sensing and geographic information system (GIS) techniques. Furthermore, analysis on historical hydrological data during 1962-2005 was performed. Results show that rapid urbanization has resulted in losses of farmland, forest and shrub since 1988. In addition, in order to compensate or offset the loss of farmland due to rapid urban expansion, more than 30 % of the forest and 20 % of the shrub areas were transformed into farmlands. Inevitably, both the urban and agricultural lands increased the pressure on the drainage systems. Furthermore, over the past decades human activities such as dredging up the floodways, excavating sand and building water facilities in the rivers, significantly changed the hydrological conditions, and therefore impaired the rivers' capacity to buffer floods. Lessons from the Foshan case implied that, in addition to natural processes, human activities driven by socio-economic factors should be considered responsible for the recently increasing level of flood risks. Both economically and environmentally, it is irrational and impractical to encourage encroachment of lands vulnerable to floods. It is also realistic and urgent to effectively prevent and control the adverse ecological consequences of urbanization and economic activities for building their wealth and prominence. PMID:27879819

The KULTURisk Regional Risk Assessment methodology for flood risk: the case of Sihl river in Zurich

NASA Astrophysics Data System (ADS)

Ronco, Paolo; Bullo, Martina; Gallina, Valentina; Torresan, Silvia; Critto, Andrea; Zabeo, Alex; Semenzin, Elena; Buchecker, Matthias; Marcomini, Antonio

2014-05-01

In recent years, the frequency of catastrophes induced by natural hazard has increased and flood events in particular have been recognized as one of the most threatening water-related disasters. Severe floods have occurred in Europe over the last decade causing loss of life, displacement of people and heavy economic losses. Flood disasters are growing as a consequence of many factors both climatic and non-climatic. Indeed, the current increase of water-related disasters can be mainly attributed to the increase of exposure (elements potentially at risk in floodplains area) and vulnerability (i.e. economic, social, geographic, cultural, and physical/environmental characteristics of the exposure). Besides these factors, the strong effect of climate change is projected to radically modify the usual pattern of the hydrological cycle by intensifying the frequency and severity of flood events both at local, regional and global scale. Within this context, it is necessary to develop effective and pro-active strategies, tools and actions which allow to assess and (possibly) to reduce the risk of floods. In light of the recent European Flood Directive (FD), the KULTURisk-FP7 Project developed a state-of-the-art Regional Risk Assessment (RRA) methodology for assessing the risk imposed by floods events. The KULTURisk RRA methodology is based on the concept of risk being function of hazard, exposure and vulnerability. It is a flexible that can be adapted to different case studies (i.e. large rivers, alpine/mountain catchments, urban areas and coastal areas) and spatial scales (i.e. from the large river to the urban scale) that integrates the outputs of various hydrodynamics models (hazard) with sito-specific geophysical and socio-economic indicators (exposure and vulnerability factors such as land cover, slope, soil permeability, population density, economic activities, etc.). The main outputs of the methodology are GIS-based risk maps that identify and prioritize relative hot-spot areas and targets at risk (i.e. people, buildings, infrastructures, agriculture, natural and semi-natural systems, cultural heritages) in the considered region by comparing the baseline scenario with alternative scenarios, where different structural and/or non-structural mitigation measures are planned. Risk maps, along with related statistics, provide crucial information about flood risk pattern, and allow the development of relevant and strategic mitigation and prevention measures to minimizing flood risk in urban areas. The present study applied and validated the KULTURisk RRA methodology to the Sihl river case study in Zurich (Switzerland). Through a tuning process of the methodology to the site-specific context and features, flood related risks have been assessed for different receptors lying on the Sihl river valley, which represents a typical case of river flooding in urban area. The total risk maps obtained under a 300 years return period scenario (selected as the reference one) have highlighted that the area is associated with the lower class of risk. Moreover, the relative risk is higher in Zurich city centre, in the few residential areas around the city centre and within the districts that rely just beside to the Sihl river course.

Near Real Time Flood Warning System for National Capital Territory of Delhi

NASA Astrophysics Data System (ADS)

Goyal, A.; Yadav, H.; Tyagi, H.; Gosain, A. K.

2017-12-01

Extreme floods are common phenomena during Indian Monsoons. The National Capital Territory area of India, Delhi, frequently experiences fluvial as well as pluvial inundation due to its proximity to river Yamuna and poor functioning of its stormwater drainage system. The urban floods result in severe waterlogging and heavy traffic snarls, bringing life in this megapolis to a halt. The city has witnessed six major floods since 1900 and thus its residents are well conscious of potential flood risks but the city still lacks a flood warning system. The flood related risks can be considerably reduced, if not eliminated, by issuing timely warnings and implementing adaptive measures. Therefore, the present study attempts to develop a web based platform that integrates Web-GIS technology and mathematical simulation modelling to provide an effective and reliable early flood warning service for Delhi. The study makes use of India Metorological Department's Doppler radar-derived near real time rainfall estimates of 15 minutes time step. The developed SWMM model has been validated using information from gauges, monitoring sensors and crowd sourcing techniques and utilises capabilities of cloud computing on server side for fast processing. This study also recommends safe evacuation policy and remedial measures for flooding hotspots as part of flood risk management plan. With heightened risk of floods in fast urbanizing areas, this work becomes highly pertinent as flood warning system with adequate lead time can not only save precious lives but can also substantially reduce flood damages.

Towards River Rehabilitation as AN Integrated Approach to Flood Management in Asian Cities

NASA Astrophysics Data System (ADS)

Higgitt, David L.

Flood management in Asian cities has conventionally been approached through structural intervention where floods are regarded as a threat requiring control through engineering infrastructure. Such a command and control paradigm represents a marked transition from the way that monsoon flood regimes have been traditionally perceived across Asia. Rapid urbanization and climate change has imposed increasingly difficult flood management challenges as an extension of impermeable surfaces generates rapid runoff and flash flooding, while cities expand into flood-prone areas. Property and communities are placed at enhanced risk. Urbanization reallocates risk as channel and floodplain modification influences flood regimes, while demands for flood protection at certain locations can redistribute risk to other areas. An increasing concern about flood hazard across Asian cities questions whether conventional solutions reliant on structural intervention are sustainable. Such questioning is mirrored by an alternative paradigm of rehabilitation in integrated river basin management — a recognition that restoring and sustaining functional river ecosystems with high biodiversity is one of the greatest challenges facing society. Rehabilitation initiatives demand a new approach to river basin management which encourage interdisciplinary activity, particularly between engineers, hydrologists, geomorphologists and ecologists. The paper sets out some preliminary ideas from a research project investigating the potential for river rehabilitation as a central tenet of flood management, with a particular focus on Asian cities.

Development of high-resolution multi-scale modelling system for simulation of coastal-fluvial urban flooding

NASA Astrophysics Data System (ADS)

Comer, Joanne; Indiana Olbert, Agnieszka; Nash, Stephen; Hartnett, Michael

2017-02-01

Urban developments in coastal zones are often exposed to natural hazards such as flooding. In this research, a state-of-the-art, multi-scale nested flood (MSN_Flood) model is applied to simulate complex coastal-fluvial urban flooding due to combined effects of tides, surges and river discharges. Cork city on Ireland's southwest coast is a study case. The flood modelling system comprises a cascade of four dynamically linked models that resolve the hydrodynamics of Cork Harbour and/or its sub-region at four scales: 90, 30, 6 and 2 m. Results demonstrate that the internalization of the nested boundary through the use of ghost cells combined with a tailored adaptive interpolation technique creates a highly dynamic moving boundary that permits flooding and drying of the nested boundary. This novel feature of MSN_Flood provides a high degree of choice regarding the location of the boundaries to the nested domain and therefore flexibility in model application. The nested MSN_Flood model through dynamic downscaling facilitates significant improvements in accuracy of model output without incurring the computational expense of high spatial resolution over the entire model domain. The urban flood model provides full characteristics of water levels and flow regimes necessary for flood hazard identification and flood risk assessment.

Fault tree analysis for urban flooding.

PubMed

ten Veldhuis, J A E; Clemens, F H L R; van Gelder, P H A J M

2009-01-01

Traditional methods to evaluate flood risk generally focus on heavy storm events as the principal cause of flooding. Conversely, fault tree analysis is a technique that aims at modelling all potential causes of flooding. It quantifies both overall flood probability and relative contributions of individual causes of flooding. This paper presents a fault model for urban flooding and an application to the case of Haarlem, a city of 147,000 inhabitants. Data from a complaint register, rainfall gauges and hydrodynamic model calculations are used to quantify probabilities of basic events in the fault tree. This results in a flood probability of 0.78/week for Haarlem. It is shown that gully pot blockages contribute to 79% of flood incidents, whereas storm events contribute only 5%. This implies that for this case more efficient gully pot cleaning is a more effective strategy to reduce flood probability than enlarging drainage system capacity. Whether this is also the most cost-effective strategy can only be decided after risk assessment has been complemented with a quantification of consequences of both types of events. To do this will be the next step in this study.

Modelling urban rainfall-runoff responses using an experimental, two-tiered physical modelling environment

NASA Astrophysics Data System (ADS)

Green, Daniel; Pattison, Ian; Yu, Dapeng

2016-04-01

Surface water (pluvial) flooding occurs when rainwater from intense precipitation events is unable to infiltrate into the subsurface or drain via natural or artificial drainage channels. Surface water flooding poses a serious hazard to urban areas across the world, with the UK's perceived risk appearing to have increased in recent years due to surface water flood events seeming more severe and frequent. Surface water flood risk currently accounts for 1/3 of all UK flood risk, with approximately two million people living in urban areas at risk of a 1 in 200-year flood event. Research often focuses upon using numerical modelling techniques to understand the extent, depth and severity of actual or hypothetical flood scenarios. Although much research has been conducted using numerical modelling, field data available for model calibration and validation is limited due to the complexities associated with data collection in surface water flood conditions. Ultimately, the data which numerical models are based upon is often erroneous and inconclusive. Physical models offer a novel, alternative and innovative environment to collect data within, creating a controlled, closed system where independent variables can be altered independently to investigate cause and effect relationships. A physical modelling environment provides a suitable platform to investigate rainfall-runoff processes occurring within an urban catchment. Despite this, physical modelling approaches are seldom used in surface water flooding research. Scaled laboratory experiments using a 9m2, two-tiered 1:100 physical model consisting of: (i) a low-cost rainfall simulator component able to simulate consistent, uniformly distributed (>75% CUC) rainfall events of varying intensity, and; (ii) a fully interchangeable, modular plot surface have been conducted to investigate and quantify the influence of a number of terrestrial and meteorological factors on overland flow and rainfall-runoff patterns within a modelled urban setting. Terrestrial factors investigated include altering the physical model's catchment slope (0°- 20°), as well as simulating a number of spatially-varied impermeability and building density/configuration scenarios. Additionally, the influence of different storm dynamics and intensities were investigated. Preliminary results demonstrate that rainfall-runoff responses in the physical modelling environment are highly sensitive to slight increases in catchment gradient and rainfall intensity and that more densely distributed building layouts significantly increase peak flows recorded at the physical model outflow when compared to sparsely distributed building layouts under comparable simulated rainfall conditions.

Uncertainty assessment of urban pluvial flood risk in a context of climate change adaptation decision making

NASA Astrophysics Data System (ADS)

Arnbjerg-Nielsen, Karsten; Zhou, Qianqian

2014-05-01

There has been a significant increase in climatic extremes in many regions. In Central and Northern Europe, this has led to more frequent and more severe floods. Along with improved flood modelling technologies this has enabled development of economic assessment of climate change adaptation to increasing urban flood risk. Assessment of adaptation strategies often requires a comprehensive risk-based economic analysis of current risk, drivers of change of risk over time, and measures to reduce the risk. However, such studies are often associated with large uncertainties. The uncertainties arise from basic assumptions in the economic analysis and the hydrological model, but also from the projection of future societies to local climate change impacts and suitable adaptation options. This presents a challenge to decision makers when trying to identify robust measures. We present an integrated uncertainty analysis, which can assess and quantify the overall uncertainty in relation to climate change adaptation to urban flash floods. The analysis is based on an uncertainty cascade that by means of Monte Carlo simulations of flood risk assessments incorporates climate change impacts as a key driver of risk changes over time. The overall uncertainty is then attributed to six bulk processes: climate change impact, urban rainfall-runoff processes, stage-depth functions, unit cost of repair, cost of adaptation measures, and discount rate. We apply the approach on an urban hydrological catchment in Odense, Denmark, and find that the uncertainty on the climate change impact appears to have the least influence on the net present value of the studied adaptation measures-. This does not imply that the climate change impact is not important, but that the uncertainties are not dominating when deciding on action or in-action. We then consider the uncertainty related to choosing between adaptation options given that a decision of action has been taken. In this case the major part of the uncertainty on the estimated net present values is identical for all adaptation options and will therefore not affect a comparison between adaptation measures. This makes the chose among the options easier. Furthermore, the explicit attribution of uncertainty also enables a reduction of the overall uncertainty by identifying the processes which contributes the most. This knowledge can then be used to further reduce the uncertainty related to decision making, as a substantial part of the remaining uncertainty is epistemic.

Flood forecasting within urban drainage systems using NARX neural network.

PubMed

Abou Rjeily, Yves; Abbas, Oras; Sadek, Marwan; Shahrour, Isam; Hage Chehade, Fadi

2017-11-01

Urbanization activity and climate change increase the runoff volumes, and consequently the surcharge of the urban drainage systems (UDS). In addition, age and structural failures of these utilities limit their capacities, and thus generate hydraulic operation shortages, leading to flooding events. The large increase in floods within urban areas requires rapid actions from the UDS operators. The proactivity in taking the appropriate actions is a key element in applying efficient management and flood mitigation. Therefore, this work focuses on developing a flooding forecast system (FFS), able to alert in advance the UDS managers for possible flooding. For a forecasted storm event, a quick estimation of the water depth variation within critical manholes allows a reliable evaluation of the flood risk. The Nonlinear Auto Regressive with eXogenous inputs (NARX) neural network was chosen to develop the FFS as due to its calculation nature it is capable of relating water depth variation in manholes to rainfall intensities. The campus of the University of Lille is used as an experimental site to test and evaluate the FFS proposed in this paper.

What are people thinking about floods? A study in two Mediterranean areas: Costa Brava, Spain and Talcahuano City, Chile

NASA Astrophysics Data System (ADS)

Lara, A.; Ribas, A.; Cifuentes, L. A.

2013-05-01

Mediterranean areas are not immune to flood problems. The Spanish Mediterranean coast is a reflection of this, where flooding continues to be the greatest natural hazard with negative effects on the territory. The urbanization of coastal watersheds, very pronounced in the last 15 years, has led to the creation of authentic urban continuums in the seafront and the appearance of residential developments therein. The municipalities of Costa Brava, in the province of Girona, are an example of this dynamic of the increasing risk, exposure, and impact of floods. In Chile, floods are considered one of the main natural hazards, especially in the province of Concepcion. One of the most important cities of this area is Talcahuano, which has suffered continual flood episodes during recent years. Flood episodes could yet increase in the future due to the high frequency of extraordinary atmospheric events and a higher exposure to flood risk created by the development of intensive urbanization processes. However, after the February 27th 8.8 degrees earthquake (Richter scale) that affected the center-south of Chile and originated the tsunami which flooded a large percentage of the residential area and military base of the city of Talcahuano, the risk, vulnerability, resilience and copy capacity concepts changed. This research looks at the social perception and social knowledge of Mediterranean residents affected and unaffected by floods, emphasizing which is their risk, vulnerability, resilience and copy capacity concept and what kind of measures they proposed to reduce their flood vulnerability. The end objective of this research is to become a framework for future local flood policies and a tool that could be reviewed by specialists in other regions that might be affected by this hazard. This social assessment has been carried out through surveys of residents in Costa Brava and Talcahuano whose endogenous and exogenous characteristics have been significant in explaining their perceptions. The main results show that: a) the flood experience is a determinant in social perception of flood risk; b) fear has a strong role in the livelihood of Talcahuano residents; c) Insurance is the main solution for Spanish residents; d) the residents surveyed feel that the government and disaster managers ignore the local community for design measures to improve local vulnerability against floods and; e) both areas give strong support to implementing structural measures.

Assessment on the pedestrian risk during floods based on numerical simulation - A case study in Jinan City

NASA Astrophysics Data System (ADS)

Cheng, T.; Xu, Z.; Hong, S.

2017-12-01

Flood disasters frequently attack the urban area in Jinan City during past years, and the city is faced with severe road flooding which greatly threaten pedestrians' safety. Therefore, it is of great significance to investigate the pedestrian risk during floods under specific topographic condition. In this study, a model coupled hydrological and hydrodynamic processes is developed in the study area to simulate the flood routing process on the road for the "7.18" rainstorm and validated with post-disaster damage survey information. The risk of pedestrian is estimated with a flood risk assessment model. The result shows that the coupled model performs well in the rainstorm flood process. On the basis of the simulation result, the areas with extreme risk, medium risk, and mild risk are identified, respectively. Regions with high risk are generally located near the mountain front area with steep slopes. This study will provide scientific support for the flood control and disaster reduction in Jinan City.

Using risk-based analysis and geographic information systems to assess flooding problems in an urban watershed in Rhode Island.

PubMed

Hardmeyer, Kent; Spencer, Michael A

2007-04-01

This article provides an overview of the use of risk-based analysis (RBA) in flood damage assessment, and it illustrates the use of Geographic Information Systems (GIS) in identifying flood-prone areas, which can aid in flood-mitigation planning assistance. We use RBA to calculate expected annual flood damages in an urban watershed in the state of Rhode Island, USA. The method accounts for the uncertainty in the three primary relationships used in computing flood damage: (1) the probability that a given flood will produce a given amount of floodwater, (2) the probability that a given amount of floodwater will reach a certain stage or height, and (3) the probability that a certain stage of floodwater will produce a given amount of damage. A greater than 50% increase in expected annual flood damage is estimated for the future if previous development patterns continue and flood-mitigation measures are not taken. GIS is then used to create a map that shows where and how often floods might occur in the future, which can help (1) identify priority areas for flood-mitigation planning assistance and (2) disseminate information to public officials and other decision-makers.

A framework for probabilistic pluvial flood nowcasting for urban areas

NASA Astrophysics Data System (ADS)

Ntegeka, Victor; Murla, Damian; Wang, Lipen; Foresti, Loris; Reyniers, Maarten; Delobbe, Laurent; Van Herk, Kristine; Van Ootegem, Luc; Willems, Patrick

2016-04-01

Pluvial flood nowcasting is gaining ground not least because of the advancements in rainfall forecasting schemes. Short-term forecasts and applications have benefited from the availability of such forecasts with high resolution in space (~1km) and time (~5min). In this regard, it is vital to evaluate the potential of nowcasting products for urban inundation applications. One of the most advanced Quantitative Precipitation Forecasting (QPF) techniques is the Short-Term Ensemble Prediction System, which was originally co-developed by the UK Met Office and Australian Bureau of Meteorology. The scheme was further tuned to better estimate extreme and moderate events for the Belgian area (STEPS-BE). Against this backdrop, a probabilistic framework has been developed that consists of: (1) rainfall nowcasts; (2) sewer hydraulic model; (3) flood damage estimation; and (4) urban inundation risk mapping. STEPS-BE forecasts are provided at high resolution (1km/5min) with 20 ensemble members with a lead time of up to 2 hours using a 4 C-band radar composite as input. Forecasts' verification was performed over the cities of Leuven and Ghent and biases were found to be small. The hydraulic model consists of the 1D sewer network and an innovative 'nested' 2D surface model to model 2D urban surface inundations at high resolution. The surface components are categorized into three groups and each group is modelled using triangular meshes at different resolutions; these include streets (3.75 - 15 m2), high flood hazard areas (12.5 - 50 m2) and low flood hazard areas (75 - 300 m2). Functions describing urban flood damage and social consequences were empirically derived based on questionnaires to people in the region that were recently affected by sewer floods. Probabilistic urban flood risk maps were prepared based on spatial interpolation techniques of flood inundation. The method has been implemented and tested for the villages Oostakker and Sint-Amandsberg, which are part of the larger city of Gent, Belgium. After each of the different above-mentioned components were evaluated, they were combined and tested for recent historical flood events. The rainfall nowcasting, hydraulic sewer and 2D inundation modelling and socio-economical flood risk results each could be partly evaluated: the rainfall nowcasting results based on radar data and rain gauges; the hydraulic sewer model results based on water level and discharge data at pumping stations; the 2D inundation modelling results based on limited data on some recent flood locations and inundation depths; the results for the socio-economical flood consequences of the most extreme events based on claims in the database of the national disaster agency. Different methods for visualization of the probabilistic inundation results are proposed and tested.

Fundamental concepts and research priorities for advancing the science of urban stormwater hydrology and flood management

NASA Astrophysics Data System (ADS)

Nytch, C. J.; Meléndez-Ackerman, E. J.; Vivoni, E. R.; Grove, J. M.; Ortiz, J.

2016-12-01

In cities, hydrologic processes are drastically altered by human interventions. Modification of land cover and the enhancement of hydraulic efficiency have been documented as root causes of augmented stormwater runoff in urban watersheds, contributing to higher magnitude discharge events that pose flood risks for human communities. Climate change is expected to accelerate the hydrologic cycle, leading to more extreme events and increased flood risk. We present a synthesis of the physical and conceptual components and processes that govern urban stormwater runoff, and highlight key areas for future research. There is limited understanding about the fine-scale spatio-temporal relationships between gray, green, brown, and blue land cover features, the underlying social-ecological mechanisms responsible for their distribution, and the resulting effects on runoff dynamics. Horizontal and vertical complexity of urban morphological features and connectivity with the network of stormwater management infrastructure leads to heterogeneous and non-linear runoff responses that confound efforts for accurately predicting flood hazards. Quantitative analysis is needed to understand how urban drainage network structure varies across stream orders, and illuminate the landscape-scale patterns that potentially serve as organizing principles for generating hydrologic processes across diverse socio-bio-climatic domains and scales. Field-based and modeling studies are also needed to quantify the individual hydrologic capacities of urban structural elements and their cumulative effects at the watershed scale, particularly in developing regions. Integrated, transdisciplinary, multi-scalar approaches to framing and investigating complex socio-eco-techno-hydrologic systems are essential for advancing the science of urban stormwater hydrology, and developing resilient, multifunctional management solutions appropriate to the challenges of urban flooding in the twenty-first century.

Analysing urban resilience through alternative stormwater management options: application of the conceptual Spatial Decision Support System model at the neighbourhood scale.

PubMed

Balsells, M; Barroca, B; Amdal, J R; Diab, Y; Becue, V; Serre, D

2013-01-01

Recent changes in cities and their environments, caused by rapid urbanisation and climate change, have increased both flood probability and the severity of flooding. Consequently, there is a need for all cities to adapt to climate and socio-economic changes by developing new strategies for flood risk management. Following a risk paradigm shift from traditional to more integrated approaches, and considering the uncertainties of future urban development, one of the main emerging tasks for city managers becomes the development of resilient cities. However, the meaning of the resilience concept and its operability is still not clear. The goal of this research is to study how urban engineering and design disciplines can improve resilience to floods in urban neighbourhoods. This paper presents the conceptual Spatial Decision Support System (DS3) model which we consider a relevant tool to analyse and then implement resilience into neighbourhood design. Using this model, we analyse and discuss alternative stormwater management options at the neighbourhood scale in two specific areas: Rotterdam and New Orleans. The results obtained demonstrate that the DS3 model confirmed in its framework analysis that stormwater management systems can positively contribute to the improved flood resilience of a neighbourhood.

Climate change induced risk analysis of Dar es Salaam city (Tanzania)

NASA Astrophysics Data System (ADS)

Topa, Maria Elena; Herslund, Lise; Cavan, Gina; Printz, Andreas; Simonis, Ingo; Bucchignani, Edoardo; Jean-Baptiste, Nathalie; Hellevik, Siri; Johns, Regina; Kibassa, Deusdedit; Kweka, Clara; Magina, Fredrick; Mangula, Alpha; Mbuya, Elinorata; Uhinga, Guido; Kassenga, Gabriel; Kyessi, Alphonce; Shemdoe, Riziki; Kombe, Wilbard

2013-04-01

CLUVA (CLimate change and Urban Vulnerability in Africa; http://www.cluva.eu/) is a 3 years project, funded by the European Commission in 2010. The main objective of CLUVA is to develop context-centered methods and knowledge to be applied to African cities to assess vulnerabilities and increase knowledge on managing climate related risks. The project estimates the impacts of climate changes in the next 40 years at urban scale and downscales IPCC climate projections to evaluate specific threats to selected African test cities. These are mainly from floods, sea-level rise, droughts, heat waves, and desertification. The project evaluates and links: social vulnerability; urban green structures and ecosystem services; urban-rural interfaces; vulnerability of urban built environment and lifelines; and related institutional and governance dimensions of adaptation. The multi-scale and multi-disciplinary qualitative, quantitative and probabilistic approach of CLUVA is currently being applied to selected African test cities (Addis Ababa - Ethiopia; Dar es Salaam - Tanzania; Douala - Cameroun; Ouagadougou - Burkina Faso; St. Louis - Senegal). In particular, the poster will present preliminary findings for the Dar es Salaam case study. Dar es Salaam, which is Tanzania's largest coastal city, is exposed to floods, coastal erosion, droughts and heat waves, and highly vulnerable to impacts as a result of ineffective urban planning (about 70% unplanned settlements), poverty and lack of basic infrastructure (e.g. lack of or poor quality storm water drainage systems). Climate change could exacerbate the current situation increasing hazard-exposure alongside the impacts of development pressures which act to increase urban vulnerability for example because of informal (unregulated) urbanization. The CLUVA research team - composed of climate and environmental scientists, risk management experts, urban planners and social scientists from both European and African institutions - has started to produce research outputs suitable for use in evidence-based planning activities in the case study cities through interdisciplinary methods and analysis. Climate change projections at 8 km resolution are ready for regions containing each of the case study cities; a preliminary hazard assessment for floods, droughts and heat waves has been performed, based on historical data; urban morphology and related green structures have been characterized; preliminary findings in social vulnerability provide insights how communities and households can resist and cope with, as well as recover from climate induced hazards; vulnerability of informal settlements to floods has been assessed for a case study area (Suna sub ward) and a GIS based identification of urban residential hotspots to flooding is completed. Furthermore, a set of indicators has been identified and the most relevant for Dar es Salaam has been selected by local stakeholders to identify particular vulnerable high risk areas and communities. An investigation of the existing urban planning and governance system and its interface with climate risks and vulnerability has inter-alia suggested severe institutional deficits including over-centralized institutions for disaster risk management and climate change adaptation. A multi-risk framework considering climate-related hazards, and physical and social fragilities has been set up.

DECENTRALIZED STORMWATER MANAGEMENT: RETROFITTING HOMES, RESTORING WATERSHEDS

EPA Science Inventory

Stormwater runoff from impervious surfaces in urban and suburban areas has led to human safety risks and widespread stream ecosystem impairment. While centralized stormwater management can minimize large fluctuations in stream flows and flooding risk to urban areas, this approac...

Assessing the effects of Climate Change on Urban Pluvial Flooding to provide a Risk Management Framework

NASA Astrophysics Data System (ADS)

Rianna, G.; Mercogliano, P.

2017-12-01

Urbanization increases the flood risk because of heightened vulnerability, stemming from population concentration and hazard due to soil sealing affecting the largest part of urban settlements and reducing the concentration time of interested basins. Furthermore, current and future hazards are exacerbated by expected increases in extreme rainfall events due to Climate Changes (CC) making inadequate urban drainage infrastructures designed under the assumption of steady conditions. In this work, we present a modeling chain/algorithm to assess potential increase in pluvial flood hazard able to take into account CC forcing. The adopted simulation chain reckon on three main elements: Regional Climate Model, COSMO_CLM, dynamically downscaling GCM CMCC_CM (Scoccimarro et al., 2011) and optimized, at high resolution (about 8km), by Bucchignani et al. (2015) on Italy provide projections about precipitation up to 2100 under two concentration scenarios (RCP4.5 and RCP8.5). Such projections are used in Equidistance Quantile Mapping (EQM) approach, developed by Srivastav et al. (2014) to estimate expected variations in IDF (Intensity-Duration-Frequency) curves calculated through Generalized Extreme Value (GEV) approach on the basis of available rainfall data. To this aim, 1971-2000 observations are used as reference. Finally, a 1-D/2-D coupled urban drainage/flooding model forced by IDF (current and projected) is used to simulate storm-sewer surcharge and surface inundation to establish the variations in urban flooding risk. As test case is considered the city center of Naples (Southern Italy). In this respective, the sewage and urban drainage network is highly complex due to the historical and subsequent transformations of the city. Under such constraints, the reliability of the results maybe deeply conditioned by uncertainties not undermining the illustrative purposes of the work. Briefly, EQM returns a remarkable increase in extreme precipitations; such increase is driven by concentration scenarios (higher for RCP8.5) and investigated time horizon (more significant for 2071-2100 time span). Furthermore, results provided by hydraulic models clearly highlight the inadequacy of the actual drainage system especially under a RCP8.5-driven scenario showing large portions of the city center flooded.

Beyond the Floodplain: Drivers of Flood Risk in Coastal Cities

NASA Astrophysics Data System (ADS)

Rosenzweig, B.; McPhearson, T.; Rosi, E. J.

2017-12-01

While the catastrophic impacts of Hurricane Katrina increased awareness of coastal flood risk, conventional approaches to flood risk assessment do not adequately represent the drivers of flood risk in the unique, highly engineered landscape of dense cities. We review the recent (1996-2016) history of flooding events and current regional climate change projection for 4 diverse coastal cities in the United States: San Juan, Miami, Baltimore and New York. Our review suggests that while all 4 of these cities face increased risk from direct coastal flooding with climate change, pluvial flooding will be an additional, important driver of risk that is currently poorly quantified. Unlike other types of flooding, pluvial flood risk is not limited to a contiguous riverine or coastal floodplain, but is instead driven by interactions between spatially variable geophysical drivers (intense rainfall, shallow groundwater, and influent tidal water), social drivers (patterns of land use) and technical drivers (urban stormwater and coastal infrastructure). We discuss approaches for quantitative assessment of pluvial flood risk, the challenges presented by the lack of data on geophysical flooding drivers in dense cities, and opportunities for integrated research to provide the scientific information needed by practitioners.

Analysis of economic vulnerability to flash floods in urban areas of Castilla y León (Spain)

NASA Astrophysics Data System (ADS)

Aroca-Jimenez, Estefanía; Bodoque, Jose Maria; García, Juan Antonio; Diez-Herrero, Andres

2017-04-01

The growth of exposed population to floods, the expansion in allocation of economical activities to flood-prone areas and the rise of extraordinary event frequency over the last few decades, have resulted in an increase of flash flood-related casualties and economic losses. The increase in these losses at an even higher rate than the increase of magnitude and frequency of extreme events, underline that the vulnerability of societies exposed is a key aspect to be considered. Vulnerability is defined as the conditions determined by physical, social, economic and environmental factors or processes which increase the susceptibility of a community to the impact of hazards such as floods, being flash floods one of the natural hazards with the greatest capacity to generate risk. In recent years, numerous papers have deal with the assessment of the social dimension of vulnerability. However, economic factors are often a neglected aspect in traditional risk assessments which mainly focus on structural measures and flood damage models. In this context, the aim of this research is to identify those economic characteristics which render people vulnerable to flash flood hazard, and consider whether these characteristics are identifiable as local patterns at regional level. The result of this task is an Economic Vulnerability Index (EVI) based on susceptibility profiles of the population per township. These profiles are obtained by Hierarchical Segmentation and Latent Class Cluster Analysis of economic information provided by different public institutional databases. The methodology proposed here is implemented in the region of Castilla y León (94,230 km2), placed in Central-Northern Spain. Townships included in this study meet two requirements: i) urban areas are potentially affected by flash floods (i.e. villages are crossed by rivers or streams with a longitudinal slope higher than 0.01 m m-1); ii) urban areas are affected by an area with low or exceptional probability of flooding (as provided by Directive 2007/60/EC of 23 October 2007 on the assessment and management of flood risks) according with the preliminary assessment of flood risk made by water authorities.

USING MARKET INCENTIVES TO PROMOTE DECENTRALIZED STORMWATER MANAGEMENT

EPA Science Inventory

Stormwater runoff from impervious surfaces in urban and suburban areas has led to human safety risks and widespread stream ecosystem impairment. While centralized stormwater management can minimize large fluctuations in stream flows and flooding risk to urban areas, this approac...

Monitoring urban land cover with the use of satellite remote sensing techniques as a means of flood risk assessment in Cyprus

NASA Astrophysics Data System (ADS)

Alexakis, Dimitris; Hadjimitsis, Diofantos; Agapiou, Athos; Themistocleous, Kyriacos; Retalis, Adrianos

2011-11-01

The increase of flood inundation occuring in different regions all over the world have enhanced the need for effective flood risk management. As floods frequency is increasing with a steady rate due to ever increasing human activities on physical floodplains there is a respectively increasing of financial destructive impact of floods. A flood can be determined as a mass of water that produces runoff on land that is not normally covered by water. However, earth observation techniques such as satellite remote sensing can contribute toward a more efficient flood risk mapping according to EU Directives of 2007/60. This study strives to highlight the need of digital mapping of urban sprawl in a catchment area in Cyprus and the assessment of its contribution to flood risk. The Yialias river (Nicosia, Cyprus) was selected as case study where devastating flash floods events took place at 2003 and 2009. In order to search the diachronic land cover regime of the study area multi-temporal satellite imagery was processed and analyzed (e.g Landsat TMETM+, Aster). The land cover regime was examined in detail by using sophisticated post-processing classification algorithms such as Maximum Likelihood, Parallelepiped Algorithm, Minimum Distance, Spectral Angle and Isodata. Texture features were calculated using the Grey Level Co-Occurence Matrix. In addition three classification techniques were compared : multispectral classification, texture based classification and a combination of both. The classification products were compared and evaluated for their accuracy. Moreover, a knowledge-rule method is proposed based on spectral, texture and shape features in order to create efficient land use and land cover maps of the study area. Morphometric parameters such as stream frequency, drainage density and elongation ratio were calculated in order to extract the basic watershed characteristics. In terms of the impacts of land use/cover on flooding, GIS and Fragstats tool were used to detect identifying trends, both visually and statistically, resulting from land use changes in a flood prone area such as Yialias by the use of spatial metrics. The results indicated that there is a considerable increase of urban areas cover during the period of the last 30 years. All these denoted that one of the main driving force of the increasing flood risk in catchment areas in Cyprus is generally associated to human activities.

Urban and peri-urban flood impact change: the case of the Metropolitan Area of Barcelona

NASA Astrophysics Data System (ADS)

Cortès, Maria; Gilabert, Joan; Llasat-Botija, Montserrat; Marcos, Raül; Llasat, Maria del Carmen

2017-04-01

Floods are the most important natural hazard in the world. Nowadays, mitigation and adaptation strategies to reduce the impact that climate change will have on them, are a priority in most government agendas. Recent reports from the IPCC (2012, 2014) still show significant uncertainty associated with future projections of precipitation extremes. This uncertainty is higher when referred to floods and even larger when interactions with society and the changes in vulnerability are considered. Consequently, there is now a call to treat floods from a holistic perspective that integrates bottom-up (from impact and vulnerability) and top-down (from hazard) approaches (Hall et al., 2014). The study of flood risk in urban and peri-urban areas is complex and involves multiple factors. This is the case of the Metropolitan Area of Barcelona (AMB), which concentrates 43% of total population of Catalonia in less than 2% of the whole territory. The impervious soil has grown more than 200% from 1956 to 2009 (resulting in higher values of runoff), the population has increased more than 80% in the same period and, simultaneously, an improvement of the drainage system and flood prevention has been developed. As a result, we have seen that the flood risk evolution in the area holds a strong link to these human changes. Actually, floods in this region are usually due to drainage problems, flash floods in ungauged torrential catchments and, only in some occasions, river floods are produced (i.e. the Llobregat River on September 1971). But, in all the cases they are due to heavy precipitations. The main objective of the contribution is assessing the relationship between precipitation in the AMB and the social impacts produced. In order to do it, different impact indicators have been proposed, such as the population affected or the duration of the flood event (Merz et al., 2010). These indicators have been implemented for the different cases analyzed, which affected AMB for the period 1981-2015. These indicators have allowed developing a risk index based on the research of Amaro et al. (2010) and Barberia et al. (2014). Furthermore, the results are validated with damage information provided by the Insurance Compensation Consortium of Spain. The study also explores the evolution of land uses, population and precipitation from the middle of the 20th century until now, and how these changes have affected (or not) the flood risk in the AMB. This work has been developed in the framework of the Spanish project HOPE (CGL2014-52571-R) and METROBS study.

Evaluation of urban flood damages in climate and land use changes: Case Studies from Southeast Asia

NASA Astrophysics Data System (ADS)

Kefi, M.; Binaya, M. K.; Kumar, P.; Fukushi, K.

2017-12-01

Urbanization, changes in land use and global warming increase the threat of natural disasters such as flooding. In recent decades, it was observed a rise of intensity and frequency of flood events. The exposure both of people and the national economy to flood hazards is amplified and can induce serious economic and social damages. For this reason, local governments adopted several strategies to cope with flood risk in urban areas in particular, but a better comprehension of the flood hazard factors may enhance the efficiency of mitigating measures overall. For this research, a spatial analysis is applied to estimate future direct flood damage for 2030 in three Southeast Asian megacities: Jakarta (Indonesia), Metro-Manila (Philippines) and Hanoi (Vietnam). This comprehensive method combined flood characteristics (flood depth) obtained from flood simulation using FLO-2D, land use generated from supervised classification and remote sensing products, property value of affected buildings and flood damage rate derived from flood depth function. This function is established based on field surveys with local people affected by past flood events. Additionally, two scenarios were analyzed to simulate the future conditions. The first one is related to climate change and it is based on several General Circulation Models (GCMs). However, the second one is establish to point out the effect of adaptation strategies. The findings shows that the climate change combined with the expansion of built-up areas increase the vulnerability of urban areas to flooding and the economic damage. About 16%, 8% and 19% of flood inundation areas are expected to increase respectively in Metro-Manila, Jakarta and Hanoi. However, appropriate flood control measures can be helpful to reduce the impact of natural disaster. Furthermore, flood damage maps are generated at a large scale, which can be helpful to local stakeholders when prioritizing their mitigation strategies on urban disaster resilience.

Evaluation of Flooding Risk and Engineering Protection Against Floods for Ulan-Ude

NASA Astrophysics Data System (ADS)

Borisova, T. A.

2017-11-01

The report presents the results of the study on analysis and risk assessment in relation to floods for Ulan-Ude and provides the developed recommendations of the activities for engineering protection of the population and economic installations. The current situation is reviewed and the results of the site survey are shown to identify the challenges and areas of negative water influence along with the existing security system. The report presents a summary of floods and index risk assessment. The articles describes the scope of eventual flooding, underflooding and enumerates the economic installations inside the urban areas’ research-based zones of flooding at the rated levels of water to identify the likeliness of exceedance. The assessment of damage from flood equal to 1% is shown.

Striving to Reduce Vulnerability:Lessons from the Poor Community Livelihoodsin the Jakarta Bay Facing High Risk of Rapid Urbanization and Climate Changes

NASA Astrophysics Data System (ADS)

Hidayati, D.; Delinom, R. M.; Abdurachim, A. Y.; Dalimunthe, S.; Haba, J.; Pawitan, H.

2014-12-01

This paper discusses water-food issues in relation to how livelihoods of the poor community in Jakarta Bayarein high risk ofrapid urbanization and climate changes. As a part of the capital city of Indonesia, this area has experienced rapid increase in populationand extensive developments causing significant increase in the built up area. This city is unable to keep with demand on sewers, water and solid waste management, leading to settlement with concentrated slum pockets areas and widespread of flooding. The community is mostly poor people of productive group, live with urban pressure in fragile home and livelihoods.The situation becomes much worse due to the impact of climate change with flooding as the greatest climate and disaster risk. With lack of basic services, coastal water inundation (BanjirRob)commonly occursand floods the community housing areaswithout patternanymore. The community has lack of fresh and clean water sources and facedeconomic problem, particularly significant reduction of fishing activities. Coastal reclamation and water pollution from nearby industries are blamed as the main reason for these problems. Strategies therefore have to be developed, especially increasing community awareness and preparedness, and poverty alleviation, to sustain their livelihoods in this high risk urban area.

Discover Floods Educators Guide

ERIC Educational Resources Information Center

Project WET Foundation, 2009

2009-01-01

Now available as a Download! This valuable resource helps educators teach students about both the risks and benefits of flooding through a series of engaging, hands-on activities. Acknowledging the different roles that floods play in both natural and urban communities, the book helps young people gain a global understanding of this common--and…

The Development and Assesment of Adaptation Pathways for Urban Pluvial Flooding

NASA Astrophysics Data System (ADS)

Babovic, F.; Mijic, A.; Madani, K.

2017-12-01

Around the globe, urban areas are growing in both size and importance. However, due to the prevalence of impermeable surfaces within the urban fabric of cities these areas have a high risk of pluvial flooding. Due to the convergence of population growth and climate change the risk of pluvial flooding is growing. When designing solutions and adaptations to pluvial flood risk urban planners and engineers encounter a great deal of uncertainty due to model uncertainty, uncertainty within the data utilised, and uncertainty related to future climate and land use conditions. The interaction of these uncertainties leads to conditions of deep uncertainty. However, infrastructure systems must be designed and built in the face of this deep uncertainty. An Adaptation Tipping Points (ATP) methodology was used to develop a strategy to adapt an urban drainage system in the North East of London under conditions of deep uncertainty. The ATP approach was used to assess the current drainage system and potential drainage system adaptations. These adaptations were assessed against potential changes in rainfall depth and peakedness-defined as the ratio of mean to peak rainfall. These solutions encompassed both traditional and blue-green solutions that the Local Authority are known to be considering. This resulted in a set of Adaptation Pathways. However, theses pathways do not convey any information regarding the relative merits and demerits of the potential adaptation options presented. To address this a cost-benefit metric was developed that would reflect the solutions' costs and benefits under uncertainty. The resulting metric combines elements of the Benefits of SuDS Tool (BeST) with real options analysis in order to reflect the potential value of ecosystem services delivered by blue-green solutions under uncertainty. Lastly, it is discussed how a local body can utilise the adaptation pathways; their relative costs and benefits; and a system of local data collection to help guide better decision making with respect to urban flood adaptation.

keep your models up-to-date: connecting community mapping data to complex urban flood modelling

NASA Astrophysics Data System (ADS)

Winsemius, Hessel; Eilander, Dirk; Ward, Philip; Diaz Loaiza, Andres; Iliffe, Mark; Mawanda, Shaban; Luo, Tianyi; Kimacha, Nyambiri; Chen, Jorik

2017-04-01

The world is urbanizing rapidly. According to the United Nation's World Urbanization Prospect, 50% of the global population already lives in urban areas today. This number is expected to grow to 66% by 2050. The rapid changes in these urban environments go hand in hand with rapid changes in natural hazard risks, in particular in informal unplanned neighbourhoods. In Dar Es Salaam - Tanzania, flood risk dominates and given the rapid changes in the city, continuous updates of detailed street level hazard and risk mapping are needed to adequately support decision making for urban planning, infrastructure design and disaster response. Over the past years, the Ramani Huria and Zuia Mafuriko projects have mapped the most flood prone neighbourhoods, including roads, buildings, drainage and land use and contributed data to the open-source OpenStreetMap database. In this contribution, we will demonstrate how we mobilize these contributed data to establish dynamic flood models for Dar Es Salaam and keep these up-to-date by making a direct link between the data, and model schematization. The tools automatically establish a sound 1D drainage network as well as a high resolution terrain dataset, by fusing the OpenStreetMap data with existing lower resolution terrain data such as the globally available satellite based SRTM 30. It then translates these fully automatically into the inputs required for the D-HYDRO modeling suite. Our tools are built such that community and stakeholder knowledge can be included in the model details through workshops with the tools so that missing essential information about the city's details can be augmented on-the-fly. This process creates a continuous dialogue between members of the community that collect data, and stakeholders requiring data for flood models. Moreover, used taxonomy and data filtering can be configured to conditions in other cities, making the tools generic and scalable. The tools are made available open-source.

Mapping Urban Risk: Flood Hazards, Race, & Environmental Justice In New York”

PubMed Central

Maantay, Juliana; Maroko, Andrew

2009-01-01

This paper demonstrates the importance of disaggregating population data aggregated by census tracts or other units, for more realistic population distribution/location. A newly-developed mapping method, the Cadastral-based Expert Dasymetric System (CEDS), calculates population in hyper-heterogeneous urban areas better than traditional mapping techniques. A case study estimating population potentially impacted by flood hazard in New York City compares the impacted population determined by CEDS with that derived by centroid-containment method and filtered areal weighting interpolation. Compared to CEDS, 37 percent and 72 percent fewer people are estimated to be at risk from floods city-wide, using conventional areal weighting of census data, and centroid-containment selection, respectively. Undercounting of impacted population could have serious implications for emergency management and disaster planning. Ethnic/racial populations are also spatially disaggregated to determine any environmental justice impacts with flood risk. Minorities are disproportionately undercounted using traditional methods. Underestimating more vulnerable sub-populations impairs preparedness and relief efforts. PMID:20047020

Flood risk changes over centuries in Rome: an empirical study

NASA Astrophysics Data System (ADS)

Di Baldassarre, Giuliano; Saccà, Smeralda; Tito Aronica, Giuseppe; Grimaldi, Salvatore; Crisci, Massimiliano

2015-04-01

Over centuries, the development of the historical city of Rome -close to one of the largest Italian rivers, the Tiber- has been intertwined with the magnitude and frequency of flooding events. The ancient Rome mostly developed on the (seven) hills, while the Tiber's floodplain was mainly exploited for agricultural purposes. A few small communities did settle in the riparian areas of the Tiber, but they had a relatively peaceful relationships with the frequent occurrence of flooding events. Nowadays, numerous people live in modern districts in the Tiber's floodplain, unaware of their exposure to potentially catastrophic flooding. The main goal of this research is to explore the dynamics of changing flood risk over the centuries between these two extreme pictures of the ancient and contemporary Rome. To this end, we carried out a socio-hydrological study by exploiting long time series of physical (flooding, river morphology) and social (urbanization, population dynamics) processes together with information about human interactions with the environment (flood defense structures). This empirical analysis showed how human and physical systems have been co-evolving over time, while being abruptly altered by the occurrence of extreme events. For instance, a large flooding event occurred in 1870 and contributed to the constructions of levees, which in turn facilitated the development of new urban areas in the Tiber's floodplain, while changed the societal memory of floods as well as the communities' perception of risk. This research work was also used to test the hypotheses of recent-developed models conceptualizing the interplay between floods and societies and simulating the long-term behavior of coupled human-water systems. The outcomes of this test provided interesting insights about the dynamics of flood risk, which are expected to support a better anticipation of future changes.

Advancing flood risk analysis by integrating adaptive behaviour in large-scale flood risk assessments

NASA Astrophysics Data System (ADS)

Haer, T.; Botzen, W.; Aerts, J.

2016-12-01

In the last four decades the global population living in the 1/100 year-flood zone has doubled from approximately 500 million to a little less than 1 billion people. Urbanization in low lying -flood prone- cities further increases the exposed assets, such as buildings and infrastructure. Moreover, climate change will further exacerbate flood risk in the future. Accurate flood risk assessments are important to inform policy-makers and society on current- and future flood risk levels. However, these assessment suffer from a major flaw in the way they estimate flood vulnerability and adaptive behaviour of individuals and governments. Current flood risk projections commonly assume that either vulnerability remains constant, or try to mimic vulnerability through incorporating an external scenario. Such a static approach leads to a misrepresentation of future flood risk, as humans respond adaptively to flood events, flood risk communication, and incentives to reduce risk. In our study, we integrate adaptive behaviour in a large-scale European flood risk framework through an agent-based modelling approach. This allows for the inclusion of heterogeneous agents, which dynamically respond to each other and a changing environment. We integrate state-of-the-art flood risk maps based on climate scenarios (RCP's), and socio-economic scenarios (SSP's), with government and household agents, which behave autonomously based on (micro-)economic behaviour rules. We show for the first time that excluding adaptive behaviour leads to a major misrepresentation of future flood risk. The methodology is applied to flood risk, but has similar implications for other research in the field of natural hazards. While more research is needed, this multi-disciplinary study advances our understanding of how future flood risk will develop.

Hydrodynamic modeling of urban flooding taking into account detailed data about city infrastructure

NASA Astrophysics Data System (ADS)

Belikov, Vitaly; Norin, Sergey; Aleksyuk, Andrey; Krylenko, Inna; Borisova, Natalya; Rumyantsev, Alexey

2017-04-01

Flood waves moving across urban areas have specific features. Thus, the linear objects of infrastructure (such as embankments, roads, dams) can change the direction of flow or block the water movement. On the contrary, paved avenues and wide streets in the cities contribute to the concentration of flood waters. Buildings create an additional resistance to the movement of water, which depends on the urban density and the type of constructions; this effect cannot be completely described by Manning's resistance law. In addition, part of the earth surface, occupied by buildings, is excluded from the flooded area, which results in a substantial (relative to undeveloped areas) increase of the depth of flooding, especially for unsteady flow conditions. An approach to numerical simulation of urban areas flooding that consists in direct allocating of all buildings and structures on the computational grid are proposed. This can be done in almost full automatic way with usage of modern software. Real geometry of all objects of infrastructure can be taken into account on the base of highly detailed digital maps and satellite images. The calculations based on two-dimensional Saint-Venant equations on irregular adaptive computational meshes, which can contain millions of cells and take into account tens of thousands of buildings and other objects of infrastructure. Flood maps, received as result of modeling, are the basis for the damage and risk assessment for urban areas. The main advantage of the developed method is high-precision calculations, realistic modeling results and appropriate graphical display of the flood dynamics and dam-break wave's propagation on urban areas. Verification of this method has been done on the experimental data and real events simulations, including catastrophic flooding of the Krymsk city in 2012 year.

Modeling urbanized watershed flood response changes with distributed hydrological model: key hydrological processes, parameterization and case studies

NASA Astrophysics Data System (ADS)

Chen, Y.

2017-12-01

Urbanization is the world development trend for the past century, and the developing countries have been experiencing much rapider urbanization in the past decades. Urbanization brings many benefits to human beings, but also causes negative impacts, such as increasing flood risk. Impact of urbanization on flood response has long been observed, but quantitatively studying this effect still faces great challenges. For example, setting up an appropriate hydrological model representing the changed flood responses and determining accurate model parameters are very difficult in the urbanized or urbanizing watershed. In the Pearl River Delta area, rapidest urbanization has been observed in China for the past decades, and dozens of highly urbanized watersheds have been appeared. In this study, a physically based distributed watershed hydrological model, the Liuxihe model is employed and revised to simulate the hydrological processes of the highly urbanized watershed flood in the Pearl River Delta area. A virtual soil type is then defined in the terrain properties dataset, and its runoff production and routing algorithms are added to the Liuxihe model. Based on a parameter sensitive analysis, the key hydrological processes of a highly urbanized watershed is proposed, that provides insight into the hydrological processes and for parameter optimization. Based on the above analysis, the model is set up in the Songmushan watershed where there is hydrological data observation. A model parameter optimization and updating strategy is proposed based on the remotely sensed LUC types, which optimizes model parameters with PSO algorithm and updates them based on the changed LUC types. The model parameters in Songmushan watershed are regionalized at the Pearl River Delta area watersheds based on the LUC types of the other watersheds. A dozen watersheds in the highly urbanized area of Dongguan City in the Pearl River Delta area were studied for the flood response changes due to urbanization, and the results show urbanization has big impact on the watershed flood responses. The peak flow increased a few times after urbanization which is much higher than previous reports.

The Two Edged Sword; Illinois' Risk Reduction Success Through Managed Retreat And Strong Regulations

NASA Astrophysics Data System (ADS)

Osman, P.

2017-12-01

Illinois has the nation's largest inland system of rivers, lakes, and streams. Two thirds of the continental US and two Canadian provinces drain thru Illinois. Although a blessing, these waterways also result in frequent flooding. Historically, Illinois ranked among the top five states in the nation for flood losses. However, using a combination of strong floodplain regulations and proactive flood mitigation programs, Illinois now ranks near the bottom of flood loss states. Following the 1993 flood, the State of Illinois began an aggressive program to remove flood prone structures from the floodplain. Using a combination of state, federal, and local funds, towns like Valmeyer and Grafton have largely been relocated outside of the floodplain. Likewise, in dozens of communities across the state, thousands of structures have been have purchased to create open space in the floodplain. In addition, new structures in the floodplain must meet strict state and local floodplain construction standards. Major floods now routinely pass Illinois unnoticed. Many communities once ravaged by flooding now pass large floods unscathed. Due largely to climate change, flood losses in many areas are evolving. The majority of flood losses in Illinois now occur outside of the mapped floodplain. The State of Illinois has recently completed a detailed analysis of the state's urban flood exposure. Flood risk is changing and methods to address that risk must evolve accordingly. Accurate climate change data on major inland waterways and urban areas remain elusive. This presentation will highlight simple steps any state or community can take to reduce existing flood losses and be better prepared to address changing impacts due to climate change.

Climate change induced risk analysis of Addis Ababa city (Ethiopia)

NASA Astrophysics Data System (ADS)

Jalayer, Fatemeh; Herslund, Lise; Cavan, Gina; Printz, Andreas; Simonis, Ingo; Bucchignani, Edoardo; Jean-Baptiste, Nathalie; Hellevik, Siri; Fekade, Rebka; Nebebe, Alemu; Woldegerima, Tekle; Workalemahu, Liku; Workneh, Abraham; Yonas, Nebyou; Abebe Bekele, Essete; Yeshitela, Kumelachew

2013-04-01

CLUVA (CLimate change and Urban Vulnerability in Africa; http://www.cluva.eu/) is a 3 years project, funded by the European Commission in 2010. Its objective is to develop context-centered methods to assess vulnerability and increase knowledge on managing climate related risks and to estimate the impacts of climate changes in the next 40 years at urban scale in Africa. The project downscales IPCC climate projections to evaluate threats to selected African test cities; mainly floods, sea-level rise, droughts, heat waves, desertification. It also evaluates and links: social vulnerability; urban green structures and ecosystem services; urban-rural interfaces; vulnerability of urban built environment and lifelines; and related institutional and governance dimensions of adaptation. CLUVA combines assessment approaches to investigate how cities, communities and households can resist and cope with, as well as recover from climate induced hazards. This multi-scale and multi-disciplinary qualitative, quantitative and probabilistic approach of CLUVA is currently being applied to selected African test cities (Addis Ababa - Ethiopia; Dar es Salaam - Tanzania; Douala - Cameroun; Ouagadougou - Burkina Faso; St. Louis - Senegal). In particular, the poster will report on the progresses of the Addis Ababa case study. Addis Ababa, the largest city in Ethiopia, is exposed to heat waves, drought, and, more recently, to flash floods. Due to undulating topography, poor waste management and the absence of sustainable storm water management, Addis Ababa is prone to severe flood events during the rainy seasons. Metropolitan Addis Ababa is crossed by several small watercourses. Torrential rains, very common during the rainy season, cause a sudden rise in the flow of these water courses, inundating and damaging the settlements along their banks and affecting the livelihood of the local population. The combination of climate change and development pressures are expected to exacerbate the current situation. The CLUVA research team - composed of climate and environmental scientists, engineers, risk management experts, urban planners and social scientists from both European and African institutions - has started to produce research outputs suitable for use in evidence-based planning activities in the case study cities. Indeed, climate change projections at 8 km resolution are ready for regions containing each of the case study cities; a preliminary hazard assessment for floods, drought and heat waves has already been performed, based on historical data; urban morphology and related green structures have been characterized; preliminary findings in social vulnerability have been achieved; a GIS based identification of Urban Residential hotspots to flooding is completed; and the vulnerability of informal settlements to flooding has been evaluated for one of the hotspots identified (Little Akaki case study area). Furthermore, a set of indicators relevant for Addis Ababa has been selected by local stakeholders to identify especially vulnerable, high risk areas and communities and an investigation of existing urban planning and governance systems and its interface with climate risks and vulnerability is ongoing. Evidence from the CLUVA project is being used to develop the next Master Plan for the Addis Ababa metropolitan area.

Patterns and comparisons of human-induced changes in river flood impacts in cities

NASA Astrophysics Data System (ADS)

Clark, Stephanie; Sharma, Ashish; Sisson, Scott A.

2018-03-01

In this study, information extracted from the first global urban fluvial flood risk data set (Aqueduct) is investigated and visualized to explore current and projected city-level flood impacts driven by urbanization and climate change. We use a novel adaption of the self-organizing map (SOM) method, an artificial neural network proficient at clustering, pattern extraction, and visualization of large, multi-dimensional data sets. Prevalent patterns of current relationships and anticipated changes over time in the nonlinearly-related environmental and social variables are presented, relating urban river flood impacts to socioeconomic development and changing hydrologic conditions. Comparisons are provided between 98 individual cities. Output visualizations compare baseline and changing trends of city-specific exposures of population and property to river flooding, revealing relationships between the cities based on their relative map placements. Cities experiencing high (or low) baseline flood impacts on population and/or property that are expected to improve (or worsen), as a result of anticipated climate change and development, are identified and compared. This paper condenses and conveys large amounts of information through visual communication to accelerate the understanding of relationships between local urban conditions and global processes.

KULTURisk regional risk assessment methodology for water-related natural hazards - Part 2: Application to the Zurich case study

NASA Astrophysics Data System (ADS)

Ronco, P.; Bullo, M.; Torresan, S.; Critto, A.; Olschewski, R.; Zappa, M.; Marcomini, A.

2015-03-01

The aim of this paper is the application of the KULTURisk regional risk assessment (KR-RRA) methodology, presented in the companion paper (Part 1, Ronco et al., 2014), to the Sihl River basin, in northern Switzerland. Flood-related risks have been assessed for different receptors lying on the Sihl River valley including Zurich, which represents a typical case of river flooding in an urban area, by calibrating the methodology to the site-specific context and features. Risk maps and statistics have been developed using a 300-year return period scenario for six relevant targets exposed to flood risk: people; economic activities: buildings, infrastructure and agriculture; natural and semi-natural systems; and cultural heritage. Finally, the total risk index map has been produced to visualize the spatial pattern of flood risk within the target area and, therefore, to identify and rank areas and hotspots at risk by means of multi-criteria decision analysis (MCDA) tools. Through a tailored participatory approach, risk maps supplement the consideration of technical experts with the (essential) point of view of relevant stakeholders for the appraisal of the specific scores weighting for the different receptor-relative risks. The total risk maps obtained for the Sihl River case study are associated with the lower classes of risk. In general, higher (relative) risk scores are spatially concentrated in the deeply urbanized city centre and areas that lie just above to river course. Here, predicted injuries and potential fatalities are mainly due to high population density and to the presence of vulnerable people; flooded buildings are mainly classified as continuous and discontinuous urban fabric; flooded roads, pathways and railways, most of them in regards to the Zurich central station (Hauptbahnhof) are at high risk of inundation, causing severe indirect damage. Moreover, the risk pattern for agriculture, natural and semi-natural systems and cultural heritage is relatively less important mainly because the scattered presence of these assets. Finally, the application of the KR-RRA methodology to the Sihl River case study, as well as to several other sites across Europe (not presented here), has demonstrated its flexibility and the possible adaptation of it to different geographical and socioeconomic contexts, depending on data availability and particulars of the sites, and for other (hazard) scenarios.

The KULTURisk Regional Risk Assessment methodology for water-related natural hazards - Part 2: Application to the Zurich case study

NASA Astrophysics Data System (ADS)

Ronco, P.; Bullo, M.; Torresan, S.; Critto, A.; Olschewski, R.; Zappa, M.; Marcomini, A.

2014-07-01

The main objective of the paper is the application of the KULTURisk Regional Risk Assessment (KR-RRA) methodology, presented in the companion paper (Part 1, Ronco et al., 2014), to the Sihl River valley, in Switzerland. Through a tuning process of the methodology to the site-specific context and features, flood related risks have been assessed for different receptors lying on the Sihl River valley including the city of Zurich, which represents a typical case of river flooding in urban area. After characterizing the peculiarities of the specific case study, risk maps have been developed under a 300 years return period scenario (selected as baseline) for six identified relevant targets, exposed to flood risk in the Sihl valley, namely: people, economic activities (including buildings, infrastructures and agriculture), natural and semi-natural systems and cultural heritage. Finally, the total risk index map, which allows to identify and rank areas and hotspots at risk by means of Multi Criteria Decision Analysis tools, has been produced to visualize the spatial pattern of flood risk within the area of study. By means of a tailored participative approach, the total risk maps supplement the consideration of technical experts with the (essential) point of view of the relevant stakeholders for the appraisal of the specific scores and weights related to the receptor-relative risks. The total risk maps obtained for the Sihl River case study are associated with the lower classes of risk. In general, higher relative risks are concentrated in the deeply urbanized area within and around the Zurich city centre and areas that rely just behind to the Sihl River course. Here, forecasted injuries and potential fatalities are mainly due to high population density and high presence of old (vulnerable) people; inundated buildings are mainly classified as continuous and discontinuous urban fabric; flooded roads, pathways and railways, the majority of them referring to the Zurich main train station (Hauptbahnhof), are at high risk of inundation, causing huge indirect damages. The analysis of flood risk to agriculture, natural and semi-natural systems and cultural heritage have pointed out that these receptors could be relatively less impacted by the selected flood scenario mainly because their scattered presence. Finally, the application of the KR-RRA methodology to the Sihl River case study as well as to several other sites across Europe (not presented here), has demonstrated its flexibility and possible adaptation to different geographical and socio-economic contexts, depending on data availability and peculiarities of the sites, as well as for other hazard scenarios.

Climate change and Development of a methodological approach for the implementation of a strategy of resilience in the face of floods (Tangier North of Morocco)

NASA Astrophysics Data System (ADS)

Satour, N.; Kassou, N.; Kacimi, I.; BEN-Daoud, M.; Maatouk, M.

2016-12-01

Tangier is one of the 14 priority cities, cited in the National Plan for the fight against the floods in Morocco with the specifics linked to its geographical position and socio-economic factors. The city needs more strategies to improve it response and confidence in front of floods risk. Climate change exacerbates this problem by causing more frequent extreme precipitation events. Several different traditional methods were used to modelling, understanding and anticipating the phenomenon but the urban resilience is studied by few authors in Morocco. The approach should uncover the role of all components of the urban system, economic, institutional and natural. The central aim of this study is to develop a new resilience strategy of urban system of Tangier to floods across temporal and spatial scales to maintain or rapidly return to desired functions in the face of disturbance to adapt to change, and to quickly transform systems that limit current or future adaptive capacity. The Flood resilience index (FRI) is developed as an approach for evaluation of flood resilience using Geographic Information Systems. The research for this study started from the findings and conclusion of Meerow, Sara. 2016 and Batica, Jelena 2015. . Here we seek to introduce the factor "Climate Change" in the forecast scenarios of the resilience of the city by 2030. This suggests additional thinks about flood risks and adaptation strategies in Morocco.

Flood management: prediction of microbial contamination in large-scale floods in urban environments.

PubMed

Taylor, Jonathon; Lai, Ka Man; Davies, Mike; Clifton, David; Ridley, Ian; Biddulph, Phillip

2011-07-01

With a changing climate and increased urbanisation, the occurrence and the impact of flooding is expected to increase significantly. Floods can bring pathogens into homes and cause lingering damp and microbial growth in buildings, with the level of growth and persistence dependent on the volume and chemical and biological content of the flood water, the properties of the contaminating microbes, and the surrounding environmental conditions, including the restoration time and methods, the heat and moisture transport properties of the envelope design, and the ability of the construction material to sustain the microbial growth. The public health risk will depend on the interaction of these complex processes and the vulnerability and susceptibility of occupants in the affected areas. After the 2007 floods in the UK, the Pitt review noted that there is lack of relevant scientific evidence and consistency with regard to the management and treatment of flooded homes, which not only put the local population at risk but also caused unnecessary delays in the restoration effort. Understanding the drying behaviour of flooded buildings in the UK building stock under different scenarios, and the ability of microbial contaminants to grow, persist, and produce toxins within these buildings can help inform recovery efforts. To contribute to future flood management, this paper proposes the use of building simulations and biological models to predict the risk of microbial contamination in typical UK buildings. We review the state of the art with regard to biological contamination following flooding, relevant building simulation, simulation-linked microbial modelling, and current practical considerations in flood remediation. Using the city of London as an example, a methodology is proposed that uses GIS as a platform to integrate drying models and microbial risk models with the local building stock and flood models. The integrated tool will help local governments, health authorities, insurance companies and residents to better understand, prepare for and manage a large-scale flood in urban environments. Copyright © 2011 Elsevier Ltd. All rights reserved.

Comparison of the impacts of urban development and climate change on exposing European cities to pluvial flooding

NASA Astrophysics Data System (ADS)

Skougaard Kaspersen, Per; Høegh Ravn, Nanna; Arnbjerg-Nielsen, Karsten; Madsen, Henrik; Drews, Martin

2017-08-01

The economic and human consequences of extreme precipitation and the related flooding of urban areas have increased rapidly over the past decades. Some of the key factors that affect the risks to urban areas include climate change, the densification of assets within cities and the general expansion of urban areas. In this paper, we examine and compare quantitatively the impact of climate change and recent urban development patterns on the exposure of four European cities to pluvial flooding. In particular, we investigate the degree to which pluvial floods of varying severity and in different geographical locations are influenced to the same extent by changes in urban land cover and climate change. We have selected the European cities of Odense, Vienna, Strasbourg and Nice for analyses to represent different climatic conditions, trends in urban development and topographical characteristics. We develop and apply a combined remote-sensing and flood-modelling approach to simulate the extent of pluvial flooding for a range of extreme precipitation events for historical (1984) and present-day (2014) urban land cover and for two climate-change scenarios (i.e. representative concentration pathways, RCP 4.5 and RCP 8.5). Changes in urban land cover are estimated using Landsat satellite imagery for the period 1984-2014. We combine the remote-sensing analyses with regionally downscaled estimates of precipitation extremes of current and expected future climate to enable 2-D overland flow simulations and flood-hazard assessments. The individual and combined impacts of urban development and climate change are quantified by examining the variations in flooding between the different simulations along with the corresponding uncertainties. In addition, two different assumptions are examined with regards to the development of the capacity of the urban drainage system in response to urban development and climate change. In the stationary approach, the capacity resembles present-day design, while it is updated in the evolutionary approach to correspond to changes in imperviousness and precipitation intensities due to urban development and climate change respectively. For all four cities, we find an increase in flood exposure corresponding to an observed absolute growth in impervious surfaces of 7-12 % during the past 30 years of urban development. Similarly, we find that climate change increases exposure to pluvial flooding under both the RCP 4.5 and RCP 8.5 scenarios. The relative importance of urban development and climate change on flood exposure varies considerably between the cities. For Odense, the impact of urban development is comparable to that of climate change under an RCP 8.5 scenario (2081-2100), while for Vienna and Strasbourg it is comparable to the impacts of an RCP 4.5 scenario. For Nice, climate change dominates urban development as the primary driver of changes in exposure to flooding. The variation between geographical locations is caused by differences in soil infiltration properties, historical trends in urban development and the projected regional impacts of climate change on extreme precipitation. Developing the capacity of the urban drainage system in relation to urban development is found to be an effective adaptation measure as it fully compensates for the increase in run-off caused by additional sealed surfaces. On the other hand, updating the drainage system according to changes in precipitation intensities caused by climate change only marginally reduces flooding for the most extreme events.

Mapping Infected Area after a Flash-Flooding Storm Using Multi Criteria Analysis and Spectral Indices

NASA Astrophysics Data System (ADS)

Al-Akad, S.; Akensous, Y.; Hakdaoui, M.

2017-11-01

This research article is summarize the applications of remote sensing and GIS to study the urban floods risk in Al Mukalla. Satellite acquisition of a flood event on October 2015 in Al Mukalla (Yemen) by using flood risk mapping techniques illustrate the potential risk present in this city. Satellite images (The Landsat and DEM images data were atmospherically corrected, radiometric corrected, and geometric and topographic distortions rectified.) are used for flood risk mapping to afford a hazard (vulnerability) map. This map is provided by applying image-processing techniques and using geographic information system (GIS) environment also the application of NDVI, NDWI index, and a method to estimate the flood-hazard areas. Four factors were considered in order to estimate the spatial distribution of the hazardous areas: flow accumulation, slope, land use, geology and elevation. The multi-criteria analysis, allowing to deal with vulnerability to flooding, as well as mapping areas at the risk of flooding of the city Al Mukalla. The main object of this research is to provide a simple and rapid method to reduce and manage the risks caused by flood in Yemen by take as example the city of Al Mukalla.

Developments in remote sensing technology enable more detailed urban flood risk analysis.

NASA Astrophysics Data System (ADS)

Denniss, A.; Tewkesbury, A.

2009-04-01

Spaceborne remote sensors have been allowing us to build up a profile of planet earth for many years. With each new satellite launched we see the capabilities improve: new bands of data, higher resolution imagery, the ability to derive better elevation information. The combination of this geospatial data to create land cover and usage maps, all help inform catastrophe modelling systems. From Landsat 30m resolution to 2.44m QuickBird multispectral imagery; from 1m radar data collected by TerraSAR-X which enables rapid tracking of the rise and fall of a flood event, and will shortly have a twin satellite launched enabling elevation data creation; we are spoilt for choice in available data. However, just what is cost effective? It is always a question of choosing the appropriate level of input data detail for modelling, depending on the value of the risk. In the summer of 2007, the cost of the flooding in the UK was approximately £3bn and affected over 58,000 homes and businesses. When it comes to flood risk, we have traditionally considered rising river levels and surge tides, but with climate change and variations in our own construction behaviour, there are other factors to be taken into account. During those summer 2007 events, the Environment Agency suggested that around 70% of the properties damaged were the result of pluvial flooding, where high localised rainfall events overload localised drainage infrastructure, causing widespread flooding of properties and infrastructure. To create a risk model that is able to simulate such an event requires much more accurate source data than can be provided from satellite or radar. As these flood events cause considerable damage within relatively small, complex urban environments, therefore new high resolution remote sensing techniques have to be applied to better model these events. Detailed terrain data of England and Wales, plus cities in Scotland, have been produced by combining terrain measurements from the latest digital airborne sensors, both optical and lidar, to produce the input layer for surface water flood modelling. A national flood map product has been created. The new product utilises sophisticated modelling techniques, perfected over many years, which harness graphical processing power. This product will prove particularly valuable for risk assessment decision support within insurance/reinsurance, property/environmental, utilities, risk management and government agencies. However, it is not just the ground elevation that determines the behaviour of surface water. By combining height information (surface and terrain) with high resolution aerial photography and colour infrared imagery, a high definition land cover mapping dataset (LandBase) is being produced, which provides a precise measure of sealed versus non sealed surface. This will allows even more sophisticated modelling of flood scenarios. Thus, the value of airborne survey data can be demonstrated by flood risk analysis down to individual addresses in urban areas. However for some risks, an even more detailed survey may be justified. In order to achieve this, Infoterra is testing new 360˚ mobile lidar technology. Collecting lidar data from a moving vehicle allows each street to be mapped in very high detail, allowing precise information about the location, size and shape of features such as kerbstones, gullies, road camber and building threshold level to be captured quickly and accurately. These data can then be used to model the problem of overland flood risk at the scale of individual properties. Whilst at present it might be impractical to undertake such detailed modelling for all properties, these techniques can certainly be used to improve the flood risk analysis of key locations. This paper will demonstrate how these new high resolution remote sensing techniques can be combined to provide a new resolution of detail to aid urban flood modelling.

Main drivers of flood-risk dynamics along the Po River

NASA Astrophysics Data System (ADS)

Domeneghetti, Alessio; Carisi, Francesca; Castellarin, Attilio; Brath, Armando

2017-04-01

The increasing frequency with which floods damages are recorded, or reported by media, strengthen the common perception that the flood risk is dramatically increasing in Europe and other areas of the world, due to a combination of different causes, among which climate change is often described as the major factor. However, there is a growing awareness of how anthropogenic pressures, such as uncontrolled urban and industrial expansion on flood-prone areas, may strongly impact the evolution of flood-risk in a given area, increasing potential flood damages and losses. Starting from these considerations, our study aims at shedding some light on the impact and relative importance of different factors controlling the flood risk. Focusing in particular on the middle-lower portion of the River Po, we analyze the evolution of flood hazard in the last half century referring to long streamflow series for different gauging stations located along the study reach ( 450 km), while the modification of anthropogenic pressure is evaluated by referring to land-use and demographic dynamics observed from 1950s. Our study proposes simplified flood-vulnerability indices to be used for large scale flood-risk assessments and, on the basis of these indices, (1) we assess the importance of the different elements contributing to the definition of flood risk and (2) represent the evolution of flood risk in time along the middle and lower portion of the River Po.

Influence of urban land cover changes and climate change for the exposure of European cities to flooding during high-intensity precipitation

NASA Astrophysics Data System (ADS)

Skougaard Kaspersen, P.; Høegh Ravn, N.; Arnbjerg-Nielsen, K.; Madsen, H.; Drews, M.

2015-06-01

The extent and location of impervious surfaces within urban areas due to past and present city development strongly affects the amount and velocity of run-off during high-intensity rainfall and consequently influences the exposure of cities towards flooding. The frequency and intensity of extreme rainfall are expected to increase in many places due to climate change and thus further exacerbate the risk of pluvial flooding. This paper presents a combined hydrological-hydrodynamic modelling and remote sensing approach suitable for examining the susceptibility of European cities to pluvial flooding owing to recent changes in urban land cover, under present and future climatic conditions. Estimated changes in impervious urban surfaces based on Landsat satellite imagery covering the period 1984-2014 are combined with regionally downscaled estimates of current and expected future rainfall extremes to enable 2-D overland flow simulations and flood hazard assessments. The methodology is evaluated for the Danish city of Odense. Results suggest that the past 30 years of urban development alone has increased the city's exposure to pluvial flooding by 6% for 10-year rainfall up to 26% for 100-year rainfall. Corresponding estimates for RCP4.5 and RCP8.5 climate change scenarios (2071-2100) are in the order of 40 and 100%, indicating that land cover changes within cities can play a central role for the cities' exposure to flooding and conversely also for their adaptation to a changed climate.

Assess the flood resilience tools integration in the landuse projects

NASA Astrophysics Data System (ADS)

Moulin, E.; Deroubaix, J.-F.

2012-04-01

Despite a severe regulation concerning the building in flooding areas, 80% of these areas are already built in the Greater Paris (Paris, Val-de-Marne, Hauts-de-Seine and Seine-Saint-Denis). The land use in flooding area is presented as one of the main solutions to solve the ongoing real estate pressure. For instance some of the industrial wastelands located along the river are currently in redevelopment and residential buildings are planned. So the landuse in the flooding areas is currently a key issue in the development of the Greater Paris area. To deal with floods there are some resilience tools, whether structural (such as perimeter barriers or building aperture barriers, etc) or non structural (such as warning systems, etc.). The technical solutions are available and most of the time efficient1. Still, we notice that these tools are not much implemented. The people; stakeholders and inhabitants, literally seems to be not interested. This papers focus on the integration of resilience tools in urban projects. Indeed one of the blockages in the implementation of an efficient flood risk prevention policy is the lack of concern of the landuse stakeholders and the inhabitants for the risk2. We conducted an important number of interviews with stakeholders involved in various urban projects and we assess, in this communication, to what extent the improvement of the resilience to floods is considered as a main issue in the execution of an urban project? How this concern is maintained or could be maintained throughout the project. Is there a dilution of this concern? In order to develop this topic we rely on a case study. The "Ardoines" is a project aiming at redeveloping an industrial site (South-East Paris), into a project including residential and office buildings and other amenities. In order to elaborate the master plan, the urban planning authority brought together some flood risk experts. According to the comments of the experts, the architect in charge of the landuse elaborated the master plan taking into account the flood risk; reducing vulnerability of the area and improving the resilience in case of floods, towards a threshold plan. We set this case-study back in the French policy context of prevention and protection against floods and in the context of the Greater Paris development. There are two levels of problems: In the case of the Ardoines project, the reduction of vulnerability isn't linked with the improvement of the resilience. Indeed, the stakeholders do not envisage an event worst than the 100-years flood return period, the one taken into account in a flood prevention plan. The regulation is the guide for construction rules but there is no consideration for the crisis management. Moreover, the reduction of vulnerability appears less important than the economical issues in the management of a project. This case study illustrates how the lack of awareness for territorial resilience issues and the lack of interest for flood resilience tools are embedded in the "governance" of the risk in the greater Paris area.

Risk assessment of flash floods in central Pyrenees (Spain) through land use change analysis

NASA Astrophysics Data System (ADS)

Serrano-Notivoli, Roberto; Mora, Daniel; Sánchez-Fabre, Miguel; Ángel Saz, Miguel; Ollero, Alfredo

2015-04-01

Nowadays, the main cause of the damages to human areas is the increased risk exposure. The urbanization in touristic areas in Pyrenees has increased enormously in last 25 years, and the most of urban development have been made on land occupied by the stream channel. We present two different case studies in central Pyrenees: one in Aragón river and one in Ésera river. We made a land use analysis from 1956 to 2013 in the headwaters of these two rivers delimiting the channel in different flash floods events, and analysing the amount and distribution of precipitation at the same time. The results show that the risk exposure is one of the main factors of the impact of flash floods. We found that most of the damage on urbanization and human activities was caused by the urban occupation of areas that were located on the floodplain of the river. For both Aragon and Esera headwaters precipitation events were considered extreme in their time series. However, the amount of precipitation of these extreme events does not support the consequences in geomorphological and human environments. The events of high intensity rainfall over the last years could be expected, yet, it had unexpected consequences that could be predictable by land managers through an appropriate regional planning.

Calibration and validation of a small-scale urban surface water flood event using crowdsourced images

NASA Astrophysics Data System (ADS)

Green, Daniel; Yu, Dapeng; Pattison, Ian

2017-04-01

Surface water flooding occurs when intense precipitation events overwhelm the drainage capacity of an area and excess overland flow is unable to infiltrate into the ground or drain via natural or artificial drainage channels, such as river channels, manholes or SuDS. In the UK, over 3 million properties are at risk from surface water flooding alone, accounting for approximately one third of the UK's flood risk. The risk of surface water flooding is projected to increase due to several factors, including population increases, land-use alterations and future climatic changes in precipitation resulting in an increased magnitude and frequency of intense precipitation events. Numerical inundation modelling is a well-established method of investigating surface water flood risk, allowing the researcher to gain a detailed understanding of the depth, velocity, discharge and extent of actual or hypothetical flood scenarios over a wide range of spatial scales. However, numerical models require calibration of key hydrological and hydraulic parameters (e.g. infiltration, evapotranspiration, drainage rate, roughness) to ensure model outputs adequately represent the flood event being studied. Furthermore, validation data such as crowdsourced images or spatially-referenced flood depth collected during a flood event may provide a useful validation of inundation depth and extent for actual flood events. In this study, a simplified two-dimensional inertial based flood inundation model requiring minimal pre-processing of data (FloodMap-HydroInundation) was used to model a short-duration, intense rainfall event (27.8 mm in 15 minutes) that occurred over the Loughborough University campus on the 28th June 2012. High resolution (1m horizontal, +/- 15cm vertical) DEM data, rasterised Ordnance Survey topographic structures data and precipitation data recorded at the University weather station were used to conduct numerical modelling over the small (< 2km2), contained urban catchment. To validate model outputs and allow a reconstruction of spatially referenced flood depth and extent during the flood event, crowdsourced images were obtained from social media (Twitter) and from individuals present during the flood event via the University noticeboards, as well as using dGPS flood depth data collected at one of the worst affected areas. An investigation into the sensitivity of key model parameters suggests that the numerical model code is highly sensitivity to changes within the recommended range of roughness and infiltration values, as well as changes in DEM and building mesh resolutions, but less sensitive to changes in evapotranspiration and drainage capacity parameters. The study also demonstrates the potential of using crowdsourced images to validate urban surface water flood models and inform parameterisation when calibrating numerical inundation models.

BN-FLEMOps pluvial - A probabilistic multi-variable loss estimation model for pluvial floods

NASA Astrophysics Data System (ADS)

Roezer, V.; Kreibich, H.; Schroeter, K.; Doss-Gollin, J.; Lall, U.; Merz, B.

2017-12-01

Pluvial flood events, such as in Copenhagen (Denmark) in 2011, Beijing (China) in 2012 or Houston (USA) in 2016, have caused severe losses to urban dwellings in recent years. These floods are caused by storm events with high rainfall rates well above the design levels of urban drainage systems, which lead to inundation of streets and buildings. A projected increase in frequency and intensity of heavy rainfall events in many areas and an ongoing urbanization may increase pluvial flood losses in the future. For an efficient risk assessment and adaptation to pluvial floods, a quantification of the flood risk is needed. Few loss models have been developed particularly for pluvial floods. These models usually use simple waterlevel- or rainfall-loss functions and come with very high uncertainties. To account for these uncertainties and improve the loss estimation, we present a probabilistic multi-variable loss estimation model for pluvial floods based on empirical data. The model was developed in a two-step process using a machine learning approach and a comprehensive database comprising 783 records of direct building and content damage of private households. The data was gathered through surveys after four different pluvial flood events in Germany between 2005 and 2014. In a first step, linear and non-linear machine learning algorithms, such as tree-based and penalized regression models were used to identify the most important loss influencing factors among a set of 55 candidate variables. These variables comprise hydrological and hydraulic aspects, early warning, precaution, building characteristics and the socio-economic status of the household. In a second step, the most important loss influencing variables were used to derive a probabilistic multi-variable pluvial flood loss estimation model based on Bayesian Networks. Two different networks were tested: a score-based network learned from the data and a network based on expert knowledge. Loss predictions are made through Bayesian inference using Markov chain Monte Carlo (MCMC) sampling. With the ability to cope with incomplete information and use expert knowledge, as well as inherently providing quantitative uncertainty information, it is shown that loss models based on BNs are superior to deterministic approaches for pluvial flood risk assessment.

A simple statistical method for analyzing flood susceptibility with incorporating rainfall and impervious surface

NASA Astrophysics Data System (ADS)

Chiang, Shou-Hao; Chen, Chi-Farn

2016-04-01

Flood, as known as the most frequent natural hazard in Taiwan, has induced severe damages of residents and properties in urban areas. The flood risk is even more severe in Tainan since 1990s, with the significant urban development over recent decades. Previous studies have indicated that the characteristics and the vulnerability of flood are affected by the increase of impervious surface area (ISA) and the changing climate condition. Tainan City, in southern Taiwan is selected as the study area. This study uses logistic regression to functionalize the relationship between rainfall variables, ISA and historical flood events. Specifically, rainfall records from 2001 to 2014 were collected and mapped, and Landsat images of year 2001, 2004, 2007, 2010 and 2014 were used to generate the ISA with SVM (support vector machine) classifier. The result shows that rainfall variables and ISA are significantly correlated to the flood occurrence in Tainan City. With applying the logistic function, the likelihood of flood occurrence can be estimated and mapped over the study area. This study suggests the method is simple and feasible for rapid flood susceptibility mapping, when real-time rainfall observations can be available, and it has potential for future flood assessment, with incorporating climate change projections and urban growth prediction.

Flood Hazard and Risk Analysis in Urban Area

NASA Astrophysics Data System (ADS)

Huang, Chen-Jia; Hsu, Ming-hsi; Teng, Wei-Hsien; Lin, Tsung-Hsien

2017-04-01

Typhoons always induce heavy rainfall during summer and autumn seasons in Taiwan. Extreme weather in recent years often causes severe flooding which result in serious losses of life and property. With the rapid industrial and commercial development, people care about not only the quality of life, but also the safety of life and property. So the impact of life and property due to disaster is the most serious problem concerned by the residents. For the mitigation of the disaster impact, the flood hazard and risk analysis play an important role for the disaster prevention and mitigation. In this study, the vulnerability of Kaohsiung city was evaluated by statistics of social development factor. The hazard factors of Kaohsiung city was calculated by simulated flood depth of six different return periods and four typhoon events which result in serious flooding in Kaohsiung city. The flood risk can be obtained by means of the flood hazard and social vulnerability. The analysis results provide authority to strengthen disaster preparedness and to set up more resources in high risk areas.

Next generation paradigm for urban pluvial flood modelling, prediction, management and vulnerability reduction - Interaction between RainGain and Blue Green Dream projects

NASA Astrophysics Data System (ADS)

Maksimovic, C.

2012-04-01

The effects of climate change and increasing urbanisation call for a new paradigm for efficient planning, management and retrofitting of urban developments to increase resilience to climate change and to maximize ecosystem services. Improved management of urban floods from all sources in required. Time scale for well documented fluvial and coastal floods allows for timely response but surface (pluvial) flooding caused by intense local storms had not been given appropriate attention, Pitt Review (UK). Urban surface floods predictions require fine scale data and model resolutions. They have to be tackled locally by combining central inputs (meteorological services) with the efforts of the local entities. Although significant breakthrough in modelling of pluvial flooding was made there is a need to further enhance short term prediction of both rainfall and surface flooding. These issues are dealt with in the EU Iterreg project Rain Gain (RG). Breakthrough in urban flood mitigation can only be achieved by combined effects of advanced planning design, construction and management of urban water (blue) assets in interaction with urban vegetated areas' (green) assets. Changes in design and operation of blue and green assets, currently operating as two separate systems, is urgently required. Gaps in knowledge and technology will be introduced by EIT's Climate-KIC Blue Green Dream (BGD) project. The RG and BGD projects provide synergy of the "decoupled" blue and green systems to enhance multiple benefits to: urban amenity, flood management, heat island, biodiversity, resilience to drought thus energy requirements, thus increased quality of urban life at lower costs. Urban pluvial flood management will address two priority areas: Short Term rainfall Forecast and Short term flood surface forecast. Spatial resolution of short term rainfall forecast below 0.5 km2 and lead time of a few hours are needed. Improvements are achievable by combining data sources of raingauge networks with C-Band and X-Band radars with NWP and pluvial flood prediction models. The RG project deals with the merging and providing synergy of these technologies. Combined effects of BG technologies can totally reduce the risk of surface flooding for low return period events and up to 50-80% for high return periods. Demonstration technology testing sites for both BGD and RG projects will be established in 5 participating countries. Decision Support Systems will enhance full scale implementation of both BGD and RG project deliverables. A BGD efficiency rating scheme and training guidelines and e-learning tools will be developed. Experimental/demo sites for BDG and RG technology development and testing in Rotterdam, Paris, Berlin, Leuven and London and the expected results with concepts of RG and BGD projects and the initial results will be presented in the paper.

Vulnerability Assessment Using LIDAR Data in Silang-Sta Rosa Subwatershed, Philippines

NASA Astrophysics Data System (ADS)

Bragais, M. A.; Magcale-Macandog, D. B.; Arizapa, J. L.; Manalo, K. M.

2016-10-01

Silang-Sta. Rosa Subwatershed is experiencing rapid urbanization. Its downstream area is already urbanized and the development is moving fast upstream. With the rapid land conversion of pervious to impervious areas and increase frequency of intense rainfall events, the downstream of the watershed is at risk of flood hazard. The widely used freeware HEC-RAS (Hydrologic Engineering Center- River Analysis System) model was used to implement the 2D unsteady flow analysis to develop a flood hazard map. The LiDAR derived digital elevation model (DEM) with 1m resolution provided detailed terrain that is vital for producing reliable flood extent map that can be used for early warning system. With the detailed information from the simulation like areas to be flooded, the predicted depth and duration, we can now provide specific flood forecasting and mitigation plan even at community level. The methodology of using 2D unsteady flow modelling and high resolution DEM in a watershed can be replicated to other neighbouring watersheds specially those areas that are not yet urbanized so that their development will be guided to be flood hazard resilient. LGUs all over the country will benefit from having a high resolution flood hazard map.

Evaluation of low impact development approach for mitigating flood inundation at a watershed scale in China.

PubMed

Hu, Maochuan; Sayama, Takahiro; Zhang, Xingqi; Tanaka, Kenji; Takara, Kaoru; Yang, Hong

2017-05-15

Low impact development (LID) has attracted growing attention as an important approach for urban flood mitigation. Most studies evaluating LID performance for mitigating floods focus on the changes of peak flow and runoff volume. This paper assessed the performance of LID practices for mitigating flood inundation hazards as retrofitting technologies in an urbanized watershed in Nanjing, China. The findings indicate that LID practices are effective for flood inundation mitigation at the watershed scale, and especially for reducing inundated areas with a high flood hazard risk. Various scenarios of LID implementation levels can reduce total inundated areas by 2%-17% and areas with a high flood hazard level by 6%-80%. Permeable pavement shows better performance than rainwater harvesting against mitigating urban waterlogging. The most efficient scenario is combined rainwater harvesting on rooftops with a cistern capacity of 78.5 mm and permeable pavement installed on 75% of non-busy roads and other impervious surfaces. Inundation modeling is an effective approach to obtaining the information necessary to guide decision-making for designing LID practices at watershed scales. Copyright © 2017 Elsevier Ltd. All rights reserved.

Assessing Current and Future Freshwater Flood Risk from North Atlantic Tropical Cyclones via Insurance Claims

NASA Astrophysics Data System (ADS)

Czajkowski, Jeffrey; Villarini, Gabriele; Montgomery, Marilyn; Michel-Kerjan, Erwann; Goska, Radoslaw

2017-02-01

The most recent decades have witnessed record breaking losses associated with U.S. landfalling tropical cyclones (TCs). Flood-related damages represent a large portion of these losses, and although storm surge is typically the main focus in the media and of warnings, much of the TC flood losses are instead freshwater-driven, often extending far inland from the landfall locations. Despite this actuality, knowledge of TC freshwater flood risk is still limited. Here we provide for the first time a comprehensive assessment of the TC freshwater flood risk from the full set of all significant flood events associated with U.S. landfalling TCs from 2001 to 2014. We find that the areas impacted by freshwater flooding are nearly equally divided between coastal and inland areas. We determine the statistical relationship between physical hazard and residential economic impact at a community level for the entire country. These results allow us to assess the potential future changes in TC freshwater flood risk due to changing climate pattern and urbanization in a more heavily populated U.S. Findings have important implications for flood risk management, insurance and resilience.

Assessing Current and Future Freshwater Flood Risk from North Atlantic Tropical Cyclones via Insurance Claims

PubMed Central

Czajkowski, Jeffrey; Villarini, Gabriele; Montgomery, Marilyn; Michel-Kerjan, Erwann; Goska, Radoslaw

2017-01-01

The most recent decades have witnessed record breaking losses associated with U.S. landfalling tropical cyclones (TCs). Flood-related damages represent a large portion of these losses, and although storm surge is typically the main focus in the media and of warnings, much of the TC flood losses are instead freshwater-driven, often extending far inland from the landfall locations. Despite this actuality, knowledge of TC freshwater flood risk is still limited. Here we provide for the first time a comprehensive assessment of the TC freshwater flood risk from the full set of all significant flood events associated with U.S. landfalling TCs from 2001 to 2014. We find that the areas impacted by freshwater flooding are nearly equally divided between coastal and inland areas. We determine the statistical relationship between physical hazard and residential economic impact at a community level for the entire country. These results allow us to assess the potential future changes in TC freshwater flood risk due to changing climate pattern and urbanization in a more heavily populated U.S. Findings have important implications for flood risk management, insurance and resilience. PMID:28148952

A Framework and Metric for resilience concept in water infrastructure

NASA Astrophysics Data System (ADS)

Karamouz, M.; Olyaei, M.

2017-12-01

The collaborators of water industries are looking for ways and means to bring resilience into our water infrastructure systems. The key to this conviction is to develop a shared vision among the engineers, builders and decision makers of our water executive branch and policy makers, utilities, community leaders, players, end users and other stakeholders of our urban environment. Among water infrastructures, wastewater treatment plants (WWTP) have a significant role on urban systems' serviceability. These facilities, especially when located in coastal regions, are vulnerable to heavy rain, surface runoff, storm surges and coastal flooding. Flooding can cause overflows from treatment facilities into the natural water bodies and result in environmental predicament of significant proportions. In order to minimize vulnerability to flood, a better understanding of flood risk must be realized. Vulnerability to floods frequency and intensity is increasing by external forcing such as climate change, as well as increased interdependencies in urban systems. Therefore, to quantify the extent of efforts for flood risk management, a unified index is needed for evaluating resiliency of infrastructure. Resiliency is a key concept in understanding vulnerability in dealing with flood. New York City based on its geographic location, its urbanized nature, densely populated area, interconnected water bodies and history of the past flooding events is extremely vulnerable to flood and was selected as the case study. In this study, a framework is developed to evaluate resiliency of WWTPs. An analysis of the current understanding of vulnerability is performed and a new perspective utilizing different components of resiliency including resourcefulness, robustness, rapidity and redundancy is presented. To quantify resiliency and rank the wastewater treatment plants in terms of how resilient they are, an index is developed using Multi Criteria Decision Making (MCDM) technique. Moreover, Improvement of WWTPs' performance is investigated by allocating financial resources to attain a desirable level of resiliency. The result of this study shows the significant value of quantifying and improving flood resiliency of WWTPs that could be used for other water infrastructure and in planning of investment strategies for a region

Economic assessment of climate adaptation options for urban drainage design in Odense, Denmark.

PubMed

Zhou, Q; Halsnæs, K; Arnbjerg-Nielsen, K

2012-01-01

Climate change is likely to influence the water cycle by changing the precipitation patterns, in some cases leading to increased occurrences of precipitation extremes. Urban landscapes are vulnerable to such changes due to the concentrated population and socio-economic values in cities. Feasible adaptation requires better flood risk quantification and assessment of appropriate adaptation actions in term of costs and benefits. This paper presents an economic assessment of three prevailing climate adaptation options for urban drainage design in a Danish case study, Odense. A risk-based evaluation framework is used to give detailed insights of the physical and economic feasibilities of each option. Estimation of marginal benefits of adaptation options are carried out through a step-by-step cost-benefit analysis. The results are aimed at providing important information for decision making on how best to adapt to urban pluvial flooding due to climate impacts in cities.

Cities and Sea Level Rise: A Roadmap for Flood Hazard Adaptation

NASA Astrophysics Data System (ADS)

Horn, D. P.; Cousins, A.

2015-12-01

Coastal cities will face a range of increasingly severe challenges as sea level rises, and adaptation to future flood risk will require more than structural defences. Many cities will not be able to rely solely on engineering structures for protection and will need to develop a suite of policy responses to increase their resilience to impacts of rising sea level. Local governments generally maintain day-to-day responsibility and control over the use of the vast majority of property at risk of flooding, and the tools to promote flood risk adaptation are already within the capacity of most cities. Policy tools available to address other land-use problems can be refashioned and used to adapt to sea level rise. This study reviews approaches for urban adaptation through case studies of cities which have developed flood adaptation strategies that combine structural defences with innovative approaches to living with flood risk. The aim of the overall project is to produce a 'roadmap' to guide practitioners through the process of analysing coastal flood risk in urban areas. Technical knowledge of flood risk reduction measures is complemented with a consideration of the essential impact that local policy has on the treatment of coastal flooding and the constraints and opportunities that result from the specific country or locality characteristics in relation to economic, political, social and environmental priorities, which are likely to dictate the approach to coastal flooding and the actions proposed. Detailed analyses of the adaptation strategies used by Rotterdam (Netherlands), Bristol (UK), and Norfolk (Virginia) are used to draw out a range of good practice elements that promote effective adaptation to sea level rise. These can be grouped into risk reduction, governance issues, and insurance, and can be used to provide examples of how other cities could adopt and implement flood adaptation strategies from a relatively limited starting position. Most cities will neither be able to defend all areas nor retreat entirely and will need to make a decision to retreat from certain locations or to relocate particular assets in areas at lower risk. We identify a series of specific questions which should be answered by city managers when selecting the most appropriate response for a particular location.

Hurricane Sandy: Caught in the eye of the storm and a city's adaptation response

NASA Astrophysics Data System (ADS)

Orton, P. M.; Horton, R. M.; Blumberg, A. F.; Rosenzweig, C.; Solecki, W.; Bader, D.

2015-12-01

The NOAA RISA program has funded the seven-institution Consortium for Climate Risk in the Urban Northeast (CCRUN) for the past five years to serve stakeholder needs in assessing and managing risks from climate variability and change. When Hurricane Sandy struck, we were in an ideal position, making flood forecasts and communicating NOAA forecasts to the public with dozens of media placements, translating the poorly understood flood forecasts into human dimensions. In 2013 and 2015, by request of New York City (NYC), we worked through the NYC Panel on Climate Change to deliver updated climate risk assessment reports, to be used in the post-Sandy rebuilding and resiliency efforts. These utilized innovative methodologies for probabilistic local and regional sea level change projections, and contrasted methods of dynamic versus (the more common) static flood mapping. We participated in a federal-academic partnership that developed a Sea Level Tool for Sandy Recovery that integrates CCRUN sea level rise projections with policy-relevant FEMA flood maps, and now several updated flood maps and coastal flood mapping tools (NOAA, FEMA, and USACE) incorporate our projections. For the adaptation response, we helped develop NYC's $20 billion flood adaptation plan, and we were on a winning team under the Housing and Urban Development Rebuild By Design (RBD) competition, a few of the many opportunities that arose with negligible additional funding and which CCRUN funds supported. Our work at times disrupted standard lines of thinking, but NYC showed an openness to altering course. In one case we showed that an NYC plan of wetland restoration in Jamaica Bay would provide no reduction in flooding unless deep-dredged channels circumventing them were shallowed or narrowed. In another, the lead author's RBD team challenged the notion at one location that levees were the solution to accelerating sea level rise, developing a plan to use ecological breakwaters and layered components of physical and social resilience. CCRUN has succeeded in winning another five years of RISA funding, and this will enable us to continue our climate risk and adaptation work for the entire Urban Northeast.

The urban forest and ecosystem services: impact on urban water, heat, and pollution cycles at the tree, street, and city scale

Treesearch

S. J. Livesley; E. G. McPherson; C. Calfapietra

2016-01-01

Many environmental challenges are exacerbated within the urban landscape, such as stormwater runoff and flood risk, chemical and particulate pollution of urban air, soil and water, the urban heat island, and summer heat waves. Urban trees, and the urban forest as a whole, can be managed to have an impact on the urban water, heat, carbon and pollution cycles. However,...

Flood risk analysis and adaptive strategy in context of uncertainties: a case study of Nhieu Loc Thi Nghe Basin, Ho Chi Minh City

NASA Astrophysics Data System (ADS)

Ho, Long-Phi; Chau, Nguyen-Xuan-Quang; Nguyen, Hong-Quan

2013-04-01

The Nhieu Loc - Thi Nghe basin is the most important administrative and business area of Ho Chi Minh City. Due to system complexity of the basin such as the increasing trend of rainfall intensity, (tidal) water level and land subsidence, the simulation of hydrological, hydraulic variables for flooding prediction seems rather not adequate in practical projects. The basin is still highly vulnerable despite of multi-million USD investment for urban drainage improvement projects since the last decade. In this paper, an integrated system analysis in both spatial and temporal aspects based on statistical, GIS and modelling approaches has been conducted in order to: (1) Analyse risks before and after projects, (2) Foresee water-related risk under uncertainties of unfavourable driving factors and (3) Develop a sustainable flood risk management strategy for the basin. The results show that given the framework of risk analysis and adaptive strategy, certain urban developing plans in the basin must be carefully revised and/or checked in order to reduce the highly unexpected loss in the future

The Ischia island flash flood of November 2009 (Italy): Phenomenon analysis and flood hazard

NASA Astrophysics Data System (ADS)

Santo, A.; Di Crescenzo, G.; Del Prete, S.; Di Iorio, L.

The island of Ischia is particularly susceptible to landslides and flash floods due to its particular geological and geomorphological context. Urbanization in recent decades coupled with the development of tourism has increased the risk. After the November 10, 2009 event occurring in the northern sector of the island (the town of Casamicciola), a detailed geo-morphological survey was conducted to ascertain the evolution of the phenomenon. In the watersheds upstream of Casamicciola, many landslides were mapped and the volume of material involved during detachment and sliding was estimated. In the lower course area, near the town and towards the sea, flow pathways were reconstructed with the aid of extensive video footage taken during the event. Rainfall data were also analyzed and a relationship was established between the hourly rainfall rate and the flash flood. The phenomenon was found to be quite complex, with many upstream landslides stopping before reaching the urban area. In the lower course the alluvial event occurred as a flood with a very small sediment discharge, which left a very thin layer of sediment. Reconstruction of the flash flood phenomenon suggested possible action for future risk mitigation, early warning and civil protection plans.

Community Based Flood Modeling in Southern and Baja California to Meet End User Needs for Decision-Making

NASA Astrophysics Data System (ADS)

Sanders, B. F.

2017-12-01

Flooding of coastal and fluvial systems are the most significant natural hazards facing society, and damages have been escalating for decades globally and in the U.S. Almost all metropolitan areas are exposed to flood risk. The threat from river flooding is especially high in India and China, and coastal cities around the world are threatened by storm surge and rising sea levels. Several trends including rising sea levels, urbanization, deforestation, and rural-to-urban population shifts will increase flood exposure in the future. Flood impacts are escalating despite advances in hazards science and extensive effort to manage risks. The fundamental issue is not that flooding is becoming more severe, even though it is in some places, but rather that societies are become more vulnerable to flood impacts. A critical factor contributing to the escalation of flood impacts is that the most vulnerable sectors of communities are left out of processes to prepare for and respond to flooding. Furthermore, the translation of knowledge about flood hazards and vulnerabilities into actionable information for communities has not been effective. In Southern and Baja California, an interdisciplinary team of researchers has partnered with stakeholders in flood vulnerable communities to co-develop flood hazard information systems designed to meet end-user needs for decision-making. The initiative leveraged the power of advanced, fine-scale hydraulic models of flooding to craft intuitive visualizations of context-sensitive scenarios. This presentation will cover the ways by which the process of flood inundation modeling served as a focal point for knowledge development, as well as the unique visualizations that populate on-line information systems accessible here: http://floodrise.uci.edu/online-flood-hazard-viewers/

Perceptions of Risk and Vulnerability Following Exposure to a Major Natural Disaster: The Calgary Flood of 2013.

PubMed

Tanner, Alexa; Árvai, Joseph

2018-03-01

Many studies have examined the general public's flood risk perceptions in the aftermath of local and regional flooding. However, relatively few studies have focused on large-scale events that affect tens of thousands of people within an urban center. Similarly, in spite of previous research on flood risks, unresolved questions persist regarding the variables that might influence perceptions of risk and vulnerability, along with management preferences. In light of the opportunities presented by these knowledge gaps, the research reported here examined public perceptions of flood risk and vulnerability, and management preferences, within the city of Calgary in the aftermath of extensive flooding in 2013. Our findings, which come from an online survey of residents, reveal that direct experience with flooding is not a differentiating factor for risk perceptions when comparing evacuees with nonevacuees who might all experience future risks. However, we do find that judgments about vulnerability-as a function of how people perceive physical distance-do differ according to one's evacuation experience. Our results also indicate that concern about climate change is an important predictor of flood risk perceptions, as is trust in government risk managers. In terms of mitigation preferences, our results reveal differences in support for large infrastructure projects based on whether respondents feel they might actually benefit from them. © 2017 Society for Risk Analysis.

Rehabilitation and Flood Management Planning in a Steep, Boulder-Bedded Stream

NASA Astrophysics Data System (ADS)

Caruso, Brian S.; Downs, Peter W.

2007-08-01

This study demonstrates the integration of rehabilitation and flood management planning in a steep, boulder-bedded stream in a coastal urban catchment on the South Island of New Zealand. The Water of Leith, the primary stream flowing through the city of Dunedin, is used as a case study. The catchment is steep, with a short time of concentration and rapid hydrologic response, and the lower stream reaches are highly channelized with floodplain encroachment, a high potential for debris flows, significant flood risks, and severely degraded aquatic habitat. Because the objectives for rehabilitation and flood management in urban catchments are often conflicting, a number of types of analyses at both the catchment and the reach scales and careful planning with stakeholder consultation were needed for successful rehabilitation efforts. This included modeling and analysis of catchment hydrology, fluvial geomorphologic assessment, analysis of water quality and aquatic ecology, hydraulic modeling and flood risk evaluation, detailed feasibility studies, and preliminary design to optimize multiple rehabilitation and flood management objectives. The study showed that all of these analyses were needed for integrated rehabilitation and flood management and that some incremental improvements in stream ecological health, aesthetics, and public recreational opportunities could be achieved in this challenging environment. These methods should be considered in a range of types of stream rehabilitation projects.

The Efficacy of Blue-Green Infrastructure for Pluvial Flood Prevention under Conditions of Deep Uncertainty

NASA Astrophysics Data System (ADS)

Babovic, Filip; Mijic, Ana; Madani, Kaveh

2017-04-01

Urban areas around the world are growing in size and importance; however, cities experience elevated risks of pluvial flooding due to the prevalence of impermeable land surfaces within them. Urban planners and engineers encounter a great deal of uncertainty when planning adaptations to these flood risks, due to the interaction of multiple factors such as climate change and land use change. This leads to conditions of deep uncertainty. Blue-Green (BG) solutions utilise natural vegetation and processes to absorb and retain runoff while providing a host of other social, economic and environmental services. When utilised in conjunction with Decision Making under Deep Uncertainty (DMDU) methodologies, BG infrastructure provides a flexible and adaptable method of "no-regret" adaptation; resulting in a practical, economically efficient, and socially acceptable solution for flood risk mitigation. This work presents the methodology for analysing the impact of BG infrastructure in the context of the Adaptation Tipping Points approach to protect against pluvial flood risk in an iterative manner. An economic analysis of the adaptation pathways is also conducted in order to better inform decision-makers on the benefits and costs of the adaptation options presented. The methodology was applied to a case study in the Cranbrook Catchment in the North East of London. Our results show that BG infrastructure performs better under conditions of uncertainty than traditional grey infrastructure.

1D and 2D urban dam-break flood modelling in Istanbul, Turkey

NASA Astrophysics Data System (ADS)

Ozdemir, Hasan; Neal, Jeffrey; Bates, Paul; Döker, Fatih

2014-05-01

Urban flood events are increasing in frequency and severity as a consequence of several factors such as reduced infiltration capacities due to continued watershed development, increased construction in flood prone areas due to population growth, the possible amplification of rainfall intensity due to climate change, sea level rise which threatens coastal development, and poorly engineered flood control infrastructure (Gallegos et al., 2009). These factors will contribute to increased urban flood risk in the future, and as a result improved modelling of urban flooding according to different causative factor has been identified as a research priority (Gallegos et al., 2009; Ozdemir et al. 2013). The flooding disaster caused by dam failures is always a threat against lives and properties especially in urban environments. Therefore, the prediction of dynamics of dam-break flows plays a vital role in the forecast and evaluation of flooding disasters, and is of long-standing interest for researchers. Flooding occurred on the Ayamama River (Istanbul-Turkey) due to high intensity rainfall and dam-breaching of Ata Pond in 9th September 2009. The settlements, industrial areas and transportation system on the floodplain of the Ayamama River were inundated. Therefore, 32 people were dead and millions of Euros economic loses were occurred. The aim of this study is 1 and 2-Dimensional flood modelling of the Ata Pond breaching using HEC-RAS and LISFLOOD-Roe models and comparison of the model results using the real flood extent. The HEC-RAS model solves the full 1-D Saint Venant equations for unsteady open channel flow whereas LISFLOOD-Roe is the 2-D shallow water model which calculates the flow according to the complete Saint Venant formulation (Villanueva and Wright, 2006; Neal et al., 2011). The model consists a shock capturing Godunov-type scheme based on the Roe Riemann solver (Roe, 1981). 3 m high resolution Digital Surface Model (DSM), natural characteristics of the pond and its breaching such as depth, wide, length, volume and breaching shape and daily total rainfall data were used in the models. The simulated flooding in the both models were compared with the real flood extent which gathered from photos taken after the flood event, high satellite images acquired after 20 days from the flood event, and field works. The results show that LISFLOOD-Roe hydraulic model gives more than 80% fit to the extent of real flood event. Also both modelling results show that the embankment breaching of the Ata Pond directly affected the flood magnitude and intensity on the area. This study reveals that modelling of the probable flooding in urban areas is necessary and very important in urban planning. References Gallegos, H. A., Schubert, J. E., and Sanders, B. F.: Two dimensional, high-resolution modeling of urban dam-break flooding: A case study of Baldwin Hills California, Adv. Water Resour., 32, 1323-1335, 2009. Neal, J., Villanueva, I., Wright, N., Willis, T., Fewtrell, T. and Bates, P.: How mush physical complexity is needed to model flood inundation? Hydrological Processes, DOI: 10.1002/hyp.8339. Ozdemir H., Sampson C., De Almeida G., Bates P.D.: Evaluating scale and roughness effects in urban flood modelling using terrestrial LiDAR data, Hydrology and Earth System Sciences, vol.17, pp.4015-4030, 2013. Roe P.: Approximate Riemann solvers, parameter vectors, and difference-schemes. Journal of Computational Physics 43(2): 357-372, 1981. Villanueva I, Wright NG.: Linking Riemann and storage cell models for flood prediction. Proceedings of the Institution of Civil Engineers, Journal of Water Management 159: 27-33, 2006.

A multi-disciplinary approach to evaluate pluvial floods risk under changing climate: The case study of the municipality of Venice (Italy).

PubMed

Sperotto, A; Torresan, S; Gallina, V; Coppola, E; Critto, A; Marcomini, A

2016-08-15

Global climate change is likely to pose increasing threats in nearly all sectors and across all sub-regions worldwide (IPCC, 2014). Particularly, extreme weather events (e.g. heavy precipitations), together with changing exposure and vulnerability patterns, are expected to increase the damaging effect of storms, pluvial floods and coastal flooding. Developing climate and adaptation services for local planners and decision makers is becoming essential to transfer and communicate sound scientific knowledge about climate related risks and foster the development of national, regional and local adaptation strategies. In order to analyze the effect of climate change on pluvial flood risk and advice adaptation planning, a Regional Risk Assessment (RRA) methodology was developed and applied to the urban territory of the municipality of Venice. Based on the integrated analysis of hazard, exposure, vulnerability and risk, RRA allows identifying and prioritizing targets and sub-areas that are more likely to be affected by pluvial flood risk due to heavy precipitation events in the future scenario 2041-2050. From the early stages of its development and application, the RRA followed a bottom-up approach taking into account the requests, knowledge and perspectives of local stakeholders of the North Adriatic region by means of interactive workshops, surveys and discussions. Results of the analysis showed that all targets (i.e. residential, commercial-industrial areas and infrastructures) are vulnerable to pluvial floods due to the high impermeability and low slope of the topography. The spatial pattern of risk mostly reflects the distribution of the hazard and the districts with the higher percentage of receptors' surface in the higher risk classes (i.e. very high, high and medium) are Lido-Pellestrina and Marghera. The paper discusses how risk-based maps and statistics integrate scientific and local knowledge with the final aim to mainstream climate adaptation in the development of risk mitigation and urban plans. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of a smart flood warning system in urban areas: A case study of Huwei area in Taiwan

NASA Astrophysics Data System (ADS)

Yang, Sheng-Chi; Hsu, Hao-Ming; Kao, Hong-Ming

2016-04-01

In this study, we developed a smart flood warning system to clearly understand flood propagations in urban areas. The science and technology park of Huwei, located in the southwest of Taiwan, was selected as a study area. It was designated to be an important urban area of optoelectronics and biotechnology. The region has an area about 1 km2 with approximately 1 km in both length and width. The discrepancy between the highest and lowest elevations is 6.3 m and its elevation decreases along the northeast to the southwest. It is an isolated urban drainage area due to its urban construction plan. The storm sewer system in this region includes three major networks that collect the runoff and drain to the detention pond where is located in the southwest corner of the region. The proposed smart flood warning system combines three important parts, i.e. the physical world, the cyber-physical interface, and the cyber space, to identify how the flood affects urban areas from now until the next three hours. In the physical world, when a rainfall event occurs, monitoring sensors (e.g. rainfall gauges and water level gauges built in the sewer system and ground surface), which are established in several essential locations of the study area, collect in situ hydrological data and then these data being transported to the cyber-physical interface. The cyber-physical interface is a data preprocess space that includes data analysis, quality control and assurance, and data integration and standardization to produce the validated data. In the cyber space, it has missions to receive the validated data from the cyber-physical interface and to run the time machine that has flood analyses of data mining, inundation scenarios simulation, risk and economic assessments, and so on, based on the validated data. After running the time machine, it offers the analyzed results related to flooding planning, mitigation, response, and recovery. According to the analyzed results, the decision supporting system, therefore, can publish warning information in urban areas at the right time. Keywords: flood warning system, flood mitigation, inundation.

Accuracy Analysis and Parameters Optimization in Urban Flood Simulation by PEST Model

NASA Astrophysics Data System (ADS)

Keum, H.; Han, K.; Kim, H.; Ha, C.

2017-12-01

The risk of urban flooding has been increasing due to heavy rainfall, flash flooding and rapid urbanization. Rainwater pumping stations, underground reservoirs are used to actively take measures against flooding, however, flood damage from lowlands continues to occur. Inundation in urban areas has resulted in overflow of sewer. Therefore, it is important to implement a network system that is intricately entangled within a city, similar to the actual physical situation and accurate terrain due to the effects on buildings and roads for accurate two-dimensional flood analysis. The purpose of this study is to propose an optimal scenario construction procedure watershed partitioning and parameterization for urban runoff analysis and pipe network analysis, and to increase the accuracy of flooded area prediction through coupled model. The establishment of optimal scenario procedure was verified by applying it to actual drainage in Seoul. In this study, optimization was performed by using four parameters such as Manning's roughness coefficient for conduits, watershed width, Manning's roughness coefficient for impervious area, Manning's roughness coefficient for pervious area. The calibration range of the parameters was determined using the SWMM manual and the ranges used in the previous studies, and the parameters were estimated using the automatic calibration method PEST. The correlation coefficient showed a high correlation coefficient for the scenarios using PEST. The RPE and RMSE also showed high accuracy for the scenarios using PEST. In the case of RPE, error was in the range of 13.9-28.9% in the no-parameter estimation scenarios, but in the scenario using the PEST, the error range was reduced to 6.8-25.7%. Based on the results of this study, it can be concluded that more accurate flood analysis is possible when the optimum scenario is selected by determining the appropriate reference conduit for future urban flooding analysis and if the results is applied to various rainfall event scenarios and parameter optimization. Keywords: Parameters Optimization; PEST model; Urban area Acknowledgement This research was supported by a grant (17AWMP-B079625-04) from Water Management Research Program funded by Ministry of Land, Infrastructure and Transport of Korean government.

Enhancement of global flood damage assessments using building material based vulnerability curves

NASA Astrophysics Data System (ADS)

Englhardt, Johanna; de Ruiter, Marleen; de Moel, Hans; Aerts, Jeroen

2017-04-01

This study discusses the development of an enhanced approach for flood damage and risk assessments using vulnerability curves that are based on building material information. The approach draws upon common practices in earthquake vulnerability assessments, and is an alternative for land-use or building occupancy approach in flood risk assessment models. The approach is of particular importance for studies where there is a large variation in building material, such as large scale studies or studies in developing countries. A case study of Ethiopia is used to demonstrate the impact of the different methodological approaches on direct damage assessments due to flooding. Generally, flood damage assessments use damage curves for different land-use or occupancy types (i.e. urban or residential and commercial classes). However, these categories do not necessarily relate directly to vulnerability of damage by flood waters. For this, the construction type and building material may be more important, as is used in earthquake risk assessments. For this study, we use building material classification data of the PAGER1 project to define new building material based vulnerability classes for flood damage. This approach will be compared to the widely applied land-use based vulnerability curves such as used by De Moel et al. (2011). The case of Ethiopia demonstrates and compares the feasibility of this novel flood vulnerability method on a country level which holds the potential to be scaled up to a global level. The study shows that flood vulnerability based on building material also allows for better differentiation between flood damage in urban and rural settings, opening doors to better link to poverty studies when such exposure data is available. Furthermore, this new approach paves the road to the enhancement of multi-risk assessments as the method enables the comparison of vulnerability across different natural hazard types that also use material-based vulnerability curves. Finally, this approach allows for more accuracy in estimating losses as a result of direct damages. 1 http://earthquake.usgs.gov/data/pager/

A Mediterranean case study of flood evolution: the Metropolitan Area of Barcelona

NASA Astrophysics Data System (ADS)

Llasat, Maria Carmen; Gilabert, Joan; Llasat-Botija, Montserrat; Cortès, Maria; Marcos, Raül; Martín-Vide, Juan Pedro; Turco, Marco; Falcón, Lluis

2016-04-01

Flood risk changes in Mediterranean Region integrate multiple factors, some of them related with the hazard (i.e. rainfall intensity), the vulnerability and exposure (i.e. population or assets), feedback processes that affect both hazard and vulnerability (i.e. urbanization of flood prone areas), mitigation and adaptation measures (i.e. rainwater tanks or early warning systems), and the available information used to estimate flood events (i.e. newspapers or gauged data). Flood events in the West Mediterranean region are usually produced as a consequence of very intense and local precipitation, mainly recorded on late summer and autumn that can give place to flash-floods in little torrential rivers (usually non-permanent flows) or urban floods. The Metropolitan Area of Barcelona (AMB), Spain, constitutes a good paradigm of a Mediterranean coast region, with strong urbanization of flood prone areas and high population density in an area crossed by numerous streams. The AMB is constituted by 36 municipalities with a total population above 3.200.000 inhabitants in an extension of 636 km². The major part of the population is concentrated between the Besós River and the Llobregat River, the Littoral Range and the Mediterranean Sea. Although both rivers have experienced catastrophic flood events (i.e. 25 September 1962, 815 deaths; 19-23 September 1971, 19 deaths; October 1987, 8 deaths), the most frequent situation is related with floods in non-permanent streams. Their main impacts are consequence of drainage and runoff problems and can affect both urban and rural areas. This contribution explores the evolution of land uses, population and precipitation from the middle of the 20th century until now, and how these changes have affected (or not), the flood risk. To do it, daily and sub-daily rainfall series, discharge series for the Llobregat and Besós Rivers, population data and land use changes have been analyzed. Future precipitation projections provided by an ensemble of regional models (ENSEMBLES project) have been also considered. Flood events have been obtained from newspapers, reports and insurance data. The role played by prevention measures, particularly in the specific case of Barcelona, which has been recognized by UNISDR (United Nations International Strategy for Disaster Reduction) as resilient city in front of floods, is also presented. Results confirm the strong role played by the increase of urban surface (from less than 15% in 1956 to near 40% in 2009) and explore future adaptation measures in the context of the 2030 Agenda for Sustainable Development. This work has been supported by the Spanish project HOPE and the Metropolitan Area of Barcelona, and developed by an interdisciplinary team that include experts from hydrology, meteorology, geography, environmental sciences and architecture.

High-resolution urban flood modelling - a joint probability approach

NASA Astrophysics Data System (ADS)

Hartnett, Michael; Olbert, Agnieszka; Nash, Stephen

2017-04-01

The hydrodynamic modelling of rapid flood events due to extreme climatic events in urban environment is both a complex and challenging task. The horizontal resolution necessary to resolve complexity of urban flood dynamics is a critical issue; the presence of obstacles of varying shapes and length scales, gaps between buildings and the complex geometry of the city such as slopes affect flow paths and flood levels magnitudes. These small scale processes require a high resolution grid to be modelled accurately (2m or less, Olbert et al., 2015; Hunter et al., 2008; Brown et al., 2007) and, therefore, altimetry data of at least the same resolution. Along with availability of high-resolution LiDAR data and computational capabilities, as well as state of the art nested modelling approaches, these problems can now be overcome. Flooding and drying, domain definition, frictional resistance and boundary descriptions are all important issues to be addressed when modelling urban flooding. In recent years, the number of urban flood models dramatically increased giving a good insight into various modelling problems and solutions (Mark et al., 2004; Mason et al., 2007; Fewtrell et al., 2008; Shubert et al., 2008). Despite extensive modelling work conducted for fluvial (e.g. Mignot et al., 2006; Hunter et al., 2008; Yu and Lane, 2006) and coastal mechanisms of flooding (e.g. Gallien et al., 2011; Yang et al., 2012), the amount of investigations into combined coastal-fluvial flooding is still very limited (e.g. Orton et al., 2012; Lian et al., 2013). This is surprising giving the extent of flood consequences when both mechanisms occur simultaneously, which usually happens when they are driven by one process such as a storm. The reason for that could be the fact that the likelihood of joint event is much smaller than those of any of the two contributors occurring individually, because for fast moving storms the rainfall-driven fluvial flood arrives usually later than the storm surge (Divoky et al., 2005). Nevertheless, such events occur and in Ireland alone there are several cases of serious damage due to flooding resulting from a combination of high sea water levels and river flows driven by the same meteorological conditions (e.g. Olbert et al. 2015). A November 2009 fluvial-coastal flooding of Cork City bringing €100m loss was one such incident. This event was used by Olbert et al. (2015) to determine processes controlling urban flooding and is further explored in this study to elaborate on coastal and fluvial flood mechanisms and their roles in controlling water levels. The objective of this research is to develop a methodology to assess combined effect of multiple source flooding on flood probability and severity in urban areas and to establish a set of conditions that dictate urban flooding due to extreme climatic events. These conditions broadly combine physical flood drivers (such as coastal and fluvial processes), their mechanisms and thresholds defining flood severity. The two main physical processes controlling urban flooding: high sea water levels (coastal flooding) and high river flows (fluvial flooding), and their threshold values for which flood is likely to occur, are considered in this study. Contribution of coastal and fluvial drivers to flooding and their impacts are assessed in a two-step process. The first step involves frequency analysis and extreme value statistical modelling of storm surges, tides and river flows and ultimately the application of joint probability method to estimate joint exceedence return periods for combination of surges, tide and river flows. In the second step, a numerical model of Cork Harbour MSN_Flood comprising a cascade of four nested high-resolution models is used to perform simulation of flood inundation under numerous hypothetical coastal and fluvial flood scenarios. The risk of flooding is quantified based on a range of physical aspects such as the extent and depth of inundation (Apel et al., 2008) The methodology includes estimates of flood probabilities due to coastal- and fluvial-driven processes occurring individually or jointly, mechanisms of flooding and their impacts on urban environment. Various flood scenarios are examined in order to demonstrate that this methodology is necessary to quantify the important physical processes in coastal flood predictions. Cork City, located on the south of Ireland subject to frequent coastal-fluvial flooding, is used as a study case.

Insurance data as way to evaluate the performance of a sustainable urban drainage system (SUDS) in Augustenborg, Malmö

NASA Astrophysics Data System (ADS)

Sörensen, Johanna; Emilsson, Tobias

2017-04-01

Sustainable Urban Drainage Systems (SUDS) has been put forward as a concept to improve stormwater management in urban areas. The damage reduction due to reduced flooding and storm water detention during extreme events is one of many important features of SUDS. As extreme events are rare, few assessments have earlier been made to evaluate the risk reduction. So far, most assessments have been done by hydraulic modelling, rather than analyses based on data from real flood events. In 2014, Malmö was hit with an extreme rainfall event which led to severe flooding in most parts of the city. This event gave an opportunity to evaluate the efficiency of SUDS during extreme events. In this study, flood claim data were analysed to evaluate flood risk reduction by the SUDS system in Augustenborg. Flood claim data were collected from both an insurance company, as well as the water utility company of Malmö for 5 neighbourhoods in close proximity in Malmö. The study uses the Augustenborg neighbourhood as an example of a retrofitted neighbourhood with an open SUDS. Augustenborg (Malmö, Sweden) was retrofitted 15 years ago using a combination of hard infrastructure and naturebased solutions, to alleviate basement flooding, to reduce combined sewer overflows (CSO) and to increase the ecological and aesthetical values of the area. The introduction of ponds, channels and green roofs dramatically changed the appearance of the area and the more or less regular floods were stopped. Augustenborg and its sustainable drainage system was compared with five similar neighbourhoods nearby. The long-term development of reported insurance claims in the selected neighbourhoods showed a reduction of flooding in Augustenborg compared to the nearby areas. Pre- and post-installation data showed a direct effect of the refurbishment with SUDS. Even though a few properties were flooded in Augustenborg, it was shown that the SUDS performed successfully during the extreme storm event that was the most severe flooding in Malmö in modern history. In conclusion, the SUDS in Augustenborg, Malmö, has been efficient in flood reduction during minor as well as severe flood events.

Using open source data for flood risk mapping and management in Brazil

NASA Astrophysics Data System (ADS)

Whitley, Alison; Malloy, James; Chirouze, Manuel

2013-04-01

Whitley, A., Malloy, J. and Chirouze, M. Worldwide the frequency and severity of major natural disasters, particularly flooding, has increased. Concurrently, countries such as Brazil are experiencing rapid socio-economic development with growing and increasingly concentrated populations, particularly in urban areas. Hence, it is unsurprising that Brazil has experienced a number of major floods in the past 30 years such as the January 2011 floods which killed 900 people and resulted in significant economic losses of approximately 1 billion US dollars. Understanding, mitigating against and even preventing flood risk is high priority. There is a demand for flood models in many developing economies worldwide for a range of uses including risk management, emergency planning and provision of insurance solutions. However, developing them can be expensive. With an increasing supply of freely-available, open source data, the costs can be significantly reduced, making the tools required for natural hazard risk assessment more accessible. By presenting a flood model developed for eight urban areas of Brazil as part of a collaboration between JBA Risk Management and Guy Carpenter, we explore the value of open source data and demonstrate its usability in a business context within the insurance industry. We begin by detailing the open source data available and compare its suitability to commercially-available equivalents for datasets including digital terrain models and river gauge records. We present flood simulation outputs in order to demonstrate the impact of the choice of dataset on the results obtained and its use in a business context. Via use of the 2D hydraulic model JFlow+, our examples also show how advanced modelling techniques can be used on relatively crude datasets to obtain robust and good quality results. In combination with accessible, standard specification GPU technology and open source data, use of JFlow+ has enabled us to produce large-scale hazard maps suitable for business use and emergency planning such as those we show for Brazil.

Influence of urban surface properties and rainfall characteristics on surface water flood outputs - insights from a physical modelling environment

NASA Astrophysics Data System (ADS)

Green, Daniel; Pattison, Ian; Yu, Dapeng

2017-04-01

Surface water (pluvial) flooding occurs when excess rainfall from intense precipitation events is unable to infiltrate into the subsurface or drain via natural or artificial drainage channels. Surface water flood events pose a major hazard to urban regions across the world, with nearly two thirds of flood damages in the UK being caused by surface water flood events. The perceived risk of surface water flooding appears to have increased in recent years due to several factors, including (i) precipitation increases associated with climatic change and variability; (ii) population growth meaning more people are occupying flood risk areas, and; (iii) land-use changes. Because urban areas are often associated with a high proportion of impermeable land-uses (e.g. tarmacked or paved surfaces and buildings) and a reduced coverage of vegetated, permeable surfaces, urban surface water flood risk during high intensity precipitation events is often exacerbated. To investigate the influence of urbanisation and terrestrial factors on surface water flood outputs, rainfall intensity, catchment slope, permeability, building density/layout scenarios were designed within a novel, 9m2 physical modelling environment. The two-tiered physical model used consists of (i) a low-cost, nozzle-type rainfall simulator component which is able to simulate consistent, uniformly distributed rainfall events of varying duration and intensity, and; (ii) a reconfigurable, modular plot surface. All experiments within the physical modelling environment were subjected to a spatiotemporally uniform 45-minute simulated rainfall event, while terrestrial factors on the physical model plot surface were altered systematically to investigate their hydrological response on modelled outflow and depth profiles. Results from the closed, controlled physical modelling experiments suggest that meteorological factors, such as the duration and intensity of simulated rainfall, and terrestrial factors, such as model slope, surface permeability and building density have a significant influence on physical model hydrological outputs. For example, changes in building density across the urban model catchment are shown to result in hydrographs having (i) a more rapid rising limb; (ii) higher peak discharges; (iii) a reduction in the total hydrograph time, and; (iv) a faster falling limb, with the dense building scenario having a 22% increase in peak discharge when compared to the no building scenario. Furthermore, the layout of buildings across the plot surface and their proximity to the outflow unit (i.e. downstream, upstream or to the side of the physical model outlet) is shown to influence outflow hydrograph response, with downstream concentrated building scenarios resulting in a delay in hydrograph onset time and a reduction in the time of the total outflow hydrograph event.

Health Effects of Coastal Storms and Flooding in Urban Areas: A Review and Vulnerability Assessment

PubMed Central

Charles-Guzman, Kizzy; Matte, Thomas

2013-01-01

Coastal storms can take a devastating toll on the public's health. Urban areas like New York City (NYC) may be particularly at risk, given their dense population, reliance on transportation, energy infrastructure that is vulnerable to flood damage, and high-rise residential housing, which may be hard-hit by power and utility outages. Climate change will exacerbate these risks in the coming decades. Sea levels are rising due to global warming, which will intensify storm surge. These projections make preparing for the health impacts of storms even more important. We conducted a broad review of the health impacts of US coastal storms to inform climate adaptation planning efforts, with a focus on outcomes relevant to NYC and urban coastal areas, and incorporated some lessons learned from recent experience with Superstorm Sandy. Based on the literature, indicators of health vulnerability were selected and mapped within NYC neighborhoods. Preparing for the broad range of anticipated effects of coastal storms and floods may help reduce the public health burden from these events. PMID:23818911

Health effects of coastal storms and flooding in urban areas: a review and vulnerability assessment.

PubMed

Lane, Kathryn; Charles-Guzman, Kizzy; Wheeler, Katherine; Abid, Zaynah; Graber, Nathan; Matte, Thomas

2013-01-01

Coastal storms can take a devastating toll on the public's health. Urban areas like New York City (NYC) may be particularly at risk, given their dense population, reliance on transportation, energy infrastructure that is vulnerable to flood damage, and high-rise residential housing, which may be hard-hit by power and utility outages. Climate change will exacerbate these risks in the coming decades. Sea levels are rising due to global warming, which will intensify storm surge. These projections make preparing for the health impacts of storms even more important. We conducted a broad review of the health impacts of US coastal storms to inform climate adaptation planning efforts, with a focus on outcomes relevant to NYC and urban coastal areas, and incorporated some lessons learned from recent experience with Superstorm Sandy. Based on the literature, indicators of health vulnerability were selected and mapped within NYC neighborhoods. Preparing for the broad range of anticipated effects of coastal storms and floods may help reduce the public health burden from these events.

Multifunctional benefits of SuDS: techno-economic evaluation of decentralised solutions for urban water management

NASA Astrophysics Data System (ADS)

Mijic, Ana; Ossa-Moreno, Juan; Smith, Karl M.

2016-04-01

The increased frequency of extreme weather events associated with climate change poses a significant threat to the integrity and function of critical urban infrastructure - rail, road, telecommunications, power and water supply/sewerage networks. A key threat within the United Kingdom (UK) is the increased risk of pluvial flooding; the conventional approach of channeling runoff to an outfall has proven to be unsustainable during severe storm events. Green infrastructure, in the form of Sustainable Urban Drainage Systems (SuDS), has been proposed as a means of minimising the risk of pluvial flooding. However, despite their technical performance, SuDS uptake in the UK has not reached its full capacity yet, mostly due to reasons that go beyong the engineering realm. This work investigated the strategic role of SuDS retrofit in managing environmental risks to urban infrastructure in London at a catchment level, through an economic appraisal of multifunctional benefits. It was found that by including the multifunctional benefits of SuDS, the economic feasibility of the project improves considerably. The case study has also shown a mechanism towards achieving wider-scale SuDS retrofit, whereby the investments are split amongst multiple stakeholder groups by highlighting the additional benefits each group derives. Groups include water utilities and their users, local government and critical infrastructure owners. Finally, limitations to the existing cost-benefit methdology in the UK were identified, and recommendations made regarding incentives and governmental regulations to enhance the uptake of SuDS in London. The proposed methodology provides compelling and robust, cost-benefit based evidence of SUDS' effectiveness within the flood risk management planning framework, but also with regard to the additional benefits of Nature Based Solutions in urban environments.

Insights from socio-hydrology modelling on dealing with flood risk: roles of collective memory, risk-taking attitude and trust (Invited)

NASA Astrophysics Data System (ADS)

Viglione, A.; Di Baldassarre, G.; Brandimarte, L.; Kuil, L.; Carr, G.; Salinas, J.; Scolobig, A.

2013-12-01

The risk coping culture of a community plays a major role in decision making in urban flood plains. While flood awareness is not necessarily linked to being prepared to face flooding at an individual level, the connection at the community level seems to be stronger through creating policy and initiating protection works. In this work we analyse, in a conceptual way, the interplay of community risk coping culture, flooding damage and economic growth. We particularly focus on three aspects: (i) collective memory, i.e., the capacity of the community to keep the awareness of flooding high; (ii) risk-taking attitude, i.e., the amount of risk a community is collectively willing to expose themselves to; and (iii) trust of people in risk protection measures. We use a dynamic model that represents the feedbacks between the hydrological and social system components. The model results indicate that, on one hand, by under perceiving the risk of flooding (because of short collective memory and too much trust in flood protection structures) in combination with a high risk-attitude, community survival is severely limited because of destruction caused by flooding. On the other hand, high perceived risk (long memory and lack of trust in flood protection structures) relative to the actual risk leads to lost economic opportunities and recession. There are many optimal scenarios for survival and economic growth, but greater certainty of survival plus economic growth can be achieved by ensuring community has accurate risk perception (memory neither too long nor too short and trust in flood protection neither too great nor too low) combined with a low to moderate risk-taking attitude. Interestingly, the model gives rise to situations in which the development of the community in the floodplain is path dependent, i.e., the history of flooding may lead to its growth or recession. Schematic of human adjustments to flooding: (a) settling away from the river; (b) raising levees/dikes.

Modelling the ability of source control measures to reduce inundation risk in a community-scale urban drainage system

NASA Astrophysics Data System (ADS)

Mei, Chao; Liu, Jiahong; Wang, Hao; Shao, Weiwei; Xia, Lin; Xiang, Chenyao; Zhou, Jinjun

2018-06-01

Urban inundation is a serious challenge that increasingly confronts the residents of many cities, as well as policymakers, in the context of rapid urbanization and climate change worldwide. In recent years, source control measures (SCMs) such as green roofs, permeable pavements, rain gardens, and vegetative swales have been implemented to address flood inundation in urban settings, and proven to be cost-effective and sustainable. In order to investigate the ability of SCMs on reducing inundation in a community-scale urban drainage system, a dynamic rainfall-runoff model of a community-scale urban drainage system was developed based on SWMM. SCMs implementing scenarios were modelled under six design rainstorm events with return period ranging from 2 to 100 years, and inundation risks of the drainage system were evaluated before and after the proposed implementation of SCMs, with a risk-evaluation method based on SWMM and analytic hierarchy process (AHP). Results show that, SCMs implementation resulting in significantly reduction of hydrological indexes that related to inundation risks, range of reduction rates of average flow, peak flow, and total flooded volume of the drainage system were 28.1-72.1, 19.0-69.2, and 33.9-56.0 %, respectively, under six rainfall events with return periods ranging from 2 to 100 years. Corresponding, the inundation risks of the drainage system were significantly reduced after SCMs implementation, the risk values falling below 0.2 when the rainfall return period was less than 10 years. Simulation results confirm the effectiveness of SCMs on mitigating inundation, and quantified the potential of SCMs on reducing inundation risks in the urban drainage system, which provided scientific references for implementing SCMs for inundation control of the study area.

Resilience and renewal of public policies for flood risk management. Between globalized approach and localized stakes. Is there still a place for threat ?

NASA Astrophysics Data System (ADS)

Baldet, Bertrand

2010-05-01

The incertainties due to climate changes are often evocated in order to explain the increase of natural threats. This study aims to explore the dynamics that are at work within the systems of actors dealing with policies for flood risk management and to introduce the evolutions of public action in this field. We will be showing that there are two different levels of changes. The first mutation is based on the integration of (…). This evolution, albeit it isn' t specific with policies for flood risk management, contributes nevertheless to a renewal recognition of the threat. Secondly, we will indicate that the approach of flood risk changed by itself, it is more « including ». In nowadays, to be able to understand natural risk one needs a positioning all-embracing wich is not confined to the hydraulic dimension. To be able to manage the threat one needs to reconsider all the activities of the valley and to put forward a new approach of the natural environment. In order to explain that changes, we will use the resilience concept. In outline, resilience is defined "as the measure of a part of system's capacity to absorb and recover from occurrence of a hazardous event" (Timmerman). This concept allows to describe the system stability and the capacity to confront change and to manage incertainty. The incertainties due to climate change, the troubles to identify the hazards, the multiplicity of representations about the stakes that have to be protected are a lot of factors wich make the flood risk management more complex and lead the system of actors to regular adaptations. This analysis is based on a ethnographic study, we met local government actors, ecological associations, riverside residents associations, experts…. These actors have to manage the floods of the « Touch ». This river is located in south of France, it crosses his valley (…) before to reach the Garonne near to Toulouse. An historic (view) of the management of the river will lead us to understand the current situation and to show the auto-organisation capacity of the system. We suggest by « system » a whole set of elements localisated in the valley. So, we refer to social, economical, politic, technic and natural factors involved with the flood risk management. For a long time, the « Touch » was only considered like a « irrigating canal ». Beforehand, it crossed only farmlands and his management was entrusted to a riverside residents farmers association. However, during the last decades, the zoning of the downstream banks had changed and some villages (d'autrefois) were been densely urbanized and are now considered as great towns. So, the approach of the threat along the river was renewaled. According the new configuration, an intercommunity union was created - wich gather together all the districts crossed by the Touch - and substitued the farmers association. The approach of flood risk was moved : the management of the threat was « private » but with the creation of the intercommunity union became « political » and « public ». Nowadays, the main stake is to operate a balanced management of the flood risk in order to allocate a well-proportioned constraints. The banks zoning - an agricultural upstream and an urbanized downstream - cause an opposition between farming world wich has to be defend and urban population wich needs protection. The public policies for flood risk management have to juggle between various requirements and deal with conflicting interests - we will see that public policies try to rethink agricultural practices (a decrease of irrigation, planting hedges...) and urbanization dynamics. The concept of resilience can explain the activities of the intercommunity union and the pratices of the actors around it. The working of this organization based on a balanced representation of the riverside cities - every city is represented by two delegates whatever the tall of the city - allows the integration of various stakes (agricultural, environmental, urban...). In spite of heterogeneous situations - (…) - we will see that the global approach of the valley permits the integration of risk, the spreading of the culture of risk and allows the auto-organization of the system.

Quantifying the Influence of Urbanization on a Coastal Floodplain

NASA Astrophysics Data System (ADS)

Sebastian, A.; Juan, A.; Bedient, P. B.

2016-12-01

The U.S. Gulf Coast is the fastest growing region in the United States; between 1960 and 2010, the number of housing units along the Gulf of Mexico increased by 246%, vastly outpacing growth in other parts of the country (NOAA 2013). Numerous studies have shown that increases in impervious surface associated with urbanization reduce infiltration and increase surface runoff. While empirical evidence suggests that changes in land use are leading to increased flood damage in overland areas, earlier studies have largely focused on the impacts of urbanization on surface runoff and watershed hydrology, rather than quantifying its influence on the spatial extent of flooding. In this study, we conduct a longitudinal assessment of the evolution of flood risk since 1970 in an urbanizing coastal watershed. Utilizing the distributed hydrologic model, Vflo®, in combination with the hydraulic model, HEC-RAS, we quantify the impact of localized land use/land cover (LULC) change on the spatial extent of flooding in the watershed and the underlying flood hazard structure. The results demonstrate that increases in impervious cover between 1970 and 2010 (34%) and 2010 and 2040 (18%) increase the size of the floodplain by 26 and 17%, respectively. Furthermore, the results indicate that the depth and frequency of flooding in neighborhoods within the 1% floodplain have increased substantially (see attached figure). Finally, this analysis provides evidence that outdated FEMA floodplain maps could be underestimating the extent of the floodplain by upwards of 25%, depending on the rate of urbanization in the watershed; and, that by incorporating physics-based distributed hydrologic models into floodplain studies, floodplain maps can be easily updated to reflect the most recent LULC information available. The methods presented in this study have important implications for the development of mitigation strategies in coastal areas, such as deterring future development in flood prone areas and directing flood mitigation efforts in already flood prone communities. ReferencesNational Oceanic and Atmospheric Administration (NOAA). (2013). National Coastal Population Report: Population Trends from 1970 to 2020.

Evaluating the 100 year floodplain as an indicator of flood risk in low-lying coastal watersheds

NASA Astrophysics Data System (ADS)

Sebastian, A.; Brody, S.; Bedient, P. B.

2013-12-01

The Gulf of Mexico is the fastest growing region in the United States. Since 1960, the number of housing units built in the low-lying coastal counties has increased by 246%. The region experiences some of the most intense rainfall events in the country and coastal watersheds are prone to severe flooding characterized by wide floodplains and ponding. This flooding is further exacerbated as urban development encroaches on existing streams and waterways. While the 100 year floodplain should play an important role in our ability to develop disaster resilient communities, recent research has indicated that existing floodplain delineations are a poor indicator of actual flood losses in low-lying coastal regions. Between 2001 and 2005, more than 30% of insurance claims made to FEMA in the Gulf Coast region were outside of the 100 year floodplain and residential losses amounted to more than $19.3 billion. As population density and investments in this region continue to increase, addressing flood risk in coastal communities should become a priority for engineers, urban planners, and decision makers. This study compares the effectiveness of 1-D and a 2-D modeling approaches to spatially capture flood claims from historical events. Initial results indicate that 2-D models perform much better in coastal environments and may serve better for floodplain modeling helping to prevent unintended losses. The results of this study encourage a shift towards better engineering practices using existing 2-D models in order to protect resources and provide guidance for urban development in low-lying coastal regions.

Coastal Floods: Urban Planning as a Resilience System

NASA Astrophysics Data System (ADS)

Diez Gonzalez, J. J.; Esteban, M. D.; Monnot, J. V.; López Gutiérrez, J. S.; Negro Valdecantos, V.; Calderón, E. J.; Márquez Paniagua, P.; Silvestre, J. M.

2012-04-01

Despite some research efforts can be found across the literature, FRe system (Flood resilient system) is still a vaguely defined concept. Therefore, a comprehensive presentation of existing FRe systems would provide valuable contribution in order to illuminate objects laying behind this term. A systematical literature review scanning existing FRe objects will submerge us in a melting pot involving an extremely wide and heterogeneous range of elements like land planning, opening barriers, river channeling, rain forecasting… Carrying out an analyze of the resulting matter and focusing on the nature and spatial range of application of each element, a FRe objects comprehensive typology will be sorted out, leading into the end to a better understanding of the ways human societies can improve their resilience against floods. Coastal areas have been characterized by an urban expansion due mainly to the increase and displacement of the population, being this process highly increasing during the last century. On the other hand, climate has been changing leading to the increase of coastal floods, through both sea level rise and several meteorological phenomena accentuation. And also, other longer term local/regional coastal changes, most occasionally favoring floods, interfere leading to more frequent and intense flood risks and damages. As "living with floods" became an objective in many coastal cities, the previous clas-sification will be put into practice focusing on one particular FRe system scale: Urban Flood Resilience. This resilience can be achieved by means of planning procedures and building infrastructures, but in many cases these measures cannot be enough, having to be complemented with different technologies and systems. With suitable applications, Flood Resilience Systems substantially reduce damages, costs and health impacts associated with flood hazards. The importance of the urban planning as a Flood Resilience System in coastal areas will be analyzed in the research project FP7 - SMARTEST by means of different cases study: cold drop floods (Valencia 1776, 1957 and 1982; and Murcia, 1879 and 1997), hurricanes on Caribbean and western North-Atlantic areas, or to typhoons.

Urban flood early warning systems: approaches to hydrometeorological forecasting and communicating risk

NASA Astrophysics Data System (ADS)

Cranston, Michael; Speight, Linda; Maxey, Richard; Tavendale, Amy; Buchanan, Peter

2015-04-01

One of the main challenges for the flood forecasting community remains the provision of reliable early warnings of surface (or pluvial) flooding. The Scottish Flood Forecasting Service has been developing approaches for forecasting the risk of surface water flooding including capitalising on the latest developments in quantitative precipitation forecasting from the Met Office. A probabilistic Heavy Rainfall Alert decision support tool helps operational forecasters assess the likelihood of surface water flooding against regional rainfall depth-duration estimates from MOGREPS-UK linked to historical short-duration flooding in Scotland. The surface water flood risk is communicated through the daily Flood Guidance Statement to emergency responders. A more recent development is an innovative risk-based hydrometeorological approach that links 24-hour ensemble rainfall forecasts through a hydrological model (Grid-to-Grid) to a library of impact assessments (Speight et al., 2015). The early warning tool - FEWS Glasgow - presents the risk of flooding to people, property and transport across a 1km grid over the city of Glasgow with a lead time of 24 hours. Communication of the risk was presented in a bespoke surface water flood forecast product designed based on emergency responder requirements and trialled during the 2014 Commonwealth Games in Glasgow. The development of new approaches to surface water flood forecasting are leading to improved methods of communicating the risk and better performance in early warning with a reduction in false alarm rates with summer flood guidance in 2014 (67%) compared to 2013 (81%) - although verification of instances of surface water flooding remains difficult. However the introduction of more demanding hydrometeorological capabilities with associated greater levels of uncertainty does lead to an increased demand on operational flood forecasting skills and resources. Speight, L., Cole, S.J., Moore, R.J., Pierce, C., Wright, B., Golding, B., Cranston, M., Tavendale, A., Ghimire, S., and Dhondia, J. (2015) Developing surface water flood forecasting capabilities in Scotland: an operational pilot for the 2014 Commonwealth Games in Glasgow. Journal of Flood Risk Management, In Press.

Construction of an integrated social vulnerability index in urban areas prone to flash flooding

NASA Astrophysics Data System (ADS)

Aroca-Jimenez, Estefania; Bodoque, Jose Maria; Garcia, Juan Antonio; Diez-Herrero, Andres

2017-09-01

Among the natural hazards, flash flooding is the leading cause of weather-related deaths. Flood risk management (FRM) in this context requires a comprehensive assessment of the social risk component. In this regard, integrated social vulnerability (ISV) can incorporate spatial distribution and contribution and the combined effect of exposure, sensitivity and resilience to total vulnerability, although these components are often disregarded. ISV is defined by the demographic and socio-economic characteristics that condition a population's capacity to cope with, resist and recover from risk and can be expressed as the integrated social vulnerability index (ISVI). This study describes a methodological approach towards constructing the ISVI in urban areas prone to flash flooding in Castilla y León (Castile and León, northern central Spain, 94 223 km2, 2 478 376 inhabitants). A hierarchical segmentation analysis (HSA) was performed prior to the principal components analysis (PCA), which helped to overcome the sample size limitation inherent in PCA. ISVI was obtained from weighting vulnerability factors based on the tolerance statistic. In addition, latent class cluster analysis (LCCA) was carried out to identify spatial patterns of vulnerability within the study area. Our results show that the ISVI has high spatial variability. Moreover, the source of vulnerability in each urban area cluster can be identified from LCCA. These findings make it possible to design tailor-made strategies for FRM, thereby increasing the efficiency of plans and policies and helping to reduce the cost of mitigation measures.

Flooding and the framing of risk in British broadsheets, 1985-2010.

PubMed

Escobar, Maria Paula; Demeritt, David

2014-05-01

Our analysis of 2707 news stories explores the framing of flooding in Britain over the past quarter century and the displacement of a once dominant understanding of flooding as an agricultural problem of land drainage by the contemporary concern for its urban impacts, particularly to homes and property. We document dramatic changes in the volume and variety of reporting about flooding since 2000 as the risks of flooding have become more salient, the informal 'Gentlemen's Agreement' between government and private insurers has broken down, and flood management subjected to greater public scrutiny. While the historic reliance on private insurance remains largely unchallenged, we show that other aspects of flood hazard management are now topics of active political debate to which the looming threat of climate change adds both urgency and exculpatory excuses for poor performance. We conclude by reflecting on the significance of the case for grand theories of neoliberalisation and governmentality.

Geospatial Tools for Prevention of Urban Floods Case Study: River of EL Maleh (city of Mohammedia - Morocco)

NASA Astrophysics Data System (ADS)

Chaabane, M. S.; Abouali, N.; Boumeaza, T.; Zahouily, M.

2017-11-01

Today, the prevention and the risk management occupy an important part of public policy activities and are considered as major components in the process of sustainable development of territories. Due to the expansion of IT processes, in particular the geomatics sciences, decision-makers are increasingly requesting for digital tools before, during and after the risks of natural disasters. Both, the geographic information system (GIS) and the remote sensing are considered as geospatial and fundamental tools which help to understand the evolution of risks, to analyze their temporality and to make the right decisions. The historic events (on 1996, 2002 and 2010) which struck the city of Mohammedia and having caused the consequent damage to vital infrastructure and private property, require a thorough and rational analyze to benefit from it and well manage the floods phenomena. This article present i) the contribution of the geospatial tools for the floods simulation of Oued of el Maleh city at various return periods. These tools allow the demarcation of flood-risk areas and so to make floods simulations in several scenarios (decadal flood, 20-year flood, 50-year flood, 100-year flood, 500-year flood & also millennial flood) and besides (ii) present a synthesis map combining the territorial stakes superposed on the flood scenarios at different periods of return.

Flood risk management in the Souss watershed

NASA Astrophysics Data System (ADS)

Bouaakkaz, Brahim; El Abidine El Morjani, Zine; Bouchaou, Lhoussaine; Elhimri, Hamza

2018-05-01

Flooding is the most devasting natural hazards that causes more damage throughout the world. In 2016, for the fourth year in a row, it was the most costly natural disaster, in terms of global economic losses: 62 billion, according to a Benfield's 2016 annual report on climate and natural disasters [1]. The semi-arid to arid Souss watershed is vulnerable to floods, whose the intensity is becoming increasingly alarming and this area does not escape to the effects of this extreme event.. Indeed, the susceptibility of this region to this type of hazard is accentuated by its rapid evolution in terms of demography, uncontrolled land use, anthropogenic actions (uncontrolled urbanization, encroachment of the hydraulic public domain, overgrazing, clearing and deforestation).), and physical behavior of the environment (higher slope, impermeable rocks, etc.). It is in this context, that we have developed a strategic plan of action to manage this risk in the Souss basin in order to reduce the human, economic and environmental losses, after the modeling of the flood hazard in the study area, using georeferenced information systems (GIS), satellite remote sensing space and multi-criteria analysis techniques, as well as the history of major floods. This study, which generated the high resolution 30m flood hazard spatial distribution map of with accuracy of 85%, represents a decision tool to identify and prioririze area with high probability of hazard occurrence. It can also serve as a basis for urban evacuation plans for anticipating and preventing flood risk in the region, in order to ovoid any dramatic disaster.

Insights from socio-hydrology modelling on dealing with flood risk - Roles of collective memory, risk-taking attitude and trust

NASA Astrophysics Data System (ADS)

Viglione, Alberto; Di Baldassarre, Giuliano; Brandimarte, Luigia; Kuil, Linda; Carr, Gemma; Salinas, José Luis; Scolobig, Anna; Blöschl, Günter

2014-10-01

The risk coping culture of a community plays a major role in the development of urban floodplains. In this paper we analyse, in a conceptual way, the interplay of community risk coping culture, flooding damage and economic growth. We particularly focus on three aspects: (i) collective memory, i.e., the capacity of the community to keep risk awareness high; (ii) risk-taking attitude, i.e., the amount of risk the community is collectively willing to be exposed to; and (iii) trust of the community in risk reduction measures. To this end, we use a dynamic model that represents the feedback between the hydrological and social system components. Model results indicate that, on the one hand, by under perceiving the risk of flooding (because of short collective memory and too much trust in flood protection structures) in combination with a high risk-taking attitude, community development is severely limited because of high damages caused by flooding. On the other hand, overestimation of risk (long memory and lack of trust in flood protection structures) leads to lost economic opportunities and recession. There are many scenarios of favourable development resulting from a trade-off between collective memory and trust in risk reduction measures combined with a low to moderate risk-taking attitude. Interestingly, the model gives rise to situations in which the development of the community in the floodplain is path dependent, i.e., the history of flooding may lead to community growth or recession.

Urban Flood Prevention and Early Warning System in Jinan City

NASA Astrophysics Data System (ADS)

Feng, Shiyuan; Li, Qingguo

2018-06-01

The system construction of urban flood control and disaster reduction in China is facing pressure and challenge from new urban water disaster. Under the circumstances that it is difficult to build high standards of flood protection engineering measures in urban areas, it is particularly important to carry out urban flood early warning. In Jinan City, a representative inland area, based on the index system of early warning of flood in Jinan urban area, the method of fuzzy comprehensive evaluation was adopted to evaluate the level of early warning. Based on the cumulative rainfall of 3 hours, the CAflood simulation results based on cellular automaton model of urban flooding were used as evaluation indexes to realize the accuracy and integration of urban flood control early warning.

How did the urban land in floodplains distribute and expand in China from 1992-2015?

NASA Astrophysics Data System (ADS)

Du, Shiqiang; He, Chunyang; Huang, Qingxu; Shi, Peijun

2018-03-01

Urban land in floodplains (ULF) is a vital component of flood exposure and its variations can cause changes in flood risk. In the context of rapid urbanization, ULF is expanding rapidly in China and imperiling societal sustainability. However, a national-scale analysis of ULF patterns and dynamics has yet to be conducted. Therefore, this study aims to investigate the spatiotemporal changes in China’s ULF at different spatial scales (the country, region, basin, and sub-basin scales) from 1992-2015. We found that ULF accounted for 44.41% of the total urban land in China in 2015, which was 3.68 times greater than the proportion of floodplains relative to the total land area in China (12.06%). From 1992-2015, the ULF area increased by 26.43 × 103 km2, or 542.21%. Moreover, the ULF area is expected to grow by 16.89 × 103 km2 (53.38%) between 2015 and 2050. ULF growth was strongly associated with the flood occurrence in China, and continued growth will pose a considerable challenge to urban sustainability, particularly in basins with poor flood defenses. Greater attention should thus be paid to ULF dynamics in China.

Improving the analysis of social component of flash-floods risk assessment: Application to urban areas of Castilla y León (Spain)

NASA Astrophysics Data System (ADS)

Aroca Jimenez, Estefanía; Bodoque del Pozo, Jose Maria; Garcia Martin, Juan Antonio; Diez Herrero, Andres

2016-04-01

The increasing evidence of anthropogenic climate change, the respective intensification of extreme events as well as the increase in human exposure to natural hazards and their vulnerability show that the enhancement of strategies on how to reduce disaster risk and promote adaptation to extreme events is critical to increase resilience. Growing economic losses, high numbers of casualties and the disruption of livelihoods in various places of the world, at an even higher rate than the increase of magnitude and frequency of extreme events, underline that the vulnerability of societies exposed is a key aspect to be considered. Social vulnerability characterizes the predisposition of society to be afflicted by hazards such as floods, being flash floods one of the hazards with the greatest capacity to generate risk. Despite its importance, social vulnerability is often a neglected aspect of traditional risk assessments which mainly focus on economic and structural measures. The aim of this research is to identify those social characteristics which render people vulnerable to flash flood hazards, and consider whether these characteristics are identifiable as local patterns at regional level. The result of this task is a Social Susceptibility Index (SSI) based on susceptibility profiles of the population per township. These profiles are obtained by Hierarchical Segmentation and Latent Class Analysis of demographic and socio-economic information provided by different public organisms. By adding exposure information to SSI, a Social and Infraestructure Flood Vulnerability Index (SIFVI) is created. The methodology proposed here is implemented in the region of Castilla y León (94,226 km2). Townships that are included in this study meet two requirements: i) city centres are affected by an area where potential significant flash-flood risk exists (i.e. villages are crossed by rivers with a longitudinal slope higher than 0.01); ii) city centres are affected by an area with low or exceptional probability of flooding (as provided by Directive 2007/60/EC of 23 october 2007 on the assessment and management of flood risks) acording with the preliminary assessment of flood risk made by water authorities. This analysis of social vulnerability to flash floods means an advance in relation to disaster risk reduction allowing for grouping urban areas with similar resilience. With regard to the above, strengthening of resilience is one of the most important foundation of risk mitigation.

Real-time flood forecasts & risk assessment using a possibility-theory based fuzzy neural network

NASA Astrophysics Data System (ADS)

Khan, U. T.

2016-12-01

Globally floods are one of the most devastating natural disasters and improved flood forecasting methods are essential for better flood protection in urban areas. Given the availability of high resolution real-time datasets for flood variables (e.g. streamflow and precipitation) in many urban areas, data-driven models have been effectively used to predict peak flow rates in river; however, the selection of input parameters for these types of models is often subjective. Additionally, the inherit uncertainty associated with data models along with errors in extreme event observations means that uncertainty quantification is essential. Addressing these concerns will enable improved flood forecasting methods and provide more accurate flood risk assessments. In this research, a new type of data-driven model, a quasi-real-time updating fuzzy neural network is developed to predict peak flow rates in urban riverine watersheds. A possibility-to-probability transformation is first used to convert observed data into fuzzy numbers. A possibility theory based training regime is them used to construct the fuzzy parameters and the outputs. A new entropy-based optimisation criterion is used to train the network. Two existing methods to select the optimum input parameters are modified to account for fuzzy number inputs, and compared. These methods are: Entropy-Wavelet-based Artificial Neural Network (EWANN) and Combined Neural Pathway Strength Analysis (CNPSA). Finally, an automated algorithm design to select the optimum structure of the neural network is implemented. The overall impact of each component of training this network is to replace the traditional ad hoc network configuration methods, with one based on objective criteria. Ten years of data from the Bow River in Calgary, Canada (including two major floods in 2005 and 2013) are used to calibrate and test the network. The EWANN method selected lagged peak flow as a candidate input, whereas the CNPSA method selected lagged precipitation and lagged mean daily flow as candidate inputs. Model performance metric show that the CNPSA method had higher performance (with an efficiency of 0.76). Model output was used to assess the risk of extreme peak flows for a given day using an inverse possibility-to-probability transformation.

Flood vulnerability evaluation in complex urban areas

NASA Astrophysics Data System (ADS)

Giosa, L.; Pascale, S.; Sdao, F.; Sole, A.; Cantisani, A.

2009-04-01

This paper deals the conception, the development and the subsequent validation of an integrated numerical model for the assessment of systemic vulnerability in complex and urbanized areas, subject to flood risk. The proposed methodology is based on the application of the concept of "systemic vulnerability", the model is a mathematician-decisional model action to estimate the vulnerability of complex a territorial system during a flood event. The model uses a group of "pressure pointers" in order to define, qualitatively and quantitatively, the influence exercised on the territorial system from factors like as those physicists, social, economic, etc.. The model evaluates the exposure to the flood risk of the elements that belong to a system. The proposed model, which is based on the studies of Tamura et al., 2000; Minciardi et al., 2004; Pascale et al., 2008; considers the vulnerability not as a characteristic of a particular element at risk, but as a peculiarity of a complex territorial system, in which the different elements are reciprocally linked in a functional way. The proposed model points out the elements with the major functional lost and that make the whole system critical. This characteristic makes the proposed model able to support a correct territorial planning and a suitable management of the emergency following natural disasters such as floods. The proposed approach was tested on the study area in the city of Potenza, southern Italy.

Integrated Urban Flood Analysis considering Optimal Operation of Flood Control Facilities in Urban Drainage Networks

NASA Astrophysics Data System (ADS)

Moon, Y. I.; Kim, M. S.; Choi, J. H.; Yuk, G. M.

2017-12-01

eavy rainfall has become a recent major cause of urban area flooding due to the climate change and urbanization. To prevent property damage along with casualties, a system which can alert and forecast urban flooding must be developed. Optimal performance of reducing flood damage can be expected of urban drainage facilities when operated in smaller rainfall events over extreme ones. Thus, the purpose of this study is to execute: A) flood forecasting system using runoff analysis based on short term rainfall; and B) flood warning system which operates based on the data from pump stations and rainwater storage in urban basins. In result of the analysis, it is shown that urban drainage facilities using short term rainfall forecasting data by radar will be more effective to reduce urban flood damage than using only the inflow data of the facility. Keywords: Heavy Rainfall, Urban Flood, Short-term Rainfall Forecasting, Optimal operating of urban drainage facilities. AcknowledgmentsThis research was supported by a grant (17AWMP-B066744-05) from Advanced Water Management Research Program (AWMP) funded by Ministry of Land, Infrastructure and Transport of Korean government.

Modeling tools for the assessment of microbiological risks during floods: a review

NASA Astrophysics Data System (ADS)

Collender, Philip; Yang, Wen; Stieglitz, Marc; Remais, Justin

2015-04-01

Floods are a major, recurring source of harm to global economies and public health. Projected increases in the frequency and intensity of heavy precipitation events under future climate change, coupled with continued urbanization in areas with high risk of floods, may exacerbate future impacts of flooding. Improved flood risk management is essential to support global development, poverty reduction and public health, and is likely to be a crucial aspect of climate change adaptation. Importantly, floods can facilitate the transmission of waterborne pathogens by changing social conditions (overcrowding among displaced populations, interruption of public health services), imposing physical challenges to infrastructure (sewerage overflow, reduced capacity to treat drinking water), and altering fate and transport of pathogens (transport into waterways from overland flow, resuspension of settled contaminants) during and after flood conditions. Hydrological and hydrodynamic models are capable of generating quantitative characterizations of microbiological risks associated with flooding, while accounting for these diverse and at times competing physical and biological processes. Despite a few applications of such models to the quantification of microbiological risks associated with floods, there exists limited guidance as to the relative capabilities, and limitations, of existing modeling platforms when used for this purpose. Here, we review 17 commonly used flood and water quality modeling tools that have demonstrated or implicit capabilities of mechanistically representing and quantifying microbial risk during flood conditions. We compare models with respect to their capabilities of generating outputs that describe physical and microbial conditions during floods, such as concentration or load of non-cohesive sediments or pathogens, and the dynamics of high flow conditions. Recommendations are presented for the application of specific modeling tools for assessing particular flood-related microbial risks, and model improvements are suggested that may better characterize key microbial risks during flood events. The state of current tools are assessed in the context of a changing climate where the frequency, intensity and duration of flooding are shifting in some areas.

Large Scale Flood Risk Analysis using a New Hyper-resolution Population Dataset

NASA Astrophysics Data System (ADS)

Smith, A.; Neal, J. C.; Bates, P. D.; Quinn, N.; Wing, O.

2017-12-01

Here we present the first national scale flood risk analyses, using high resolution Facebook Connectivity Lab population data and data from a hyper resolution flood hazard model. In recent years the field of large scale hydraulic modelling has been transformed by new remotely sensed datasets, improved process representation, highly efficient flow algorithms and increases in computational power. These developments have allowed flood risk analysis to be undertaken in previously unmodeled territories and from continental to global scales. Flood risk analyses are typically conducted via the integration of modelled water depths with an exposure dataset. Over large scales and in data poor areas, these exposure data typically take the form of a gridded population dataset, estimating population density using remotely sensed data and/or locally available census data. The local nature of flooding dictates that for robust flood risk analysis to be undertaken both hazard and exposure data should sufficiently resolve local scale features. Global flood frameworks are enabling flood hazard data to produced at 90m resolution, resulting in a mis-match with available population datasets which are typically more coarsely resolved. Moreover, these exposure data are typically focused on urban areas and struggle to represent rural populations. In this study we integrate a new population dataset with a global flood hazard model. The population dataset was produced by the Connectivity Lab at Facebook, providing gridded population data at 5m resolution, representing a resolution increase over previous countrywide data sets of multiple orders of magnitude. Flood risk analysis undertaken over a number of developing countries are presented, along with a comparison of flood risk analyses undertaken using pre-existing population datasets.

Flood resilience urban territories. Flood resilience urban territories.

NASA Astrophysics Data System (ADS)

Beraud, Hélène; Barroca, Bruno; Hubert, Gilles

2010-05-01

The flood's impact during the last twenty years on French territory reveals our lack of preparation towards large-extended floods which might cause the stopping of companies' activity, services, or lead to housing unavailability during several months. New Orleans' case has to exemplify us: four years after the disaster, the city still couldn't get back its dynamism. In France, more than 300 towns are flood-exposed. While these towns are the mainspring of territory's development, it is likely that the majority of them couldn't get up quickly after a large-extended flood. Therefore, to understand and improve the urban territory's resilience facing floods is a real stake for territory's development. Urban technical networks supply, unify and irrigate all urban territories' constituents. Characterizing their flood resilience can be interesting to understand better urban resilience. In this context, waste management during and after floods is completely crucial. During a flood, the waste management network can become dysfunctional (roads cut, waste storage installations or waste treatment flooded). How can the mayor respect his obligation to guarantee salubrity and security in his city? In post flood the question is even more problematic. The waste management network presents a real stake for territory's restart. After a flood, building materials, lopped-of branches, furniture, business stocks, farm stocks, mud, rubbles, animal cadavers are wet, mixed, even polluted by hydrocarbons or toxic substances. The waste's volume can be significant. Sanitary and environmental risks can be crucial. In view of this situation, waste's management in post crisis period raises a real problem. What to make of this waste? How to collect it? Where to stock it? How to process it? Who is responsible? Answering these questions is all the more strategic since this waste is the mark of disaster. Thus, cleaning will be the first population's and local actor's reflex in order to forget the flood but also to restart as fast as possible (for example, the clearing of roads is a prerequisite for electricity's restoration which is a vital network for territory's functioning). While the waste management is a main stage of post crisis, these questions are still without answer. The extend of this network influence also leads us to think about the means to prevent from waste production and service's dysfunction. How to develop the territory to limit the floods' impact on the waste management network? Are there techniques or equipments allowing stakeholders to limit these impacts? How to increase population's, entrepreneur's or farmer's awareness to get ready to face floods, to limit the waste production, but also to react well during and after the floods? Throughout means of prevention and thanks to actor's technical and organizational adaptations towards the waste network, or by raising population's awareness and preparation, economic and institutional actors of urban territories might improve the waste's network flood resilience, and thus, cities' flood resilience. Through experience feedbacks about countries recently affected by large-extended floods and field reflection with local actors, the stakes of this PhD research are thus to think about means (1) to maintain the activity out of flood plains during a flood, (2) to increase the waste management network's activity in post crisis period in order to be able to deal with a new waste production both by its quality and its quantity, but also (3) to study the means to prevent this new production. This work will use the concept of urban system to describe urban territory because it allows us to study both its behaviour and functioning. The interest of this methodological choice is to take into account the impacts of the disruption of waste management networks on cities' functioning, and thus, on cities' flood resilience.

Influence of risk factors and past events on flood resilience in coastal megacities: Comparative analysis of NYC and Shanghai.

PubMed

Xian, Siyuan; Yin, Jie; Lin, Ning; Oppenheimer, Michael

2018-01-01

Coastal flood protection measures have been widely implemented to improve flood resilience. However, protection levels vary among coastal megacities globally. This study compares the distinct flood protection standards for two coastal megacities, New York City and Shanghai, and investigates potential influences such as risk factors and past flood events. Extreme value analysis reveals that, compared to NYC, Shanghai faces a significantly higher flood hazard. Flood inundation analysis indicates that Shanghai has a higher exposure to extreme flooding. Meanwhile, Shanghai's urban development, population, and economy have increased much faster than NYC's over the last three decades. These risk factors provide part of the explanation for the implementation of a relatively high level of protection (e.g. reinforced concrete sea-wall designed for a 200-year flood return level) in Shanghai and low protection (e.g. vertical brick and stone walls and sand dunes) in NYC. However, individual extreme flood events (typhoons in 1962, 1974, and 1981) seem to have had a greater impact on flood protection decision-making in Shanghai, while NYC responded significantly less to past events (with the exception of Hurricane Sandy). Climate change, sea level rise, and ongoing coastal development are rapidly changing the hazard and risk calculus for both cities and both would benefit from a more systematic and dynamic approach to coastal protection. Copyright © 2017 Elsevier B.V. All rights reserved.

The complexities of urban flood response: Flood frequency analyses for the Charlotte metropolitan region

NASA Astrophysics Data System (ADS)

Zhou, Zhengzheng; Smith, James A.; Yang, Long; Baeck, Mary Lynn; Chaney, Molly; Ten Veldhuis, Marie-Claire; Deng, Huiping; Liu, Shuguang

2017-08-01

We examine urban flood response through data-driven analyses for a diverse sample of "small" watersheds (basin scale ranging from 7.0 to 111.1 km2) in the Charlotte Metropolitan region. These watersheds have experienced extensive urbanization and suburban development since the 1960s. The objective of this study is to develop a broad characterization of land surface and hydrometeorological controls of urban flood hydrology. Our analyses are based on peaks-over-threshold flood data developed from USGS streamflow observations and are motivated by problems of flood hazard characterization for urban regions. We examine flood-producing rainfall using high-resolution (1 km2 spatial resolution and 15 min time resolution), bias-corrected radar rainfall fields that are developed through the Hydro-NEXRAD system. The analyses focus on the 2001-2015 period. The results highlight the complexities of urban flood response. There are striking spatial heterogeneities in flood peak magnitudes, response times, and runoff ratios across the study region. These spatial heterogeneities are mainly linked to watershed scale, the distribution of impervious cover, and storm water management. Contrasting land surface properties also determine the mixture of flood-generating mechanisms for a particular watershed. Warm-season thunderstorm systems and tropical cyclones are main flood agents in Charlotte, with winter/spring storms playing a role in less-urbanized watersheds. The mixture of flood agents exerts a strong impact on the upper tail of flood frequency distributions. Antecedent watershed wetness plays a minor role in urban flood response, compared with less-urbanized watersheds. Implications for flood hazard characterization in urban watersheds and for advances in flood science are discussed.

Evaluation of the magnitude and frequency of floods in urban watersheds in Phoenix and Tucson, Arizona

USGS Publications Warehouse

Kennedy, Jeffrey R.; Paretti, Nicholas V.

2014-01-01

Flooding in urban areas routinely causes severe damage to property and often results in loss of life. To investigate the effect of urbanization on the magnitude and frequency of flood peaks, a flood frequency analysis was carried out using data from urbanized streamgaging stations in Phoenix and Tucson, Arizona. Flood peaks at each station were predicted using the log-Pearson Type III distribution, fitted using the expected moments algorithm and the multiple Grubbs-Beck low outlier test. The station estimates were then compared to flood peaks estimated by rural-regression equations for Arizona, and to flood peaks adjusted for urbanization using a previously developed procedure for adjusting U.S. Geological Survey rural regression peak discharges in an urban setting. Only smaller, more common flood peaks at the 50-, 20-, 10-, and 4-percent annual exceedance probabilities (AEPs) demonstrate any increase in magnitude as a result of urbanization; the 1-, 0.5-, and 0.2-percent AEP flood estimates are predicted without bias by the rural-regression equations. Percent imperviousness was determined not to account for the difference in estimated flood peaks between stations, either when adjusting the rural-regression equations or when deriving urban-regression equations to predict flood peaks directly from basin characteristics. Comparison with urban adjustment equations indicates that flood peaks are systematically overestimated if the rural-regression-estimated flood peaks are adjusted upward to account for urbanization. At nearly every streamgaging station in the analysis, adjusted rural-regression estimates were greater than the estimates derived using station data. One likely reason for the lack of increase in flood peaks with urbanization is the presence of significant stormwater retention and detention structures within the watershed used in the study.

Economic impacts of urban flooding in South Florida: Potential consequences of managing groundwater to prevent salt water intrusion.

PubMed

Czajkowski, Jeffrey; Engel, Vic; Martinez, Chris; Mirchi, Ali; Watkins, David; Sukop, Michael C; Hughes, Joseph D

2018-04-15

High-value urban zones in coastal South Florida are considered particularly vulnerable to salt water intrusion into the groundwater-based, public water supplies caused by sea level rise (SLR) in combination with the low topography, existing high water table, and permeable karst substrate. Managers in the region closely regulate water depths in the extensive South Florida canal network to control closely coupled groundwater levels and thereby reduce the risk of saltwater intrusion into the karst aquifer. Potential SLR adaptation strategies developed by local managers suggest canal and groundwater levels may have to be increased over time to prevent the increased salt water intrusion risk to groundwater resources. However, higher canal and groundwater levels cause the loss of unsaturated zone storage and lead to an increased risk of inland flooding when the recharge from rainfall exceeds the capacity of the unsaturated zone to absorb it and the water table reaches the surface. Consequently, higher canal and groundwater levels are also associated with increased risk of economic losses, especially during the annual wet seasons. To help water managers and urban planners in this region better understand this trade-off, this study models the relationships between flood insurance claims and groundwater levels in Miami-Dade County. Via regression analyses, we relate the incurred number of monthly flood claims in 16 Miami-Dade County watersheds to monthly groundwater levels over the period from 1996 to 2010. We utilize these estimated statistical relationships to further illustrate various monthly flood loss scenarios that could plausibly result, thereby providing an economic quantification of a "too much water" trade-off. Importantly, this understanding is the first of its kind in South Florida and is exceedingly useful for regional-scale hydro-economic optimization models analyzing trade-offs associated with high water levels. Copyright © 2017 Elsevier B.V. All rights reserved.

Urban Flood Risk Assessment Under Uncertain Conditions and Scarce Information

NASA Astrophysics Data System (ADS)

Rodríguez-Gaviria, E. M.; Botero-Fernandez, V.

2015-12-01

Flood risk management in small urban areas in Colombia has a great degree of uncertainty due to the low availability and quality of data, the non-existent personnel qualified in the collection and processing of data, and the insufficient information to evaluate the risk and vulnerability. It is because of this that two methods are developed: one for the generation of flood threat maps for different return periods combining historical, geomorphological, and hydrological hydraulic methods assisted by remote sensors and SIG through the use of data acquired through field campaigns, official hydrological networks, orthophotos, multitemporal topographic maps, and ASTER, STRM, and LiDAR images. And another method in which categorical variables are established, linking local physical, social, economical, environmental and political-institutional factors that are explored through different media such as reports, news, databases, transects, interviews, community workshops, and surveys conducted at homes. Such variables were included within an analysis of multiple correspondence to conduct a descriptive study of the exposure, susceptibility, and capacity conditions and to create a vulnerability index that was spatially plotted spatially on maps. The uncertainty is reduced in the measure in which local knowledge is used as a source of information acquisition, of validation of what already exists, and of calibration of the proposed methods. This research was applied to the urban centers of Caucasia (Antioquia) and Plato (Magdalena), which have been historically affected by slow flooding of the Magdalena and Cauca river, it being especially useful in the selection of best alternatives for risk management, planning for development, and land use management, with the possibility of replicating it to benefit other municipalities that experience the same reality.

Simulating groundwater-induced sewer flooding

NASA Astrophysics Data System (ADS)

Mijic, A.; Mansour, M.; Stanic, M.; Jackson, C. R.

2016-12-01

During the last decade, Chalk catchments of southern England experienced severe groundwater flooding. High groundwater levels resulted in the groundwater ingress into the sewer network that led to restricted toilet use and the overflow of diluted, but untreated sewage to road surfaces, rivers and water courses. In response to these events the water and sewerage company Thames Water Utilities Ltd (TWUL) had to allocate significant funds to mitigate the impacts. It was estimated that approximately £19m was spent responding to the extreme wet weather of 2013-14, along with the use of a fleet of over 100 tankers. However, the magnitude of the event was so large that these efforts could not stop the discharge of sewage to the environment. This work presents the analysis of the risk of groundwater-induced sewer flooding within the Chalk catchment of the River Lambourn, Berkshire. A spatially distributed groundwater model was used to assess historic groundwater flood risk and the potential impacts of changes in future climate. We then linked this model to an urban groundwater model to enable us to simulate groundwater-sewer interaction in detail. The modelling setup was used to identify relationships between infiltration into sewers and groundwater levels at specific points on TWUL's sewer network, and to estimate historic and future groundwater flood risk, and how this varies across the catchment. The study showed the significance of understanding the impact of groundwater on the urban water systems, and producing information that can inform a water company's response to groundwater flood risk, their decision making process and their asset management planning. However, the knowledge gained through integrated modelling of groundwater-sewer interactions has highlighted limitations of existing approaches for the simulation of these coupled systems. We conclude this work with number of recommendations about how to improve such hydrological/sewer analysis.

Impact of urbanization on flood of Shigu creek in Dongguan city

NASA Astrophysics Data System (ADS)

Pan, Luying; Chen, Yangbo; Zhang, Tao

2018-06-01

Shigu creek is a highly urbanized small watershed in Dongguan City. Due to rapid urbanization, quick flood response has been observed, which posted great threat to the flood security of Dongguan City. To evaluate the impact of urbanization on the flood changes of Shigu creek is very important for the flood mitigation of Shigu creek, which will provide insight for flood planners and managers for if to build a larger flood mitigation system. In this paper, the Land cover/use changes of Shigu creek from 1987-2015 induced by urbanization was first extracted from a local database, then, the Liuxihe model, a physically based distributed hydrological model, is employed to simulate the flood processes impacted by urbanization. Precipitation of 3 storms was used for flood processes simulation. The results show that the runoff coefficient and peak flow have increased sharply.

Damage estimation of subterranean building constructions due to groundwater inundation - the GIS-based model approach GRUWAD

NASA Astrophysics Data System (ADS)

Schinke, R.; Neubert, M.; Hennersdorf, J.; Stodolny, U.; Sommer, T.; Naumann, T.

2012-09-01

The analysis and management of flood risk commonly focuses on surface water floods, because these types are often associated with high economic losses due to damage to buildings and settlements. The rising groundwater as a secondary effect of these floods induces additional damage, particularly in the basements of buildings. Mostly, these losses remain underestimated, because they are difficult to assess, especially for the entire building stock of flood-prone urban areas. For this purpose an appropriate methodology has been developed and lead to a groundwater damage simulation model named GRUWAD. The overall methodology combines various engineering and geoinformatic methods to calculate major damage processes by high groundwater levels. It considers a classification of buildings by building types, synthetic depth-damage functions for groundwater inundation as well as the results of a groundwater-flow model. The modular structure of this procedure can be adapted in the level of detail. Hence, the model allows damage calculations from the local to the regional scale. Among others it can be used to prepare risk maps, for ex-ante analysis of future risks, and to simulate the effects of mitigation measures. Therefore, the model is a multifarious tool for determining urban resilience with respect to high groundwater levels.

Coupled 1-D sewer and street networks and 2-D flooding model to rapidly evaluate surface inundation

NASA Astrophysics Data System (ADS)

Kao, Hong-Ming; Hsu, Hao-Ming

2017-04-01

Flash floods have occurred frequently in the urban areas around the world and cause the infrastructure and people living to expose continuously in the high risk level of pluvial flooding. According to historical surveys, the major reasons of severe surface inundations in the urban areas can be attributed to heavy rainfall in the short time and/or drainage system failure. In order to obtain real-time flood forecasting with high accuracy and less uncertainty, an appropriate system for predicting floods is necessary. For the reason, this study coupled 1-D sewer and street networks and 2-D flooding model as an operational modelling system for rapidly evaluating surface inundation. The proposed system is constructed by three significant components: (1) all the rainfall-runoff of a sub-catchment collected via gullies is simulated by the RUNOFF module of the Storm Water Management Model (SWMM); (2) and directly drained to the 1-D sewer and street networks via manholes as inflow discharges to conduct flow routing by using the EXTRAN module of SWMM; (3) after the 1-D simulations, the surcharges from manholes are considered as point sources in 2-D overland flow simulations that are executed by the WASH123D model. It can thus be used for urban flood modelling that reflects the rainfall-runoff processes, and the dynamic flow interactions between the storm sewer system and the ground surface in urban areas. In the present study, we adopted the Huwei Science and Technology Park, located in the south-western part of Taiwan, as the demonstration area because of its high industrial values. The region has an area about 1 km2 with approximately 1 km in both length and width. It is as isolated urban drainage area in which there is a complete sewer system that collects the runoff and drains to the detention pond. Based on the simulated results, the proposed modelling system was found that the simulated floods fit to the survey records because the physical rainfall-runoff phenomena in urban environment were better reflected. Keywords: SWMM, WASH123D, surface inundation, real-time.

Uncorrected land-use planning highlighted by flooding: the Alba case study (Piedmont, Italy)

NASA Astrophysics Data System (ADS)

Luino, F.; Turconi, L.; Petrea, C.; Nigrelli, G.

2012-07-01

Alba is a town of over 30 000 inhabitants located along the Tanaro River (Piedmont, northwestern Italy) and is famous for its wine and white truffles. Many important industries and companies are based in Alba, including the famous confectionery group Ferrero. The town suffered considerably from a flood that occurred on 5-6 November 1994. Forty-eight percent of the urban area was inundated, causing severe damage and killing nine people. After the flood, the Alba area was analysed in detail to determine the reasons for its vulnerability. Information on serious floods in this area since 1800 was gathered from official records, state technical office reports, unpublished documents in the municipal archives, and articles published in local and national newspapers. Maps, plans and aerial photographs (since 1954) were examined to reconstruct Alba's urban development over the last two centuries and the planform changes of the Tanaro River. The results were compared with the effects of the November 1994 flood, which was mapped from aerial photographs taken immediately after the flood, field surveys and eyewitness reports. The territory of Alba was subdivided into six categories: residential; public service; industrial, commercial and hotels; sports areas, utilities and standards (public gardens, parks, athletics grounds, private and public sport clubs); aggregate plants and dumps; and agriculture and riverine strip. The six categories were then grouped into three classes with different flooding-vulnerability levels according to various parameters. Using GIS, the three river corridors along the Tanaro identified by the Autorità di Bacino del Fiume Po were overlaid on the three classes to produce a final map of the risk areas. This study shows that the historic floods and their dynamics have not been duly considered in the land-use planning of Alba. The zones that were most heavily damaged in the 1994 flood were those that were frequently affected in the past and sites of more recent urbanisation. Despite recurrent severe flooding of the Tanaro River and its tributaries, areas along the riverbed and its paleochannels have been increasingly used for infrastructure and building (e.g., roads, a municipal dump, a prison, natural aggregate plants, a nomad camp), which has often interfered with the natural spread of the floodwaters. Since the 1994 flood, many remedial projects have been completed along the Tanaro and its tributaries, including levees, bank protection, concrete walls and floodway channels. In spite of these costly projects, some areas remain at high risk for flooding. The method used, which considered historical data, river corridors identified by hydraulic calculations, geomorphological aspects and land-use planning, can indicate with good accuracy flood-prone areas and in consequence to be an useful tool for the coherent planning of urban expansion and the mitigation of flood risk.

From flood management systems to flood resilient systems: integration of flood resilient technologies

NASA Astrophysics Data System (ADS)

Salagnac, J.-L.; Diez, J.; Tourbier, J.

2012-04-01

Flooding has always been a major risk world-wide. Humans chose to live and develop settlements close to water (rivers, seas) due to the resources water brings, i.e. food, energy, capacity to economically transport persons and goods, and recreation. However, the risk from flooding, including pluvial flooding, often offsets these huge advantages. Floods sometimes have terrible consequences from both a human and economic point of view. The permanence and growth of urban areas in flood-prone zones despite these risks is a clear indication of the choices of concerned human groups. The observed growing concentration of population along the sea shore, the increase of urban population worldwide, the exponential growth of the world population and possibly climate change are factors that confirm flood will remain a major issue for the next decades. Flood management systems are designed and implemented to cope with such situations. In spite of frequent events, lessons look to be difficult to draw out and progresses are rather slow. The list of potential triggers to improve flood management systems is nevertheless well established: information, education, awareness raising, alert, prevention, protection, feedback from events, ... Many disciplines are concerned which cover a wide range of soft and hard sciences. A huge amount of both printed and electronic literature is available. Regulations are abundant. In spite of all these potentially favourable elements, similar questions spring up after each new significant event: • Was the event forecast precise enough? • Was the alert system efficient? • Why were buildings built in identified flood prone areas? • Why did the concerned population not follow instructions? • Why did the dike break? • What should we do to avoid it happens again? • What about damages evaluation, wastes and debris evacuation, infrastructures and buildings repair, activity recovery, temporary relocation of inhabitants, health concerns, insurance concerns, water-resistant materials, vulnerability assessment ? Flood resilient system (FReS) concept has been proposed as a new framework to address flood situations. Such systems intend to better approach such situations from a holistic point of view. FReS encompass ecologic, spatial, structural, social, disaster relief and flood risk aspects. FReS design and implementation conditions have been addressed by the FP7 SMARTeST (Smart Resilience Technology, Systems and Tools) project. The focus of this Project on the use of available and innovative communication, forecasting and flood protection technologies leads to an original contribution which highlights both the scope and the limits of this technology driven approach. These reflexions contribute to the elaboration of guidelines for the design of FReS.

Damaging events along roads during bad weather periods: a case study in Calabria (Italy)

NASA Astrophysics Data System (ADS)

Petrucci, O.; Pasqua, A. A.

2012-02-01

The study focuses on circumstances that affect people during periods of bad weather conditions characterised by winds, rainfall, landslides, flooding, and storm surges. A methodological approach and its application to a study area in southern Italy are presented here. A 10-yr database was generated by mining data from a newspaper. Damaging agents were sorted into five types: flood, urban flooding, landslide, wind, and storm surge. Damage to people occurred in 126 cases, causing 13 victims, 129 injured and about 782 people involved but not injured. For cases of floods, urban flooding and landslides, the analysis does not highlight straightforward relationships between rainfall and damage to people, even if the events showed different features according to the months of occurrence. The events occurring between May and October were characterised by concentrated and intense rainfall, and between May and July, the highest values of hourly (103 mm on the average) and monthly rainfall (114 mm on the average) were recorded. Urban flooding and flash floods were the most common damaging agents: injured, involved people and more rarely, cases with victims were reported. Between November and April, the highest number of events was recorded. Rainfall presented longer durations and hourly and sub-hourly rainfall were lower than those recorded between May and October. Landslides were the most frequent damaging agents but the highest number of cases with victims, which occurred between November and January, were mainly related to floods and urban flooding. Motorists represent the totality of the victims; 84% of the people were injured and the whole of people involved. All victims were men, and the average age was 43 yr. The primary cause of death was drowning caused by floods, and the second was trauma suffered in car accidents caused by urban flooding. The high number of motorists rescued in submerged cars reveals an underestimation of danger in the case of floods, often increased by the sense of security related to the familiarity of the road. In contrast, in the cases of people involved in landslides, when there was enough time to realise the potential risk, people behaved appropriately to avoid negative consequences. Of the victims, 50% were killed along fast-flowing roads; this may be related to the high speed limit in force on these roads, as a car's speed reduces the reaction time of a driver's response to an unexpected situation, whatever the damaging agent is. These results can be used in local information/education campaigns to both increase risk awareness and promote self-protective behaviours. Moreover, the mapping of damaging effects pointed out the regional sectors in which the high frequency of the events suggests further planning of in-depth examinations, which can individuate the critical points and local regulator interventions that might change damage incidences in the future.

RNICO: a new simple geometric index for assessing the impact of urban development pattern on peak flows in urban catchments

NASA Astrophysics Data System (ADS)

Kasaee Roodsari, B.; Chandler, D. G.

2016-12-01

Urban sprawl is widespread across the world and the associated hydrologic impacts are increasing in peri-urban catchments due to increased area of impervious. There is a strong agreement on the positive correlation between the fractional impervious area and peak flows in urban catchments. Nevertheless, the effect of land development pattern on peak flows is not well investigated. In this study, a new simple geometric index, Relative Nearness of Imperviousness to the Catchment Outlet (RNICO), is defined to correlate imperviousness distribution of peri-urban catchments to runoff peak flows. Results of applying RNICO to 20 sub-catchments in New York State showed a strong positive correlation (R2>0.97) between RNICO and runoff peak flows for small peri-urban catchments (A< 42 km2) indicating higher flood risk of downstream urbanization. For large catchments (A> 42 km2), no correlation was indicated between RNICO and peak flows. We highlight the necessity of a greater discharge monitoring network at small peri-urban catchments to support local urban flood forecast.

Nested 1D-2D approach for urban surface flood modeling

NASA Astrophysics Data System (ADS)

Murla, Damian; Willems, Patrick

2015-04-01

Floods in urban areas as a consequence of sewer capacity exceedance receive increased attention because of trends in urbanization (increased population density and impermeability of the surface) and climate change. Despite the strong recent developments in numerical modeling of water systems, urban surface flood modeling is still a major challenge. Whereas very advanced and accurate flood modeling systems are in place and operation by many river authorities in support of flood management along rivers, this is not yet the case in urban water management. Reasons include the small scale of the urban inundation processes, the need to have very high resolution topographical information available, and the huge computational demands. Urban drainage related inundation modeling requires a 1D full hydrodynamic model of the sewer network to be coupled with a 2D surface flood model. To reduce the computational times, 0D (flood cones), 1D/quasi-2D surface flood modeling approaches have been developed and applied in some case studies. In this research, a nested 1D/2D hydraulic model has been developed for an urban catchment at the city of Gent (Belgium), linking the underground sewer (minor system) with the overland surface (major system). For the overland surface flood modelling, comparison was made of 0D, 1D/quasi-2D and full 2D approaches. The approaches are advanced by considering nested 1D-2D approaches, including infiltration in the green city areas, and allowing the effects of surface storm water storage to be simulated. An optimal nested combination of three different mesh resolutions was identified; based on a compromise between precision and simulation time for further real-time flood forecasting, warning and control applications. Main streets as mesh zones together with buildings as void regions constitute one of these mesh resolution (3.75m2 - 15m2); they have been included since they channel most of the flood water from the manholes and they improve the accuracy of interactions within the 1D sewer network. Other areas that recorded flooding outside the main streets have been also included with the second mesh resolution for an accurate determination of flood maps (12.5m2 - 50m2). Permeable areas have been identified and used as infiltration zones using the Horton infiltration model. A mesh sensitivity analysis has been performed for the low flood risk areas for a proper model optimization. As outcome of that analysis, the third mesh resolution has been chosen (75m2 - 300m2). Performance tests have been applied for several synthetic design storms as well as historical storm events displaying satisfactory results upon comparing the flood mapping outcomes produced by the different approaches. Accounting for the infiltration in the green city spaces reduces the flood extents in the range 39% - 68%, while the average reduction in flood volume equals 86%. Acknowledgement: Funding for this research was provided by the Interreg IVB NWE programme (project RainGain) and the Belgian Science Policy Office (project PLURISK). The high resolution topographical information data were obtained from the geographical information service AGIV; the original full hydrodynamic sewer network model from the service company Farys, and the InfoWorks licence from Innovyze.

Assessing urban potential flooding risk and identifying effective risk-reduction measures.

PubMed

Cherqui, Frédéric; Belmeziti, Ali; Granger, Damien; Sourdril, Antoine; Le Gauffre, Pascal

2015-05-01

Flood protection is one of the traditional functions of any drainage system, and it remains a major issue in many cities because of economic and health impact. Heavy rain flooding has been well studied and existing simulation software can be used to predict and improve level of protection. However, simulating minor flooding remains highly complex, due to the numerous possible causes related to operational deficiencies or negligent behaviour. According to the literature, causes of blockages vary widely from one case to another: it is impossible to provide utility managers with effective recommendations on how to improve the level of protection. It is therefore vital to analyse each context in order to define an appropriate strategy. Here we propose a method to represent and assess the flooding risk, using GIS and data gathered during operation and maintenance. Our method also identifies potential management responses. The approach proposed aims to provide decision makers with clear and comprehensible information. Our method has been successfully applied to the Urban Community of Bordeaux (France) on 4895 interventions related to flooding recorded during the 2009-2011 period. Results have shown the relative importance of different issues, such as human behaviour (grease, etc.) or operational deficiencies (roots, etc.), and lead to identify corrective and proactive. This study also confirms that blockages are not always directly due to the network itself and its deterioration. Many causes depend on environmental and operating conditions on the network and often require collaboration between municipal departments in charge of roads, green spaces, etc. Copyright © 2015 Elsevier B.V. All rights reserved.

Examining the effects of urban agglomeration polders on flood events in Qinhuai River basin, China with HEC-HMS model.

PubMed

Gao, Yuqin; Yuan, Yu; Wang, Huaizhi; Schmidt, Arthur R; Wang, Kexuan; Ye, Liu

2017-05-01

The urban agglomeration polders type of flood control pattern is a general flood control pattern in the eastern plain area and some of the secondary river basins in China. A HEC-HMS model of Qinhuai River basin based on the flood control pattern was established for simulating basin runoff, examining the impact of urban agglomeration polders on flood events, and estimating the effects of urbanization on hydrological processes of the urban agglomeration polders in Qinhuai River basin. The results indicate that the urban agglomeration polders could increase the peak flow and flood volume. The smaller the scale of the flood, the more significant the influence of the polder was to the flood volume. The distribution of the city circle polder has no obvious impact on the flood volume, but has effect on the peak flow. The closer the polder is to basin output, the smaller the influence it has on peak flows. As the level of urbanization gradually improving of city circle polder, flood volumes and peak flows gradually increase compared to those with the current level of urbanization (the impervious rate was 20%). The potential change in flood volume and peak flow with increasing impervious rate shows a linear relationship.

Designing a spatial decision-support system to improve urban resilience to floods

NASA Astrophysics Data System (ADS)

Heinzlef, Charlotte; Ganz, François; Becue, Vincent; Serre, Damien

2017-04-01

Since Hurricane Katrina (2005), the scientific-political-urban attention is focusing on urban resilience to floods. To prevent the recurrence of such a deadly and costly event ( 82 billion, Serre et al, 2014), experts began to question pre- and post- disaster management. Until now, managers and urban planners have been working on flood risk, according to the paradigm of prevention. However, following Katrina, a new approach was gradually integrated and the concept of resilience applied to urban areas (Serre, 2011). The resilience concept, used in ecology and defined by Holling (1973), refers to the ability of a system to keep its own variables despite changes and analyses the capacity of an (eco)system to tolerate disturbances without changing its state. To link it with flood risk management, this concept takes more into account water and would lead to technical, architectural, social, urban and political innovation (Serre et al, 2016). However, despite 12 years after Katrina, very few concrete actions have been made (Barroca and Serre, 2013). Based on this argument, and several abortive studies, we wish to re-address the operationalization of resilience by redefining its objectives and expectations. While in Europe some studies have been done to build up vulnerability indicators (Barroca et al, 2006; Opach et al, 2016; Wiréhn et al, 2016), few still talk about resilience. When some do (Folke et al, 2010; Lhomme et al, 2011; Nguyen et al, 2013; Suarez et al, 2016), they mainly speak about technical resilience without integrating social resilience. Our objective is thus to imagine a system facilitating the understanding of this concept, its integration in management and development policies. We started on the methodology of information systems, organized system for collection, organization, storage and communication of information, and more precisely on observatories, information systems using the methodology of observation. These last years, we assist to an increase of these observatories (Dolique, 2013), observatories which are focused on different fields as, risk observation (PACA regional risks observatory), environmental observation (Environmental virtual observatory), ecological observation (National ecological observatory), etc. Usually, an observatory focuses either on a scale (generally national or regional) or on a fact (risks, environment, energy, economy, etc) Our objective is to develop an observatory tested on the territory of Avignon, to design a tool for analyzing resilience according to indicators which would measure technical resilience (urban and suburban networks), urban resilience (buildings and critical infrastructures) and social resilience (knowledge of risk, memory of the disaster, perception of vulnerability). Our tool would be designed with the help of our socio-economic partner which is the city of Avignon, and would provide a clearer picture of the resilience for managers and inhabitants. It would be participatory and social insofar as, following the assessment of the existing resilience thanks to the indicators, it would be make the territory more resilient thanks to expert advices and participatory workshops for the inhabitants and managers.

Resilience of sewage services to climate change uncertainty: analysis of the management of sewer overflows in two Parisian suburban areas.

NASA Astrophysics Data System (ADS)

Rioust, E.; Deroubaix, J. F.; Barroca, B.; Bonierbale, T.; de Gouvello, B.; Deutsch, J. C.; Hubert, G.

2009-04-01

This paper considers the resilience perspective as an approach for understanding social and political vulnerabilities of urban services. The authors examine to what extend uncertainty due to climate change may affect the resilience of these urban services. The resilience perspective is increasingly used for analysing social groups' capacities to adapt to and live with disturbances. A lot of work on resilience has focused on the capacity to absorb shocks and still maintain functions. But there is also another aspect of resilience, which leads to take into account systems vulnerabilities and to aim at understanding their equilibrium and re-organization capacity. The purpose with this paper is to assess sewage systems capacities to adapt to climate change. Indeed, climate change could cause an increase of extreme rain events and, as a matter of consequence, an increase of sewer overflows and flooding of urbanised areas. Sewer systems have to cope with this change that may gravely affect urban planning. In recent studies of political science, risk management has been considered as a public policy involving and resulting from complex social, political and technical processes (Gilbert et al. 2003). From this point of view, the management of wastewaters and storm waters has to be considered not only as a technical but also as a political and a social system. Therefore, political science can be a fruitful perspective to understand the stakeholders perceptions of uncertainty and the way they are going to integrate this issue in their practices. The authors analyse the adaptive capacities of two sewer systems located in the Parisian suburban area. The chosen areas are highly populated. Each network is managed within a political and administrative unit called "Département". Both authorities of these "Départements" implement a public sewage service. Nonetheless these networks are connected and part of the greater Paris sewage policy. In both areas a real time control of urban wastewater systems has been developed. At last, both sewage services have make flood management their prior objective. Both "Départements" have developed retention capacities. One of them has implemented a source control strategy including daywatering while the other one has intent on building up a "culture of risk" on the territory. In this paper we compare how these social and technical systems cope with risks and face to climate change. Relying on interviews conducted with engineers and technical agents of water and sewage services and with a few residents in the concerned areas, we define three types of actors who take part to the social and technical systems. There are, on the one hand, the technical actors, including the agents currently managing the sewer network. On the other hand, there are the political actors in charge of elaborating and implementing a policy of risk prevention and managing the security force. Last but not least, there are the inhabitants who take an important part in the crisis management and in the mobilisations against the existing risk policy. The first part of the paper describes the sewage systems while there is no crisis. We explicit the actors' perceptions of risk and the risk management strategies they develop. The risk perceptions of technicians are truly different than the citizens' ones. For the technicians, floods, and their possible worsening, could be controlled. The problem is generated by the increasing impervious areas but it can be solved with technologies (real time control, best management practices and compensatory measures). In the technicians' perceptions, the risk is inherent to technical failures and can be reduced. For citizens, the concern is more for economics and personal goods losses. However both types of actors deal with the matter of submerged territories as a problem of institutional inertia (lack of financial resource, problem of governance). The second part presents the crisis management in these areas. We explain how various actors cope with flood when the risk occurs. The analysis of the actors' reaction to the flood event contributes (1) to further characterise the social and political system dealing with the flooding risk and, (2) to assess the adaptive capacities of the technicians to the risk. The crisis moment gives a specific role for each actor of the social, political and technical systems. Technical actors manage natural hazard through the remote control system and their major concern is for network disruption. Once flood has occurred, they may assist residents cleaning out public space. Nonetheless, after the crisis, the technical actors are seen by the others as the responsible for the flood. They are considered as the ones in charge of preventing the future flood event, even if they claim that they cannot protect urban areas and population up to a determined risk threshold. Neither technicians nor other actor settle the question of urban planning or existing vulnerability of the flooded areas.

Is there really "nothing you can do"? Pathways to enhanced flood-risk preparedness

NASA Astrophysics Data System (ADS)

Fox-Rogers, Linda; Devitt, Catherine; O'Neill, Eoin; Brereton, Finbarr; Clinch, J. Peter

2016-12-01

Whilst policy makers have tended to adopt an 'information-deficit model' to bolster levels of flood-risk preparedness primarily though communication strategies promoting awareness, the assumed causal relation between awareness and preparedness is empirically weak. As such, there is a growing interest amongst scholars and policy makers alike to better understand why at-risk individuals are underprepared. In this vein, empirical studies, typically employing quantitative methods, have tended to focus on exploring the extent to which flood-risk preparedness levels vary depending not only on socio-demographic variables, but also (and increasingly so) the perceptual factors that influence flood risk preparedness. This study builds upon and extends this body of research by offering a more solution-focused approach that seeks to identify how pathways to flood-risk preparedness can be opened up. Specifically, through application of a qualitative methodology, we seek to explore how the factors that negatively influence flood-risk preparedness can be addressed to foster a shift towards greater levels of mitigation behaviour. In doing so, we focus our analysis on an urban community in Ireland that is identified as 'at risk' of flash flooding and is currently undergoing significant flood relief works. In this regard, the case study offers an interesting laboratory to explore how attitudes towards flood-risk preparedness at the individual level are being influenced within the context of a flood relief scheme that is only partially constructed. In order to redress the dearth of theoretically informed qualitative studies in this field, we draw on Protection Motivation Theory (PMT) to help guide our analysis and make sense of our results. Our findings demonstrate that flood-risk preparedness can be undermined by low levels of efficacy amongst individuals in terms of the preparedness measures available to them and their own personal capacity to implement them. We also elucidate that the 'levee effect' can occur before engineered flood defences are fully constructed as the flood relief works within our case study are beginning to affect people's perception of flood risk in the case study area. We conclude by arguing that (1) individuals' coping appraisals need to be enhanced through communication strategies and other interventions which highlight that future floods may not replicate past events; and (2) the concept of residual risk needs to be communicated at all stages of a flood relief scheme, not just upon completion.

Predicting the microbial exposure risks in urban floods using GIS, building simulation, and microbial models.

PubMed

Taylor, Jonathon; Biddulph, Phillip; Davies, Michael; Lai, Ka man

2013-01-01

London is expected to experience more frequent periods of intense rainfall and tidal surges, leading to an increase in the risk of flooding. Damp and flooded dwellings can support microbial growth, including mould, bacteria, and protozoa, as well as persistence of flood-borne microorganisms. The amount of time flooded dwellings remain damp will depend on the duration and height of the flood, the contents of the flood water, the drying conditions, and the building construction, leading to particular properties and property types being prone to lingering damp and human pathogen growth or persistence. The impact of flooding on buildings can be simulated using Heat Air and Moisture (HAM) models of varying complexity in order to understand how water can be absorbed and dry out of the building structure. This paper describes the simulation of the drying of building archetypes representative of the English building stock using the EnergyPlus based tool 'UCL-HAMT' in order to determine the drying rates of different abandoned structures flooded to different heights and during different seasons. The results are mapped out using GIS in order to estimate the spatial risk across London in terms of comparative flood vulnerability, as well as for specific flood events. Areas of South and East London were found to be particularly vulnerable to long-term microbial exposure following major flood events. Copyright © 2012 Elsevier Ltd. All rights reserved.

Pluvial, urban flood mechanisms and characteristics - Assessment based on insurance claims

NASA Astrophysics Data System (ADS)

Sörensen, Johanna; Mobini, Shifteh

2017-12-01

Pluvial flooding is a problem in many cities and for city planning purpose the mechanisms behind pluvial flooding are of interest. Previous studies seldom use insurance claim data to analyse city scale characteristics that lead to flooding. In the present study, two long time series (∼20 years) of flood claims from property owners have been collected and analysed in detail to investigate the mechanisms and characteristics leading to urban flooding. The flood claim data come from the municipal water utility company and property owners with insurance that covers property loss from overland flooding, groundwater intrusion through basement walls and flooding from the drainage system. These data are used as a proxy for flood severity for several events in the Swedish city of Malmö. It is discussed which rainfall characteristics give most flooding and why some rainfall events do not lead to severe flooding, how city scale topography and sewerage system type influence spatial distribution of flood claims, and which impact high sea level has on flooding in Malmö. Three severe flood events are described in detail and compared with a number of smaller flood events. It was found that the main mechanisms and characteristics of flood extent and its spatial distribution in Malmö are intensity and spatial distribution of rainfall, distance to the main sewer system as well as overland flow paths, and type of drainage system, while high sea level has little impact on the flood extent. Finally, measures that could be taken to lower the flood risk in Malmö, and other cities with similar characteristics, are discussed.

Flood Risk Management Policy in Scotland: Research Questions Past, Present and Future

NASA Astrophysics Data System (ADS)

Wilkinson, Mark; Hastings, Emily; MacDonald, Jannette

2016-04-01

Scotland's Centre of Expertise for Waters (CREW) delivers accessible research and expert opinion to support the Scottish Government and its delivery partners in the development and implementation of water policy. It was established in 2011 by the Scottish Government (Rural and Environmental Science and Analytical Services) in recognition of a gap in the provision of short term advice and research to policy (development and implementation). Key policy areas include the Water Framework Directive, Floods Directive, Drinking Water Directive, Habitats Directive and Scotland's Hydro Nation Strategy. CREW is unique in its demand-driven and free service for policy makers and practitioners, managing the engagement between scientists, policy makers and practitioners to work effectively across this interface. The users of CREW are the Scottish Government, Scottish Environment Protection Agency, Scottish Natural Heritage and Scottish Water. CREW has funded around 100 projects relating to water policy since its inception in 2011. Of these, a significant number relate to flood risk management policy. Based on a review of work to date, this poster will give an overview of these projects and a forward look at the challenges that remain. From learning from community led flood risk management to surface water flood forecasting for urban communities, links will be made between sustainable and traditional flood risk management while considering the perceptions of stakeholders to flood risk management. How can we deliver fully integrated flood risk management options? How policy makers, scientists and land managers can better work together will also be explored.

Palaeoflood hydrology in Europe: towards a better understanding of extreme floods

NASA Astrophysics Data System (ADS)

Benito, G.; Thorndycraft, V. R.; Rico, M.; Sheffer, N.; Enzel, Y.

2003-04-01

Floods are the most common natural disasters in Europe and, in terms of economic damage, costs are increasing spectacularly with time. Flood risk assessment associated with extreme floods is difficult due to the scarcity of hydrological measurements, that rarely go beyond 1000 years, which is clearly not sufficient for flood management in urban and industrial areas. Besides the use of conventional hydrologic data, the pre-instrumental record can be completed from palaeoflood hydrology or from documentary flood information, or through the combined use of both these tools. Recent developments of palaeoflood hydrology in Europe provide (1) major improvements in flood risk assessment, and (2) a better understanding of long-term flood-climate relationships. Palaeoflood hydrology has been successfully applied in large, medium rivers as well as small ungauged mountain drainage basins. Long-term palaeoflood records from Spain and France show that recent extraordinary flooding (causing huge economic damages) are not the largest ones, but that similar or even greater floods occurred several times in the past. In addition, clusters of floods coinciding in time at several European rivers point out to climatic factors as responsible mechanisms, although in recent time flood magnitude can be magnified by increasing human activity.

Combined fluvial and pluvial urban flood hazard analysis: method development and application to Can Tho City, Mekong Delta, Vietnam

NASA Astrophysics Data System (ADS)

Apel, H.; Trepat, O. M.; Hung, N. N.; Chinh, D. T.; Merz, B.; Dung, N. V.

2015-08-01

Many urban areas experience both fluvial and pluvial floods, because locations next to rivers are preferred settlement areas, and the predominantly sealed urban surface prevents infiltration and facilitates surface inundation. The latter problem is enhanced in cities with insufficient or non-existent sewer systems. While there are a number of approaches to analyse either fluvial or pluvial flood hazard, studies of combined fluvial and pluvial flood hazard are hardly available. Thus this study aims at the analysis of fluvial and pluvial flood hazard individually, but also at developing a method for the analysis of combined pluvial and fluvial flood hazard. This combined fluvial-pluvial flood hazard analysis is performed taking Can Tho city, the largest city in the Vietnamese part of the Mekong Delta, as example. In this tropical environment the annual monsoon triggered floods of the Mekong River can coincide with heavy local convective precipitation events causing both fluvial and pluvial flooding at the same time. Fluvial flood hazard was estimated with a copula based bivariate extreme value statistic for the gauge Kratie at the upper boundary of the Mekong Delta and a large-scale hydrodynamic model of the Mekong Delta. This provided the boundaries for 2-dimensional hydrodynamic inundation simulation for Can Tho city. Pluvial hazard was estimated by a peak-over-threshold frequency estimation based on local rain gauge data, and a stochastic rain storm generator. Inundation was simulated by a 2-dimensional hydrodynamic model implemented on a Graphical Processor Unit (GPU) for time-efficient flood propagation modelling. All hazards - fluvial, pluvial and combined - were accompanied by an uncertainty estimation considering the natural variability of the flood events. This resulted in probabilistic flood hazard maps showing the maximum inundation depths for a selected set of probabilities of occurrence, with maps showing the expectation (median) and the uncertainty by percentile maps. The results are critically discussed and ways for their usage in flood risk management are outlined.

Comparative analysis between the floods and the rate of urbanization in the Ribeira Valley, São Paulo - Brazil

NASA Astrophysics Data System (ADS)

Ferreira, B. C.; Valverde, M. C.

2013-05-01

The aim of this paper is to analyze the occurrence of floods facing the rate of urbanization in the Ribeira Valley. The Ribeira Valley is located on the basin of Ribeira de Iguape River in eastern Paraná and southeastern São Paulo state in Brazil. The region has been considered one of the most important international conservation priorities by agencies such as the International Union for the Conservation of Nature (IUCN), and the UNESCO/MAB Program. This region has a history of recurrent floods, causing huge financial losses particularly to the poorest people, including casualties as well as material losses. This study analyzed three flood events that occurred in January 1995, January 1997 and February-March 1998, reaching the towns of Eldorado, Ribeira and Sete Barras. To determine the affected areas, the researchers used the shapes (digital data) obtained from the Geographic Information System of Ribeira de Iguape River Basin which is maintained by the Ribeira de Iguape River Basin and South Seashore Committee. The SPRING was the processing tool used for data manipulation. Additionally we used rainfall data, flow and water level elevation for the years 1983, 1995, 1997, 1998 and 2011. The results show that in January 1997 there happened the largest flood area across the three cities and this effect coincides with the highest levels of rainfall and flow. The second largest flood happened in January 1995 and the smallest one was in February-March 1998. Another important aspect to be noted is that all floods affected a large floodplain in both rural and urban areas. It was also found a direct relationship between the rate of urbanization and the area affected by the floods. The results show that the larger the area of urbanization, the larger the flooded area. It was also verified in the precipitation climatology that most extreme events occurred in 1983 and 2011. Specifically the 2011 event occurred during dry season bringing the whole region to a state of emergency, reaching 17 municipalities. The Ribeira Valley reached its flood peak of 13.45 m on 08/02/2011 in Eldorado with a total of 27,931 people affected. Since the urban areas for the cities studied are vulnerable to flood risk, it is necessary a thorough registration of the worst event reaching the whole area and the people affected in order to find the best way to mitigate the impacts of this natural disaster.

Front gardens to car parks: changes in garden permeability and effects on flood regulation.

PubMed

Warhurst, Jennifer R; Parks, Katherine E; McCulloch, Lindsay; Hudson, Malcolm D

2014-07-01

This study addresses the consequences of widespread conversion of permeable front gardens to hard standing car parking surfaces, and the potential consequences in high-risk urban flooding hotspots, in the city of Southampton. The last two decades has seen a trend for domestic front gardens in urban areas to be converted for parking, driven by the lack of space and increased car ownership. Despite media and political attention, the effects of this change are unknown, but increased and more intense rainfall, potentially linked to climate change, could generate negative consequences as runoff from impermeable surfaces increases. Information is limited on garden permeability change, despite the consequences for ecosystem services, especially flood regulation. We focused on eight flooding hotspots identified by the local council as part of a wider urban flooding policy response. Aerial photographs from 1991, 2004 and 2011 were used to estimate changes in surface cover and to analyse permeability change within a digital surface model in a GIS environment. The 1, 30 and 100 year required attenuation storage volumes were estimated, which are the temporary storage required to reduce the peak flow rate given surface permeability. Within our study areas, impermeable cover in domestic front gardens increased by 22.47% over the 20-year study period (1991-2011) and required attenuation storage volumes increased by 26.23% on average. These increases suggest that a consequence of the conversion of gardens to parking areas will be a potential increase in flooding frequency and severity - a situation which is likely to occur in urban locations worldwide. Copyright © 2014 Elsevier B.V. All rights reserved.

A new approach to flood vulnerability assessment for historic buildings in England

NASA Astrophysics Data System (ADS)

Stephenson, V.; D'Ayala, D.

2014-05-01

The recent increase in frequency and severity of flooding in the UK has led to a shift in the perception of risk associated with flood hazards. This has extended to the conservation community, and the risks posed to historic structures that suffer from flooding are particularly concerning for those charged with preserving and maintaining such buildings. In order to fully appraise the risks in a manner appropriate to the complex issue of preservation, a new methodology is presented here that studies the nature of the vulnerability of such structures, and places it in the context of risk assessment, accounting for the vulnerable object and the subsequent exposure of that object to flood hazards. The testing of the methodology is carried out using three urban case studies and the results of the survey analysis provide guidance on the development of fragility curves for historic structures exposed to flooding. This occurs through appraisal of vulnerability indicators related to building form, structural and fabric integrity, and preservation of architectural and archaeological values. Key findings of the work include determining the applicability of these indicators to fragility analysis, and the determination of the relative vulnerability of the three case study sites.

A new approach to flood loss estimation and vulnerability assessment for historic buildings in England

NASA Astrophysics Data System (ADS)

Stephenson, V.; D'Ayala, D.

2013-10-01

The recent increase in frequency and severity of flooding in the UK has led to a shift in the perception of risk associated with flood hazards. This has extended to the conservation community, and the risks posed to historic structures that suffer from flooding are particularly concerning for those charged with preserving and maintaining such buildings. In order to fully appraise the risks in a manner appropriate to the complex issue of preservation, a new methodology is proposed that studies the nature of vulnerability of such structures, and places it in the context of risk assessment, accounting for the vulnerable object and the subsequent exposure of that object to flood hazards. The testing of the methodology is carried out using three urban case studies and the results of the survey analysis provide key findings and guidance on the development of fragility curves for historic structures exposed to flooding. This occurs through appraisal of key vulnerability indicators related to building form, structural and fabric integrity, and preservation of architectural and archaeological values. This in turn facilitates the production of strategies for mitigating and managing the losses threatened by such extreme climate events.

Adaption to Extreme Rainfall with Open Urban Drainage System: An Integrated Hydrological Cost-Benefit Analysis

NASA Astrophysics Data System (ADS)

Zhou, Qianqian; Panduro, Toke Emil; Thorsen, Bo Jellesmark; Arnbjerg-Nielsen, Karsten

2013-03-01

This paper presents a cross-disciplinary framework for assessment of climate change adaptation to increased precipitation extremes considering pluvial flood risk as well as additional environmental services provided by some of the adaptation options. The ability of adaptation alternatives to cope with extreme rainfalls is evaluated using a quantitative flood risk approach based on urban inundation modeling and socio-economic analysis of corresponding costs and benefits. A hedonic valuation model is applied to capture the local economic gains or losses from more water bodies in green areas. The framework was applied to the northern part of the city of Aarhus, Denmark. We investigated four adaptation strategies that encompassed laissez-faire, larger sewer pipes, local infiltration units, and open drainage system in the urban green structure. We found that when taking into account environmental amenity effects, an integration of open drainage basins in urban recreational areas is likely the best adaptation strategy, followed by pipe enlargement and local infiltration strategies. All three were improvements compared to the fourth strategy of no measures taken.

Adaption to extreme rainfall with open urban drainage system: an integrated hydrological cost-benefit analysis.

PubMed

Zhou, Qianqian; Panduro, Toke Emil; Thorsen, Bo Jellesmark; Arnbjerg-Nielsen, Karsten

2013-03-01

This paper presents a cross-disciplinary framework for assessment of climate change adaptation to increased precipitation extremes considering pluvial flood risk as well as additional environmental services provided by some of the adaptation options. The ability of adaptation alternatives to cope with extreme rainfalls is evaluated using a quantitative flood risk approach based on urban inundation modeling and socio-economic analysis of corresponding costs and benefits. A hedonic valuation model is applied to capture the local economic gains or losses from more water bodies in green areas. The framework was applied to the northern part of the city of Aarhus, Denmark. We investigated four adaptation strategies that encompassed laissez-faire, larger sewer pipes, local infiltration units, and open drainage system in the urban green structure. We found that when taking into account environmental amenity effects, an integration of open drainage basins in urban recreational areas is likely the best adaptation strategy, followed by pipe enlargement and local infiltration strategies. All three were improvements compared to the fourth strategy of no measures taken.

Ho Chi Minh City adaptation to increasing risk of coastal and fluvial floods

NASA Astrophysics Data System (ADS)

Scussolini, Paolo; Lasage, Ralph

2016-04-01

Coastal megacities in southeast Asia are a hotspot of vulnerability to floods. In such contexts, the combination of fast socio-economic development and of climate change impacts on precipitation and sea level generates concerns about the flood damage to people and assets. This work focuses on Ho Chi Minh City, Vietnam, for which we estimate the present and future direct risk from river and coastal floods. A model cascade is used that comprises the Saigon river basin and the urban network, plus the land-use-dependent damaging process. Changes in discharge for five return periods are simulated, enabling the probabilistic calculation of the expected annual economic damage to assets, for differnt scenarios of global emissions, local socio-economic growth, and land subsidence, up to year 2100. The implementation of a range of adaptation strategies is simulated, including building dykes, elevating, creating reservoirs, managing water and sediment upstream, flood-proofing, halting groundwater abstraction. Results are presented on 1) the relative weight of each future driver in determining the flood risk of Ho Chi Minh, and 2) the efficiency and feasibility of each adaptation strategy.

Climate change, urbanization, and optimal long-term floodplain protection

NASA Astrophysics Data System (ADS)

Zhu, Tingju; Lund, Jay R.; Jenkins, Marion W.; Marques, Guilherme F.; Ritzema, Randall S.

2007-06-01

This paper examines levee-protected floodplains and economic aspects of adaptation to increasing long-term flood risk due to urbanization and climate change. The lower American River floodplain in the Sacramento, California, metropolitan area is used as an illustration to explore the course of optimal floodplain protection decisions over long periods. A dynamic programming model is developed and suggests economically desirable adaptations for floodplain levee systems given simultaneous changes in flood climate and urban land values. Economic engineering optimization analyses of several climate change and urbanization scenarios are made. Sensitivity analyses consider assumptions about future values of floodplain land and damageable property along with the discount rate. Methodological insights and policy lessons are drawn from modeling results, reflecting the joint effects and relationships that climate, economic costs, and regional economic growth can have on floodplain levee planning decisions.

The Complexities of Urban Flood Response: Hydrologic Analyses for the Charlotte, North Carolina Metropolitan Region

NASA Astrophysics Data System (ADS)

Zhou, Z.; Smith, J. A.; Yang, L.; Baeck, M. L.; Liu, S.; Ten Veldhuis, M. C.

2016-12-01

The objective of this study is to develop a broad characterization of land surface and hydrometeorological controls of urban flood frequency. We focus on a collection of "small" urban watersheds (with drainage area ranging from 7 to 200 km2) in Charlotte metropolitan region, North Carolina. These watersheds are contrasted by a variety of land surface properties, such as size, shape, land use/land cover type, impervious coverage pattern, stormwater infrastructure, etc. We carried out empirical analyses based on long-term (15 years), high-resolution (1 15 minutes) instantaneous USGS stream gaging observations as well as bias-corrected, high-resolution (1 km2, 15 min) radar rainfall fields developed through the Hydro-NEXRAD system. Extreme floods in Charlotte urban watersheds are primarily induced by a mixture of flood agents including warm season thunderstorms and tropical cyclones, which ultimately contributed to the upper-tail properties of flood frequency. Flood response in urban watersheds is dominantly dictated by space-time characteristics of rainfall, with relatively significant correlation between runoff and rainfall over more developed watersheds. The roles of antecedent soil moisture and stormwater management infrastructure in flood response are also contrasted across the urban watersheds. The largest variability of flood response, in terms of flood peak and timing, exists in the watershed at a scale of 100 km2. The scale-dependent hydrological response is closely related to the pattern and evolution of urban development across watersheds. Our analyses show the complexities of urban flood response in Charlotte metropolitan region. There are no simple metrics that could perfectly explain the contrasts in flood response across urban watersheds. Future research is directed towards sophisticated modeling studies for a predictive understanding of flood frequency in urban watersheds.

Flood resilience technology, systems and toolls

NASA Astrophysics Data System (ADS)

Garvin, S.; Kelly, D.

2012-04-01

In recent years there has been a general acceptance that the risk from flooding is increasing, primarily due to increased urbanization and the impact of climate change (Zevenbergen et al, 2010). Flood resilience technology (FRe T) is a term used to describe a collection of technologies, materials and products that are used to protect and allow recovery of buildings, communities and infrastructure from flooding. River or coastal flooding is the focus of the legislation, regulation and guidance that is intended to control development and ensure the risk to new properties is low. However, the cost of building and maintaining primary flood defense systems for rivers and coasts is becoming prohibitive and as such future flood management needs to consider a range of measures to manage risk, in particular improving the resilience of buildings, infrastructure and communities. Surface water flooding is now known to cause as much damage as coastal and riverine flooding combined and is as likely to be experienced by both existing and new developments. Therefore FRe T solutions need to be adaptable and flexible. Previous research has shown that barriers exist to the acceptance and use of FRe T by a range of stakeholders. This includes the need to deploy household level items in time, the uncertainty over the performance of FRe T in actual flood situations or reluctance to adopt new or unknown solutions. Investment by public authorities in FRe Technology in recent years has typically increased in countries such as the UK. However, there has been to date little consideration of the system within which the technology has been employed and there is a lack of tools to assist decision makers. The SMARTeST project (an EU FP7 research project) is addressing the issues involved in FRe technology implementation. The findings of the research will be presented, including case studies where the integrated approaches of technology, systems and tools have been considered. SMARTeST seeks to create an environment for innovation in FRe technology, using new approaches that will reduce the risks involved in function, deployment, performance. The paper will describe how alliances of manufacturers, test houses and research organizations can bring about innovation. (Reference; Zevenbergen C, et al, C22 Book, Urban Flood Management, 2010)

Characterizing urban hydrodynamic models in densely settled river-corridors: Lessons from Jakarta

NASA Astrophysics Data System (ADS)

Shaad, K.; Ninsalam, Y.; Padawangi, R.; Burlando, P.

2016-12-01

The nature and pace of urbanization in South and South-east Asia has created unique circumstances for the inter-action between social and ecological systems linked to water resources - with the growing density of population; frequent and extensive modification on the flood plain alongside governance challenges creating large segment of the settled regions exposed to water security issues and flooding risks. The densely-settled river corridor in Jakarta, with nearly 590 km of waterfront exposed to frequent flooding, captures the scale and complexity typical of these systems. Developing models that can help improve our insights into these urban areas remain a challenge. Here, we present our attempts to apply high-resolution aerial and ground based mapping methods, alongside shallow groundwater monitoring and household surveys, to characterize hydrodynamic models of varying complexity, for a 7 km stretch on the Ciliwung River in the center of Jakarta. We explore the uncertainty associated with obtaining "hydraulically representative" ground description and influence of representation of structures in flood propagation over the short-term, while linking it to the diffusive forcings from settlement acting on the floodplain-river interaction over the long-term. Connecting, thus, flooding with water availability and contamination, we speculate on the ability to scale these approaches and technologies beyond the limits of the test site.

The KULTURisk Regional Risk Assessment methodology for water-related natural hazards - Part 1: Physical-environmental assessment

NASA Astrophysics Data System (ADS)

Ronco, P.; Gallina, V.; Torresan, S.; Zabeo, A.; Semenzin, E.; Critto, A.; Marcomini, A.

2014-12-01

In recent years, the frequency of catastrophes induced by natural hazards has increased, and flood events in particular have been recognized as one of the most threatening water-related disasters. Severe floods have occurred in Europe over the last decade, causing loss of life, displacement of people and heavy economic losses. Flood disasters are growing in frequency as a consequence of many factors, both climatic and non-climatic. Indeed, the current increase of water-related disasters can be mainly attributed to the increase of exposure (elements potentially at risk in flood-prone area) and vulnerability (i.e. economic, social, geographic, cultural and physical/environmental characteristics of the exposure). Besides these factors, the undeniable effect of climate change is projected to strongly modify the usual pattern of the hydrological cycle by intensifying the frequency and severity of flood events at the local, regional and global scale. Within this context, the need for developing effective and pro-active strategies, tools and actions which allow one to assess and (possibly) to reduce the flood risks that threatens different relevant receptors becomes urgent. Several methodologies to assess the risk posed by water-related natural hazards have been proposed so far, but very few of them can be adopted to implement the last European Flood Directive (FD). This paper is intended to introduce and present a state-of-the-art Regional Risk Assessment (RRA) methodology to appraise the risk posed by floods from a physical-environmental perspective. The methodology, developed within the recently completed FP7-KULTURisk Project (Knowledge-based approach to develop a cULTUre of Risk prevention - KR) is flexible and can be adapted to different case studies (i.e. plain rivers, mountain torrents, urban and coastal areas) and spatial scales (i.e. from catchment to the urban scale). The FD compliant KR-RRA methodology is based on the concept of risk being function of hazard, exposure and vulnerability. It integrates the outputs of various hydrodynamic models with site-specific bio-geophysical and socio-economic indicators (e.g. slope, land cover, population density, economic activities etc.) to develop tailored risk indexes and GIS-based maps for each of the selected receptors (i.e. people, buildings, infrastructure, agriculture, natural and semi-natural systems, cultural heritage) in the considered region. It further compares the baseline scenario with alternative scenarios, where different structural and/or non-structural mitigation measures are planned and eventually implemented. As demonstrated in the companion paper (Part 2, Ronco et al., 2014), risk maps, along with related statistics, allow one to identify and classify, on a relative scale, areas at risk which are more likely to be affected by floods and support the development of strategic adaptation and prevention measures to minimizing flood impacts. In addition, the outcomes of the RRA can be eventually used for a further socio-economic assessment, considering the tangible and intangible costs as well as the human dimension of vulnerability.

Systematic flood modelling to support flood-proof urban design

NASA Astrophysics Data System (ADS)

Bruwier, Martin; Mustafa, Ahmed; Aliaga, Daniel; Archambeau, Pierre; Erpicum, Sébastien; Nishida, Gen; Zhang, Xiaowei; Pirotton, Michel; Teller, Jacques; Dewals, Benjamin

2017-04-01

Urban flood risk is influenced by many factors such as hydro-meteorological drivers, existing drainage systems as well as vulnerability of population and assets. The urban fabric itself has also a complex influence on inundation flows. In this research, we performed a systematic analysis on how various characteristics of urban patterns control inundation flow within the urban area and upstream of it. An urban generator tool was used to generate over 2,250 synthetic urban networks of 1 km2. This tool is based on the procedural modelling presented by Parish and Müller (2001) which was adapted to generate a broader variety of urban networks. Nine input parameters were used to control the urban geometry. Three of them define the average length, orientation and curvature of the streets. Two orthogonal major roads, for which the width constitutes the fourth input parameter, work as constraints to generate the urban network. The width of secondary streets is given by the fifth input parameter. Each parcel generated by the street network based on a parcel mean area parameter can be either a park or a building parcel depending on the park ratio parameter. Three setback parameters constraint the exact location of the building whithin a building parcel. For each of synthetic urban network, detailed two-dimensional inundation maps were computed with a hydraulic model. The computational efficiency was enhanced by means of a porosity model. This enables the use of a coarser computational grid , while preserving information on the detailed geometry of the urban network (Sanders et al. 2008). These porosity parameters reflect not only the void fraction, which influences the storage capacity of the urban area, but also the influence of buildings on flow conveyance (dynamic effects). A sensitivity analysis was performed based on the inundation maps to highlight the respective impact of each input parameter characteristizing the urban networks. The findings of the study pinpoint which properties of urban networks have a major influence on urban inundation flow, enabling better informed flood-proof urban design. References: Parish, Y. I. H., Muller, P. 2001. Procedural modeling of cities. SIGGRAPH, pp. 301—308. Sanders, B.F., Schubert, J.E., Gallegos, H.A., 2008. Integral formulation of shallow-water equations with anisotropic porosity for urban flood modeling. Journal of Hydrology 362, 19-38. Acknowledgements: The research was funded through the ARC grant for Concerted Research Actions, financed by the Wallonia-Brussels Federation.

Conjunctively optimizing flash flood control and water quality in urban water reservoirs by model predictive control and dynamic emulation

NASA Astrophysics Data System (ADS)

Galelli, Stefano; Goedbloed, Albert; Schmitter, Petra; Castelletti, Andrea

2014-05-01

Urban water reservoirs are a viable adaptation option to account for increasing drinking water demand of urbanized areas as they allow storage and re-use of water that is normally lost. In addition, the direct availability of freshwater reduces pumping costs and diversifies the portfolios of drinking water supply. Yet, these benefits have an associated twofold cost. Firstly, the presence of large, impervious areas increases the hydraulic efficiency of urban catchments, with short time of concentration, increased runoff rates, losses of infiltration and baseflow, and higher risk of flash floods. Secondly, the high concentration of nutrients and sediments characterizing urban discharges is likely to cause water quality problems. In this study we propose a new control scheme combining Model Predictive Control (MPC), hydro-meteorological forecasts and dynamic model emulation to design real-time operating policies that conjunctively optimize water quantity and quality targets. The main advantage of this scheme stands in its capability of exploiting real-time hydro-meteorological forecasts, which are crucial in such fast-varying systems. In addition, the reduced computational requests of the MPC scheme allows coupling it with dynamic emulators of water quality processes. The approach is demonstrated on Marina Reservoir, a multi-purpose reservoir located in the heart of Singapore and characterized by a large, highly urbanized catchment with a short (i.e. approximately one hour) time of concentration. Results show that the MPC scheme, coupled with a water quality emulator, provides a good compromise between different operating objectives, namely flood risk reduction, drinking water supply and salinity control. Finally, the scheme is used to assess the effect of source control measures (e.g. green roofs) aimed at restoring the natural hydrological regime of Marina Reservoir catchment.

Analysis of recent changes of rainfall in the foothill of the Isonzo basin and effects on the safety of urbanized areas

NASA Astrophysics Data System (ADS)

Fazzini, Massimiliano; Vaccaro, Carmela

2015-04-01

The knowledge of the distribution of rainfall in mountain environments Mediterranean is still very complex and requires a comprehensive monitoring and appropriate analytical techniques - statistics to be scientifically valid and easily communicable. The Isonzo's basin - located between Slovenia and Italy within the Julian Alps - has characteristics meteoric absolutely uncommon, revealing the wettest of entire southern side of the Alps. Nonetheless, the climatological studies of detail are very rare; resulting an insufficient knowledge of specific themes, a lack of information for the purpose of territorial planning and especially the development of forecasting future scenarios according to the IPCC guidelines. The lower valley bottom of the Soca river is particularly urbanized and cultivated and the numerous, short minor streams - such as Corno and Versotizza - run within the city of Nova Gorica and Gorizia and their industrial areas. Their torrential regime can cause a flood events in relation to the intensity of more irregular and often very abundant rainfall. In this regard, the meteorological year 2014, was the wettest and perturbed the last thirty years in the whole mountain sector of the Isonzo basin, with punctual values ranging between about 2150 mm in Gorizia and 5600 mm in Musi di Udine, compared to their respective averages of 1400 and 3000 mm in the 1981-2010 period. The high frequency of days with precipitation sufficient to cause local flooding and floods from the minor watercourses is significant increase in recent years; consequently must be considered some fundamental aspects in the planning of little space land not yet urbanized and in the exploitation of agricultural and trade resources - heart of the local economy - increasingly exposed to the floods risk. This study aims to provide a thorough knowledge of the precipitation context of the urban agglomeration of Gorizia - Nova Gorica and its significant around; so to be provided the necessary knowledge to a hydraulic design of that allows the complete safety measures in existing production sites and the correct design of urban areas not yet built up through an comprehensive and precise definition of the areas at flood risk.

Climate Change Resilience in the Urban Environment

NASA Astrophysics Data System (ADS)

Kershaw, Tristan

2017-12-01

Between 1930 and 2030, the world's population will have flipped from 70% rural to 70% urban. While much has been written about the impacts of climate change and mitigation of its effects on individual buildings or infrastructure, this book is one of the first to focus on the resilience of whole cities. It covers a broad range of area-wide disaster-level impacts, including drought, heatwaves, flooding, storms and air quality, which many of our cities are ill-adapted to cope with, and unless we can increase the resilience of our urban areas then much of our current building stock may become uninhabitable. Climate Resilience in Urban Environments provides a detailed overview of the risks for urban areas, including those risks to human health as well as to building integrity, the physical processes involved, and presents key information in which way the risks can be reduced and urban areas made more resilient.

Impacts of future climate change on urban flood volumes in Hohhot in northern China: benefits of climate change mitigation and adaptations

NASA Astrophysics Data System (ADS)

Zhou, Qianqian; Leng, Guoyong; Huang, Maoyi

2018-01-01

As China becomes increasingly urbanised, flooding has become a regular occurrence in its major cities. Assessing the effects of future climate change on urban flood volumes is crucial to informing better management of such disasters given the severity of the devastating impacts of flooding (e.g. the 2016 flooding events across China). Although recent studies have investigated the impacts of future climate change on urban flooding, the effects of both climate change mitigation and adaptation have rarely been accounted for together in a consistent framework. In this study, we assess the benefits of mitigating climate change by reducing greenhouse gas (GHG) emissions and locally adapting to climate change by modifying drainage systems to reduce urban flooding under various climate change scenarios through a case study conducted in northern China. The urban drainage model - Storm Water Management Model - was used to simulate urban flood volumes using current and two adapted drainage systems (i.e. pipe enlargement and low-impact development, LID), driven by bias-corrected meteorological forcing from five general circulation models in the Coupled Model Intercomparison Project Phase 5 archive. Results indicate that urban flood volume is projected to increase by 52 % over 2020-2040 compared to the volume in 1971-2000 under the business-as-usual scenario (i.e. Representative Concentration Pathway (RCP) 8.5). The magnitudes of urban flood volumes are found to increase nonlinearly with changes in precipitation intensity. On average, the projected flood volume under RCP 2.6 is 13 % less than that under RCP 8.5, demonstrating the benefits of global-scale climate change mitigation efforts in reducing local urban flood volumes. Comparison of reduced flood volumes between climate change mitigation and local adaptation (by improving drainage systems) scenarios suggests that local adaptation is more effective than climate change mitigation in reducing future flood volumes. This has broad implications for the research community relative to drainage system design and modelling in a changing environment. This study highlights the importance of accounting for local adaptation when coping with future urban floods.

Impacts of future climate change on urban flood volumes in Hohhot in northern China: benefits of climate change mitigation and adaptations

DOE PAGES

Zhou, Qianqian; Leng, Guoyong; Huang, Maoyi

2018-01-15

As China becomes increasingly urbanised, flooding has become a regular occurrence in its major cities. Assessing the effects of future climate change on urban flood volumes is crucial to informing better management of such disasters given the severity of the devastating impacts of flooding (e.g. the 2016 flooding events across China). Although recent studies have investigated the impacts of future climate change on urban flooding, the effects of both climate change mitigation and adaptation have rarely been accounted for together in a consistent framework. In this study, we assess the benefits of mitigating climate change by reducing greenhouse gas (GHG)more » emissions and locally adapting to climate change by modifying drainage systems to reduce urban flooding under various climate change scenarios through a case study conducted in northern China. The urban drainage model – Storm Water Management Model – was used to simulate urban flood volumes using current and two adapted drainage systems (i.e. pipe enlargement and low-impact development, LID), driven by bias-corrected meteorological forcing from five general circulation models in the Coupled Model Intercomparison Project Phase 5 archive. Results indicate that urban flood volume is projected to increase by 52 % over 2020–2040 compared to the volume in 1971–2000 under the business-as-usual scenario (i.e. Representative Concentration Pathway (RCP) 8.5). The magnitudes of urban flood volumes are found to increase nonlinearly with changes in precipitation intensity. On average, the projected flood volume under RCP 2.6 is 13 % less than that under RCP 8.5, demonstrating the benefits of global-scale climate change mitigation efforts in reducing local urban flood volumes. Comparison of reduced flood volumes between climate change mitigation and local adaptation (by improving drainage systems) scenarios suggests that local adaptation is more effective than climate change mitigation in reducing future flood volumes. This has broad implications for the research community relative to drainage system design and modelling in a changing environment. Furthermore, this study highlights the importance of accounting for local adaptation when coping with future urban floods.« less

Impacts of future climate change on urban flood volumes in Hohhot in northern China: benefits of climate change mitigation and adaptations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Qianqian; Leng, Guoyong; Huang, Maoyi

As China becomes increasingly urbanised, flooding has become a regular occurrence in its major cities. Assessing the effects of future climate change on urban flood volumes is crucial to informing better management of such disasters given the severity of the devastating impacts of flooding (e.g. the 2016 flooding events across China). Although recent studies have investigated the impacts of future climate change on urban flooding, the effects of both climate change mitigation and adaptation have rarely been accounted for together in a consistent framework. In this study, we assess the benefits of mitigating climate change by reducing greenhouse gas (GHG)more » emissions and locally adapting to climate change by modifying drainage systems to reduce urban flooding under various climate change scenarios through a case study conducted in northern China. The urban drainage model – Storm Water Management Model – was used to simulate urban flood volumes using current and two adapted drainage systems (i.e. pipe enlargement and low-impact development, LID), driven by bias-corrected meteorological forcing from five general circulation models in the Coupled Model Intercomparison Project Phase 5 archive. Results indicate that urban flood volume is projected to increase by 52 % over 2020–2040 compared to the volume in 1971–2000 under the business-as-usual scenario (i.e. Representative Concentration Pathway (RCP) 8.5). The magnitudes of urban flood volumes are found to increase nonlinearly with changes in precipitation intensity. On average, the projected flood volume under RCP 2.6 is 13 % less than that under RCP 8.5, demonstrating the benefits of global-scale climate change mitigation efforts in reducing local urban flood volumes. Comparison of reduced flood volumes between climate change mitigation and local adaptation (by improving drainage systems) scenarios suggests that local adaptation is more effective than climate change mitigation in reducing future flood volumes. This has broad implications for the research community relative to drainage system design and modelling in a changing environment. Furthermore, this study highlights the importance of accounting for local adaptation when coping with future urban floods.« less

Mapping resilience not risk: Turning the tide in New York City and Jamaica Bay

NASA Astrophysics Data System (ADS)

Parris, A. S.; Sanderson, E. W.

2015-12-01

Resilience in urban coastal areas is affected by actions at multiple levels from individuals to community groups to city, state and federal governments. At any level, actions can be a response to immediate hazards (e.g. flooding of coastal homes) or long-term drivers of change (e.g. sea level rise). Jamaica Bay, a highly urbanized estuary within New York City, exemplifies the Nation's coastal zone challenges. Prior to Hurricane Sandy, city, state, and federal governments had made the estuary a major focal point for habitat restoration, improvements to public access and outdoor recreation, and sustainable development. Sandy caused the highest flood level in the recorded history of New York City, eventually claiming 44 lives and costing over $19 billion. Electrical system failure caused four of NYCs wastewater pollution control plants to shutdown, discharging untreated sewage into Jamaica Bay. The Sea Level Rise Tool for Sandy Recovery (the Tool), a flood mapping tool developed by several government agencies including FEMA, NYC, and the Executive Branch, integrated science from the National Flood Insurance Program and the New York City Panel on Climate Change (NPCC). While compound flooding hazards (stormwater plus coastal flooding) remain an important uncertainty, the Tool and subsequent NPCC mapping efforts provide sufficient evidence for science-based discourse around coastal flood risks in Jamaica Bay. But toward what outcome? Coastal flood risk reduction measures and other management actions are managed within existing regulatory frameworks. Disaster relief funds appropriated by Congress in the immediate aftermath of Sandy have provided critical resources to the Jamaica Bay region. However, the challenge now is to transition from the short-term response to long-term resilience planning, a challenge which requires new institutional capacity. This transition to resilience planning and implementation is not only critical in New York City, but in other coastal cities around the nation. The Science and Resilience Institute at Jamaica Bay is a rare partnership between the City of New York, the National Park Service and a consortium of nine research institutions, focused on collaborative problem solving. Central to the Institute's to success will be the question - can we start mapping resilience and not risk?

Local adaptive capacity as an alternative approach in dealing with hydrometeorological risk at Depok Peri-Urban City

NASA Astrophysics Data System (ADS)

Fitrinitia, I. S.; Junadi, P.; Sutanto, E.; Nugroho, D. A.; Zubair, A.; Suyanti, E.

2018-03-01

Located in a tropical area, cities in Indonesia are vulnerable to hydrometeorological risks such as flood and landslide and thus become prone to the climate change effects. Moreover, peri-urban cities had double burden as the consequences of main city spill over and also lack of urban facilities in overcoming the disaster. In another perspective, the city has many alternative resources to recover, so its create urban resiliency. Depok city becomes a case study of this research regarding with its development following the impact of Jakarta growth. This research purposes to capture how the local city dwellers could anticipate and adaptive with flood and landslide with their own mitigation version. Through mix method and spatial analysis using GIS techniques, it derives the two comparison approach, the normative and alternative that had been done by the city dwellers. It uses a spatial analysis to have a big picture of Depok and its environmental changing. It also divided into 4 local group of communities as a representative of city dwellers regarding the characteristic of a settlement with their level of risk. The result found type or characteristic of settlement which influenced the local adaptive capacity, from the establishment of infrastructure, health fulfillment and social livelihood with different kind of methods.

Flooding of property by runoff from agricultural land in northwestern Europe

NASA Astrophysics Data System (ADS)

Boardman, John; Ligneau, Laurence; de Roo, Ad; Vandaele, Karel

1994-08-01

In the last twenty years there has been an increase in the incidence of flooding of property by runoff from agricultural land in many areas of northwestern Europe. These events take the form of inundations by soil-laden water associated with erision and the formation of ephemeral or talweg gullies developed in normally dry valley bottoms. Costs of such events may be considerable e.g. almost US$2M at Rottingdean, southern England, in 1987. These costs are largely borne by individual house occupants, insurance companies and local councils. The distribution of flooding is widespread but areas of high risk can be identified: the hilly area of central Belgium, parts of northern France, the South Downs in southern England and South-Limburg (the Netherlands). All these areas have silty, more or less loessial soils. Two types of flooding may be distinguished: winter flooding associated with wet soils and the cultivation of winter cereals, and summer flooding due to thunderstorm activity and runoff particularly from sugar beet, maize and potato crops. The distribution of these types of erosion varies in relation to the interaction between physical characteristics (soils and topography), climatic conditions and land use across the region. The reason for the recent increase in flooding events appears to be changes in land use, in the area of arable cropping, and the continued intensification of farming such as the use of chemical fertilizers, the decline in aggregate stability, the increase in the size of fields and compaction by farm vehicles. In some regions the risk of flooding has also increased because of expansion of urban areas in valley bottom locations. Communities have responded to the flooding hazard with emergency or protective measures usually involving engineered structures rather than land use change. The policy response to the increased risk of flooding has been very limited especially at the national and provincial level, the exception being plans developed with farming organisations in South-Limburg and the Pays de Caux. In southern England initiatives have been few and largely consist of protective measures undertaken by urban municipalities.

Assessment of Coastal and Urban Flooding Hazards Applying Extreme Value Analysis and Multivariate Statistical Techniques: A Case Study in Elwood, Australia

NASA Astrophysics Data System (ADS)

Guimarães Nobre, Gabriela; Arnbjerg-Nielsen, Karsten; Rosbjerg, Dan; Madsen, Henrik

2016-04-01

Traditionally, flood risk assessment studies have been carried out from a univariate frequency analysis perspective. However, statistical dependence between hydrological variables, such as extreme rainfall and extreme sea surge, is plausible to exist, since both variables to some extent are driven by common meteorological conditions. Aiming to overcome this limitation, multivariate statistical techniques has the potential to combine different sources of flooding in the investigation. The aim of this study was to apply a range of statistical methodologies for analyzing combined extreme hydrological variables that can lead to coastal and urban flooding. The study area is the Elwood Catchment, which is a highly urbanized catchment located in the city of Port Phillip, Melbourne, Australia. The first part of the investigation dealt with the marginal extreme value distributions. Two approaches to extract extreme value series were applied (Annual Maximum and Partial Duration Series), and different probability distribution functions were fit to the observed sample. Results obtained by using the Generalized Pareto distribution demonstrate the ability of the Pareto family to model the extreme events. Advancing into multivariate extreme value analysis, first an investigation regarding the asymptotic properties of extremal dependence was carried out. As a weak positive asymptotic dependence between the bivariate extreme pairs was found, the Conditional method proposed by Heffernan and Tawn (2004) was chosen. This approach is suitable to model bivariate extreme values, which are relatively unlikely to occur together. The results show that the probability of an extreme sea surge occurring during a one-hour intensity extreme precipitation event (or vice versa) can be twice as great as what would occur when assuming independent events. Therefore, presuming independence between these two variables would result in severe underestimation of the flooding risk in the study area.

Long-term dynamics emerging in floodplains and deltas from the interactions between hydrology and society in a changing climate

NASA Astrophysics Data System (ADS)

Di Baldassarre, Giuliano; Viglione, Alberto; Yan, Kun; Brandimarte, Luigia; Blöschl, Günter

2014-05-01

Economic losses and fatalities associated to flood events have increased dramatically over the past decades. This situation might worsen in the near future because of rapid urbanization of many floodplains and deltas, along with enhancement of flood water levels as a result of human interventions, climate variability or sea level rise. To explore future dynamics, we developed a novel approach, which takes into account the dynamic nature of flood risk by an explicit treatment of the interactions and feedbacks between the hydrological and social components of flood risk (i.e. probability of flooding, and potential adverse consequences). In particular, we developed a socio-hydrological model that allows considering how the frequency and magnitude of flooding shapes the evolution of societies, while, at the same time, dynamic societies shape the frequency and magnitude of flooding. We then use this model to simulate long-term dynamics of different types of societies under hydrological change, e.g. increasing flood frequency. Based on the study of long-term dynamics of different floodplains and deltas around the world (e.g. Netherlands, Bangladesh), we identify two main typologies of flood-shaped societies: i) techno-societies, which "fight floods", and typically deal with risk by building and strengthening flood protection structures, such as levees or dikes; and ii) green-societies, which "lives with floods", and mainly cope with risk via adaptation measures, such as resettling out of flood prone areas. The outcomes of this study are relevant for the management of deltas and floodplains as they allow a comparison of long-term dynamics between diverse types of societies in terms of robustness to hydrological change.

Modelling large floating bodies in urban area flash-floods via a Smoothed Particle Hydrodynamics model

NASA Astrophysics Data System (ADS)

Albano, Raffaele; Sole, Aurelia; Mirauda, Domenica; Adamowski, Jan

2016-10-01

Large debris, including vehicles parked along floodplains, can cause severe damage and significant loss of life during urban area flash-floods. In this study, the authors validated and applied the Smoothed Particle Hydrodynamics (SPH) model, developed in Amicarelli et al. (2015), which reproduces in 3D the dynamics of rigid bodies driven by free surface flows, to the design of flood mitigation measures. To validate the model, the authors compared the model's predictions to the results of an experimental setup, involving a dam breach that strikes two fixed obstacles and three transportable floating bodies. Given the accuracy of the results, in terms of water depth over time and the time history of the bodies' movements, the SPH model explored in this study was used to analyse the mitigation efficiency of a proposed structural intervention - the use of small barriers (groynes) to prevent the transport of floating bodies. Different groynes configurations were examined to identify the most appropriate design and layout for urban area flash-flood damage mitigation. The authors found that groynes positioned upstream and downstream of each floating body can be effective as a risk mitigation measure for damage resulting from their movement.

Holistic flood risk assessment using agent-based modelling: the case of Sint Maarten Island

NASA Astrophysics Data System (ADS)

Abayneh Abebe, Yared; Vojinovic, Zoran; Nikolic, Igor; Hammond, Michael; Sanchez, Arlex; Pelling, Mark

2015-04-01

Floods in coastal regions are regarded as one of the most dangerous and harmful disasters. Though commonly referred to as natural disasters, coastal floods are also attributable to various social, economic, historical and political issues. Rapid urbanisation in coastal areas combined with climate change and poor governance can lead to a significant increase in the risk of pluvial flooding coinciding with fluvial and coastal flooding posing a greater risk of devastation in coastal communities. Disasters that can be triggered by hydro-meteorological events are interconnected and interrelated with both human activities and natural processes. They, therefore, require holistic approaches to help understand their complexity in order to design and develop adaptive risk management approaches that minimise social and economic losses and environmental impacts, and increase resilience to such events. Being located in the North Atlantic Ocean, Sint Maarten is frequently subjected to hurricanes. In addition, the stormwater catchments and streams on Sint Maarten have several unique characteristics that contribute to the severity of flood-related impacts. Urban environments are usually situated in low-lying areas, with little consideration for stormwater drainage, and as such are subject to flash flooding. Hence, Sint Maarten authorities drafted policies to minimise the risk of flood-related disasters on the island. In this study, an agent-based model is designed and applied to understand the implications of introduced policies and regulations, and to understand how different actors' behaviours influence the formation, propagation and accumulation of flood risk. The agent-based model built for this study is based on the MAIA meta-model, which helps to decompose, structure and conceptualize socio-technical systems with an agent-oriented perspective, and is developed using the NetLogo simulation environment. The agents described in this model are households and businesses, and policies on spatial planning rules are implemented. Preliminary results demonstrate the evolving nature of flood risks and describe the effectiveness of different planning policies to reduce risk and increase resilience.

Modeling Urban Growth Spatial Dynamics: Case studies of Addis Ababa and Dar es Salaam

NASA Astrophysics Data System (ADS)

Buchta, Katja; Abo El Wafa, Hany; Printz, Andreas; Pauleit, Stephan

2013-04-01

Rapid urbanization, and consequently, the dramatic spatial expansion of mostly informal urban areas increases the vulnerability of African cities to the effects of climate change such as sea level rise, more frequent flooding, droughts and heat waves. The EU FP 7 funded project CLUVA (Climate Change and Urban Vulnerability in Africa, www.cluva.eu) aims to develop strategies for minimizing the risks of natural hazards caused by climate change and to improve the coping capacity of African cities. Green infrastructure may play a particular role in climate change adaptation by providing ecosystem services for flood protection, stormwater retention, heat island moderation and provision of food and fuel wood. In this context, a major challenge is to gain a better understanding of the spatial and temporal dynamics of the cities and how these impact on green infrastructure and hence their vulnerability. Urban growth scenarios for two African cities, namely Addis Ababa, Ethiopia and Dar es Salaam, Tanzania, were developed based on a characterization of their urban morphology. A population growth driven - GIS based - disaggregation modeling approach was applied. Major impact factors influencing the urban dynamics were identified both from literature and interviews with local experts. Location based factors including proximity to road infrastructure and accessibility, and environmental factors including slope, surface and flood risk areas showed a particular impact on urban growth patterns. In Addis Ababa and Dar es Salaam, population density scenarios were modeled comparing two housing development strategies. Results showed that a densification scenario significantly decreases the loss of agricultural and green areas such as forests, bushland and sports grounds. In Dar es Salaam, the scenario of planned new settlements with a population density of max. 350 persons per hectare would lead until 2025 to a loss of agricultural land (-10.1%) and green areas (-6.6%). On the other hand, 12.4% of agricultural land and 16.1% of green areas would be lost in the low density development scenario of unplanned settlements of max. 150 persons per hectare. Relocating the population living in flood prone areas in the case of Addis Ababa and keeping those areas free from further settlements in the case of Dar es Salaam would result in even lower losses (agricultural land: -10.0%, green areas: -5.6%) as some flood prone areas overlap with agricultural/ green areas. The scenario models introduced in this research can be used by planners as tools to understand and manage the different outcomes of distinctive urban development strategies on growth patterns and how they interact with different climate change drivers such as loss of green infrastructure and effects such as frequent flooding hazards. Due to the relative simplicity of their structure and the single modeling environment, the models can be transferred to similar cities with minor modifications accommodating the different conditions of each city. Already, in Addis Ababa the results of the model will be used in the current revision of the Master plan of the city. Keywords: GIS, modeling, Urban Dynamics, Dar es Salaam, Addis Ababa, urbanization

Flood risk assessment in a Spanish Mediterranean catchment

NASA Astrophysics Data System (ADS)

Salazar, S.; Francés, F.; García-Bartual, R.; Ortiz, E.; Múnera, J. C.; Vélez, J. J.

2009-04-01

This paper describes a multidisciplinary approach for the risk assessment and its application to analysing the effects of extreme flood events on the Mediterranean catchment called "Rambla del Poyo" in Valencia (Spain). This catchment located in the East coast of Spain has an area of 380 km2 and is clearly open to the Mediterranean Mesoscale Convective Storms. The climate is semiarid, and the flow regime is typically ephemeral, but with highly frequent flash floods, with peak flows in the order of 500 m3/s. Recently, in 2000 and 2002 the area was severe flooded. The flood prone area is located in the lower part of the basin, with an important concentration of different urban centers and industrial and commercial areas (including part of the Valencia International Airport). For this reason, the analysis of damages of residential, industrial and commercial urbanized areas is essential for the prevention of damages with a proper flood risk management. The approach is based on three main steps. The first step entails a detailed hydrological analysis (parameter estimation, calibration-validation and simulations) using a distributed rainfall-runoff model called TETIS. In the case study, on one hand, high temporal resolutions rain gauge data are scarce, because of this, in addition to a small number of historic events, 100 synthetic rainstorms were generated using the multidimensional stochastic model called RAINGEN, which adequately represents the main structural properties typical of intense convective storms, including occurrence of raincells in space and time and the generated intensities. An equivalent daily maximum precipitation Pd was estimated for each synthetic event, thus allowing a return period assignment using the known statistical distribution of Pd in the region. On the other hand, the initial soil moisture condition can have a strong influence in the runoff production, for this reason, long term daily simulation has been done in order to asses the probability distribution of the initial situation before the extreme flood events (dry and wet conditions). For all combinations of precipitation inputs and initial conditions, 200 hydrological simulations has been done in order to obtain the input hydrographs for the hydraulic model. Finally in this step, a frequency analysis to obtain the non-exceedence probability of the peak discharges has been developed using the annual maximum daily precipitation and the initial soil moisture condition with this expression: ž« FX (x) = FX |r (x|r).fR (r).dr -ž where: X= random variable of interest (peak discharge), R= annual maximum daily precipitation, fR(r)= probability density function of R, FX•r(x/r)= conditional density function of X given r obtained from simulations. The main objective of second step is flood hazard estimation, which, the hydraulic modelling has been developed using the coupled computing version of Sobek 1D/2D. In this task, the treatment of DEM calculation can be a key task depending on the scale of work. The introduction of buildings, walls, the opening of drainage works… improving the quality of results in areas with high anthropogenic influence; in our case has been made 6 simulations with 3 different resolutions, after all, the model has been done with a model one-dimensional (1D), logging throughout the stretch to two-dimensional (2D) grid with the parent of 30x30 metres, except for its passage through the urban, commercial and industrial land uses in the flood prone area where it connects with the child grid of 10x10 metres. Unfortunately, for reasons of computer time, the hydraulic model has not been run for the 200 available events. However, 20 events have been carefully select trying to cover the best probabilistic interest spectrum for this study (from two to one thousand years of return period). From the 20 selected flooding maps it has been developed a GIS computational tool for calculating a regression between the independent variable (maximum water depth) and the dependent variable return period transformed into natural logarithm. Using this methodology have been generated the hazard maps for the return periods of interest. Finally, the third step concerns to the flood risk, which was defined as probabilistic integral of the combination of flood hazard and land use vulnerability: ž« R = V (h).fH (h).dh 0 Where: R is the flood risk, V(h) is the land use vulnerability, h is the flood magnitude and fH(h) is its probability density function. The land use vulnerability is expressed in terms of stage-damage functions for urban, commercial and industrial land uses. Both, flood hazard and land use vulnerability are defined in terms of magnitude (water depth). This integral has been solved in discrete form using a GIS tools. The flood risk assessment by a resolution of 10 meters in size cell in the flood prone area of the "Rambla del Poyo" has been done. With this useful methodology, we believe that a complete flood risk analysis is needed in order to objectively compare different future scenarios that can affect either the flood hazard and/or the vulnerability in the flood prone area.

Cities and Sea Level Rise: A Roadmap for Flood Hazard Adaptation

NASA Astrophysics Data System (ADS)

Horn, Diane; Cousins, Ann

2016-04-01

Coastal cities will face a range of increasingly severe challenges as sea level rises, and adaptation to future flood risk will require more than structural defences. Many cities will not be able to rely solely on engineering structures for protection and will need to develop a suite of policy responses to increase their resilience to impacts of rising sea level. The tools to promote flood risk adaptation are already within the capacity of most cities, with an assortment of policy tools available to address other land-use problems which can be refashioned and used to adapt to sea level rise. This study reviews approaches for urban adaptation through detailed analyses of case studies of cities which have developed flood adaptation strategies that combine structural defences with innovative approaches to living with flood risk. The aim of the overall project is to produce a 'roadmap' to guide practitioners through the process of analysing coastal flood risk in urban areas. Methodologies and tools to estimate vulnerability to coastal flooding, damages suffered, and the assessment of flood defences and adaptation measures are complemented with a discussion on the essential impact that local policy has on the treatment of coastal flooding and the constraints and opportunities that result from the specific country or locality characteristics in relation to economic, political, social and environmental priorities, which are likely to dictate the approach to coastal flooding and the actions proposed. Case studies of adaptation strategies used by Rotterdam, Bristol, Ho Chi Minh City and Norfolk, Virginia, are used to draw out a range of good practice elements that promote effective adaptation to sea level rise. These can be grouped into risk reduction, governance issues, and insurance, and can be used to provide examples of how other cities could adopt and implement flood adaptation strategies from a relatively limited starting position. Most cities will neither be able to defend all areas nor retreat entirely and will need to make a decision to retreat from certain locations or to relocate particular assets in areas at lower risk. We identify a series of specific questions which should be answered by city managers when selecting the most appropriate response for a particular location. The selection of options appropriate for building resilience does not depend entirely on the nature of the physical hazard and the accommodation space available, but also on the socio-political and environmental context in which adaptation decisions are made. The most important element in adapting to sea level rise is to have policies in place that incentivise risk reduction. The more comprehensively adaptation measures can be integrated into related policy areas and linked up with existing economic, social and environment measures, the more successful adaptation policies are likely to be. Changes to planning regulations, although resource-intensive, are the most cost-effective way of managing risk exposure over time. Flood insurance can also serve as a highly persuasive financial incentive for flood-resilient construction and locating businesses and homes in safer locations.

24 CFR 241.265 - Insurance of property against flood.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Insurance of property against flood. 241.265 Section 241.265 Housing and Urban Development Regulations Relating to Housing and Urban... Insurance of property against flood. The mortgaged property shall be insured against flood as stipulated by...

Urban flooding and Resilience: concepts and needs

NASA Astrophysics Data System (ADS)

Gourbesville, Ph.

2012-04-01

During the recent years, a growing interest for resilience has been expressed in the natural disaster mitigation area and especially in the flood related events. The European Union, under the Seventh Framework Programme (FP7), has initiated several research initiatives in order to explore this concept especially for the urban environments. Under urban resilience is underlined the ability of system potentially exposed to hazard to resist, respond, recover and reflect up to stage which is enough to preserve level of functioning and structure. Urban system can be resilient to lot of different hazards. Urban resilience is defined as the degree to which cities are able to tolerate some disturbance before reorganizing around a new set of structures and processes (Holling 1973, De Bruijn 2005). The United Nation's International strategy for Disaster Reductions has defined resilience as "the capacity of a system, community or society potentially exposed to hazards to adapt, by resisting or changing in order to reach and maintain an acceptable level of functioning and structure. This is determined by the degree to which the social system is capable of organizing itself to increase this capacity for learning from past disasters for better future protection and to improve risk reduction measures."(UN/ISDR 2004). According to that, system should be able to accept the hazard and be able to recover up to condition that provides acceptable operational level of city structure and population during and after hazard event. Main elements of urban system are built environment and population. Physical characteristic of built environment and social characteristic of population have to be examined in order to evaluate resilience. Therefore presenting methodology for assessing flood resilience in urban areas has to be one of the focal points for the exposed cities. Strategies under flood management planning related to resilience of urban systems are usually regarding controlling runoff volume, increasing capacity of drainage systems, spatial planning, building regulations, etc. Resilience also considers resilience of population to floods and it's measured with time. Assessment of resilience that is focused on population is following bottom-up approach starting from individual and then assessing community level. Building resilience involves also contribution of social networks, increasing response capacity of communities, self-organization, learning and education and cheering adaptation culture. Measures for improving social side of resilience covers: raising public awareness, implementation of flood forecasting and warning, emergency response planning and training, sharing information, education and communication. Most of these aspects are analyzed with the CORFU FP7 project. Collaborative Research on Flood Resilience in Urban areas (CORFU) is a major project involving 17 European and Asian institutions, funded by a grant from the European Commission under the Seventh Framework Programme. The overall aim of CORFU is to enable European and Asian partners to learn from each other through joint investigation, development, implementation and dissemination of short to medium term strategies that will enable more scientifically sound management of the consequences of urban flooding in the future and to develop resilience strategies according to each situation. The CORFU project looks at advanced and novel strategies and provide adequate measures for improved flood management in cities. The differences in urban flooding problems in Asia and in Europe range from levels of economic development, infrastructure age, social systems and decision making processes, to prevailing drainage methods, seasonality of rainfall patterns and climate change trends. The study cases are, in Europe, the cities of Hamburg, Barcelona and Nice, and in Asia, Beijing, Dhaka, Mumbai, Taipei, Seoul and Incheon.

Flood Insurance Affordability and Risk Notification Act

THOMAS, 111th Congress

Sen. Durbin, Richard J. [D-IL

2010-12-01

Senate - 12/01/2010 Read twice and referred to the Committee on Banking, Housing, and Urban Affairs. (All Actions) Tracker: This bill has the status IntroducedHere are the steps for Status of Legislation:

Flood-frequency relations for urban streams in Georgia; 1994 update

USGS Publications Warehouse

Inman, Ernest J.

1995-01-01

A statewide study of flood magnitude and frequency in urban areas of Georgia was made to develop methods of estimating flood characteristics at ungaged urban sites. A knowledge of the magnitude and frequency of floods is needed for the design of highway drainage structures, establishing flood- insurance rates, and other uses by urban planners and engineers. A U.S. Geological Survey rainfall-runoff model was calibrated for 65 urban drainage basins ranging in size from 0.04 to 19.1 square miles in 10 urban areas of Georgia. Rainfall-runoff data were collected for a period of 5 to 7 years at each station beginning in 1973 in Metropolitan Atlanta and ending in 1993 in Thomasville, Ga. Calibrated models were used to synthesize long-term annual flood peak discharges for these basins from existing Long-term rainfall records. The 2- to 500-year flood-frequency estimates were developed for each basin by fitting a Pearson Type III frequency distribution curve to the logarithms of these annual peak discharges. Multiple-regression analyses were used to define relations between the station flood-frequency data and several physical basin characteristics, of which drainage area and total impervious area were the most statistically significant. Using theseregression equations and basin characteristics, the magnitude and frequency of floods at ungaged urban basins can be estimated throughout Georgia.

Lagtime relations for urban streams in Georgia

USGS Publications Warehouse

Inman, Ernest J.

2000-01-01

Urban flood hydrographs are needed for the design of many highway drainage structures, embankments, and entrances to detention ponds. The three components that are needed to simulate urban flood hydrographs at ungaged sites are the design flood, the dimensionless hydrograph, and lagtime. The design flood and the dimensionless hydrograph have been presented in earlier studies for urban streams in Georgia. The objective of this study was to develop equations for estimating lagtime for urban streams in Georgia. Lagtimes were computed for 329 floods at 69 urban gaging stations in 11 cities in Georgia. These data were used to compute an average lagtime for each gaging station. Multiple regression analysis was then used to define relations between lagtime and certain physical basin characteristics, of which drainage area, slope, and impervious area were found to be significant. A qualitative variable was used to account for a geographical bias in flood-frequency region 4, a small area of southwestern Georgia. Information from this report can be used to simulate a flood hydrograph using a dimensionless hydrograph, the design flood, and the lagtime obtained from regression equations for any urban site with less than a 25-square-mile drainage area in Georgia.

Flood Disaster Risk Reduction in municipality-scale in Rio de Janeiro State

NASA Astrophysics Data System (ADS)

Japiassú Viana, Viviane; Formiga Johnsson, Rosa Maria; De Gouvello, Bernard

2015-04-01

In Brazil, flood disasters causing human damage, pecuniary loss and environmental damage, are mainly due to greater exposure of the population; urban densification on the riverbanks and margins, incurring vulnerability due to changes in river level and climate changes. This article presents the data and studies required in the Brazilian legal basis and analyzes the scales adopted by planners in contrast to the scales demands by the executing agencies in the context of prevention and adaptation to climate change, particularly to flood disaster reduction in municipality-scale.

Incidence of and risk factors for musculoskeletal symptoms in the neck and low-back during severe flooding in Bangkok in 2011.

PubMed

Sihawong, Rattaporn; Janwantanakul, Prawit; Pensri, Praneet

2012-07-01

To examine whether the incidences of neck and low-back symptoms were elevated during the severe floods that occurred in Bangkok, Thailand in 2011, and to explore flood-related risk factors for neck and low-back symptoms. Prospective cohort design. Severe flooding occurred in Bangkok and surrounding neighbourhoods between October and December, 2011. After the flood had subsided (January 2012), 377 healthy office workers, who were already taking part in a study on musculoskeletal symptoms, were asked about their contact with floodwater. Data were gathered from subjects, who had reported no neck and low-back symptoms at the end of September 2011 and who were affected by the flood. Two regression models for the outcomes of 3-month incidence of neck and low-back symptoms, respectively, were performed. Eighty-two percent of the subjects were affected by the flood. No flood-related factor was found to associate significantly with either neck or low-back symptoms. However, neck symptoms may be associated with commuting frequently through flooded areas, and low-back symptoms may be associated with the subjects' homes or workplaces being flooded. These findings indicate that more attention needs to be paid to the problem of musculoskeletal symptoms during flooding in urban areas, and that preventive measures are required.

Modeling Compound Flood Hazards in Coastal Embayments

NASA Astrophysics Data System (ADS)

Moftakhari, H.; Schubert, J. E.; AghaKouchak, A.; Luke, A.; Matthew, R.; Sanders, B. F.

2017-12-01

Coastal cities around the world are built on lowland topography adjacent to coastal embayments and river estuaries, where multiple factors threaten increasing flood hazards (e.g. sea level rise and river flooding). Quantitative risk assessment is required for administration of flood insurance programs and the design of cost-effective flood risk reduction measures. This demands a characterization of extreme water levels such as 100 and 500 year return period events. Furthermore, hydrodynamic flood models are routinely used to characterize localized flood level intensities (i.e., local depth and velocity) based on boundary forcing sampled from extreme value distributions. For example, extreme flood discharges in the U.S. are estimated from measured flood peaks using the Log-Pearson Type III distribution. However, configuring hydrodynamic models for coastal embayments is challenging because of compound extreme flood events: events caused by a combination of extreme sea levels, extreme river discharges, and possibly other factors such as extreme waves and precipitation causing pluvial flooding in urban developments. Here, we present an approach for flood risk assessment that coordinates multivariate extreme analysis with hydrodynamic modeling of coastal embayments. First, we evaluate the significance of correlation structure between terrestrial freshwater inflow and oceanic variables; second, this correlation structure is described using copula functions in unit joint probability domain; and third, we choose a series of compound design scenarios for hydrodynamic modeling based on their occurrence likelihood. The design scenarios include the most likely compound event (with the highest joint probability density), preferred marginal scenario and reproduced time series of ensembles based on Monte Carlo sampling of bivariate hazard domain. The comparison between resulting extreme water dynamics under the compound hazard scenarios explained above provides an insight to the strengths/weaknesses of each approach and helps modelers choose the appropriate scenario that best fit to the needs of their project. The proposed risk assessment approach can help flood hazard modeling practitioners achieve a more reliable estimate of risk, by cautiously reducing the dimensionality of the hazard analysis.

Emotional engagement with participatory simulations as a tool for learning and decision-support for coupled human-natural systems: Flood hazards and urban development

NASA Astrophysics Data System (ADS)

Gilligan, J. M.; Corey, B.; Camp, J. V.; John, N. J.; Sengupta, P.

2015-12-01

The complex interactions between land use and natural hazards pose serious challenges in education, research, and public policy. Where complex nonlinear interactions produce unintuitive results, interactive computer simulations can be useful tools for education and decision support. Emotions play important roles in cognition and learning, especially where risks are concerned. Interactive simulations have the potential to harness emotional engagement to enhance learning and understanding of risks in coupled human-natural systems. We developed a participatory agent-based simulation of cities at risk of river flooding. Participants play the role of managers of neighboring cities along a flood-prone river and make choices about building flood walls to protect their inhabitants. Simulated agents participate in dynamic real estate markets in which demand for property, and thus values and decisions to build, respond to experience with flooding over time. By reducing high-frequency low-magnitude flooding, flood walls may stimulate development, thus increasing tax revenues but also increasing vulnerability to uncommon floods that overtop the walls. Flood waves are launched stochastically and propagate downstream. Flood walls that restrict overbank flow at one city can increase the amplitude of a flood wave at neighboring cities, both up and downstream. We conducted a pilot experiment with a group of three pre-service teachers. The subjects successfully learned key concepts of risk tradeoffs and unintended consequences that can accompany flood-control measures. We also observed strong emotional responses, including hope, fear, and sense of loss. This emotional engagement with a model of coupled human-natural systems was very different from previous experiments on participatory simulations of purely natural systems for physics pedagogy. We conducted a second session in which the participants were expert engineers. We will present the results of these experiments and the prospects for using such models for middle-school, high-school, and post-secondary environmental science pedagogy, for improving public understanding of flood risks, and as decision support tools for planners.

Assessment of flood hazard in a combined sewer system in Reykjavik city centre.

PubMed

Hlodversdottir, Asta Osk; Bjornsson, Brynjolfur; Andradottir, Hrund Olof; Eliasson, Jonas; Crochet, Philippe

2015-01-01

Short-duration precipitation bursts can cause substantial property damage and pose operational risks for wastewater managers. The objective of this study was to assess the present and possible future flood hazard in the combined sewer system in Reykjavik city centre. The catchment is characterised by two hills separated by a plain. A large portion of the pipes in the aging network are smaller than the current minimum diameter of 250 mm. Runoff and sewer flows were modelled using the MIKE URBAN software package incorporating both historical precipitation and synthetic storms derived from annual maximum rainfall data. Results suggest that 3% of public network manholes were vulnerable to flooding during an 11-year long rainfall sequence. A Chicago Design Storm (CDS) incorporating a 10-minute rainfall burst with a 5-year return period predicted twice as many flooded manholes at similar locations. A 20% increase in CDS intensity increased the number of flooded manholes and surface flood volume by 70% and 80%, respectively. The flood volume tripled if rainfall increase were combined with urban re-development, leading to a 20% increase in the runoff coefficient. Results highlight the need for reducing network vulnerabilities, which include decreased pipe diameters and low or drastically varying pipe grades.

Uncertainty and Sensitivity of Direct Economic Flood Damages: the FloodRisk Free and Open-Source Software

NASA Astrophysics Data System (ADS)

Albano, R.; Sole, A.; Mancusi, L.; Cantisani, A.; Perrone, A.

2017-12-01

The considerable increase of flood damages in the the past decades has shifted in Europe the attention from protection against floods to managing flood risks. In this context, the expected damages assessment represents a crucial information within the overall flood risk management process. The present paper proposes an open source software, called FloodRisk, that is able to operatively support stakeholders in the decision making processes with a what-if approach by carrying out the rapid assessment of the flood consequences, in terms of direct economic damage and loss of human lives. The evaluation of the damage scenarios, trough the use of the GIS software proposed here, is essential for cost-benefit or multi-criteria analysis of risk mitigation alternatives. However, considering that quantitative assessment of flood damages scenarios is characterized by intrinsic uncertainty, a scheme has been developed to identify and quantify the role of the input parameters in the total uncertainty of flood loss model application in urban areas with mild terrain and complex topography. By the concept of parallel models, the contribution of different module and input parameters to the total uncertainty is quantified. The results of the present case study have exhibited a high epistemic uncertainty on the damage estimation module and, in particular, on the type and form of the utilized damage functions, which have been adapted and transferred from different geographic and socio-economic contexts because there aren't depth-damage functions that are specifically developed for Italy. Considering that uncertainty and sensitivity depend considerably on local characteristics, the epistemic uncertainty associated with the risk estimate is reduced by introducing additional information into the risk analysis. In the light of the obtained results, it is evident the need to produce and disseminate (open) data to develop micro-scale vulnerability curves. Moreover, the urgent need to push forward research into the implementation of methods and models for the assimilation of uncertainties in decision-making processes emerges.

Urban sprawl and flooding in southern California

USGS Publications Warehouse

Rantz, S.E.

1970-01-01

The floods of January 1969 in south-coastal California provide a timely example of the effect of urban sprawl on flood damage. Despite recordbreaking, or near recordbreaking, stream discharges, damage was minimal in the older developed areas that are protected against inundation and debris damage by carefully planned flood-control facilities, including debris basins and flood-conveyance channels. By contrast, heavy damage occurred in areas of more recent urban sprawl, where the hazards of inundation and debris or landslide damage have not been taken into consideration, and where the improvement and development of drainage or flood-control facilities have not kept pace with expanding urbanization.

Simulation of floods caused by overloaded sewer systems: extensions of shallow-water equations

NASA Astrophysics Data System (ADS)

Hilden, Michael

2005-03-01

The outflow of water from a manhole onto a street is a typical flow problem within the simulation of floods in urban areas that are caused by overloaded sewer systems in the event of heavy rains. The reliable assessment of the flood risk for the connected houses requires accurate simulations of the water flow processes in the sewer system and in the street.The Navier-Stokes equations (NSEs) describe the free surface flow of the fluid water accurately, but since their numerical solution requires high CPU times and much memory, their application is not practical. However, their solutions for selected flow problems are applied as reference states to assess the results of other model approaches.The classical shallow-water equations (SWEs) require only fractions (factor 1/100) of the NSEs' computational effort. They assume hydrostatic pressure distribution, depth-averaged horizontal velocities and neglect vertical velocities. These shallow-water assumptions are not fulfilled for the outflow of water from a manhole onto the street. Accordingly, calculations show differences between NSEs and SWEs solutions.The SWEs are extended in order to assess the flood risks in urban areas reliably within applicable computational efforts. Separating vortex regions from the main flow and approximating vertical velocities to involve their contributions into a pressure correction yield suitable results.

Exposure to Flood Hazards in Miami and Houston: Are Hispanic Immigrants at Greater Risk than Other Social Groups?

PubMed Central

Maldonado, Alejandra; Collins, Timothy W.; Grineski, Sara E.; Chakraborty, Jayajit

2016-01-01

Although numerous studies have been conducted on the vulnerability of marginalized groups in the environmental justice (EJ) and hazards fields, analysts have tended to lump people together in broad racial/ethnic categories without regard for substantial within-group heterogeneity. This paper addresses that limitation by examining whether Hispanic immigrants are disproportionately exposed to risks from flood hazards relative to other racial/ethnic groups (including US-born Hispanics), adjusting for relevant covariates. Survey data were collected for 1283 adult householders in the Houston and Miami Metropolitan Statistical Areas (MSAs) and flood risk was estimated using their residential presence/absence within federally-designated 100-year flood zones. Generalized estimating equations (GEE) with binary logistic specifications that adjust for county-level clustering were used to analyze (separately) and compare the Houston (N = 546) and Miami (N = 560) MSAs in order to clarify determinants of household exposure to flood risk. GEE results in Houston indicate that Hispanic immigrants have the greatest likelihood, and non-Hispanic Whites the least likelihood, of residing in a 100-year flood zone. Miami GEE results contrastingly reveal that non-Hispanic Whites have a significantly greater likelihood of residing in a flood zone when compared to Hispanic immigrants. These divergent results suggest that human-flood hazard relationships have been structured differently between the two MSAs, possibly due to the contrasting role that water-based amenities have played in urbanization within the two study areas. Future EJ research and practice should differentiate between Hispanic subgroups based on nativity status and attend to contextual factors influencing environmental risk disparities. PMID:27490561

Exposure to Flood Hazards in Miami and Houston: Are Hispanic Immigrants at Greater Risk than Other Social Groups?

PubMed

Maldonado, Alejandra; Collins, Timothy W; Grineski, Sara E; Chakraborty, Jayajit

2016-08-01

Although numerous studies have been conducted on the vulnerability of marginalized groups in the environmental justice (EJ) and hazards fields, analysts have tended to lump people together in broad racial/ethnic categories without regard for substantial within-group heterogeneity. This paper addresses that limitation by examining whether Hispanic immigrants are disproportionately exposed to risks from flood hazards relative to other racial/ethnic groups (including US-born Hispanics), adjusting for relevant covariates. Survey data were collected for 1283 adult householders in the Houston and Miami Metropolitan Statistical Areas (MSAs) and flood risk was estimated using their residential presence/absence within federally-designated 100-year flood zones. Generalized estimating equations (GEE) with binary logistic specifications that adjust for county-level clustering were used to analyze (separately) and compare the Houston (N = 546) and Miami (N = 560) MSAs in order to clarify determinants of household exposure to flood risk. GEE results in Houston indicate that Hispanic immigrants have the greatest likelihood, and non-Hispanic Whites the least likelihood, of residing in a 100-year flood zone. Miami GEE results contrastingly reveal that non-Hispanic Whites have a significantly greater likelihood of residing in a flood zone when compared to Hispanic immigrants. These divergent results suggest that human-flood hazard relationships have been structured differently between the two MSAs, possibly due to the contrasting role that water-based amenities have played in urbanization within the two study areas. Future EJ research and practice should differentiate between Hispanic subgroups based on nativity status and attend to contextual factors influencing environmental risk disparities.

Flood Impacts on People: from Hazard to Risk Maps

NASA Astrophysics Data System (ADS)

Arrighi, C.; Castelli, F.

2017-12-01

The mitigation of adverse consequences of floods on people is crucial for civil protection and public authorities. According to several studies, in the developed countries the majority of flood-related fatalities occurs due to inappropriate high risk behaviours such as driving and walking in floodwaters. In this work both the loss of stability of vehicles and pedestrians in floodwaters are analysed. Flood hazard is evaluated, based on (i) a 2D inundation model of an urban area, (ii) 3D hydrodynamic simulations of water flows around vehicles and human body and (iii) a dimensional analysis of experimental activity. Exposure and vulnerability of vehicles and population are assessed exploiting several sources of open GIS data in order to produce risk maps for a testing case study. The results show that a significant hazard to vehicles and pedestrians exists in the study area. Particularly high is the hazard to vehicles, which are likely to be swept away by flood flow, possibly aggravate damages to structures and infrastructures and locally alter the flood propagation. Exposure and vulnerability analysis identifies some structures such as schools and public facilities, which may attract several people. Moreover, some shopping facilities in the area, which attract both vehicular and pedestrians' circulation are located in the highest flood hazard zone.The application of the method demonstrates that, at municipal level, such risk maps can support civil defence strategies and education to active citizenship, thus contributing to flood impact reduction to population.

[Delimitation of urban growth boundary based on ecological suitability and risk control: A case of Taibai Lake New District in Jining City, Shandong, China.

PubMed

Liu, Yan Xu; Peng, Jian; Sun, Mao Long; Yang, Yang

2016-08-01

Urban growth boundary, with full consideration of regional ecological constraints, can effectively control the unordered urban sprawl. Thus, urban growth boundary is a significant planning concept integrating regional ecological protection and urban construction. Finding the preferential position for urban construction, as well as controlling the ecological risk, has always been the core content of urban growth boundary delimitation. This study selected Taibai Lake New District in Jining City as a case area, and analyzed the scenario of ecological suitability by ordered weighted ave-raging algorithm. Surface temperature retrieval and rain flooding simulation were used to identify the spatial ecological risk. In the result of ecological suitability, the suitable construction zone accounted for 25.3% of the total area, the unsuitable construction zone accounted for 20.4%, and the other area was in the limit construction zone. Excluding the ecological risk control region, the flexible urban growth boundary covered 2975 hm 2 in near term, and covered 6754 hm 2 in long term. The final inflexible urban growth boundary covered 9405 hm 2 . As a new method, the scenario algorithms of ordered weighted averaging and ecological risk modeling could provide effective support in urban growth boundary identification.

Delineating risk zones and evaluation of shelter centres for flood disaster management along the Pahang River Basin, Malaysia

PubMed Central

Isahak, Anizan; Siwar, Chamhuri; Ismail, Shaharuddin M.; Hanafi, Zulkifli; Zainuddin, Mohd S.

2018-01-01

Shelter centres are important locations to safeguard people from helpless situations and are an integral part of disaster risk reduction (DRR), particularly for flood DRR. The establishment of shelter centres, and their design based on scientific assessment, is crucial. Yet, they are very much related to the geographic location, socio-economic conditions and the livelihoods of the affected communities. However, many parts of the developing world are still lagging behind in ensuring such scientific design. Considering the flood disaster in 2014 that affected the residents living along the Pahang River Basin, in this study we delineate the communities at risk and evaluate the existing shelter centres to determine how they reduce people’s vulnerability to the risks associated with rural and urban landscapes. We used spatial analysis tools to delineate risk zones and to evaluate existing evacuation systems. A flood disaster risk map was produced to determine which communities are living with risks. Subsequently, the distribution of shelter centres examined whether they are able to support people living at the flood risk zones. These centres were also evaluated using a set of international guidelines for effective disaster shelters. This reveals that the number of shelter centres is not adequate. The designation and designing of shelter centres are not being done scientifically. The maps produced here have a lot of potential to support disaster management decisions, in particular site selection and the prioritisation of centres. The study concludes with a set of guidelines and recommendations for structural and non-structural measures, such as alternative livelihoods and the potential of ecotourism, which may improve the resilience among flood-affected communities; and the decision-making process for the overall flood DRR initiatives.

A methodology for the assessment of flood hazards at the regional scale

NASA Astrophysics Data System (ADS)

Gallina, Valentina; Torresan, Silvia; Critto, Andrea; Zabeo, Alex; Semenzin, Elena; Marcomini, Antonio

2013-04-01

In recent years, the frequency of water-related disasters has increased and recent flood events in Europe (e.g. 2002 in Central Europe, 2007 in UK, 2010 in Italy) caused physical-environmental and socio-economic damages. Specifically, floods are the most threatening water-related disaster that affects humans, their lives and properties. Within the KULTURisk project (FP7) a Regional Risk Assessment (RRA) methodology is proposed to evaluate the benefits of risk prevention in terms of reduced environmental risks due to floods. The method is based on the KULTURisk framework and allows the identification and prioritization of targets (i.e. people, buildings, infrastructures, agriculture, natural and semi-natural systems, cultural heritages) and areas at risk from floods in the considered region by comparing the baseline scenario (i.e. current state) with alternative scenarios (i.e. where different structural and/or non-structural measures are planned). The RRA methodology is flexible and can be adapted to different case studies (i.e. large rivers, alpine/mountain catchments, urban areas and coastal areas) and spatial scales (i.e. from the large river to the urban scale). The final aim of RRA is to help decision-makers in examining the possible environmental risks associated with uncertain future flood hazards and in identifying which prevention scenario could be the most suitable one. The RRA methodology employs Multi-Criteria Decision Analysis (MCDA functions) in order to integrate stakeholder preferences and experts judgments into the analysis. Moreover, Geographic Information Systems (GISs) are used to manage, process, analyze, and map data to facilitate the analysis and the information sharing with different experts and stakeholders. In order to characterize flood risks, the proposed methodology integrates the output of hydrodynamic models with the analysis of site-specific bio-geophysical and socio-economic indicators (e.g. slope of the territory, land cover, population density, economic activities) of several case studies in order to develop risk maps that identify and prioritize relative hot-spot areas and targets at risk at the regional scale. The main outputs of the RRA are receptor-based maps of risks useful to communicate the potential implications of floods in non-monetary terms to stakeholders and administrations. These maps can be a basis for the management of flood risks as they can provide information about the indicative number of inhabitants, the type of economic activities, natural systems and cultural heritages potentially affected by flooding. Moreover, they can provide suitable information about flood risk in the considered area in order to define priorities for prevention measures, for land use planning and management. Finally, the outputs of the RRA methodology can be used as data input in the Socio- Economic Regional Risk Assessment methodology for the economic evaluation of different damages (e.g. tangible costs, intangible costs) and for the social assessment considering the benefits of the human dimension of vulnerability (i.e. adaptive and coping capacity). Within the KULTURisk project, the methodology has been applied and validated in several European case studies. Moreover, its generalization to address other types of natural hazards (e.g. earthquakes, forest fires) will be evaluated. The preliminary results of the RRA application in the KULTURisk project will be here presented and discussed.

Understanding Socio-Hydrology System in the Kissimmee River Basin

NASA Astrophysics Data System (ADS)

Chen, X.; Wang, D.; Tian, F.; Sivapalan, M.

2014-12-01

This study is to develop a conceptual socio-hydrology model for the Kissimmee River Basin. The Kissimmee River located in Florida was channelized in mid-20 century for flood protection. However, the environmental issues caused by channelization led Floridians to conduct a restoration project recently, focusing on wetland recovery. As a complex coupled human-water system, Kissimmee River Basin shows the typical socio-hydrology interactions. Hypothetically, the major reason to drive the system from channelization to restoration is that the community sensitivity towards the environment has changed from controlling to restoring. The model developed in this study includes 5 components: water balance, flood risk, wetland area, crop land area, and community sensitivity. Furthermore, urban population and rural population in the basin have different community sensitivities towards the hydrologic system. The urban population, who live further away from the river are more sensitive to wetland restoration; while the rural population, who live closer to the river are more sensitive to flood protection. The power dynamics between the two groups and its impact on management decision making is described in the model. The model is calibrated based on the observed watershed outflow, wetland area and crop land area. The results show that the overall focus of community sensitivity has changed from flood protection to wetland restoration in the past 60 years in Kissimmee River Basin, which confirms the study hypothesis. There are two main reasons for the community sensitivity change. Firstly, people's flood memory is fading because of the effective flood protection, while the continuously shrinking wetland and the decreasing bird and fish population draw more and more attention. Secondly, in the last 60 years, the urban population in Florida drastically increased compared with a much slower increase of rural population. As a result, the community sensitivity of urban population towards wetland restoration has more weight than the rural population's towards flood protection.

Probabilistic mapping of urban flood risk: Application to extreme events in Surat, India

NASA Astrophysics Data System (ADS)

Ramirez, Jorge; Rajasekar, Umamaheshwaran; Coulthard, Tom; Keiler, Margreth

2016-04-01

Surat, India is a coastal city that lies on the banks of the river Tapti and is located downstream from the Ukai dam. Given Surat's geographic location, the population of five million people are repeatedly exposed to flooding caused by high tide combined with large emergency dam releases into the Tapti river. In 2006 such a flood event occurred when intense rainfall in the Tapti catchment caused a dam release near 25,000 m3 s-1 and flooded 90% of the city. A first step towards strengthening resilience in Surat requires a robust method for mapping potential flood risk that considers the uncertainty in future dam releases. Here, in this study we develop many combinations of dam release magnitude and duration for the Ukai dam. Afterwards we use these dam releases to drive a two dimensional flood model (CAESAR-Lisflood) of Surat that also considers tidal effects. Our flood model of Surat utilizes fine spatial resolution (30m) topography produced from an extensive differential global positioning system survey and measurements of river cross-sections. Within the city we have modelled scenarios that include extreme conditions with near maximum dam release levels (e.g. 1:250 year flood) and high tides. Results from all scenarios have been summarized into probabilistic flood risk maps for Surat. These maps are currently being integrated within the city disaster management plan for taking both mitigation and adaptation measures for different scenarios of flooding.

Combined fluvial and pluvial urban flood hazard analysis: concept development and application to Can Tho city, Mekong Delta, Vietnam

NASA Astrophysics Data System (ADS)

Apel, Heiko; Martínez Trepat, Oriol; Nghia Hung, Nguyen; Thi Chinh, Do; Merz, Bruno; Viet Dung, Nguyen

2016-04-01

Many urban areas experience both fluvial and pluvial floods, because locations next to rivers are preferred settlement areas and the predominantly sealed urban surface prevents infiltration and facilitates surface inundation. The latter problem is enhanced in cities with insufficient or non-existent sewer systems. While there are a number of approaches to analyse either a fluvial or pluvial flood hazard, studies of a combined fluvial and pluvial flood hazard are hardly available. Thus this study aims to analyse a fluvial and a pluvial flood hazard individually, but also to develop a method for the analysis of a combined pluvial and fluvial flood hazard. This combined fluvial-pluvial flood hazard analysis is performed taking Can Tho city, the largest city in the Vietnamese part of the Mekong Delta, as an example. In this tropical environment the annual monsoon triggered floods of the Mekong River, which can coincide with heavy local convective precipitation events, causing both fluvial and pluvial flooding at the same time. The fluvial flood hazard was estimated with a copula-based bivariate extreme value statistic for the gauge Kratie at the upper boundary of the Mekong Delta and a large-scale hydrodynamic model of the Mekong Delta. This provided the boundaries for 2-dimensional hydrodynamic inundation simulation for Can Tho city. The pluvial hazard was estimated by a peak-over-threshold frequency estimation based on local rain gauge data and a stochastic rainstorm generator. Inundation for all flood scenarios was simulated by a 2-dimensional hydrodynamic model implemented on a Graphics Processing Unit (GPU) for time-efficient flood propagation modelling. The combined fluvial-pluvial flood scenarios were derived by adding rainstorms to the fluvial flood events during the highest fluvial water levels. The probabilities of occurrence of the combined events were determined assuming independence of the two flood types and taking the seasonality and probability of coincidence into account. All hazards - fluvial, pluvial and combined - were accompanied by an uncertainty estimation taking into account the natural variability of the flood events. This resulted in probabilistic flood hazard maps showing the maximum inundation depths for a selected set of probabilities of occurrence, with maps showing the expectation (median) and the uncertainty by percentile maps. The results are critically discussed and their usage in flood risk management are outlined.

Uncertainty Analysis of A Flood Risk Mapping Procedure Applied In Urban Areas

NASA Astrophysics Data System (ADS)

Krause, J.; Uhrich, S.; Bormann, H.; Diekkrüger, B.

In the framework of IRMA-Sponge program the presented study was part of the joint research project FRHYMAP (flood risk and hydrological mapping). A simple con- ceptual flooding model (FLOODMAP) has been developed to simulate flooded areas besides rivers within cities. FLOODMAP requires a minimum of input data (digital el- evation model (DEM), river line, water level plain) and parameters and calculates the flood extent as well as the spatial distribution of flood depths. of course the simulated model results are affected by errors and uncertainties. Possible sources of uncertain- ties are the model structure, model parameters and input data. Thus after the model validation (comparison of simulated water to observed extent, taken from airborne pictures) the uncertainty of the essential input data set (digital elevation model) was analysed. Monte Carlo simulations were performed to assess the effect of uncertain- ties concerning the statistics of DEM quality and to derive flooding probabilities from the set of simulations. The questions concerning a minimum resolution of a DEM re- quired for flood simulation and concerning the best aggregation procedure of a given DEM was answered by comparing the results obtained using all available standard GIS aggregation procedures. Seven different aggregation procedures were applied to high resolution DEMs (1-2m) in three cities (Bonn, Cologne, Luxembourg). Basing on this analysis the effect of 'uncertain' DEM data was estimated and compared with other sources of uncertainties. Especially socio-economic information and monetary transfer functions required for a damage risk analysis show a high uncertainty. There- fore this study helps to analyse the weak points of the flood risk and damage risk assessment procedure.

The development of flood map in Malaysia

NASA Astrophysics Data System (ADS)

Zakaria, Siti Fairus; Zin, Rosli Mohamad; Mohamad, Ismail; Balubaid, Saeed; Mydin, Shaik Hussein; MDR, E. M. Roodienyanto

2017-11-01

In Malaysia, flash floods are common occurrences throughout the year in flood prone areas. In terms of flood extent, flash floods affect smaller areas but because of its tendency to occur in densely urbanized areas, the value of damaged property is high and disruption to traffic flow and businesses are substantial. However, in river floods especially the river floods of Kelantan and Pahang, the flood extent is widespread and can extend over 1,000 square kilometers. Although the value of property and density of affected population is lower, the damage inflicted by these floods can also be high because the area affected is large. In order to combat these floods, various flood mitigation measures have been carried out. Structural flood mitigation alone can only provide protection levels from 10 to 100 years Average Recurrence Intervals (ARI). One of the economically effective non-structural approaches in flood mitigation and flood management is using a geospatial technology which involves flood forecasting and warning services to the flood prone areas. This approach which involves the use of Geographical Information Flood Forecasting system also includes the generation of a series of flood maps. There are three types of flood maps namely Flood Hazard Map, Flood Risk Map and Flood Evacuation Map. Flood Hazard Map is used to determine areas susceptible to flooding when discharge from a stream exceeds the bank-full stage. Early warnings of incoming flood events will enable the flood victims to prepare themselves before flooding occurs. Properties and life's can be saved by keeping their movable properties above the flood levels and if necessary, an early evacuation from the area. With respect to flood fighting, an early warning with reference through a series of flood maps including flood hazard map, flood risk map and flood evacuation map of the approaching flood should be able to alert the organization in charge of the flood fighting actions and the authority to undertake the necessary decisions, and the general public to be aware of the impending danger. However this paper will only discuss on the generations of Flood Hazard Maps and the use of Flood Risk Map and Flood Evacuation Map by using geospatial data.

Flood projections within the Niger River Basin under future land use and climate change.

PubMed

Aich, Valentin; Liersch, Stefan; Vetter, Tobias; Fournet, Samuel; Andersson, Jafet C M; Calmanti, Sandro; van Weert, Frank H A; Hattermann, Fred F; Paton, Eva N

2016-08-15

This study assesses future flood risk in the Niger River Basin (NRB), for the first time considering the simultaneous effects of both projected climate change and land use changes. For this purpose, an ecohydrological process-based model (SWIM) was set up and validated for past climate and land use dynamics of the entire NRB. Model runs for future flood risks were conducted with an ensemble of 18 climate models, 13 of them dynamically downscaled from the CORDEX Africa project and five statistically downscaled Earth System Models. Two climate and two land use change scenarios were used to cover a broad range of potential developments in the region. Two flood indicators (annual 90th percentile and the 20-year return flood) were used to assess the future flood risk for the Upper, Middle and Lower Niger as well as the Benue. The modeling results generally show increases of flood magnitudes when comparing a scenario period in the near future (2021-2050) with a base period (1976-2005). Land use effects are more uncertain, but trends and relative changes for the different catchments of the NRB seem robust. The dry areas of the Sahelian and Sudanian regions of the basin show a particularly high sensitivity to climatic and land use changes, with an alarming increase of flood magnitudes in parts. A scenario with continuing transformation of natural vegetation into agricultural land and urbanization intensifies the flood risk in all parts of the NRB, while a "regreening" scenario can reduce flood magnitudes to some extent. Yet, land use change effects were smaller when compared to the effects of climate change. In the face of an already existing adaptation deficit to catastrophic flooding in the region, the authors argue for a mix of adaptation and mitigation efforts in order to reduce the flood risk in the NRB. Copyright © 2016 Elsevier B.V. All rights reserved.

Flooding and Flood Management

USGS Publications Warehouse

Brooks, K.N.; Fallon, J.D.; Lorenz, D.L.; Stark, J.R.; Menard, Jason; Easter, K.W.; Perry, Jim

2011-01-01

Floods result in great human disasters globally and nationally, causing an average of $4 billion of damages each year in the United States. Minnesota has its share of floods and flood damages, and the state has awarded nearly $278 million to local units of government for flood mitigation projects through its Flood Hazard Mitigation Grant Program. Since 1995, flood mitigation in the Red River Valley has exceeded $146 million. Considerable local and state funding has been provided to manage and mitigate problems of excess stormwater in urban areas, flooding of farmlands, and flood damages at road crossings. The cumulative costs involved with floods and flood mitigation in Minnesota are not known precisely, but it is safe to conclude that flood mitigation is a costly business. This chapter begins with a description of floods in Minneosta to provide examples and contrasts across the state. Background material is presented to provide a basic understanding of floods and flood processes, predication, and management and mitigation. Methods of analyzing and characterizing floods are presented because they affect how we respond to flooding and can influence relevant practices. The understanding and perceptions of floods and flooding commonly differ among those who work in flood forecasting, flood protection, or water resource mamnagement and citizens and businesses affected by floods. These differences can become magnified following a major flood, pointing to the need for better understanding of flooding as well as common language to describe flood risks and the uncertainty associated with determining such risks. Expectations of accurate and timely flood forecasts and our ability to control floods do not always match reality. Striving for clarity is important in formulating policies that can help avoid recurring flood damages and costs.

Improving flood risk management through risk communication strategies

NASA Astrophysics Data System (ADS)

Bodoque, Jose Maria; Diez Herrero, Andres; Amerigo, Maria; Garcia, Juan Antonio; Olcina, Jorge; Cortes, Beatriz

2016-04-01

A suitable level of social perception about flood risk and awareness of Civil Protection Plans are critical to minimize disasters and damages due to flash floods. In order to improve risk perception, awareness and, as a result, the effectiveness of Civil Protection Plans, it is often required the implementation of communication plans. This research proposes a guide recommendation framework to enhance local population preparedness, prevention and response when a flash flood occurs. The research setting was a village (Navaluenga) located in Central Spain with 2,027 inhabitants. It is crossed by the Alberche river and Chorreron stream (both tributaries of the Tagus river), which are prone to flash floods. In a first phase, we assessed citizens' flash-flood risk perception and level of awareness regarding some key variables of the Civil Protection Plan. To this end, a questionnaire survey was designed and 254 adults, a sample representing roughly 12% of the population census, were interviewed. Responses were analysed, comparing awareness regarding preparedness and response actions with those previously defined in the Civil Protection Plan. In addition, we carried out a latent class cluster analysis aimed at identifying the different groups present among the respondents. Next, a risk communication plan was designed and implemented. It aimed to improve the understanding of flood risk among local people; and it comprises briefings, quiz-answers, contests of stories and flood images and intergenerational workshops. Finally, participants in the first phase were reached again and a new survey was performed. The results derived from these second questionnaires were statistically treated using the same approach of the first phase. Additionally, a t-test for paired samples and Pearson Chi-Square test was implemented in order to detect possible improvements in the perception and awareness. Preliminary results indicate that in Navaluenga there is a low social perception of flood risk and a low level of awareness regarding the Civil Protection Plan. In the social context of the Iberian Peninsula, where climate change models indicate an increase in extreme weather events and, consequently, high exposure and vulnerability to flash floods, the implementation of appropriately designed communication strategies is critical to improve the resilience of urban areas in order to cope with this risk.

Spatial Optimization of Future Urban Development with Regards to Climate Risk and Sustainability Objectives.

PubMed

Caparros-Midwood, Daniel; Barr, Stuart; Dawson, Richard

2017-11-01

Future development in cities needs to manage increasing populations, climate-related risks, and sustainable development objectives such as reducing greenhouse gas emissions. Planners therefore face a challenge of multidimensional, spatial optimization in order to balance potential tradeoffs and maximize synergies between risks and other objectives. To address this, a spatial optimization framework has been developed. This uses a spatially implemented genetic algorithm to generate a set of Pareto-optimal results that provide planners with the best set of trade-off spatial plans for six risk and sustainability objectives: (i) minimize heat risks, (ii) minimize flooding risks, (iii) minimize transport travel costs to minimize associated emissions, (iv) maximize brownfield development, (v) minimize urban sprawl, and (vi) prevent development of greenspace. The framework is applied to Greater London (U.K.) and shown to generate spatial development strategies that are optimal for specific objectives and differ significantly from the existing development strategies. In addition, the analysis reveals tradeoffs between different risks as well as between risk and sustainability objectives. While increases in heat or flood risk can be avoided, there are no strategies that do not increase at least one of these. Tradeoffs between risk and other sustainability objectives can be more severe, for example, minimizing heat risk is only possible if future development is allowed to sprawl significantly. The results highlight the importance of spatial structure in modulating risks and other sustainability objectives. However, not all planning objectives are suited to quantified optimization and so the results should form part of an evidence base to improve the delivery of risk and sustainability management in future urban development. © 2017 The Authors Risk Analysis published by Wiley Periodicals, Inc. on behalf of Society for Risk Analysis.

An Investigation on the Sensitivity of the Parameters of Urban Flood Model

NASA Astrophysics Data System (ADS)

M, A. B.; Lohani, B.; Jain, A.

2015-12-01

Global climatic change has triggered weather patterns which lead to heavy and sudden rainfall in different parts of world. The impact of heavy rainfall is severe especially on urban areas in the form of urban flooding. In order to understand the effect of heavy rainfall induced flooding, it is necessary to model the entire flooding scenario more accurately, which is now becoming possible with the availability of high resolution airborne LiDAR data and other real time observations. However, there is not much understanding on the optimal use of these data and on the effect of other parameters on the performance of the flood model. This study aims at developing understanding on these issues. In view of the above discussion, the aim of this study is to (i) understand that how the use of high resolution LiDAR data improves the performance of urban flood model, and (ii) understand the sensitivity of various hydrological parameters on urban flood modelling. In this study, modelling of flooding in urban areas due to heavy rainfall is carried out considering Indian Institute of Technology (IIT) Kanpur, India as the study site. The existing model MIKE FLOOD, which is accepted by Federal Emergency Management Agency (FEMA), is used along with the high resolution airborne LiDAR data. Once the model is setup it is made to run by changing the parameters such as resolution of Digital Surface Model (DSM), manning's roughness, initial losses, catchment description, concentration time, runoff reduction factor. In order to realize this, the results obtained from the model are compared with the field observations. The parametric study carried out in this work demonstrates that the selection of catchment description plays a very important role in urban flood modelling. Results also show the significant impact of resolution of DSM, initial losses and concentration time on urban flood model. This study will help in understanding the effect of various parameters that should be part of a flood model for its accurate performance.

Multiple-resolution Modeling of flood processes in urban catchments using WRF-Hydro: A Case Study in south Louisiana.

NASA Astrophysics Data System (ADS)

Saad, H.; Habib, E. H.

2017-12-01

In August 2016, the city of Lafayette and many other urban centers in south Louisiana experienced catastrophic flooding resulting from prolonged rainfall. Statewide, this historic storm displaced more than 30,000 people from their homes, resulted in damages up to $8.7 billion, put rescue workers at risk, interrupted institutions of education and business, and worst of all, resulted in the loss of life of at least 13 Louisiana residents. With growing population and increasing signs of climate change, the frequency of major floods and severe storms is expected to increase, as will the impacts of these events on our communities. Local communities need improved capabilities for forecasting flood events, monitoring of flood impacts on roads and key infrastructure, and effectively communicating real-time flood dangers at scales that are useful to the public. The current study presents the application of the WRF-Hydro modeling system to represent integrated hydrologic, hydraulic and hydrometeorological processes that drive flooding in urban basins at temporal and spatial scales that can be useful to local communities. The study site is the 25- mile2 Coulee mine catchment in Lafayette, south Louisiana. The catchment includes two tributaries with natural streams located within mostly agricultural lands. The catchment crosses the I-10 highway and through the metropolitan area of the City of Lafayette into a man-made channel, which eventually drains into the Vermilion River and the Gulf of Mexico. Due to its hydrogeomorphic setting, local and rapid diversification of land uses, low elevation, and interdependent infrastructure, the integrated modeling of this coulee is considered a challenge. A nested multi-scale model is being built using the WRF-HYDRO, with 500m and 10m resolutions for the NOAH land-surface model and diffusive wave terrain routing grids, respectively.

A spatial Bayesian network model to assess the benefits of early warning for urban flood risk to people

NASA Astrophysics Data System (ADS)

Balbi, Stefano; Villa, Ferdinando; Mojtahed, Vahid; Hegetschweiler, Karin Tessa; Giupponi, Carlo

2016-06-01

This article presents a novel methodology to assess flood risk to people by integrating people's vulnerability and ability to cushion hazards through coping and adapting. The proposed approach extends traditional risk assessments beyond material damages; complements quantitative and semi-quantitative data with subjective and local knowledge, improving the use of commonly available information; and produces estimates of model uncertainty by providing probability distributions for all of its outputs. Flood risk to people is modeled using a spatially explicit Bayesian network model calibrated on expert opinion. Risk is assessed in terms of (1) likelihood of non-fatal physical injury, (2) likelihood of post-traumatic stress disorder and (3) likelihood of death. The study area covers the lower part of the Sihl valley (Switzerland) including the city of Zurich. The model is used to estimate the effect of improving an existing early warning system, taking into account the reliability, lead time and scope (i.e., coverage of people reached by the warning). Model results indicate that the potential benefits of an improved early warning in terms of avoided human impacts are particularly relevant in case of a major flood event.

Integrating Local Experiential and Hydrometeorological Data to Understand Knowledge Uncertainties and to Build Resilience to Flooding in Two Puerto Rican Communities.

NASA Astrophysics Data System (ADS)

Ramsey, M.; Nytch, C. J.; Branoff, B.

2016-12-01

Socio-hydrological studies that explore feedbacks between social and biophysical processes related to flood risk can help managers identify strategies that increase a community's freshwater security. However, knowledge uncertainty due to coarse spatio-temporal coverage of hydrological monitoring data, missing riverine discharge and precipitation records, assumptions of flood risk models, and effects of urbanization, can limit the ability of these studies to isolate hydrological responses to social drivers of flooding and a changing climate. Local experiential knowledge can provide much needed information about 1) actual flood spatio-temporal patterns, 2) human impacts and perceptions of flood events, and 3) mechanisms to validate flood risk studies and understand key social elements of the system. We addressed these knowledge gaps by comparing the location and timing of flood events described in resident interviews and resident drawn maps (total = 97) from two San Juan communities with NOAA and USGS precipitation and riverine discharge data archives, and FEMA flood maps. Analyses of five focal flood events revealed 1) riverine monitoring data failed to record a major flood event caused by localized blockage of the river, 2) residents did not mention multiple extreme riverine discharge events, 3) resident and FEMA flood maps matched closely but resident maps provided finer spatial information about frequency of flooding, and 4) only a small percentage of residents remembered the dates of flood events. Local knowledge provided valuable social data about flood impacts on human economic and physical/psychological wellbeing, perceptions about factors causing flooding, and what residents use as sources of flood information. A simple mechanism or tool for residents to record their flood experiences in real-time will address the uncertainties in local knowledge and improve social memory. The integration of local experiential knowledge with simulated and empirical hydro-meteorological data can be a powerful approach to increase the quality of socio-hydrological studies about flooding and freshwater security.

Gastrointestinal illness among triathletes swimming in non-polluted versus polluted seawater affected by heavy rainfall, Denmark, 2010-2011.

PubMed

Harder-Lauridsen, Nina Majlund; Kuhn, Katrin Gaardbo; Erichsen, Anders Christian; Mølbak, Kåre; Ethelberg, Steen

2013-01-01

Recent years have seen an increase in the frequency of extreme rainfall and subsequent flooding across the world. Climate change models predict that such flooding will become more common, triggering sewer overflows, potentially with increased risks to human health. In August 2010, a triathlon sports competition was held in Copenhagen, Denmark, shortly after an extreme rainfall. The authors took advantage of this event to investigate disease risks in two comparable cohorts of physically fit, long distance swimmers competing in the sea next to a large urban area. An established model of bacterial concentration in the water was used to examine the level of pollution in a spatio-temporal manner. Symptoms and exposures among athletes were examined with a questionnaire using a retrospective cohort design and the questionnaire investigation was repeated after a triathlon competition held in non-polluted seawater in 2011. Diagnostic information was collected from microbiological laboratories. The results showed that the 3.8 kilometer open water swimming competition coincided with the peak of post-flooding bacterial contamination in 2010, with average concentrations of 1.5x10(4) E. coli per 100 ml water. The attack rate of disease among 838 swimmers in 2010 was 42% compared to 8% among 931 swimmers in the 2011 competition (relative risk (RR) 5.0; 95% CI: 4.0-6.39). In 2010, illness was associated with having unintentionally swallowed contaminated water (RR 2.5; 95% CI: 1.8-3.4); and the risk increased with the number of mouthfuls of water swallowed. Confirmed aetiologies of infection included Campylobacter, Giardia lamblia and diarrhoeagenic E. coli. The study demonstrated a considerable risk of illness from water intake when swimming in contaminated seawater in 2010, and a small but measureable risk from non-polluted water in 2011. This suggests a significant risk of disease in people ingesting small amounts of flood water following extreme rainfall in urban areas.

Gastrointestinal Illness among Triathletes Swimming in Non-Polluted versus Polluted Seawater Affected by Heavy Rainfall, Denmark, 2010-2011

PubMed Central

Harder-Lauridsen, Nina Majlund; Kuhn, Katrin Gaardbo; Erichsen, Anders Christian; Mølbak, Kåre; Ethelberg, Steen

2013-01-01

Recent years have seen an increase in the frequency of extreme rainfall and subsequent flooding across the world. Climate change models predict that such flooding will become more common, triggering sewer overflows, potentially with increased risks to human health. In August 2010, a triathlon sports competition was held in Copenhagen, Denmark, shortly after an extreme rainfall. The authors took advantage of this event to investigate disease risks in two comparable cohorts of physically fit, long distance swimmers competing in the sea next to a large urban area. An established model of bacterial concentration in the water was used to examine the level of pollution in a spatio-temporal manner. Symptoms and exposures among athletes were examined with a questionnaire using a retrospective cohort design and the questionnaire investigation was repeated after a triathlon competition held in non-polluted seawater in 2011. Diagnostic information was collected from microbiological laboratories. The results showed that the 3.8 kilometer open water swimming competition coincided with the peak of post-flooding bacterial contamination in 2010, with average concentrations of 1.5x104 E. coli per 100 ml water. The attack rate of disease among 838 swimmers in 2010 was 42% compared to 8% among 931 swimmers in the 2011 competition (relative risk (RR) 5.0; 95% CI: 4.0-6.39). In 2010, illness was associated with having unintentionally swallowed contaminated water (RR 2.5; 95% CI: 1.8-3.4); and the risk increased with the number of mouthfuls of water swallowed. Confirmed aetiologies of infection included Campylobacter, Giardia lamblia and diarrhoeagenic E. coli. The study demonstrated a considerable risk of illness from water intake when swimming in contaminated seawater in 2010, and a small but measureable risk from non-polluted water in 2011. This suggests a significant risk of disease in people ingesting small amounts of flood water following extreme rainfall in urban areas. PMID:24244306

Development of Real-Time System for Urban Flooding by Surcharge of Storm Drainge and River Inundation

NASA Astrophysics Data System (ADS)

Shim, J. B.; Won, C. Y.; Park, J.; Lee, K.

2017-12-01

Korea experiences frequent flood disasters, which cause considerable economic losses and damages to towns and farms. Especially, a regional torrential storm is about 98.5mm/hr on September 21, 2010 in Seoul. The storm exceeds the capacity of urban drainage system of 75mm/hr, and 9,419 houses. How to monitor and control the urban flood disasters is an important issue in Korea. To mitigate the flood damage, a customizing system was developed to estimate urban floods and inundation using by integrating drainage system data and river information database which are managed by local governments and national agencies. In the case of Korean urban city, there are a lot of detention ponds and drainage pumping stations on end of drainage system and flow is going into river. The drainage pumping station, it is very important hydraulic facility for flood control between river and drainage system. So, it is possible to occur different patterns of flood inundation according to operation rule of drainage pumping station. A flood disaster is different damage as how to operate drainage pumping station and plan operation rule.

Mapping flood hazards under uncertainty through probabilistic flood inundation maps

NASA Astrophysics Data System (ADS)

Stephens, T.; Bledsoe, B. P.; Miller, A. J.; Lee, G.

2017-12-01

Changing precipitation, rapid urbanization, and population growth interact to create unprecedented challenges for flood mitigation and management. Standard methods for estimating risk from flood inundation maps generally involve simulations of floodplain hydraulics for an established regulatory discharge of specified frequency. Hydraulic model results are then geospatially mapped and depicted as a discrete boundary of flood extents and a binary representation of the probability of inundation (in or out) that is assumed constant over a project's lifetime. Consequently, existing methods utilized to define flood hazards and assess risk management are hindered by deterministic approaches that assume stationarity in a nonstationary world, failing to account for spatio-temporal variability of climate and land use as they translate to hydraulic models. This presentation outlines novel techniques for portraying flood hazards and the results of multiple flood inundation maps spanning hydroclimatic regions. Flood inundation maps generated through modeling of floodplain hydraulics are probabilistic reflecting uncertainty quantified through Monte-Carlo analyses of model inputs and parameters under current and future scenarios. The likelihood of inundation and range of variability in flood extents resulting from Monte-Carlo simulations are then compared with deterministic evaluations of flood hazards from current regulatory flood hazard maps. By facilitating alternative approaches of portraying flood hazards, the novel techniques described in this presentation can contribute to a shifting paradigm in flood management that acknowledges the inherent uncertainty in model estimates and the nonstationary behavior of land use and climate.

Collaborative multi-stakeholder approach to drafting flood risk management plans in Wallonia, Belgium

NASA Astrophysics Data System (ADS)

Maroy, Edith; Javaux, Mathieu; Vandermosten, Pierre; Englebert, Benjamin

2015-04-01

The Flood Directive 2007/60/CE establishes a common framework within the European Union for assessing and reducing risks posed by floods on human health, the environment, economic activity and cultural heritage. For that purpose, Member States had to establish flood areas and flood risk maps, and subsequently, flood risk management plans (due December 2015). According to the Directive, special attention is to be paid to international coordination for transboundary water courses, integrated management approaches at the catchment scale, cost-effectiveness of measures and public involvement. Management measures must focus on reducing the probability of flooding and the potential consequences of flooding. They must cover prevention, protection and preparedness and must take into account relevant aspects, such as water management, soil management, spatial planning, land use and nature conservation. Floods in Wallonia mostly originate from overflowing of both little sloped rivers and highly reactive rivers but also, from concentrated runoff in the intensely cultivated and erosion-prone region north of the Sambre-Meuse axis. Consequently, walloon flood area maps not only show flood areas based on hydraulic modelling and observations but also runoff concentration axis in agricultural areas. Now released to the public, this information can be used to assess the risk of damage for land planning and erosion control strategies. Incidentally, some 166 km2 were mapped as flood hazard area with a return period of 25 years, 28.8 of which are urbanized or destined to urbanisation and counting of number of approximatively 39.000 people living in those areas. Flood area and flood risk maps should be the starting point of elaborating flood risk management plans. In order to involve the diversity of water managers and stakeholders in the drafting of a management plan for hydrographic districts in Wallonia, responsible authorities decided to mandate scientists and engineers to organize an extensive participatory process. A series of meetings were organised, first, to raise awareness of local managers on the information provided by flood maps and on the objectives of the Directive towards integrated water management. Second, these successive meetings and the use of decision support tools such as a multicriteria analysis matrix allowed the team to collect local information on risks and opportunities, to foster emergence of integrated solutions, and to reach an agreement on priorities at the catchment scale and then at the regional level. This case study provides insights on practicability of using hydrological data on flood hazard in a collaborative, bottom-up approach to flood risk management. Lessons learnt from this project are a foundation for a realistic and effective management plan but limitations of the method and time constrains of this project leave a number of questions as to follow-up, exhaustiveness and cost-effectiveness of measures constituting the plan.

The KULTURisk Regional Risk Assessment methodology for water-related natural hazards - Part 1: Physical-environmental assessment

NASA Astrophysics Data System (ADS)

Ronco, P.; Gallina, V.; Torresan, S.; Zabeo, A.; Semenzin, E.; Critto, A.; Marcomini, A.

2014-07-01

In recent years, the frequency of catastrophes induced by natural hazard has increased and flood events in particular have been recognized as one of the most threatening water-related disasters. Severe floods have occurred in Europe over the last decade causing loss of life, displacement of people and heavy economic losses. Flood disasters are growing as a consequence of many factors, both climatic and non-climatic. Indeed, the current increase of water-related disasters can be mainly attributed to the increase of exposure (increase elements potentially at risk in floodplains area) and vulnerability (i.e. economic, social, geographic, cultural, and physical/environmental characteristics of the exposure). Besides these factors, the strong effect of climate change is projected to radically modify the usual pattern of the hydrological cycle by intensifying the frequency and severity of flood events both at local, regional and global scale. Within this context, it becomes urgent and dramatically relevant the need of promoting and developing effective and pro-active strategies, tools and actions which allow to assess and (possibly) to reduce the flood risks that threats different relevant receptors. Several methodologies to assess the risk posed by water-related natural hazards have been proposed so far, but very few of them can be adopted to implement the last European Flood Directive (FD). The present study is intended to introduce and present a state-of-the-art Regional Risk Assessment (RRA) methodology to evaluate the benefits of risk prevention in terms of reduced environmental risks due to floods. The methodology, developed within the recently phased out FP7-KULTURisk Project (Knowledge-based approach to develop a cULTUre of Risk prevention - KR) is flexible and can be adapted to different case studies (i.e. large rivers, alpine/mountain catchments, urban areas and coastal areas) and spatial scales (i.e. from the large river to the urban scale). The FD compliant KR-RRA methodology is based on the concept of risk being function of hazard, exposure and vulnerability. It integrates the outputs of various hydrodynamics models (hazard) with sito-specific bio-geophysical and socio-economic indicators (e.g. slope, land cover, population density, economic activities) to develop tailored risk indexes and GIS-based maps for each of the selected targets (i.e. people, buildings, infrastructures, agriculture, natural and semi-natural systems, cultural heritages) in the considered region, by comparing the baseline scenario with alternative scenarios, where different structural and/or non-structural mitigation measures are planned. As demonstrated in the companion paper (Part 2, Ronco et al., 2014), risk maps, along with related statistics, allow to identify and prioritize relative hotspots and targets which are more likely to be affected by flood and support the development of relevant and strategic adaptation and prevention measures to minimizing flood impacts. Moreover, the outputs of the RRA methodology can be used for the economic evaluation of different damages (e.g. tangible costs, intangible costs) and for the social assessment considering the benefits of the human dimension of vulnerability (i.e. adaptive and coping capacity).

Risk of Intestinal Parasitic Infections in People with Different Exposures to Wastewater and Fecal Sludge in Kampala, Uganda: A Cross-Sectional Study.

PubMed

Fuhrimann, Samuel; Winkler, Mirko S; Kabatereine, Narcis B; Tukahebwa, Edridah M; Halage, Abdulla A; Rutebemberwa, Elizeus; Medlicott, Kate; Schindler, Christian; Utzinger, Jürg; Cissé, Guéladio

2016-03-01

There are health risks associated with wastewater and fecal sludge management and use, but little is known about the magnitude, particularly in rapidly growing urban settings of low- and middle-income countries. We assessed the point-prevalence and risk factors of intestinal parasite infections in people with different exposures to wastewater and fecal sludge in Kampala, Uganda. A cross-sectional survey was carried out in September and October 2013, enrolling 915 adults from five distinct population groups: workers maintaining wastewater facilities; workers managing fecal sludge; urban farmers; slum dwellers at risk of flooding; and slum dwellers without risk of flooding. Stool samples were subjected to the Kato-Katz method and a formalin-ether concentration technique for the diagnosis of helminth and intestinal protozoa infections. A questionnaire was administered to determine self-reported signs and symptoms, and risk factors for intestinal parasite infections. Univariate and multivariate analyses, adjusted for sex, age, education, socioeconomic status, water, sanitation, and hygiene behaviors, were conducted to estimate the risk of infection with intestinal parasites and self-reported health outcomes, stratified by population group. The highest point-prevalence of intestinal parasite infections was found in urban farmers (75.9%), whereas lowest point-prevalence was found in workers managing fecal sludge (35.8%). Hookworm was the predominant helminth species (27.8%). In urban farmers, the prevalence of Trichuris trichiura, Schistosoma mansoni, Ascaris lumbricoides, and Entamoeba histolytica/E. dispar was 15% and above. For all investigated parasites, we found significantly higher odds of infection among urban farmers compared to the other groups (adjusted odds ratios ranging between 1.6 and 12.9). In general, female participants had significantly lower odds of infection with soil-transmitted helminths and S. mansoni compared to males. Higher educational attainment was negatively associated with the risk of intestinal protozoa infections, while socioeconomic status did not emerge as a significant risk factor for any tested health outcome. Urban farmers are particularly vulnerable to infections with soil-transmitted helminths, S. mansoni, and intestinal protozoa. Hence, our findings call for public health protection measures for urban farmers and marginalized communities, going hand-in-hand with integrated sanitation safety planning at city level.

Risk of Intestinal Parasitic Infections in People with Different Exposures to Wastewater and Fecal Sludge in Kampala, Uganda: A Cross-Sectional Study

PubMed Central

Fuhrimann, Samuel; Winkler, Mirko S.; Kabatereine, Narcis B.; Tukahebwa, Edridah M.; Halage, Abdulla A.; Rutebemberwa, Elizeus; Medlicott, Kate; Schindler, Christian; Utzinger, Jürg; Cissé, Guéladio

2016-01-01

Background There are health risks associated with wastewater and fecal sludge management and use, but little is known about the magnitude, particularly in rapidly growing urban settings of low- and middle-income countries. We assessed the point-prevalence and risk factors of intestinal parasite infections in people with different exposures to wastewater and fecal sludge in Kampala, Uganda. Methodology A cross-sectional survey was carried out in September and October 2013, enrolling 915 adults from five distinct population groups: workers maintaining wastewater facilities; workers managing fecal sludge; urban farmers; slum dwellers at risk of flooding; and slum dwellers without risk of flooding. Stool samples were subjected to the Kato-Katz method and a formalin-ether concentration technique for the diagnosis of helminth and intestinal protozoa infections. A questionnaire was administered to determine self-reported signs and symptoms, and risk factors for intestinal parasite infections. Univariate and multivariate analyses, adjusted for sex, age, education, socioeconomic status, water, sanitation, and hygiene behaviors, were conducted to estimate the risk of infection with intestinal parasites and self-reported health outcomes, stratified by population group. Principal Findings The highest point-prevalence of intestinal parasite infections was found in urban farmers (75.9%), whereas lowest point-prevalence was found in workers managing fecal sludge (35.8%). Hookworm was the predominant helminth species (27.8%). In urban farmers, the prevalence of Trichuris trichiura, Schistosoma mansoni, Ascaris lumbricoides, and Entamoeba histolytica/E. dispar was 15% and above. For all investigated parasites, we found significantly higher odds of infection among urban farmers compared to the other groups (adjusted odds ratios ranging between 1.6 and 12.9). In general, female participants had significantly lower odds of infection with soil-transmitted helminths and S. mansoni compared to males. Higher educational attainment was negatively associated with the risk of intestinal protozoa infections, while socioeconomic status did not emerge as a significant risk factor for any tested health outcome. Conclusions/Significance Urban farmers are particularly vulnerable to infections with soil-transmitted helminths, S. mansoni, and intestinal protozoa. Hence, our findings call for public health protection measures for urban farmers and marginalized communities, going hand-in-hand with integrated sanitation safety planning at city level. PMID:26938060

How normative interpretations of climate risk assessment affect local decision-making: an exploratory study at the city scale in Cork, Ireland.

PubMed

McDermott, T K J; Surminski, S

2018-06-13

Urban areas already suffer substantial losses in both economic and human terms from climate-related disasters. These losses are anticipated to grow substantially, in part as a result of the impacts of climate change. In this paper, we investigate the process of translating climate risk data into action for the city level. We apply a commonly used decision-framework as our backdrop and explore where in this process climate risk assessment and normative political judgements intersect. We use the case of flood risk management in Cork city in Ireland to investigate what is needed for translating risk assessment into action at the local city level. Evidence presented is based on focus group discussions at two stakeholder workshops, and a series of individual meetings and phone-discussions with stakeholders involved in local decision-making related to flood risk management and adaptation to climate change, in Ireland. Respondents were chosen on the basis of their expertise or involvement in the decision-making processes locally and nationally. Representatives of groups affected by flood risk and flood risk management and climate adaptation efforts were also included. The Cork example highlights that, despite ever more accurate data and an increasing range of theoretical approaches available to local decision-makers, it is the normative interpretation of this information that determines what action is taken. The use of risk assessments for decision-making is a process that requires normative decisions, such as setting 'acceptable risk levels' and identifying 'adequate' protection levels, which will not succeed without broader buy-in and stakeholder participation. Identifying and embracing those normative views up-front could strengthen the urban adaptation process-this may, in fact, turn out to be the biggest advantage of climate risk assessment: it offers an opportunity to create a shared understanding of the problem and enables an informed evaluation and discussion of remedial action.This article is part of the theme issue 'Advances in risk assessment for climate change adaptation policy'. © 2018 The Author(s).

How normative interpretations of climate risk assessment affect local decision-making: an exploratory study at the city scale in Cork, Ireland

NASA Astrophysics Data System (ADS)

McDermott, T. K. J.; Surminski, S.

2018-06-01

Urban areas already suffer substantial losses in both economic and human terms from climate-related disasters. These losses are anticipated to grow substantially, in part as a result of the impacts of climate change. In this paper, we investigate the process of translating climate risk data into action for the city level. We apply a commonly used decision-framework as our backdrop and explore where in this process climate risk assessment and normative political judgements intersect. We use the case of flood risk management in Cork city in Ireland to investigate what is needed for translating risk assessment into action at the local city level. Evidence presented is based on focus group discussions at two stakeholder workshops, and a series of individual meetings and phone-discussions with stakeholders involved in local decision-making related to flood risk management and adaptation to climate change, in Ireland. Respondents were chosen on the basis of their expertise or involvement in the decision-making processes locally and nationally. Representatives of groups affected by flood risk and flood risk management and climate adaptation efforts were also included. The Cork example highlights that, despite ever more accurate data and an increasing range of theoretical approaches available to local decision-makers, it is the normative interpretation of this information that determines what action is taken. The use of risk assessments for decision-making is a process that requires normative decisions, such as setting `acceptable risk levels' and identifying `adequate' protection levels, which will not succeed without broader buy-in and stakeholder participation. Identifying and embracing those normative views up-front could strengthen the urban adaptation process-this may, in fact, turn out to be the biggest advantage of climate risk assessment: it offers an opportunity to create a shared understanding of the problem and enables an informed evaluation and discussion of remedial action. This article is part of the theme issue `Advances in risk assessment for climate change adaptation policy'.

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Dynamic coupling of three hydrodynamic models

NASA Astrophysics Data System (ADS)

Hartnack, J. N.; Philip, G. T.; Rungoe, M.; Smith, G.; Johann, G.; Larsen, O.; Gregersen, J.; Butts, M. B.

2008-12-01

The need for integrated modelling is evidently present within the field of flood management and flood forecasting. Engineers, modellers and managers are faced with flood problems which transcend the classical hydrodynamic fields of urban, river and coastal flooding. Historically the modeller has been faced with having to select one hydrodynamic model to cover all the aspects of the potentially complex dynamics occurring in a flooding situation. Such a single hydrodynamic model does not cover all dynamics of flood modelling equally well. Thus the ideal choice may in fact be a combination of models. Models combining two numerical/hydrodynamic models are becoming more standard, typically these models combine a 1D river model with a 2D overland flow model or alternatively a 1D sewer/collection system model with a 2D overland solver. In complex coastal/urban areas the flood dynamics may include rivers/streams, collection/storm water systems along with the overland flow. The dynamics within all three areas is of the same time scale and there is feedback in the system across the couplings. These two aspects dictate a fully dynamic three way coupling as opposed to running the models sequentially. It will be shown that the main challenges of the three way coupling are time step issues related to the difference in numerical schemes used in the three model components and numerical instabilities caused by the linking of the model components. MIKE FLOOD combines the models MIKE 11, MIKE 21 and MOUSE into one modelling framework which makes it possible to couple any combination of river, urban and overland flow fully dynamically. The MIKE FLOOD framework will be presented with an overview of the coupling possibilities. The flood modelling concept will be illustrated through real life cases in Australia and in Germany. The real life cases reflect dynamics and interactions across all three model components which are not possible to reproduce using a two-way coupling alone. The models comprise 2D inundation modelling, river networks with multiple structures (pumps, weirs, culverts), urban drainage networks as well as dam break modelling. The models were used to quantify the results of storm events or failures (dam break, pumping failures etc) coinciding with high discharge in river system and heavy rainfall. The detailed representation of the flow path through the city allowed a direct assessment of flood risk Thus it is found that the three-way coupled model is a practical and useful tool for integrated flood management.

Influence of climate variability and urban areas on the flood events in Bari (Apulia, southern Italy)

NASA Astrophysics Data System (ADS)

Lonigro, Teresa; Polemio, Maurizio

2014-05-01

The Damaging Hydrogeological Events (DHEs) can be defined as the occurrence of one or more simultaneous phenomena, such as droughts, windstorms, heat waves, landslides, floods and secondary floods (i.e. rapid accumulation or pounding of surface water with very low flow velocity), causing damages. They represent a serious problem, especially in DHE-prone areas with growing urbanization, where the infiltration capability is limited by buildings and where the vulnerability is higher than other areas. The paper proposes a methodology, based on both historical and time series approaches, used for describing the influence of climatic variability and urban development on the number of phenomena observed. The historical approach is finalised to collect phenomenon historical data, very important for the comprehension of the evolution of a study area. Phenomenon historical data is useful for expanding the historical period of investigation in order to assess the occurrence trend of DHEs. The historical analysis of DHEs can support decision making and land-use planning, ultimately reducing natural risks. The time series approach includes the collection and the statistical analysis of climatic data (monthly rainfall, wet days, rainfall intensity, and temperature), useful to characterise the climate variations and trends and to roughly assess the effects of these trends on river discharge and on the triggering of landslides. The time series approach is completed by tools to analyse simultaneously all data types. The study of land use variations, with a special emphasis on the urban areas, is important to understand how the modifications occurred in the territory, especially in terms of vulnerability, could influence the occurrence of DHEs. The methodology can be applied simultaneously to floods and landslides and was tested considering the municipality of Bari (southern Italy), particularly affected by flood events. Since the climate trend (decreasing trend of rainfall and rainfall intensity and an increasing trend of wet days and temperatures) does not show favourable conditions for the increase of the annual number of damaging floods, its trend is increasing. The role of anthropogenic modifications and the mismanagement of risk-prone areas should be considered to justify the increasing occurrences of floods. A validation of this hypothesis comes from the study of land use modifications, carried out comparing different temporal levels of land use (from 1959 to 2006). The analysis shows, starting from 1959 to 2006, a significant increase in urban areas (of about 50%) on the entire regional territory. The municipality of Bari, the regional main town, has undergone a remarkable development of its urban areas, from 12.45 Km2 in 1959 to 58.82 Km2 in 2006. The consequent increased vulnerability of this area has been highlighted during the recent flood event occurred in 2005, which caused six casualties, numerous injuries and damages to roads, buildings, industries, agriculture, livestock and services. More details on previous results of this research activity were recently published (Polemio, 2010; Polemio and Lonigro, 2012). References Polemio M. (2010): Historical floods and a recent extreme rainfall event in the Murgia karstic environment (Southern Italy). Zeitschrift für Geomorphologie, 54(2): 195-219. Polemio M., Lonigro T. (2012): Variabilità climatica e ricorrenza delle calamità idrogeologiche in Puglia. Geologia dell'Ambiente, 2/2012: 262-266.

Flood analysis in mixed-urban areas reflecting interactions with the complete water cycle through coupled hydrologic-hydraulic modelling.

PubMed

Sto Domingo, N D; Refsgaard, A; Mark, O; Paludan, B

2010-01-01

The potential devastating effects of urban flooding have given high importance to thorough understanding and management of water movement within catchments, and computer modelling tools have found widespread use for this purpose. The state-of-the-art in urban flood modelling is the use of a coupled 1D pipe and 2D overland flow model to simultaneously represent pipe and surface flows. This method has been found to be accurate for highly paved areas, but inappropriate when land hydrology is important. The objectives of this study are to introduce a new urban flood modelling procedure that is able to reflect system interactions with hydrology, verify that the new procedure operates well, and underline the importance of considering the complete water cycle in urban flood analysis. A physically-based and distributed hydrological model was linked to a drainage network model for urban flood analysis, and the essential components and concepts used were described in this study. The procedure was then applied to a catchment previously modelled with the traditional 1D-2D procedure to determine if the new method performs similarly well. Then, results from applying the new method in a mixed-urban area were analyzed to determine how important hydrologic contributions are to flooding in the area.

Assessment of the effectiveness of participatory developed adaptation strategies for HCMC

NASA Astrophysics Data System (ADS)

Lasage, R.; Veldkamp, T. I. E.; de Moel, H.; Van, T. C.; Phi, H. L.; Vellinga, P.; Aerts, J. C. J. H.

2014-01-01

Coastal cities are vulnerable to flooding, and flood risk to coastal cities will increase due to sea-level rise. Moreover, especially Asian cities are subject to considerable population growth and associated urban developments, increasing this risk even more. Empirical data on vulnerability and the cost and benefits of flood risk reducing measures are therefore paramount for sustainable development of these cities. This paper presents an approach to explore the impacts of sea level rise and socio-economic developments on flood risk for the flood prone District 4 in Ho Chi Minh City, Vietnam, and to develop and evaluate the effects of different adaptation strategies (new levees, dry- and wet flood proofing of buildings). A flood damage model was developed to simulate current and future flood risk using the results from a household survey to establish stage-damage curves for residential buildings. the model has been used to assess the effects of several participatory developed adaptation strategies to reduce flood risk, expressed in Expected Annual Damage (EAD). Adaptation strategies were evaluated assuming combinations of both sea level scenarios and land use scenarios. Together with information on costs of these strategies, we calculated the benefit-cost ratio and net present value for the adaptation strategies until 2100, taking into account depreciation rates of 2.5% and 5%. The results of this modeling study indicate that the current flood risk in District 4 is 0.31 million USD yr-1, increasing up to 0.78 million USD yr-1 in 2100. The net present value and benefit-cost ratios using a discount rate of 5% range from USD -107 to -1.5 million, and from 0.086 to 0.796 for the different strategies. Using a discount rate of 2.5% leads to an increase in both net present value and benefit cost ratio. The adaptation strategies wet proofing and dry proofing generate the best results using these economic indicators. The information on different strategies will be used by the government of Ho Chi Minh City for selecting a new flood protection strategy. Future research should focus on gathering empirical data right after a flood on the occurring damage, as this appears to be the most uncertain factor in the risk assessment.

Assessment of the effectiveness of flood adaptation strategies for HCMC

NASA Astrophysics Data System (ADS)

Lasage, R.; Veldkamp, T. I. E.; de Moel, H.; Van, T. C.; Phi, H. L.; Vellinga, P.; Aerts, J. C. J. H.

2014-06-01

Coastal cities are vulnerable to flooding, and flood risk to coastal cities will increase due to sea-level rise. Moreover, Asian cities in particular are subject to considerable population growth and associated urban developments, increasing this risk even more. Empirical data on vulnerability and the cost and benefits of flood risk reduction measures are therefore paramount for sustainable development of these cities. This paper presents an approach to explore the impacts of sea-level rise and socio-economic developments on flood risk for the flood-prone District 4 in Ho Chi Minh City, Vietnam, and to develop and evaluate the effects of different adaptation strategies (new levees, dry- and wet proofing of buildings and elevating roads and buildings). A flood damage model was developed to simulate current and future flood risk using the results from a household survey to establish stage-damage curves for residential buildings. The model has been used to assess the effects of several participatory developed adaptation strategies to reduce flood risk, expressed in expected annual damage (EAD). Adaptation strategies were evaluated assuming combinations of both sea-level scenarios and land-use scenarios. Together with information on costs of these strategies, we calculated the benefit-cost ratio and net present value for the adaptation strategies until 2100, taking into account depreciation rates of 2.5% and 5%. The results of this modelling study indicate that the current flood risk in District 4 is USD 0.31 million per year, increasing up to USD 0.78 million per year in 2100. The net present value and benefit-cost ratios using a discount rate of 5 % range from USD -107 to -1.5 million, and from 0.086 to 0.796 for the different strategies. Using a discount rate of 2.5% leads to an increase in both net present value and benefit-cost ratio. The adaptation strategies wet-proofing and dry-proofing generate the best results using these economic indicators. The information on different strategies will be used by the government of Ho Chi Minh City to determine a new flood protection strategy. Future research should focus on gathering empirical data right after a flood on the occurring damage, as this appears to be the most uncertain factor in the risk assessment.

Radar-based Quantitative Precipitation Forecasting using Spatial-scale Decomposition Method for Urban Flood Management

NASA Astrophysics Data System (ADS)

Yoon, S.; Lee, B.; Nakakita, E.; Lee, G.

2016-12-01

Recent climate changes and abnormal weather phenomena have resulted in increased occurrences of localized torrential rainfall. Urban areas in Korea have suffered from localized heavy rainfall, including the notable Seoul flood disaster in 2010 and 2011. The urban hydrological environment has changed in relation to precipitation, such as reduced concentration time, a decreased storage rate, and increased peak discharge. These changes have altered and accelerated the severity of damage to urban areas. In order to prevent such urban flash flood damages, we have to secure the lead time for evacuation through the improvement of radar-based quantitative precipitation forecasting (QPF). The purpose of this research is to improve the QPF products using spatial-scale decomposition method for considering the life time of storm and to assess the accuracy between traditional QPF method and proposed method in terms of urban flood management. The layout of this research is as below. First, this research applies the image filtering to separate the spatial-scale of rainfall field. Second, the separated small and large-scale rainfall fields are extrapolated by each different forecasting method. Third, forecasted rainfall fields are combined at each lead time. Finally, results of this method are evaluated and compared with the results of uniform advection model for urban flood modeling. It is expected that urban flood information using improved QPF will help to reduce casualties and property damage caused by urban flooding through this research.

Piloting a real-time surface water flood nowcasting system for enhancing operational resilience of emergency responders

NASA Astrophysics Data System (ADS)

Yu, Dapeng; Guan, Mingfu; Wilby, Robert; Bruce, Wright; Szegner, Mark

2017-04-01

Emergency services (such as Fire & Rescue, and Ambulance) can face the challenging tasks of having to respond to or operate under extreme and fast changing weather conditions, including surface water flooding. UK-wide, return period based surface water flood risk mapping undertaken by the Environment Agency provides useful information about areas at risks. Although these maps are useful for planning purposes for emergency responders, their utility to operational response during flood emergencies can be limited. A street-level, high resolution, real-time, surface water flood nowcasting system, has been piloted in the City of Leicester, UK to assess emergency response resilience to surface water flooding. Precipitation nowcasting over 7- and 48-hour horizons are obtained from the UK Met Office and used as inputs to the system. A hydro-inundation model is used to simulate urban surface water flood depths/areas at both the city and basin scale, with a 20 m and 3 m spatial resolution respectively, and a 15-minute temporal resolution, 7-hour and 48-hour in advance. Based on this, we evaluate both the direct and indirect impacts of potential surface water flood events on emergency responses, including: (i) identifying vulnerable populations (e.g. care homes and schools) at risk; and (ii) generating novel metrics of accessibility (e.g. travel time from service stations to vulnerable sites; spatial coverage with certain legislative timeframes) in real-time. In doing so, real-time information on potential risks and impacts of emerging flood incidents arising from intense rainfall can be communicated via a dedicated web-based platform to emergency responders thereby improving response times and operational resilience.

Implementing sustainable drainage systems for urban surface water management within the regulatory framework in England and Wales.

PubMed

Ellis, J Bryan; Lundy, Lian

2016-12-01

The UK 2007 floods resulted in damages estimated to exceed over £4 billion. This triggered a national review of strategic flood risk management (Pitt, 2008) with its recommendations informing and implemented by the Flood and Water Management, Act (FWMA, 2010). Estimating that up to two-thirds of properties flooded in the 2007 event as a direct result of overloaded sewer systems, the FWMA set out an ambitious overhaul of flood risk management approaches including identifying bodies responsible for the management of local flood risk (local municipalities) and the development of over-arching Lead Local Flood Authorities (LLFAs) at a regional level. LLFAs duties include developing local flood risk management strategies and, aligned with this, many LLFAs and local municipalities produced sustainable drainage system (SUDS) guidance notes. In parallel, changes to the national planning policy framework (NPPF) in England give priority to the use of SUDS in new major developments, as does the related Town and Country Planning Order (2015). However, whilst all three pieces of legislation refer to the preferential use of SUDs, these requirements remain "economically proportionate" and thus the inclusion of SUDS within development controls remain desirable - but not mandatory - obligations. Within this dynamic policy context, reignited most recently by the December 2015 floods, this paper examines some of the challenges to the implementation of SUDS in England and Wales posed by the new regulatory frameworks. In particular, it examines how emerging organisational procedures and processes are likely to impact on future SUDS implementation, and highlights the need for further cross-sectoral working to ensure opportunities for cross-sectoral benefits- such as that accrued by reducing stormwater flows within combined sewer systems for water companies, property developers and environmental protection - are not lost. Copyright © 2016 Elsevier Ltd. All rights reserved.

Valuing environmental services provided by local stormwater management

NASA Astrophysics Data System (ADS)

Brent, Daniel A.; Gangadharan, Lata; Lassiter, Allison; Leroux, Anke; Raschky, Paul A.

2017-06-01

The management of stormwater runoff via distributed green infrastructures delivers a number of environmental services that go beyond the reduction of flood risk, which has been the focus of conventional stormwater systems. Not all of these services may be equally valued by the public, however. This paper estimates households' willingness to pay (WTP) for improvements in water security, stream health, recreational and amenity values, as well as reduction in flood risk and urban heat island effect. We use data from nearly 1000 personal interviews with residential homeowners in Melbourne and Sydney, Australia. Our results suggest that the WTP for the highest levels of all environmental services is A799 per household per year. WTP is mainly driven by residents valuing improvements in local stream health, exemptions in water restrictions, the prevention of flash flooding, and decreased peak urban temperatures respectively at A297, A244, A104 and A$65 per year. We further conduct a benefit transfer analysis and find that the WTP and compensating surplus are not significantly different between the study areas. Our findings provide additional support that stormwater management via green infrastructures have large nonmarket benefits and that, under certain conditions, benefit values can be transferred to different locations.

Estimation of flood-frequency characteristics of small urban streams in North Carolina

USGS Publications Warehouse

Robbins, J.C.; Pope, B.F.

1996-01-01

A statewide study was conducted to develop methods for estimating the magnitude and frequency of floods of small urban streams in North Carolina. This type of information is critical in the design of bridges, culverts and water-control structures, establishment of flood-insurance rates and flood-plain regulation, and for other uses by urban planners and engineers. Concurrent records of rainfall and runoff data collected in small urban basins were used to calibrate rainfall-runoff models. Historic rain- fall records were used with the calibrated models to synthesize a long- term record of annual peak discharges. The synthesized record of annual peak discharges were used in a statistical analysis to determine flood- frequency distributions. These frequency distributions were used with distributions from previous investigations to develop a database for 32 small urban basins in the Blue Ridge-Piedmont, Sand Hills, and Coastal Plain hydrologic areas. The study basins ranged in size from 0.04 to 41.0 square miles. Data describing the size and shape of the basin, level of urban development, and climate and rural flood charac- teristics also were included in the database. Estimation equations were developed by relating flood-frequency char- acteristics to basin characteristics in a generalized least-squares regression analysis. The most significant basin characteristics are drainage area, impervious area, and rural flood discharge. The model error and prediction errors for the estimating equations were less than those for the national flood-frequency equations previously reported. Resulting equations, which have prediction errors generally less than 40 percent, can be used to estimate flood-peak discharges for 2-, 5-, 10-, 25-, 50-, and 100-year recurrence intervals for small urban basins across the State assuming negligible, sustainable, in- channel detention or basin storage.

Geo-hydrological risk management for civil protection purposes in the urban area of Genoa (Liguria, NW Italy)

NASA Astrophysics Data System (ADS)

Brandolini, P.; Cevasco, A.; Firpo, M.; Robbiano, A.; Sacchini, A.

2012-04-01

Over the past century the municipal area of Genoa has been affected by recurring flood events and several landslides that have caused severe damage to urbanized areas on both the coastal-fluvial plains and surrounding slopes, sometimes involving human casualties. The analysis of past events' annual distribution indicates that these phenomena have occurred with rising frequency in the last seventy years, following the main land use change due to the development of harbour, industrial, and residential areas, which has strongly impacted geomorphological processes. Consequently, in Genoa, civil protection activities are taking on an increasing importance for geo-hydrological risk mitigation. The current legislative framework assigns a key role in disaster prevention to municipalities, emergency plan development, as well as response action coordination in disaster situations. In view of the geomorphological and environmental complexity of the study area and referring to environmental laws, geo-hydrological risk mitigation strategies adopted by local administrators for civil protection purposes are presented as examples of current land/urban management related to geo-hydrological hazards. Adopted measures have proven to be effective on several levels (planning, management, structure, understanding, and publication) in different cases. Nevertheless, the last flooding event (4 November 2011) has shown that communication and public information concerning the perception of geo-hydrological hazard can be improved.

Integrating Hydrologic and Water Quality Models as a Decision Support Tool for Implementation of Low Impact Development in a Coastal Urban Watershed under Climate Variability and Sea Level Rise

NASA Astrophysics Data System (ADS)

Chang, N. B.

2016-12-01

Many countries concern about development and redevelopment efforts in urban regions to reduce the flood risk by considering hazards such as high-tide events, storm surge, flash floods, stormwater runoff, and impacts of sea level rise. Combining these present and future hazards with vulnerable characteristics found throughout coastal communities such as majority low-lying areas and increasing urban development, create scenarios for increasing exposure of flood hazard. As such, the most vulnerable areas require adaptation strategies and mitigation actions for flood hazard management. In addition, in the U.S., Numeric Nutrient Criteria (NNC) are a critical tool for protecting and restoring the designated uses of a waterbody with regard to nitrogen and phosphorus pollution. Strategies such as low impact development (LID) have been promoted in recent years as an alternative to traditional stormwater management and drainage to control both flooding and water quality impact. LID utilizes decentralized multifunctional site designs and incorporates on-site storm water management practices rather than conventional storm water management approaches that divert flow toward centralized facilities. How to integrate hydrologic and water quality models to achieve the decision support becomes a challenge. The Cross Bayou Watershed of Pinellas County in Tampa Bay, a highly urbanized coastal watershed, is utilized as a case study due to its sensitivity to flood hazards and water quality management within the watershed. This study will aid the County, as a decision maker, to implement its stormwater management policy and honor recent NNC state policy via demonstration of an integrated hydrologic and water quality model, including the Interconnected Channel and Pond Routing Model v.4 (ICPR4) and the BMPTRAIN model as a decision support tool. The ICPR4 can be further coupled with the ADCIRC/SWAN model to reflect the storm surge and seal level rise in coastal regions.

Evaluation of Green Infrastructure on Peak Flow Mitigation Focusing on the Connectivity of Impervious Areas

NASA Astrophysics Data System (ADS)

Seo, Y.; Hwang, J.; Kwon, Y.

2017-12-01

The existence of impervious areas is one of the most distinguishing characteristics of urban catchments. It decreases infiltration and increases direct runoff in urban catchments. The recent introduction of green infrastructure in urban catchments for the purpose of sustainable development contributes to the decrease of the directly connected impervious areas (DCIA) by isolating existing impervious areas and consequently, to the flood risk mitigation. This study coupled the width function-based instantaneous hydrograph (WFIUH), which is able to handle the spatial distribution of the impervious areas, with the concept of the DCIA to assess the impact of decreasing DCIA on the shape of direct runoff hydrographs. Using several scenarios for typical green infrastructure and corresponding changes of DCIA in a test catchment, this study evaluated the effect of green infrastructure on the shape of the resulting direct runoff hydrographs and peak flows. The results showed that the changes in the DCIA immediately affects the shape of the direct runoff hydrograph and decreases peak flows depending on spatial implementation scenarios. The quantitative assessment of the spatial distribution of impervious areas and also the changes to the DCIA suggests effective and well-planned green infrastructure can be introduced in urban environments for flood risk management.

Water Hazard in Coastal Area: Actions for conserving and protecting European World Heritage Cities

NASA Astrophysics Data System (ADS)

Biscarini, C.; Carnevali, C.; Andah, K.

2009-04-01

It is well known that many of the European UNESCO World Heritage sites and cities are closely related to water bodies in their different forms, as they have close links with the sea (such as Venice, San Rossore, Dubrovnik) and with rivers (like Florence, Rome, Ferrara, etc). Surely there are many others with problems of water supply, water treatment, wastewater disposal, etc. The main objective of the work is therefore to institute measures which will permit to contribute towards the conservation and protection of such precious heritage sites and cities, particularly in coastal area, in the context of present urbanization and climatic modifications. It has therefore become necessary to identify and classify not only urban centres of historical importance but also historical hydraulic structures and works developed for both beneficial and harmful water management, hereinafter referred to as good water and bad water respectively. Another objective is to raise the awareness of institutions and the public in general on the historical values of Heritage cities and hence the need to protect them. The main activities of the study are directed at the following: 1) Collection and collation of information and documentation on water sources, intakes and distribution structures, flood events especially around urban centres, structural characteristics of bridges, defensive hydraulic structures of rivers from ancient times to the present. 2) Creation of an integrative water-urban data base in the form of a virtual museum. 3) Design and preparation of feasibility strategies for relevant historical works for renovation purposes and also hydrological analysis of flood events and reconstruction of historical flood series towards re-qualification of urban and riverine environments in the face of climate change. 4) Hydraulic risk analysis of complex hydraulic systems, performing flooding scenarios at different flow rates.

An empirical assessment of which inland floods can be managed

USGS Publications Warehouse

Mogollón, Beatriz; Frimpong, Emmanuel A.; Hoegh, Andrew B.; Angermeier, Paul

2016-01-01

Riverine flooding is a significant global issue. Although it is well documented that the influence of landscape structure on floods decreases as flood size increases, studies that define a threshold flood-return period, above which landscape features such as topography, land cover and impoundments can curtail floods, are lacking. Further, the relative influences of natural versus built features on floods is poorly understood. Assumptions about the types of floods that can be managed have considerable implications for the cost-effectiveness of decisions to invest in transforming land cover (e.g., reforestation) and in constructing structures (e.g., storm-water ponds) to control floods. This study defines parameters of floods for which changes in landscape structure can have an impact. We compare nine flood-return periods across 31 watersheds with widely varying topography and land cover in the southeastern United States, using long-term hydrologic records (≥20 years). We also assess the effects of built flow-regulating features (best management practices and artificial water bodies) on selected flood metrics across urban watersheds. We show that landscape features affect magnitude and duration of only those floods with return periods ≤10 years, which suggests that larger floods cannot be managed effectively by manipulating landscape structure. Overall, urban watersheds exhibited larger (270 m3/s) but quicker (0.41 days) floods than non-urban watersheds (50 m3/s and 1.5 days). However, urban watersheds with more flow-regulating features had lower flood magnitudes (154 m3/s), but similar flood durations (0.55 days), compared to urban watersheds with fewer flow-regulating features (360 m3/s and 0.23 days). Our analysis provides insight into the magnitude, duration and count of floods that can be curtailed by landscape structure and its management. Our findings are relevant to other areas with similar climate, topography, and land use, and can help ensure that investments in flood management are made wisely after considering the limitations of landscape features to regulate floods.

Coupling impervious surface rate derived from satellite remote sensing with distributed hydrological model for highly urbanized watershed flood forecasting

NASA Astrophysics Data System (ADS)

Dong, L.

2017-12-01

Abstract: The original urban surface structure changed a lot because of the rapid development of urbanization. Impermeable area has increased a lot. It causes great pressure for city flood control and drainage. Songmushan reservoir basin with high degree of urbanization is taken for an example. Pixel from Landsat is decomposed by Linear spectral mixture model and the proportion of urban area in it is considered as impervious rate. Based on impervious rate data before and after urbanization, an physically based distributed hydrological model, Liuxihe Model, is used to simulate the process of hydrology. The research shows that the performance of the flood forecasting of high urbanization area carried out with Liuxihe Model is perfect and can meet the requirement of the accuracy of city flood control and drainage. The increase of impervious area causes conflux speed more quickly and peak flow to be increased. It also makes the time of peak flow advance and the runoff coefficient increase. Key words: Liuxihe Model; Impervious rate; City flood control and drainage; Urbanization; Songmushan reservoir basin

Climate and change: simulating flooding impacts on urban transport network

NASA Astrophysics Data System (ADS)

Pregnolato, Maria; Ford, Alistair; Dawson, Richard

2015-04-01

National-scale climate projections indicate that in the future there will be hotter and drier summers, warmer and wetter winters, together with rising sea levels. The frequency of extreme weather events is expected to increase, causing severe damage to the built environment and disruption of infrastructures (Dawson, 2007), whilst population growth and changed demographics are placing new demands on urban infrastructure. It is therefore essential to ensure infrastructure networks are robust to these changes. This research addresses these challenges by focussing on the development of probabilistic tools for managing risk by modelling urban transport networks within the context of extreme weather events. This paper presents a methodology to investigate the impacts of extreme weather events on urban environment, in particular infrastructure networks, through a combination of climate simulations and spatial representations. By overlaying spatial data on hazard thresholds from a flood model and a flood safety function, mitigated by potential adaptation strategies, different levels of disruption to commuting journeys on road networks are evaluated. The method follows the Catastrophe Modelling approach and it consists of a spatial model, combining deterministic loss models and probabilistic risk assessment techniques. It can be applied to present conditions as well as future uncertain scenarios, allowing the examination of the impacts alongside socio-economic and climate changes. The hazard is determined by simulating free surface water flooding, with the software CityCAT (Glenis et al., 2013). The outputs are overlapped to the spatial locations of a simple network model in GIS, which uses journey-to-work (JTW) observations, supplemented with speed and capacity information. To calculate the disruptive effect of flooding on transport networks, a function relating water depth to safe driving car speed has been developed by combining data from experimental reports (Morris et al., 2011) safety literature (Great Britain Department for Transport, 1999), analysis of videos of cars driving through floodwater, and expert judgement. A preliminary analysis has been run in the Tyne & Wear (in North-East England) region to demonstrate how the analysis can be used to assess the disruptions for commuter journeys due to flooding and will be demonstrated in this paper. The research will also investigate the effectiveness of adaptation strategies for extreme rainfall events, such as permeable surfaces and roof storages for buildings. Multiple scenarios (from the every-day-rainfall to the extreme weather phenomena) will be modelled, with different rainfall rates, rainfall durations and return periods. The comparison between the scenarios in which no interventions are adopted and those improved by one of the adaptation option will be compared to determine the cost-effectiveness of the solution considered. Integrating spatial analysis of transport use with an urban flood model and flood safety function enables the investigation of the impacts of extreme weather on infrastructure networks. Further work will develop the analysis in a number of ways (i) testing a range of flood events with different severity and frequency, (ii) exploration of the influence of climate and socio-economic change (iii) analysis of multiple hazard events and (iv) consideration of cascading disruption across different infrastructure networks.

24 CFR 3285.406 - Flood hazard areas.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Flood hazard areas. 3285.406... URBAN DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Anchorage Against Wind § 3285.406 Flood hazard areas. Refer to § 3285.302 for anchoring requirements in flood hazard areas. ...

Mapping Flood Protection Benefits from Restored Wetlands at the Urban-Suburban Interface

EPA Science Inventory

Urbanization exacerbates flooding by increasing runoff and decreasing surface water storage. Restoring wetlands can enhance flood protection while providing a suite of co-benefits such as temperature regulation and access to open space. Spatial modeling of the delivery of flood p...

Race, Income Inequality, and Impervious Surfaces in Relation to Flooding Associated with Hurricane Harvey

NASA Astrophysics Data System (ADS)

de Sherbinin, A. M.; Mills, J.; Borkovska, O.

2017-12-01

Differential vulnerability is a concept that suggests that certain demographic groups - the poor, less educated, or minorities - are likely to be more impacted by climate extremes such as floods owing to their higher sensitivity and lower adaptive capacity. Differential exposure represents the concept that these same groups may be more highly exposed to flood events by virtue of their residing in less desirable, low-lying neighborhoods with higher percentages of impervious surface cover. This paper tests the hypothesis that poor communities of color were differentially exposed to flood risks in the aftermath of Hurricane Harvey, which struck Houston, Texas in August 2017. We explore the spatial relationship among census tracts with high percentages of low income communities of color, those with high percentages of impervious surface, and those most impacted by floods. We incorporat datasets disseminated by the NASA Socioeconomic Data and Application Center (SEDAC) - the Global Man-made Impervious Surface (GMIS) data set and the U.S. Census Grids 2010 - together with the American Community Survey (ACS) 2011-2015 and flood extent and depth data from FEMA. Preliminary analysis suggests that predominantly non-white neighborhoods have higher percentages of impervious surface cover, but that impervious surface cover is negatively correlated with flood risk. This paper will situate these findings in the context of a larger body of research exploring differential exposure to flood risks during Hurricanes Katrina and Sandy, as well as differential exposure to extreme heat in urban environments in Houston and beyond.

Urban land for a growing city at the banks of a moving river: Vienna's spread into the Danube island Unterer Werd from the late 17th to the beginning of the 20th century.

PubMed

Haidvogl, Gertrud; Guthyne-Horvath, Marianna; Gierlinger, Sylvia; Hohensinner, Severin; Sonnlechner, Christoph

In the relation between urban development and the Viennese Danube different periods can be identified from the late 17th to the early 20th century. These periods were strongly intertwined with both the history of the river and the history of the city. Urban expansion into the floodplains is demonstrated in this paper by investigating the island Unterer Werd, next to the city centre. In the late 17th century the fluvial dynamic still hampered urban development on the island. First measures to stabilise the river banks and to protect buildings from floods were taken soon thereafter, but the majority of practices aimed at mitigating the risks and impacts of the frequent floods: inundation was a part of the arrangement and the main target was to minimise the potential impacts. This practice also prevailed after the 1830s, when urban expansion began to move into the north and northwest of the island and the Danube floodplains were considered an important land resource for the growing city. In connection with new technologies and available means to channelise the river, the relationship between Vienna and the Danube changed fundamentally. Urban development in the riverine landscape gained new momentum. This process was initiated before the Great Danube Regulation from 1870 to 1875 was completed, the rate of growth accelerated after 1875. The last decades of the 19th century mark a turning point in the urban development of Vienna, with expanding urban areas becoming dependent upon a well functioning and maintained flood protection system.

On Flood Frequency in Urban Areas under Changing Conditions and Implications on Stormwater Infrastructure Planning and Design

NASA Astrophysics Data System (ADS)

Norouzi, A.; Habibi, H.; Nazari, B.; Noh, S.; Seo, D. J.; Zhang, Y.

2016-12-01

With urbanization and climate change, many areas in the US and abroad face increasing threats of flash flooding. Due to nonstationarities arising from changes in land cover and climate, however, it is not readily possible to project how such changes may modify flood frequency. In this work, we describe a simple spatial stochastic model for rainfall-to-areal runoff in urban areas, evaluate climatological mean and variance of mean areal runoff (MAR) over a range of catchment scale, translate them into runoff frequency, which is used as a proxy for flood frequency, and assess its sensitivity to precipitation, imperviousness and soil, and their changes as a function of catchment scale and magnitude of precipitation. The findings indicate that, due to large sensitivity of frequency of MAR to multiple hydrometeorological and physiographic factors, estimation of flood frequency for urban catchments is inherently more uncertain. The approach used in this work is useful in developing bounds for flood frequencies in urban areas under nonstationary conditions arising from urbanization and climate change.

Using Automatic Control Approach In Detention Storages For Storm Water Management In An Urban Watershed

NASA Astrophysics Data System (ADS)

Goyal, A.; Yadav, H.; Tyagi, H.; Gosain, A. K.; Khosa, R.

2017-12-01

Increased imperviousness due to rapid urbanization have changed the urban hydrological cycle. As watersheds are urbanized, infiltration and groundwater recharge have decreased, surface runoff hydrograph shows higher peak indicating large volumes of surface runoff in lesser time durations. The ultimate panacea is to reduce the peak of hydrograph or increase the retention time of surface flow. SWMM is widely used hydrologic and hydraulic software which helps to simulate the urban storm water management with the provision to apply different techniques to prevent flooding. A model was setup to simulate the surface runoff and channel flow in a small urban catchment. It provides the temporal and spatial information of flooding in a catchment. Incorporating the detention storages in the drainage network helps achieve reduced flooding. Detention storages provided with predefined algorithms were for controlling the pluvial flooding in urban watersheds. The algorithm based on control theory, automated the functioning of detention storages ensuring that the storages become active on occurrence of flood in the storm water drains and shuts down when flooding is over. Detention storages can be implemented either at source or at several downstream control points. The proposed piece of work helps to mitigate the wastage of rainfall water, achieve desirable groundwater and attain a controlled urban storm water management system.

Uncertainty in surface water flood risk modelling

NASA Astrophysics Data System (ADS)

Butler, J. B.; Martin, D. N.; Roberts, E.; Domuah, R.

2009-04-01

Two thirds of the flooding that occurred in the UK during summer 2007 was as a result of surface water (otherwise known as ‘pluvial') rather than river or coastal flooding. In response, the Environment Agency and Interim Pitt Reviews have highlighted the need for surface water risk mapping and warning tools to identify, and prepare for, flooding induced by heavy rainfall events. This need is compounded by the likely increase in rainfall intensities due to climate change. The Association of British Insurers has called for the Environment Agency to commission nationwide flood risk maps showing the relative risk of flooding from all sources. At the wider European scale, the recently-published EC Directive on the assessment and management of flood risks will require Member States to evaluate, map and model flood risk from a variety of sources. As such, there is now a clear and immediate requirement for the development of techniques for assessing and managing surface water flood risk across large areas. This paper describes an approach for integrating rainfall, drainage network and high-resolution topographic data using Flowroute™, a high-resolution flood mapping and modelling platform, to produce deterministic surface water flood risk maps. Information is provided from UK case studies to enable assessment and validation of modelled results using historical flood information and insurance claims data. Flowroute was co-developed with flood scientists at Cambridge University specifically to simulate river dynamics and floodplain inundation in complex, congested urban areas in a highly computationally efficient manner. It utilises high-resolution topographic information to route flows around individual buildings so as to enable the prediction of flood depths, extents, durations and velocities. As such, the model forms an ideal platform for the development of surface water flood risk modelling and mapping capabilities. The 2-dimensional component of Flowroute employs uniform flow formulae (Manning's Equation) to direct flow over the model domain, sourcing water from the channel or sea so as to provide a detailed representation of river and coastal flood risk. The initial development step was to include spatially-distributed rainfall as a new source term within the model domain. This required optimisation to improve computational efficiency, given the ubiquity of ‘wet' cells early on in the simulation. Collaboration with UK water companies has provided detailed drainage information, and from this a simplified representation of the drainage system has been included in the model via the inclusion of sinks and sources of water from the drainage network. This approach has clear advantages relative to a fully coupled method both in terms of reduced input data requirements and computational overhead. Further, given the difficulties associated with obtaining drainage information over large areas, tests were conducted to evaluate uncertainties associated with excluding drainage information and the impact that this has upon flood model predictions. This information can be used, for example, to inform insurance underwriting strategies and loss estimation as well as for emergency response and planning purposes. The Flowroute surface-water flood risk platform enables efficient mapping of areas sensitive to flooding from high-intensity rainfall events due to topography and drainage infrastructure. As such, the technology has widespread potential for use as a risk mapping tool by the UK Environment Agency, European Member States, water authorities, local governments and the insurance industry. Keywords: Surface water flooding, Model Uncertainty, Insurance Underwriting, Flood inundation modelling, Risk mapping.

Street Level Hydrology: An Urban Application of the WRF-Hydro Framework in Denver, Colorado

NASA Astrophysics Data System (ADS)

Read, L.; Hogue, T. S.; Salas, F. R.; Gochis, D.

2015-12-01

Urban flood modeling at the watershed scale carries unique challenges in routing complexity, data resolution, social and political issues, and land surface - infrastructure interactions. The ability to accurately trace and predict the flow of water through the urban landscape enables better emergency response management, floodplain mapping, and data for future urban infrastructure planning and development. These services are of growing importance as urban population is expected to continue increasing by 1.84% per year for the next 25 years, increasing the vulnerability of urban regions to damages and loss of life from floods. Although a range of watershed-scale models have been applied in specific urban areas to examine these issues, there is a trend towards national scale hydrologic modeling enabled by supercomputing resources to understand larger system-wide hydrologic impacts and feedbacks. As such it is important to address how urban landscapes can be represented in large scale modeling processes. The current project investigates how coupling terrain and infrastructure routing can improve flow prediction and flooding events over the urban landscape. We utilize the WRF-Hydro modeling framework and a high-resolution terrain routing grid with the goal of compiling standard data needs necessary for fine scale urban modeling and dynamic flood forecasting in the urban setting. The city of Denver is selected as a case study, as it has experienced several large flooding events in the last five years and has an urban annual population growth rate of 1.5%, one of the highest in the U.S. Our work highlights the hydro-informatic challenges associated with linking channel networks and drainage infrastructure in an urban area using the WRF-Hydro modeling framework and high resolution urban models for short-term flood prediction.

Urban flood mitigation planning for Guwahati: A case of Bharalu basin.

PubMed

Sarmah, Tanaya; Das, Sutapa

2018-01-15

Guwahati, the capital city of Assam and the gateway to the seven north-eastern Indian states, is located in the Brahmaputra valley-one of the most flood prone regions of the world. The city receives an average annual rainfall of 1688 mm and is highly vulnerable towards frequent urban floods because of uncontrolled dumping of solid waste and siltation have choked the natural water channels. This coupled with the absence of an integrated drainage network and rapid urbanisation causes floods in many parts of the city, after a quick downpour. Bharalu river is the main natural water channel of the city and Bharalu basin is the most vulnerable one. The present paper is an attempt to plan for urban flood mitigation, by designing an integrated drainage network for the Bharalu basin which includes the low-lying urbanized areas bordered by the Guwahati-Shillong Road, the Radha Gobindo Baruah Road and the Rajgarh Road. Data regarding land use, flood level, rainfall, urban pattern and vulnerability towards urban flood were collected from available literature, field survey to find highest water level for 11.4 km road stretch, expert opinion survey from 18 experts and feedback from 77 community elders who have been residing in the city since the 1980s. The Bharalu basin is divided into seven drainage blocks and storm run-off has been calculated based on the inputs. Seven different trapezoidal drainage sections were designed to form an integrated drainage network which is 'self-healing' to a certain extent. This can serve as a template for the other catchment basins and to design a drainage network for the entire Guwahati city, thereby reducing urban flood hazard to a significant extent. The study illustrates the necessity of an urban flood mitigation planning approach in sub-Himalayan urban settlements such as Guwahati. Copyright © 2017 Elsevier Ltd. All rights reserved.

Upstream structural management measures for an urban area flooding in Turkey

NASA Astrophysics Data System (ADS)

Akyurek, Z.; Bozoğlu, B.; Sürer, S.; Mumcu, H.

2015-06-01

In recent years, flooding has become an increasing concern across many parts of the world of both the general public and their governments. The climate change inducing more intense rainfall events occurring in short period of time lead flooding in rural and urban areas. In this study the flood modelling in an urbanized area, namely Samsun-Terme in Blacksea region of Turkey is performed. MIKE21 with flexible grid is used in 2-dimensional shallow water flow modelling. 1 × 1000-1 scaled maps with the buildings for the urbanized area and 1 × 5000-1 scaled maps for the rural parts are used to obtain DTM needed in the flood modelling. The bathymetry of the river is obtained from additional surveys. The main river passing through the urbanized area has a capacity of 500 m3 s-1 according to the design discharge obtained by simple ungauged discharge estimation depending on catchment area only. The upstream structural base precautions against flooding are modelled. The effect of four main upstream catchments on the flooding in the downstream urban area are modelled as different scenarios. It is observed that if the flow from the upstream catchments can be retarded through a detention pond constructed in one of the upstream catchments, estimated Q100 flood can be conveyed by the river without overtopping from the river channel. The operation of the upstream detention ponds and the scenarios to convey Q500 without causing flooding are also presented. Structural management measures to address changes in flood characteristics in water management planning are discussed.

High resolution modeling of a small urban catchment

NASA Astrophysics Data System (ADS)

Skouri-Plakali, Ilektra; Ichiba, Abdellah; Gires, Auguste; Tchiguirinskaia, Ioulia; Schertzer, Daniel

2016-04-01

Flooding is one of the most complex issues that urban environments have to deal with. In France, flooding remains the first natural risk with 72% of decrees state of natural disaster issued between October 1982 and mid-November 2014. Flooding is a result of meteorological extremes that are usually aggravated by the hydrological behavior of urban catchments and human factors. The continuing urbanization process is indeed changing the whole urban water cycle by limiting the infiltration and promoting runoff. Urban environments are very complex systems due to their extreme variability, the interference between human activities and natural processes but also the effect of the ongoing urbanization process that changes the landscape and hardly influences their hydrologic behavior. Moreover, many recent works highlight the need to simulate all urban water processes at their specific temporal and spatial scales. However, considering urban catchments heterogeneity still challenging for urban hydrology, even after advances noticed in term of high-resolution data collection and computational resources. This issue is more to be related to the architecture of urban models being used and how far these models are ready to take into account the extreme variability of urban catchments. In this work, high spatio-temporal resolution modeling is performed for a small and well-equipped urban catchment. The aim of this work is to identify urban modeling needs in terms of spatial and temporal resolution especially for a very small urban area (3.7 ha urban catchment located in the Perreux-sur-Marne city at the southeast of Paris) MultiHydro model was selected to carry out this work, it is a physical based and fully distributed model that interacts four existing modules each of them representing a portion of the water cycle in urban environments. MultiHydro was implemented at 10m, 5m and 2m resolution. Simulations were performed at different spatio-temporal resolutions and analyzed with respect to real flow measurements. First Results coming out show improvements obtained in terms of the model performance at high spatio-temporal resolution.

Human Leptospirosis Infection in Fiji: An Eco-epidemiological Approach to Identifying Risk Factors and Environmental Drivers for Transmission.

PubMed

Lau, Colleen L; Watson, Conall H; Lowry, John H; David, Michael C; Craig, Scott B; Wynwood, Sarah J; Kama, Mike; Nilles, Eric J

2016-01-01

Leptospirosis is an important zoonotic disease in the Pacific Islands. In Fiji, two successive cyclones and severe flooding in 2012 resulted in outbreaks with 576 reported cases and 7% case-fatality. We conducted a cross-sectional seroprevalence study and used an eco-epidemiological approach to characterize risk factors and drivers for human leptospirosis infection in Fiji, and aimed to provide an evidence base for improving the effectiveness of public health mitigation and intervention strategies. Antibodies indicative of previous or recent infection were found in 19.4% of 2152 participants (81 communities on the 3 main islands). Questionnaires and geographic information systems data were used to assess variables related to demographics, individual behaviour, contact with animals, socioeconomics, living conditions, land use, and the natural environment. On multivariable logistic regression analysis, variables associated with the presence of Leptospira antibodies included male gender (OR 1.55), iTaukei ethnicity (OR 3.51), living in villages (OR 1.64), lack of treated water at home (OR 1.52), working outdoors (1.64), living in rural areas (OR 1.43), high poverty rate (OR 1.74), living <100m from a major river (OR 1.41), pigs in the community (OR 1.54), high cattle density in the district (OR 1.04 per head/sqkm), and high maximum rainfall in the wettest month (OR 1.003 per mm). Risk factors and drivers for human leptospirosis infection in Fiji are complex and multifactorial, with environmental factors playing crucial roles. With global climate change, severe weather events and flooding are expected to intensify in the South Pacific. Population growth could also lead to more intensive livestock farming; and urbanization in developing countries is often associated with urban and peri-urban slums where diseases of poverty proliferate. Climate change, flooding, population growth, urbanization, poverty and agricultural intensification are important drivers of zoonotic disease transmission; these factors may independently, or potentially synergistically, lead to enhanced leptospirosis transmission in Fiji and other similar settings.

Ensemble urban flood simulation in comparison with laboratory-scale experiments: Impact of interaction models for manhole, sewer pipe, and surface flow

NASA Astrophysics Data System (ADS)

Noh, Seong Jin; Lee, Seungsoo; An, Hyunuk; Kawaike, Kenji; Nakagawa, Hajime

2016-11-01

An urban flood is an integrated phenomenon that is affected by various uncertainty sources such as input forcing, model parameters, complex geometry, and exchanges of flow among different domains in surfaces and subsurfaces. Despite considerable advances in urban flood modeling techniques, limited knowledge is currently available with regard to the impact of dynamic interaction among different flow domains on urban floods. In this paper, an ensemble method for urban flood modeling is presented to consider the parameter uncertainty of interaction models among a manhole, a sewer pipe, and surface flow. Laboratory-scale experiments on urban flood and inundation are performed under various flow conditions to investigate the parameter uncertainty of interaction models. The results show that ensemble simulation using interaction models based on weir and orifice formulas reproduces experimental data with high accuracy and detects the identifiability of model parameters. Among interaction-related parameters, the parameters of the sewer-manhole interaction show lower uncertainty than those of the sewer-surface interaction. Experimental data obtained under unsteady-state conditions are more informative than those obtained under steady-state conditions to assess the parameter uncertainty of interaction models. Although the optimal parameters vary according to the flow conditions, the difference is marginal. Simulation results also confirm the capability of the interaction models and the potential of the ensemble-based approaches to facilitate urban flood simulation.

24 CFR 234.17 - Mortgagor and mortgagee requirements for maintaining flood insurance coverage.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Mortgagor and mortgagee requirements for maintaining flood insurance coverage. 234.17 Section 234.17 Housing and Urban Development... maintaining flood insurance coverage. The maintenance of flood insurance coverage on the project by the...

Development of flood probability charts for urban drainage network in coastal areas through a simplified joint assessment approach

NASA Astrophysics Data System (ADS)

Archetti, R.; Bolognesi, A.; Casadio, A.; Maglionico, M.

2011-04-01

The operating conditions of urban drainage networks during storm events certainly depend on the hydraulic conveying capacity of conduits but also on downstream boundary conditions. This is particularly true in costal areas where the level of the receiving water body is directly or indirectly affected by tidal or wave effects. In such cases, not just different rainfall conditions (varying intensity and duration), but also different sea-levels and their effects on the network operation should be considered. This paper aims to study the behaviour of a seaside town storm sewer network, estimating the threshold condition for flooding and proposing a simplified method to assess the urban flooding severity as a function of either climate variables. The case study is a portion of the drainage system of Rimini (Italy), implemented and numerically modelled by means of InfoWorks CS code. The hydraulic simulation of the sewerage system has therefore allowed to identify the percentage of nodes of the drainage system where flooding is expected to occur. Combining these percentages with both climate variables values has lead to the definition charts representing the combined degree of risk "sea-rainfall" for the drainage system under investigation. A final comparison between such charts and the results obtained from a one-year sea-rainfall time series has confirmed the reliability of the analysis.

Development of flood probability charts for urban drainage network in coastal areas through a simplified joint assessment approach

NASA Astrophysics Data System (ADS)

Archetti, R.; Bolognesi, A.; Casadio, A.; Maglionico, M.

2011-10-01

The operating conditions of urban drainage networks during storm events depend on the hydraulic conveying capacity of conduits and also on downstream boundary conditions. This is particularly true in coastal areas where the level of the receiving water body is directly or indirectly affected by tidal or wave effects. In such cases, not just different rainfall conditions (varying intensity and duration), but also different sea-levels and their effects on the network operation should be considered. This paper aims to study the behaviour of a seaside town storm sewer network, estimating the threshold condition for flooding and proposing a simplified method to assess the urban flooding severity as a function of climate variables. The case study is a portion of the drainage system of Rimini (Italy), implemented and numerically modelled by means of InfoWorks CS code. The hydraulic simulation of the sewerage system identified the percentage of nodes of the drainage system where flooding is expected to occur. Combining these percentages with both climate variables' values has lead to the definition of charts representing the combined degree of risk "rainfall-sea level" for the drainage system under investigation. A final comparison between such charts and the results obtained from a one-year rainfall-sea level time series has demonstrated the reliability of the analysis.

Filling the gap between disaster preparedness and response networks of urban emergency management: Following the 2013 Seoul Floods.

PubMed

Song, Minsun; Jung, Kyujin

2015-01-01

To examine the gap between disaster preparedness and response networks following the 2013 Seoul Floods in which the rapid transmission of disaster information and resources was impeded by severe changes of interorganizational collaboration networks. This research uses the 2013 Seoul Emergency Management Survey data that were collected before and after the floods, and total 94 organizations involving in coping with the floods were analyzed in bootstrap independent-sample t-test and social network analysis through UCINET 6 and STATA 12. The findings show that despite the primary network form that is more hierarchical, horizontal collaboration has been relatively invigorated in actual response. Also, interorganizational collaboration networks for response operations seem to be more flexible grounded on improvisation to coping with unexpected victims and damages. Local organizations under urban emergency management are recommended to tightly build a strong commitment for joint response operations through full-size exercises at the metropolitan level before a catastrophic event. Also, interorganizational emergency management networks need to be restructured by reflecting the actual response networks to reduce collaboration risk during a disaster. This research presents a critical insight into inverse thinking of the view designing urban emergency management networks and provides original evidences for filling the gap between previously coordinated networks for disaster preparedness and practical response operations after a disaster.

A Methodology to Define Flood Resilience

NASA Astrophysics Data System (ADS)

Tourbier, J.

2012-04-01

Flood resilience has become an internationally used term with an ever-increasing number of entries on the Internet. The SMARTeST Project is looking at approaches to flood resilience through case studies at cities in various countries, including Washington D.C. in the United States. In light of U.S. experiences a methodology is being proposed by the author that is intended to meet ecologic, spatial, structural, social, disaster relief and flood risk aspects. It concludes that: "Flood resilience combines (1) spatial, (2) structural, (3) social, and (4) risk management levels of flood preparedness." Flood resilience should incorporate all four levels, but not necessarily with equal emphasis. Stakeholders can assign priorities within different flood resilience levels and the considerations they contain, dividing 100% emphasis into four levels. This evaluation would be applied to planned and completed projects, considering existing conditions, goals and concepts. We have long known that the "road to market" for the implementation of flood resilience is linked to capacity building of stakeholders. It is a multidisciplinary enterprise, involving the integration of all the above aspects into the decision-making process. Traditional flood management has largely been influenced by what in the UK has been called "Silo Thinking", involving constituent organizations that are responsible for different elements, and are interested only in their defined part of the system. This barrier to innovation also has been called the "entrapment effect". Flood resilience is being defined as (1) SPATIAL FLOOD RESILIENCE implying the management of land by floodplain zoning, urban greening and management to reduce storm runoff through depression storage and by practicing Sustainable Urban Drainage (SUD's), Best Management Practices (BMP's, or Low Impact Development (LID). Ecologic processes and cultural elements are included. (2) STRUCTURAL FLOOD RESILIENCE referring to permanent flood defense structures such as levies, demountable structures that are partially installed, temporary structures that are removable, as well as dry- and` wet floodproofing of structures to meet construction standards to deflect or resist pressure without breaking. (3)SOCIAL FLOOD RESILIENCE referring to the building of robust institutions (including NGO's) and governance systems that underpin our capacity to prepare for and cope with uncertainty, change, and disasters when they occur. (4) FLOOD RISK RESILIENCE implies the ability to withstand and recover from crises through financial insurance assistance and through assistance by governmental institutions, including the communication of information on floodproofing steps that individuals can take on their own. Within these four levels considerations are outlined to form categories within a matrix as a way to set planning priorities by considering existing conditions, to formulate goals and to develop concepts. The matrix can function as indicators of success for a pre-and post-project assessment. A clear formulation of goals is an essential first step in the planning process, and a pre-requisite for the monitoring of performance. Policy makers would be involved in an active policy process, which has been called "a learning and action alliance to build capacity for flood resilience.

Pregnant Women's and Community Health Workers' Perceptions of Root Causes of Malnutrition Among Infants and Young Children in the Slums of Dhaka, Bangladesh

PubMed Central

Faiz, Sabina; Bogin, Barry A.; Griffiths, Paula L.

2011-01-01

Research in Bangladesh shows that malnutrition among infants and young children is most severe in urban slums. We examined the root causes of malnutrition as perceived by pregnant women and community health workers. We conducted 10 focus group discussions in the slums of Dhaka in 2008 and 2009. Participants accurately perceived inappropriate care, inappropriate environment, inappropriate food, and flooding to be major causes. Recurrent flooding has not traditionally been identified by experts as a cause of malnutrition. We recommend further research to address the nutritional risks flooding creates for vulnerable slum populations. PMID:21653248

Evaluating scale and roughness effects in urban flood modelling using terrestrial LIDAR data

NASA Astrophysics Data System (ADS)

Ozdemir, H.; Sampson, C. C.; de Almeida, G. A. M.; Bates, P. D.

2013-10-01

This paper evaluates the results of benchmark testing a new inertial formulation of the St. Venant equations, implemented within the LISFLOOD-FP hydraulic model, using different high resolution terrestrial LiDAR data (10 cm, 50 cm and 1 m) and roughness conditions (distributed and composite) in an urban area. To examine these effects, the model is applied to a hypothetical flooding scenario in Alcester, UK, which experienced surface water flooding during summer 2007. The sensitivities of simulated water depth, extent, arrival time and velocity to grid resolutions and different roughness conditions are analysed. The results indicate that increasing the terrain resolution from 1 m to 10 cm significantly affects modelled water depth, extent, arrival time and velocity. This is because hydraulically relevant small scale topography that is accurately captured by the terrestrial LIDAR system, such as road cambers and street kerbs, is better represented on the higher resolution DEM. It is shown that altering surface friction values within a wide range has only a limited effect and is not sufficient to recover the results of the 10 cm simulation at 1 m resolution. Alternating between a uniform composite surface friction value (n = 0.013) or a variable distributed value based on land use has a greater effect on flow velocities and arrival times than on water depths and inundation extent. We conclude that the use of extra detail inherent in terrestrial laser scanning data compared to airborne sensors will be advantageous for urban flood modelling related to surface water, risk analysis and planning for Sustainable Urban Drainage Systems (SUDS) to attenuate flow.

Evaluating scale and roughness effects in urban flood modelling using terrestrial LIDAR data

NASA Astrophysics Data System (ADS)

Ozdemir, H.; Sampson, C. C.; de Almeida, G. A. M.; Bates, P. D.

2013-05-01

This paper evaluates the results of benchmark testing a new inertial formulation of the de St. Venant equations, implemented within the LISFLOOD-FP hydraulic model, using different high resolution terrestrial LiDAR data (10 cm, 50 cm and 1 m) and roughness conditions (distributed and composite) in an urban area. To examine these effects, the model is applied to a hypothetical flooding scenario in Alcester, UK, which experienced surface water flooding during summer 2007. The sensitivities of simulated water depth, extent, arrival time and velocity to grid resolutions and different roughness conditions are analysed. The results indicate that increasing the terrain resolution from 1 m to 10 cm significantly affects modelled water depth, extent, arrival time and velocity. This is because hydraulically relevant small scale topography that is accurately captured by the terrestrial LIDAR system, such as road cambers and street kerbs, is better represented on the higher resolution DEM. It is shown that altering surface friction values within a wide range has only a limited effect and is not sufficient to recover the results of the 10 cm simulation at 1 m resolution. Alternating between a uniform composite surface friction value (n = 0.013) or a variable distributed value based on land use has a greater effect on flow velocities and arrival times than on water depths and inundation extent. We conclude that the use of extra detail inherent in terrestrial laser scanning data compared to airborne sensors will be advantageous for urban flood modelling related to surface water, risk analysis and planning for Sustainable Urban Drainage Systems (SUDS) to attenuate flow.

A spatial Bayesian network model to assess the benefits of early warning for urban flood risk to people

NASA Astrophysics Data System (ADS)

Balbi, S.; Villa, F.; Mojtahed, V.; Hegetschweiler, K. T.; Giupponi, C.

2015-10-01

This article presents a novel methodology to assess flood risk to people by integrating people's vulnerability and ability to cushion hazards through coping and adapting. The proposed approach extends traditional risk assessments beyond material damages; complements quantitative and semi-quantitative data with subjective and local knowledge, improving the use of commonly available information; produces estimates of model uncertainty by providing probability distributions for all of its outputs. Flood risk to people is modeled using a spatially explicit Bayesian network model calibrated on expert opinion. Risk is assessed in terms of: (1) likelihood of non-fatal physical injury; (2) likelihood of post-traumatic stress disorder; (3) likelihood of death. The study area covers the lower part of the Sihl valley (Switzerland) including the city of Zurich. The model is used to estimate the benefits of improving an existing Early Warning System, taking into account the reliability, lead-time and scope (i.e. coverage of people reached by the warning). Model results indicate that the potential benefits of an improved early warning in terms of avoided human impacts are particularly relevant in case of a major flood event: about 75 % of fatalities, 25 % of injuries and 18 % of post-traumatic stress disorders could be avoided.

The effects of low impact development on urban flooding under different rainfall characteristics.

PubMed

Qin, Hua-peng; Li, Zhuo-xi; Fu, Guangtao

2013-11-15

Low impact development (LID) is generally regarded as a more sustainable solution for urban stormwater management than conventional urban drainage systems. However, its effects on urban flooding at a scale of urban drainage systems have not been fully understood particularly when different rainfall characteristics are considered. In this paper, using an urbanizing catchment in China as a case study, the effects of three LID techniques (swale, permeable pavement and green roof) on urban flooding are analyzed and compared with the conventional drainage system design. A range of storm events with different rainfall amounts, durations and locations of peak intensity are considered for holistic assessment of the LID techniques. The effects are measured by the total flood volume reduction during a storm event compared to the conventional drainage system design. The results obtained indicate that all three LID scenarios are more effective in flood reduction during heavier and shorter storm events. Their performance, however, varies significantly according to the location of peak intensity. That is, swales perform best during a storm event with an early peak, permeable pavements perform best with a middle peak, and green roofs perform best with a late peak, respectively. The trends of flood reduction can be explained using a newly proposed water balance method, i.e., by comparing the effective storage depth of the LID designs with the accumulative rainfall amounts at the beginning and end of flooding in the conventional drainage system. This paper provides an insight into the performance of LID designs under different rainfall characteristics, which is essential for effective urban flood management. Copyright © 2013 Elsevier Ltd. All rights reserved.

Geohydrological hazards and urban development in the Mediterranean area: an example from Genoa (Liguria, Italy)

NASA Astrophysics Data System (ADS)

Faccini, F.; Luino, F.; Sacchini, A.; Turconi, L.; De Graff, J. V.

2015-12-01

The metropolitan area and the city of Genoa has become a national and international case study for geohydrological risk, mainly due to the frequency of floods. In 2014, there were landslides again, as well as flash floods that have particularly caused casualties and economic damage. The weather features of the Gulf of Genoa and the geomorphological-environmental setting of the Ligurian coastal land are the predisposing factors that determine heavy rains and their resulting effects on the ground. This study analysed the characteristics of the main meteorological disasters that have hit Genoa since the start of the 20th century; changes in the rainfall regime are evaluated and the main stages of urbanization of the area are detailed, with the resulting changes to the drainage network, in order to identify the main causes of this high geohydrological risk. To this end, scientists have used climate data recorded at the station of Genoa University, in operation since 1833, and at Ponte Carrega station, located in the middle reach of the Bisagno stream, a well-known watercourse because of its frequent floods. Urban sprawl was evaluated through a multi-temporal mapping comparison, using maps available from the beginning of the 19th century up to the current regional technical maps. The average air temperature in Genoa shows a statistically significant increase, while the number of rainy days displays an equally clear decrease over time. The total annual rain value does not seem to indicate rather noticeable changes. The intensity of rain in Genoa expressed as rainfall rate, i.e.~the ratio of annual rainfall and number of rainy days, shows statistically significant growth. The geohydrological vulnerability in Genoa has increased over time due to urban development which has established modifications in land use, from agricultural to urban, especially in the valley floor. Waterways have been confined and reduced to artificial channels, often covered in their final stretch; in some cases they have even been totally removed. These actions should be at least partially reversed in order to reduce the presently high hydrological risk.

Flooding in the future--predicting climate change, risks and responses in urban areas.

PubMed

Ashley, R M; Balmforth, D J; Saul, A J; Blanskby, J D

2005-01-01

Engineering infrastructure is provided at high cost and is expected to have a useful operational life of decades. However, it is clear that the future is uncertain. Traditional approaches to designing and operating urban storm drainage assets have relied on past performance of natural systems and the ability to extrapolate this performance, together with that of the assets across the usable lifetime. Whether or not climate change is going to significantly alter future weather patterns in Europe, it is clear that it is now incumbent on designers and operators of storm drainage systems to prepare for greater uncertainty in the effectiveness of storm drainage systems. A recent U.K. Government study considered the potential effects of climate and socio-economic change in the U.K. in terms of four future scenarios and what the implications are for the performance of existing storm drainage facilities. In this paper the modelling that was undertaken to try to quantify the changes in risk, together with the effectiveness of responses in managing that risk, are described. It shows that flood risks may increase by a factor of almost 30 times and that traditional engineering measures alone are unlikely to be able to provide protection.

Application of the "Behind the Barriers" resilience conceptual model to a flooded rail transport system

NASA Astrophysics Data System (ADS)

Gonzva, Michael; Barroca, Bruno

2017-04-01

The vulnerability of guided transport systems facing natural hazards is a burning issue for the urban risks management. Experience feedbacks on guided transport systems show they are particularly vulnerable to natural risks, especially flood risks. Besides, the resilience concept is used as a systemic approach for making an accurate analysis of the effect of these natural risks on rail guided transport systems. In this context, several conceptual models of resilience are elaborated for presenting the various possible resilience strategies applied to urban technical systems. One of this resilience conceptual model is the so-called "Behind The Barriers" model based on the identification of four complementary types of resilience: (i) cognitive resilience, linked to knowledge of the risk and the potential failures; (ii) functional resilience, representing the capacity of a system to protect itself from damage while continuing to provide services; (iii) correlative resilience, that characterises the relationship between service demand and the capacity of the system to respond; (iv) organisational resilience, expressing the capacity to mobilise an area much wider than the one affected. In addition to the work already published during the 7th Resilience Engineering Symposium, the purpose of this paper is to offer an application of a resilience conceptual model, the "Behind the Barriers" model, relating to a specific urban technical system, the public guided transport system, and facing a particular risk, a flood hazard. To do that, the paper is focused on a past incident on a French Intercity railway line as a studied case. Indeed, on June 18th and 19th 2013, the rise of the level of the "Gave de Pau" river, located in the municipality of Coarraze, caused many disorders on the intercity line serving the cities of Tarbes, Pau and Lourdes . Among the disorders caused by the flooding, about 100 meters of railway embankments were collapsed. With a constraint to reopen the line before August 15th, reinforcements were studied in order to stabilize the railway embankment. During the works, substitute shuttle service was set up, providing services between cities. This French past incident is studied through the "Behind The Barriers" model: i. cognitive resilience: what was the level of knowledge of the stakeholders concerning the flood hazard?; ii. functional resilience: what could be done in order to maintain the railway service between the cities?; iii. correlative resilience: what was the operator's response about the service demand with respect to the capacity of the railway line to ensure service?; iv. organizational resilience: what was the mobilization of the impacted cities, the impacted French department, the National authorities… on a wider scale than the flooded area in order to restore the line? The paper gives the main qualitative conclusions of the application of the "Behind The Barriers" model to this railway flooding event. The relevance of these conclusions are also confronted with feedbacks from other experienced railway incidents due to flooding events: on October 2015, heavy rains in French Region of Provence-Alpes-Côte d'Azur that provoked damages of railway equipments in Cannes and Marseille cities; on June 2016, the rise of the Seine River in Paris strongly impacted intercity railway lines and subway lines.

Determination of Flood Reduction Alternatives for Climate Change Adaptation in Gyeongancheon basin

NASA Astrophysics Data System (ADS)

Han, D.; Joo, H. J.; Jung, J.; Kim, H. S.

2017-12-01

Recently, the frequency of extreme rainfall event has increased due to the climate change and the impermeable area in an urban watershed has also increased due to the rapid urbanization. Therefore, the flood risk is increasing and we ought to prepare countermeasures for flood damage reduction. For the determination of appropriate measures or alternatives, firstly, this study estimated the frequency based rainfall considering the climate change according to the each target period(reference : 1971˜2010, Target period Ⅰ : 2011˜2040, Target period Ⅱ : 2041˜2070, Target period Ⅲ : 2071˜2100). Then the future flood discharge was computed by using HEC-HMS model. We set 5 sizes of drainage pumps and detention ponds respectively as the flood reduction alternatives and the flood level in the river was obtained by each alternative through HEC-RAS model. The flood inundation map was constructed using topographical data and flood water level in the river and the economic analysis was conducted for the flood damage reduction studies using Multi Dimensional Flood Damage Analysis (MD-FDA) tool. As a result of the effectiveness analysis of the flood reduction alternatives, the flood level by drainage pump was reduced by 0.06m up to 0.44m while it was reduced by 0.01m up to 1.86m in the case of the detention pond. The flooded area was shrunk by up to 32.64% from 0.3% and inundation depth was also dropped. As a result of a comparison of the Benefit/Cost ratio estimated by the economic analysis, a detention pond E in the target period Ⅰ and the pump D in the periods Ⅱ and Ⅲ were considered as the appropriate alternatives for the flood damage reduction under the climate change. AcknowledgementsThis research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT & Future Planning(2017R1A2B3005695)

Techniques for estimating flood hydrographs for ungaged urban watersheds

USGS Publications Warehouse

Stricker, V.A.; Sauer, V.B.

1984-01-01

The Clark Method, modified slightly was used to develop a synthetic, dimensionless hydrograph which can be used to estimate flood hydrographs for ungaged urban watersheds. Application of the technique results in a typical (average) flood hydrograph for a given peak discharge. Input necessary to apply the technique is an estimate of basin lagtime and the recurrence interval peak discharge. Equations for this purpose were obtained from a recent nationwide study on flood frequency in urban watersheds. A regression equation was developed which relates flood volumes to drainage area size, basin lagtime, and peak discharge. This equation is useful where storage of floodwater may be a part of design of flood prevention. (USGS)

Rising floodwaters: mapping impacts and perceptions of flooding in Indonesian Borneo

NASA Astrophysics Data System (ADS)

Wells, Jessie A.; Wilson, Kerrie A.; Abram, Nicola K.; Nunn, Malcolm; Gaveau, David L. A.; Runting, Rebecca K.; Tarniati, Nina; Mengersen, Kerrie L.; Meijaard, Erik

2016-06-01

The roles of forest and wetland ecosystems in regulating flooding have drawn increasing attention in the contexts of climate change adaptation and disaster risk reduction. However, data on floods are scarce in many of the countries where people are most exposed and vulnerable to their impacts. Here, our separate analyses of village interview surveys (364 villages) and news archives (16 sources) show that floods have major impacts on lives and livelihoods in Indonesian Borneo, and flooding risks are associated with features of the local climate and landscape, particularly land uses that have seen rapid expansions over the past 30 years. In contrast with government assessments, we find that flooding is far more widespread, and that frequent, local, events can have large cumulative impacts. Over three years, local news agencies reported floods that affected 868 settlements, 966 times (including 89 in urban areas), inundated at least 197 000 houses, and displaced more than 776 000 people, possibly as many as 1.5 million (i.e. 5%-10% of the total population). Spatial analyses based on surveys in 364 villages show that flood frequency is associated with land use in catchment areas, including forest cover and condition, and the area of wetlands, mines (open-cut coal or gold mines), and oil palm. The probability that floods have become more frequent over the past 30 years was higher for villages closer to mines, and in watersheds with more extensive oil palm, but lower in watersheds with greater cover of selectively-logged or intact forests. We demonstrate that in data-poor regions, multiple sources of information can be integrated to gain insights into the hydrological services provided by forest and wetland ecosystems, and motivate more comprehensive assessment of flooding risks and options for ecosystem-based adaptation.

More frequent flooding? Changes in flood frequency in the Pearl River basin, China, since 1951 and over the past 1000 years

NASA Astrophysics Data System (ADS)

Zhang, Qiang; Gu, Xihui; Singh, Vijay P.; Shi, Peijun; Sun, Peng

2018-05-01

Flood risks across the Pearl River basin, China, were evaluated using a peak flood flow dataset covering a period of 1951-2014 from 78 stations and historical flood records of the past 1000 years. The generalized extreme value (GEV) model and the kernel estimation method were used to evaluate frequencies and risks of hazardous flood events. Results indicated that (1) no abrupt changes or significant trends could be detected in peak flood flow series at most of the stations, and only 16 out of 78 stations exhibited significant peak flood flow changes with change points around 1990. Peak flood flow in the West River basin increased and significant increasing trends were identified during 1981-2010; decreasing peak flood flow was found in coastal regions and significant trends were observed during 1951-2014 and 1966-2014. (2) The largest three flood events were found to cluster in both space and time. Generally, basin-scale flood hazards can be expected in the West and North River basins. (3) The occurrence rate of floods increased in the middle Pearl River basin but decreased in the lower Pearl River basin. However, hazardous flood events were observed in the middle and lower Pearl River basin, and this is particularly true for the past 100 years. However, precipitation extremes were subject to moderate variations and human activities, such as building of levees, channelization of river systems, and rapid urbanization; these were the factors behind the amplification of floods in the middle and lower Pearl River basin, posing serious challenges for developing measures of mitigation of flood hazards in the lower Pearl River basin, particularly the Pearl River Delta (PRD) region.

33 CFR 239.7 - Separation of flood control works from urban drainage.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Separation of flood control works... OF THE ARMY, DEPARTMENT OF DEFENSE WATER RESOURCES POLICIES AND AUTHORITIES: FEDERAL PARTICIPATION IN COVERED FLOOD CONTROL CHANNELS § 239.7 Separation of flood control works from urban drainage. Covered...

24 CFR 1000.38 - What flood insurance requirements are applicable?

Code of Federal Regulations, 2010 CFR

2010-04-01

... 24 Housing and Urban Development 4 2010-04-01 2010-04-01 false What flood insurance requirements..., DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT NATIVE AMERICAN HOUSING ACTIVITIES General § 1000.38 What flood insurance requirements are applicable? Under the Flood Disaster Protection Act of 1973, as amended (42 U.S.C...

An empirical assessment of which inland floods can be managed.

PubMed

Mogollón, Beatriz; Frimpong, Emmanuel A; Hoegh, Andrew B; Angermeier, Paul L

2016-02-01

Riverine flooding is a significant global issue. Although it is well documented that the influence of landscape structure on floods decreases as flood size increases, studies that define a threshold flood-return period, above which landscape features such as topography, land cover and impoundments can curtail floods, are lacking. Further, the relative influences of natural versus built features on floods is poorly understood. Assumptions about the types of floods that can be managed have considerable implications for the cost-effectiveness of decisions to invest in transforming land cover (e.g., reforestation) and in constructing structures (e.g., storm-water ponds) to control floods. This study defines parameters of floods for which changes in landscape structure can have an impact. We compare nine flood-return periods across 31 watersheds with widely varying topography and land cover in the southeastern United States, using long-term hydrologic records (≥20 years). We also assess the effects of built flow-regulating features (best management practices and artificial water bodies) on selected flood metrics across urban watersheds. We show that landscape features affect magnitude and duration of only those floods with return periods ≤10 years, which suggests that larger floods cannot be managed effectively by manipulating landscape structure. Overall, urban watersheds exhibited larger (270 m(3)/s) but quicker (0.41 days) floods than non-urban watersheds (50 m(3)/s and 1.5 days). However, urban watersheds with more flow-regulating features had lower flood magnitudes (154 m(3)/s), but similar flood durations (0.55 days), compared to urban watersheds with fewer flow-regulating features (360 m(3)/s and 0.23 days). Our analysis provides insight into the magnitude, duration and count of floods that can be curtailed by landscape structure and its management. Our findings are relevant to other areas with similar climate, topography, and land use, and can help ensure that investments in flood management are made wisely after considering the limitations of landscape features to regulate floods. Copyright © 2015 Elsevier Ltd. All rights reserved.

Demonstration Of A Green-blue Approach For A Strategic Management Of Urban Runoff.

NASA Astrophysics Data System (ADS)

Jonczyk, J. C.; Quinn, P. F.; Heidrich, O.; James, P.; Harris, N.; Dawson, R. J.; Pearson, D. J.

2016-12-01

With more than half of the world's population now living in cities, there is an increasing need to facilitate urban areas to be more sustainable and resilient to the impacts of extreme events such as surface water flooding. Traditionally, urban storm water is managed predominately through grey infrastructure such as sewer collection systems and flood walls, often with little consideration of the increased water utility costs or downstream flood risk. There is little collaboration between organisations and sectors on managing and mitigating the impacts of flooding at city level, with decisions made in silos. A 24-acre development zone is used as a case study to show how different sectors and organisations came to realise the multiple benefits of a blue-green, joined-up, site-wide approach to managing storm runoff. The Science Central development zone (http://www.newcastlesciencecentral.com/) is at the heart of the city and is jointly owned by Newcastle University and the Newcastle city council with an overall vision for innovation and urban sustainability. The masterplan was reviewed and agreed by the partners in 2016 to include a site-wide holistic conveyance of surface water through a series of measures across the site, and the commercial needs of the building plots were balanced with the need to manage the flood hazard. Uniquely, once constructed, the measures will be monitored to evaluate how they function and the multiple benefits they provide will also be evaluated. This will include monitoring water and air quality parameters, indicators of biodiversity and carbon capture through The Urban Observatory. The Urban Observatory (http://urbanobservatory.ac.uk/) is a research project based at Newcastle University that produces a data portal of open and scalable data from deployments of heterogeneous sensors and 3rd party data sources around the city. The site will also host a new national sustainable urban drainage research facility that will provide research infrastructure to carry out detailed experiments, with the aim of improving the evidence based for green-blue solutions. Science Central and its approach to surface runoff is to be an exemplar of a future, sustainable city with a vision to demonstrate that making space for water can provide a more liveable and thriving environment for all.

Predicting the impact of urban flooding using open data.

PubMed

Tkachenko, Nataliya; Procter, Rob; Jarvis, Stephen

2016-05-01

This paper aims to explore whether there is a relationship between search patterns for flood risk information on the Web and how badly localities have been affected by flood events. We hypothesize that localities where people stay more actively informed about potential flooding experience less negative impact than localities where people make less effort to be informed. Being informed, of course, does not hold the waters back; however, it may stimulate (or serve as an indicator of) such resilient behaviours as timely use of sandbags, relocation of possessions from basements to upper floors and/or temporary evacuation from flooded homes to alternative accommodation. We make use of open data to test this relationship empirically. Our results demonstrate that although aggregated Web search reflects average rainfall patterns, its eigenvectors predominantly consist of locations with similar flood impacts during 2014-2015. These results are also consistent with statistically significant correlations of Web search eigenvectors with flood warning and incident reporting datasets.

Progress in and prospects for fluvial flood modelling.

PubMed

Wheater, H S

2002-07-15

Recent floods in the UK have raised public and political awareness of flood risk. There is an increasing recognition that flood management and land-use planning are linked, and that decision-support modelling tools are required to address issues of climate and land-use change for integrated catchment management. In this paper, the scientific context for fluvial flood modelling is discussed, current modelling capability is considered and research challenges are identified. Priorities include (i) appropriate representation of spatial precipitation, including scenarios of climate change; (ii) development of a national capability for continuous hydrological simulation of ungauged catchments; (iii) improved scientific understanding of impacts of agricultural land-use and land-management change, and the development of new modelling approaches to represent those impacts; (iv) improved representation of urban flooding, at both local and catchment scale; (v) appropriate parametrizations for hydraulic simulation of in-channel and flood-plain flows, assimilating available ground observations and remotely sensed data; and (vi) a flexible decision-support modelling framework, incorporating developments in computing, data availability, data assimilation and uncertainty analysis.

Flood risk trends in coastal watersheds in South Spain: direct and indirect impact of river regulation

NASA Astrophysics Data System (ADS)

Egüen, M.; Polo, M. J.; Gulliver, Z.; Contreras, E.; Aguilar, C.; Losada, M. A.

2015-06-01

Spain is one of the world's countries with a large number of reservoirs per inhabitant. This intense regulation of the fluvial network during the 20th century has resulted in a decrease in flood events, a higher availability of water resources, and a high development of the irrigated crop area, even in the drier regions. For decades, flood perception was reduced since the development of reservoirs protected the floodplains of river; this resulted in later occupation of soil by urban, agricultural and industrial uses. In recent years, an increasing perception of flood events is observed, associated to the higher damage associated to extreme events in the now occupied areas, especially in coastal watersheds. This work shows the change on flood risk in the coastal areas of three hydrographic basins in Andalusia (South Spain) during the reservoir expansion period: the Guadalete, Guadalquivir and Guadalhorce river basins. The results differentiate the impact of the regulation level on both the cumulative distribution functions of the fluvial discharge near the river mouth, for different time scales, and the associated damage related to the enhanced soil occupation during this period. The different impact on the final medium and long term flood risk is also assessed in terms of the storage capacity per unit area throughout the basins, the effective annual runoff/precipitation index, the frequency of sea storms, and the human factor (change in social perception of floods), for different intervals in the flood extreme regime. The implications for adaptation actions is also assessed.

Disaster-related environmental health hazards: former lead smelting plants in the United States.

PubMed

Wang, Yao; Kanter, Robert K

2014-02-01

Natural disasters exacerbate risks of hazardous environmental exposures and adverse health consequences. The present study determined the proportion of previously identified lead industrial sites in urban locations that are at high risk for dispersal of toxic chemicals by natural disasters. Geographic analysis from publicly available data identified former lead smelting plants that coincide with populated urban areas and with high-risk locations for natural disasters. From a total of 229 urban smelting sites, 66 (29%) were in relatively high-risk areas for natural disasters: flood (39), earthquake (29), tornado (3), and hurricane (2). States with urban sites at relatively high risk for natural disaster included California (15); Pennsylvania (14); New York (7); Missouri (6); Illinois (5); New Jersey (4); Kentucky (3); Florida, Oregon, and Ohio (2 each); and Indiana, Massachusetts, Rhode Island, Texas, Utah, and Washington (1 each). Incomplete historical records showed at least 10 smelting site locations were affected by natural disaster. Forgotten environmental hazards may remain hazardous in any community. Uncertainty about risks in disasters causes disruptive public anxiety that increases difficulties in community responses and recovery. Our professional and public responsibility is to seek a better understanding of the risks of latent environmental hazards.

Modelling Atmospheric Rivers and the Potential for Southeast Texas Flooding: A Case Study of the Maya Express and the March 2016 Sabine River Flood

NASA Astrophysics Data System (ADS)

McIntosh, J.; Lander, K.

2016-12-01

For three days in March of 2016, southeast Texas was inundated with up to 19 inches of rainfall, swelling the Sabine River to record flood stages. This event was attributed to an atmospheric river (AR), regionally known as the "Maya Express," which carried moisture from the Gulf of Mexico into the Sabine River Basin. Studies by the NOAA/NWS Climate Prediction Center have shown that ARs are occurring more frequently due to the intensification of El Niño that increases the available moisture in the atmosphere. In this study, we analyzed the hydrological and meteorological setup of the event on the Sabine River to characterize the flood threat associated with AR rainfall and simulated how an equivalent AR event would impact an urban basin in Houston, Texas. Our primary data sources included WSR-88D radar-based rainfall estimates and observed data at USGS river gauges. Furthermore, the land surface parameters evaluated included land cover, soil types, basin topology, model-derived soil moisture states, and topography. The spatial distribution of precipitation from the storm was then translated west over the Houston and used to force a hydrologic model to assess the impact of an event comparable to the March 2016 event on Houston's San Jacinto River Basin. The results indicate that AR precipitation poses a flood risk to urbanized areas in southeast Texas because of the low lying topography, impervious pavement, and limited flood control. Due to this hydrologic setup, intense AR rainfall can yield a rapid urban runoff response that overwhelms the river system, potentially endangering the lives and property of millions of people in the Houston area. Ultimately, if the frequency of AR development increases, regional flood potential may increase. Given the consequences established in this study, more research should be conducted in order to better predict the rate of recurrence and effects of Maya Express generated precipitation.

Integrating heterogeneous earth observation data for assessment of high-resolution inundation boundaries generated during flood emergencies.

NASA Astrophysics Data System (ADS)

Sava, E.; Cervone, G.; Kalyanapu, A. J.; Sampson, K. M.

2017-12-01

The increasing trend in flooding events, paired with rapid urbanization and an aging infrastructure is projected to enhance the risk of catastrophic losses and increase the frequency of both flash and large area floods. During such events, it is critical for decision makers and emergency responders to have access to timely actionable knowledge regarding preparedness, emergency response, and recovery before, during and after a disaster. Large volumes of data sets derived from sophisticated sensors, mobile phones, and social media feeds are increasingly being used to improve citizen services and provide clues to the best way to respond to emergencies through the use of visualization and GIS mapping. Such data, coupled with recent advancements in data fusion techniques of remote sensing with near real time heterogeneous datasets have allowed decision makers to more efficiently extract precise and relevant knowledge and better understand how damage caused by disasters have real time effects on urban population. This research assesses the feasibility of integrating multiple sources of contributed data into hydrodynamic models for flood inundation simulation and estimating damage assessment. It integrates multiple sources of high-resolution physiographic data such as satellite remote sensing imagery coupled with non-authoritative data such as Civil Air Patrol (CAP) and `during-event' social media observations of flood inundation in order to improve the identification of flood mapping. The goal is to augment remote sensing imagery with new open-source datasets to generate flood extend maps at higher temporal and spatial resolution. The proposed methodology is applied on two test cases, relative to the 2013 Boulder Colorado flood and the 2015 floods in Texas.

Continuous hydrologic simulation and flood-frequency, hydraulic, and flood-hazard analysis of the Blackberry Creek watershed, Kane County, Illinois

USGS Publications Warehouse

Soong, David T.; Straub, Timothy D.; Murphy, Elizabeth A.

2006-01-01

Results of hydrologic model, flood-frequency, hydraulic model, and flood-hazard analysis of the Blackberry Creek watershed in Kane County, Illinois, indicate that the 100-year and 500-year flood plains range from approximately 25 acres in the tributary F watershed (a headwater subbasin at the northeastern corner of the watershed) to almost 1,800 acres in Blackberry Creek main stem. Based on 1996 land-cover data, most of the land in the 100-year and 500-year flood plains was cropland, forested and wooded land, and grassland. A relatively small percentage of urban land was in the flood plains. The Blackberry Creek watershed has undergone rapid urbanization in recent decades. The population and urbanized lands in the watershed are projected to double from the 1990 condition by 2020. Recently, flood-induced damage has occurred more frequently in urbanized areas of the watershed. There are concerns about the effect of urbanization on flood peaks and volumes, future flood-mitigation plans, and potential effects on the water quality and stream habitats. This report describes the procedures used in developing the hydrologic models, estimating the flood-peak discharge magnitudes and recurrence intervals for flood-hazard analysis, developing the hydraulic model, and the results of the analysis in graphical and tabular form. The hydrologic model, Hydrological Simulation Program-FORTRAN (HSPF), was used to perform the simulation of continuous water movements through various patterns of land uses in the watershed. Flood-frequency analysis was applied to an annual maximum series to determine flood quantiles in subbasins for flood-hazard analysis. The Hydrologic Engineering Center-River Analysis System (HEC-RAS) hydraulic model was used to determine the 100-year and 500-year flood elevations, and to determine the 100-year floodway. The hydraulic model was calibrated and verified using high water marks and observed inundation maps for the July 17-18, 1996, flood event. Digital maps of the 100-year and 500-year flood plains and the 100-year floodway for each tributary and the main stem of Blackberry Creek were compiled.

Making cities resilient: Increasing resilience to disasters at the local level.

PubMed

Albrito, Paola

2012-01-01

Half of humanity is now living in cities, according to the United Nations Population Division. The urban population exceeded the rural for the first time in 2008, and by 2050 urbanisation will rise to 70 per cent with increased urban risk. 'Today, 100 cities are in control of 30 per cent of the world's economy.' The need for maintenance and upkeep of these cities makes safety measures for their citizens crucial. In this context, urban risk, city planning and the role of local governments in dealing with risk reduction have been recognised as key factors to build communities resilient to disasters. While many local governments have taken action to reduce vulnerability, especially when it comes to government organising capacity to deal with disasters, much remains to be done. Disaster risk has become an acute and increasingly urban issue. Poorly-planned urban environments, weak urban governance, an old and fragile infrastructure, and rapid population growth have increased pressure on the urban environment and triggered exposure to disaster risk. More and more people are settling in potential danger zones such as flood plains, volcanic flanks or earthquake faults and coastal areas. They do so because planners and local governments fail to provide alternatives, or because they cannot afford safer land. Local government officials are confronted with the threat of disasters daily, and need improved access to policies and tools to cope with them effectively.

Characterization of microbial and metal contamination in flooded New York City neighborhoods following Superstorm Sandy

NASA Astrophysics Data System (ADS)

Dueker, M.; O'Mullan, G. D.; Sahajpal, R.

2013-12-01

Large scale flooding of waterfront neighborhoods occurred in New York City (NYC) during Superstorm Sandy. While NYC waterways commonly experience combined sewer overflow (CSO) and associated water quality degradation during rain storms, Superstorm Sandy was unique in that these potentially contaminated waters were transported over the banks and into city streets and buildings. Sampling of waterways, storm debris on city streets, and flood water trapped in building basements occurred in the days following Sandy, including in neighborhoods bordering the Gowanus Canal and Newtown Creek, which are both Superfund sites known to frequently contain high levels of sewage associated bacteria and metal contamination. Samples enumerated for the sewage indicating bacterium, Enterococcus, suggest that well-flushed waterways recovered quickly from sewage contamination in the days following the storm, with Enterococci concentrations similar to background levels measured before flooding occurred. In contrast, storm debris on city streets and waters from flooded basements had much higher levels of sewage-associated bacteria days after flooding occurred. Analysis of 180,000 bacterial 16S rRNA gene sequences obtained from flood water samples and flood debris confirmed the presence of bacterial genera often associated with sewage impacted samples (e.g. Escherichia, Streptococcus, Clostridium, Trichococcus, Aeromonas) and a community composition similar to CSO discharge. Elemental analysis suggests low levels of metal contamination in most flood water, but much higher levels of Cu, Pb, and Cr were found in leach from some storm debris samples found adjacent to the Newtown Creek and Gowanus Canal superfund sites. These data suggest a rapid recovery of water quality in local waterways after Superstorm Sandy, but that trapped flood water and debris samples in urban neighborhoods retained elevated levels of microbial sewage pollution, and in some cases metal pollution, days after that waterway recovery. These findings indicate a potentially significant risk to local populations exposed to trapped flood waters and debris in the aftermath of urban waterway flooding events.

Urban Infrastructure, Channel-Floodplain Morphology and Flood Flow Patterns

NASA Astrophysics Data System (ADS)

Miller, A. J.; Smith, J. A.; Nelson, C. B.

2006-12-01

The relationship between the channel and the floodplain in urban settings is heavily influenced by (1) altered watershed hydrologic response and frequency distribution of flows, (2) channel enlargement resulting from altered hydrology under conditions of limited sediment supply, (3) direct modification of channels and floodplains for purposes of erosion mitigation, flood protection, commercial development and creation of public amenities, (4) valley constrictions and flow obstructions associated with bridges, culverts, road embankments and other types of floodplain encroachment causing fragmentation or longitudinal segmentation of the riparian corridor. Field observation of inundation patterns associated with recurring floods in the Baltimore metropolitan area is used in combination with 2-dimensional hydraulic modeling to simulate patterns of floodplain inundation and to explore the relationships between magnitude and shape of the flood hydrograph, morphology of the urban channel-floodplain system, and the frequency and extent of floodplain inundation. Case studies include a July 2004 flood associated with a 300-year 2-hour rainfall in a small (14.2 km2) urban watershed, as well as several other events caused by summer thunderstorms with shorter recurrence intervals that generated an extraordinary flood response. The influence of urban infrastructure on flood inundation and flow patterns is expressed in terms of altered (and hysteretic) stage-discharge relationships, stepped flood profiles, rapid longitudinal attenuation of flood waves, and transient flow reversals at confluences and constrictions. Given the current level of interest in restoration measures these patterns merit consideration in planning future development and mitigation efforts.

Mitigation of Flood Hazards Through Modification of Urban Channels and Floodplains

NASA Astrophysics Data System (ADS)

Miller, A. J.; Lee, G.; Bledsoe, B. P.; Stephens, T.

2017-12-01

Small urban watersheds with high percent impervious cover and dense road and storm-drain networks are highly responsive to short-duration high-intensity rainfall events that lead to flash floods. The Baltimore metropolitan area has some of the flashiest urban watersheds in the conterminous U.S., high frequency of channel incision in affected areas, and a large number of watershed restoration projects designed to restore ecosystem services through reconnection of the channel with the floodplain. A question of key importance in these and other urban watersheds is to what extent we can mitigate flood hazards and urban stream syndrome through restoration activities that modify the channel and valley floor. Local and state governments have invested resources in repairing damage caused by extreme events like the July 30, 2016 Ellicott City flood in the Tiber River watershed, as well as more frequent high flows in other local urban streams. Recent reports have investigated how much flood mitigation may be achieved through modification of the channel and floodplain to enhance short-term storage of flood waters on the valley floor or in other subsurface structures, as compared with increasing stormwater management in the headwaters. Ongoing research conducted as part of the UWIN (Urban Water Innovation Network) program utilizes high-resolution topographic point clouds derived by processing of photographs from hand-held cameras or video frames from drone overflights. These are used both to track geomorphic change and to assess flood response with 2d hydraulic modeling tools under alternative mitigation scenarios. Assessment metrics include variations in inundation extent, water depth, hydrograph attenuation, and temporal and spatial characteristics of the 2d depth-averaged velocity field. Examples from diverse urban watersheds are presented to illustrate the range of anticipated outcomes and potential constraints on the effectiveness of downstream vs. headwater mitigation efforts.

A web GIS based integrated flood assessment modeling tool for coastal urban watersheds

NASA Astrophysics Data System (ADS)

Kulkarni, A. T.; Mohanty, J.; Eldho, T. I.; Rao, E. P.; Mohan, B. K.

2014-03-01

Urban flooding has become an increasingly important issue in many parts of the world. In this study, an integrated flood assessment model (IFAM) is presented for the coastal urban flood simulation. A web based GIS framework has been adopted to organize the spatial datasets for the study area considered and to run the model within this framework. The integrated flood model consists of a mass balance based 1-D overland flow model, 1-D finite element based channel flow model based on diffusion wave approximation and a quasi 2-D raster flood inundation model based on the continuity equation. The model code is written in MATLAB and the application is integrated within a web GIS server product viz: Web Gram Server™ (WGS), developed at IIT Bombay, using Java, JSP and JQuery technologies. Its user interface is developed using open layers and the attribute data are stored in MySQL open source DBMS. The model is integrated within WGS and is called via Java script. The application has been demonstrated for two coastal urban watersheds of Navi Mumbai, India. Simulated flood extents for extreme rainfall event of 26 July, 2005 in the two urban watersheds of Navi Mumbai city are presented and discussed. The study demonstrates the effectiveness of the flood simulation tool in a web GIS environment to facilitate data access and visualization of GIS datasets and simulation results.

Characterization of rainfall events and correlation with reported disasters: A case in Cali, Colombia

NASA Astrophysics Data System (ADS)

Canon, C. C.; Tischbein, B.; Bogardi, J.

2017-12-01

Flood maps generally display the area that a river might overflow after a rainfall event takes place, under different scenarios of climate, land use/land cover, and/or failure of dams and dikes. However, rainfall is not limited to feed runoff and enlarge the river: it also causes minor disasters outside the map's highlighted area. The city of Cali in Colombia illustrates very well this situation: its flat topography and its major critical infrastructure near the river make it flood-risk prone; a heavy rainfall event would potentially deplete drinking water, electrical power and drainage capacity, and trigger outbreaks of water-borne diseases in the whole city, not only in the flooded area. Unfortunately, the government's disaster prevention strategies focus on the floodplain and usually overlook the aftermath of these minor disasters for being milder and scattered. Predicted losses in flood maps are potentially big, while those from minor disasters over the city are small but real, and citizens, utility companies and urban maintenance funds must constantly take them over. Mitigation and prevention of such minor disasters can save money for the development of the city in other aspects. This paper characterizes hundreds of rainfall events selected from 10-min step time series from 2006 to 2017, and finds their correlation with reported rainfall-related disasters throughout Cali, identified by date and neighborhood. Results show which rainfall parameters are most likely to indicate the occurrence of such disasters and their approximate location in the urban area of Cali. These results, when coupled with real-time observations of rainfall data and simulations of drainage network response, may help citizens and emergency bodies prioritize zones to assist during heavy storms. In the long term, stakeholders may also implement low impact development solutions in these zones to reduce flood risks.

Developing a Malaysia flood model

NASA Astrophysics Data System (ADS)

Haseldine, Lucy; Baxter, Stephen; Wheeler, Phil; Thomson, Tina

2014-05-01

Faced with growing exposures in Malaysia, insurers have a need for models to help them assess their exposure to flood losses. The need for an improved management of flood risks has been further highlighted by the 2011 floods in Thailand and recent events in Malaysia. The increasing demand for loss accumulation tools in Malaysia has lead to the development of the first nationwide probabilistic Malaysia flood model, which we present here. The model is multi-peril, including river flooding for thousands of kilometres of river and rainfall-driven surface water flooding in major cities, which may cause losses equivalent to river flood in some high-density urban areas. The underlying hazard maps are based on a 30m digital surface model (DSM) and 1D/2D hydraulic modelling in JFlow and RFlow. Key mitigation schemes such as the SMART tunnel and drainage capacities are also considered in the model. The probabilistic element of the model is driven by a stochastic event set based on rainfall data, hence enabling per-event and annual figures to be calculated for a specific insurance portfolio and a range of return periods. Losses are estimated via depth-damage vulnerability functions which link the insured damage to water depths for different property types in Malaysia. The model provides a unique insight into Malaysian flood risk profiles and provides insurers with return period estimates of flood damage and loss to property portfolios through loss exceedance curve outputs. It has been successfully validated against historic flood events in Malaysia and is now being successfully used by insurance companies in the Malaysian market to obtain reinsurance cover.

A framework for the case-specific assessment of Green Infrastructure in mitigating urban flood hazards

NASA Astrophysics Data System (ADS)

Schubert, Jochen E.; Burns, Matthew J.; Fletcher, Tim D.; Sanders, Brett F.

2017-10-01

This research outlines a framework for the case-specific assessment of Green Infrastructure (GI) performance in mitigating flood hazard in small urban catchments. The urban hydrologic modeling tool (MUSIC) is coupled with a fine resolution 2D hydrodynamic model (BreZo) to test to what extent retrofitting an urban watershed with GI, rainwater tanks and infiltration trenches in particular, can propagate flood management benefits downstream and support intuitive flood hazard maps useful for communicating and planning with communities. The hydrologic and hydraulic models are calibrated based on current catchment conditions, then modified to represent alternative GI scenarios including a complete lack of GI versus a full implementation of GI. Flow in the hydrologic/hydraulic models is forced using a range of synthetic rainfall events with annual exceedance probabilities (AEPs) between 1-63% and durations from 10 min to 24 h. Flood hazard benefits mapped by the framework include maximum flood depths and extents, flow intensity (m2/s), flood duration, and critical storm duration leading to maximum flood conditions. Application of the system to the Little Stringybark Creek (LSC) catchment shows that across the range of AEPs tested and for storm durations equal or less than 3 h, presently implemented GI reduces downstream flooded area on average by 29%, while a full implementation of GI would reduce downstream flooded area on average by 91%. A full implementation of GI could also lower maximum flow intensities by 83% on average, reducing the drowning hazard posed by urban streams and improving the potential for access by emergency responders. For storm durations longer than 3 h, a full implementation of GI lacks the capacity to retain the resulting rainfall depths and only reduces flooded area by 8% and flow intensity by 5.5%.

Techniques for estimating flood-peak discharges from urban basins in Missouri

USGS Publications Warehouse

Becker, L.D.

1986-01-01

Techniques are defined for estimating the magnitude and frequency of future flood peak discharges of rainfall-induced runoff from small urban basins in Missouri. These techniques were developed from an initial analysis of flood records of 96 gaged sites in Missouri and adjacent states. Final regression equations are based on a balanced, representative sampling of 37 gaged sites in Missouri. This sample included 9 statewide urban study sites, 18 urban sites in St. Louis County, and 10 predominantly rural sites statewide. Short-term records were extended on the basis of long-term climatic records and use of a rainfall-runoff model. Linear least-squares regression analyses were used with log-transformed variables to relate flood magnitudes of selected recurrence intervals (dependent variables) to selected drainage basin indexes (independent variables). For gaged urban study sites within the State, the flood peak estimates are from the frequency curves defined from the synthesized long-term discharge records. Flood frequency estimates are made for ungaged sites by using regression equations that require determination of the drainage basin size and either the percentage of impervious area or a basin development factor. Alternative sets of equations are given for the 2-, 5-, 10-, 25-, 50-, and 100-yr recurrence interval floods. The average standard errors of estimate range from about 33% for the 2-yr flood to 26% for the 100-yr flood. The techniques for estimation are applicable to flood flows that are not significantly affected by storage caused by manmade activities. Flood peak discharge estimating equations are considered applicable for sites on basins draining approximately 0.25 to 40 sq mi. (Author 's abstract)

Urban permeable pavement system design based on “sponge city” concept

NASA Astrophysics Data System (ADS)

Yu, M. M.; Zhu, J. W.; Gao, W. F.; Xu, D. P.; Zhao, M.

2017-08-01

Based on the “sponge city” concept, to implement the goal of building a city within the city to solve the sponge waterlogging, rational utilization of water resources, reduce water pollution this paper, combined with the city planning level in China, establishes the design system of city road flooding from the macro, medium and micro level, explore the design method of city water permeable pavement system, and has a practical significance the lower flood risk water ecological problems. On the macro level, we established an urban pavement sponge system under the regional ecological pattern by “spot permeable open space - low impact developing rain water road system - catchment area and catchment wetland”. On a medium level, this paper proposed the permeable suitability of pavement and the planning control indicators when combined with urban functional districts to conduct permeable pavement roads plans and controls. On micro level, the paper studied sponge technology design of permeable pavement from road structure, surface material, and other aspects aimed at the pavement permeability requirements.

Modeling urban flood risk territories for Riga city

NASA Astrophysics Data System (ADS)

Piliksere, A.; Sennikovs, J.; Virbulis, J.; Bethers, U.; Bethers, P.; Valainis, A.

2012-04-01

Riga, the capital of Latvia, is located on River Daugava at the Gulf of Riga. The main flooding risks of Riga city are: (1) storm caused water setup in South part of Gulf of Riga (storm event), (2) water level increase caused by Daugava River discharge maximums (spring snow melting event) and (3) strong rainfall or rapid snow melting in densely populated urban areas. The first two flooding factors were discussed previously (Piliksere et al, 2011). The aims of the study were (1) the identification of the flood risk situations in densely populated areas, (2) the quantification of the flooding scenarios caused by rain and snow melting events of different return periods nowadays, in the near future (2021-2050), far future (2071-2100) taking into account the projections of climate change, (3) estimation of groundwater level for Riga city, (4) the building and calibration of the hydrological mathematical model based on SWMM (EPA, 2004) for the domain potentially vulnerable for rain and snow melt flooding events, (5) the calculation of rain and snow melting flood events with different return periods, (6) mapping the potentially flooded areas on a fine grid. The time series of short term precipitation events during warm time period of year (id est. rain events) were analyzed for 35 year long time period. Annual maxima of precipitation intensity for events with different duration (5 min; 15 min; 1h; 3h; 6h; 12h; 1 day; 2 days; 4 days; 10 days) were calculated. The time series of long term simultaneous precipitation data and observations of the reduction of thickness of snow cover were analyzed for 27 year long time period. Snow thawing periods were detected and maximum of snow melting intensity for events with different intensity (1day; 2 days; 4 days; 7 days; 10 days) were calculated. According to the occurrence probability six scenarios for each event for nowadays, near and far future with return period once in 5, 10, 20, 50, 100 and 200 years were constructed based on the Gumbell extreme value analysis. The hydrological modelling driven by the temperature and precipitation data series from regional climate models were used for evaluation of rain event maximums in the future periods. The usage of the climate model data in hydrological models causes systematic errors; therefore the bias correction method (Sennikovs, Bethers, 2009) was applied for determination of the future rainfall intensities. SWMM model was built for the urban area. Objects of hydraulic importance (manifold, penstock, ditch, pumping station, weir, well, catchment sub-basin etc.) were included in the model. There exist pure rain sewage system and mixed rain-water/household sewage system in Riga. Sewage system with wastewater load proportional to population density was taken account and calibrated. Model system was calibrated for a real rain event against the water flux time series into sewage treatment plant of Riga. High resolution (~1.5 points per square meter) digital terrain map was used as the base for finite element mesh for the geospatial mapping of results of hydraulic calculations. Main results of study are (1) detection of the hot spots of densely populated urban areas; (2) identification of the weak chains of the melioration and sewage systems; (3) mapping the elevation of ground water mainly caused by snow melting. A.Piliksere, A.Valainis, J.Seņņikovs, (2011), A flood risk assessment for Riga city taking account climate changes, EGU, Vienna, Austria. EPA, (2004), Storm water management model. User's manual version 5.0. US Environmental Protection Agency J.Sennikovs, U.Bethers, (2009), Statistical downscaling method of regional climate model results for hydrological modelling. 18th World IMACS/MODSIM Congress, Cairns, Australia.

Applications of Radarsat-1 synthetic aperture radar imagery to assess hurricane-related flooding of coastal Louisiana

USGS Publications Warehouse

Kiage, L.M.; Walker, N.D.; Balasubramanian, S.; Babin, A.; Barras, J.

2005-01-01

The Louisiana coast is subjected to hurricane impacts including flooding of human settlements, river channels and coastal marshes, and salt water intrusion. Information on the extent of flooding is often required quickly for emergency relief, repairs of infrastructure, and production of flood risk maps. This study investigates the feasibility of using Radarsat-1 SAR imagery to detect flooded areas in coastal Louisiana after Hurricane Lili, October 2002. Arithmetic differencing and multi-temporal enhancement techniques were employed to detect flooding and to investigate relationships between backscatter and water level changes. Strong positive correlations (R2=0.7-0.94) were observed between water level and SAR backscatter within marsh areas proximate to Atchafalaya Bay. Although variations in elevation and vegetation type did influence and complicate the radar signature at individual sites, multi-date differences in backscatter largely reflected the patterns of flooding within large marsh areas. Preliminary analyses show that SAR imagery was not useful in mapping urban flooding in New Orleans after Hurricane Katrina's landfall on 29 August 2005. ?? 2005 Taylor & Francis.

Potential of 3D City Models to assess flood vulnerability

NASA Astrophysics Data System (ADS)

Schröter, Kai; Bochow, Mathias; Schüttig, Martin; Nagel, Claus; Ross, Lutz; Kreibich, Heidi

2016-04-01

Vulnerability, as the product of exposure and susceptibility, is a key factor of the flood risk equation. Furthermore, the estimation of flood loss is very sensitive to the choice of the vulnerability model. Still, in contrast to elaborate hazard simulations, vulnerability is often considered in a simplified manner concerning the spatial resolution and geo-location of exposed objects as well as the susceptibility of these objects at risk. Usually, area specific potential flood loss is quantified on the level of aggregated land-use classes, and both hazard intensity and resistance characteristics of affected objects are represented in highly simplified terms. We investigate the potential of 3D City Models and spatial features derived from remote sensing data to improve the differentiation of vulnerability in flood risk assessment. 3D City Models are based on CityGML, an application scheme of the Geography Markup Language (GML), which represents the 3D geometry, 3D topology, semantics and appearance of objects on different levels of detail. As such, 3D City Models offer detailed spatial information which is useful to describe the exposure and to characterize the susceptibility of residential buildings at risk. This information is further consolidated with spatial features of the building stock derived from remote sensing data. Using this database a spatially detailed flood vulnerability model is developed by means of data-mining. Empirical flood damage data are used to derive and to validate flood susceptibility models for individual objects. We present first results from a prototype application in the city of Dresden, Germany. The vulnerability modeling based on 3D City Models and remote sensing data is compared i) to the generally accepted good engineering practice based on area specific loss potential and ii) to a highly detailed representation of flood vulnerability based on a building typology using urban structure types. Comparisons are drawn in terms of affected building area and estimated loss for a selection of inundation scenarios.

A GIS-based model for the hydrological and hydraulic reconstruction of historical flash-floods in urban areas. The case of the river Turia in Valencia (1957)

NASA Astrophysics Data System (ADS)

Portugués Mollá, Iván; Felici, Xavier Bonache i.; Mateu Bellés, Joan F.; Segura, Juan B. Marco

2015-04-01

Flash-floods are recurrent events in the Mediterranean arch, mostly derived from cold air pool phenomena triggering hydro-geomorphic high-intensity processes, combining high discharge and low frequency. In urban environments the complexity of the processes become higher due to the existence of very fast-response basins and quick-response runoff. However, immediate activities of cleaning up and restoration delete the urban marks. After a short time both significance and dimension of the hydro-geomorphic event become completely unrecognizable. Nevertheless, these episodes generate extensive administrative documentation which is testimony of the processes in almost real time. Exploiting this source typology in order to reconstruct events far in time within urban areas, which may lack database sufficiently rich, is necessary to understand the hydrological and hydraulic derived processes. This is particularly the case of the Valencia flash-flood (1957), located in the lower Turia River basin (6.400 km2). Within a short interval (15 hours) there were registered two flood peaks (estimated at that time at 2.500 and 3.700 m3/s). The double overflowing inundated a large proportion of the urban area. The flash-flood activated fast processes with high energy that left numerous hydro-geomorphic marks. Although those tracks were deleted in a short while after the flood, it remains a legacy that had not yet been exploited, consisting of immediate aerial and oblique high resolution photography, pictures at street level, water level record and administrative records, such as claim files for compensation. Paradoxically, despite the event is considered as a milestone on metropolitan territorial planning and it was decided to divert the river Turia definitely through a major project (12 km of channeling, known as South Solution), being the scenario notably altered, the analysis of the hydrological and hydraulic process has never been reviewed. Undoubtedly, a modern study would ensure a more effective and accurate risk management within the Valencian metropolitan area. The development of a GIS-based model enables the utilization of these materials, most of them unpublished. This non-systematic information can be treated jointly from a new perspective. In short, this model facilitates the provision of a database through a vast amount of organized, structured and georeferenced information about the event. In a second stage, it makes possible to interpret the hydro-geomorphic processes from the 1957 event (trenches along barrier beaches, erosion, deposition processes…) and hydraulic processes (main flow encroachment versus quasi-hydrostatic-flood, or 1D versus 2D flood behavior), which can be identified in order to obtain georeferenced information about spatial variability, directional information of flows and point distribution of water levels and flooded points. It is also necessary to carry out photo-interpretation works to clarify some unresolved issues with the objective of establishing the real order of magnitude of the flash-flood concerning the discharge rank. In the same way, some other elements can be identified such as urban streams along the streets, levees overtopping and breaks, flooded area, etc. Lastly, in the future the GIS database will enable to obtain a more accurate both hydraulic mathematical modelling and calibration/validation.

Water quality, sediment, and soil characteristics near Fargo-Moorhead urban areas as affected by major flooding of the Red River of the north

Treesearch

A.C. Guy; T.M. DeSutter; F.X.M. Casey; R. Kolka; H. Hakk

2012-01-01

Spring flooding of the Red River of the North (RR) is common, but little information exits on how these flood events affect water and overbank sediment quality within an urban area. With the threat of the spring 2009 flood in the RR predicted to be the largest in recorded history and the concerns about the flooding of farmsteads, outbuildings, garages, and basements,...

An integrated modeling approach to predict flooding on urban basin.

PubMed

Dey, Ashis Kumar; Kamioka, Seiji

2007-01-01

Correct prediction of flood extents in urban catchments has become a challenging issue. The traditional urban drainage models that consider only the sewerage-network are able to simulate the drainage system correctly until there is no overflow from the network inlet or manhole. When such overflows exist due to insufficient drainage capacity of downstream pipes or channels, it becomes difficult to reproduce the actual flood extents using these traditional one-phase simulation techniques. On the other hand, the traditional 2D models that simulate the surface flooding resulting from rainfall and/or levee break do not consider the sewerage network. As a result, the correct flooding situation is rarely addressed from those available traditional 1D and 2D models. This paper presents an integrated model that simultaneously simulates the sewerage network, river network and 2D mesh network to get correct flood extents. The model has been successfully applied into the Tenpaku basin (Nagoya, Japan), which experienced severe flooding with a maximum flood depth more than 1.5 m on September 11, 2000 when heavy rainfall, 580 mm in 28 hrs (return period > 100 yr), occurred over the catchments. Close agreements between the simulated flood depths and observed data ensure that the present integrated modeling approach is able to reproduce the urban flooding situation accurately, which rarely can be obtained through the traditional 1D and 2D modeling approaches.

Analyzing Flash Flood Data in an Ultra-Urban Region

NASA Astrophysics Data System (ADS)

Smith, B. K.; Rodriguez, S.

2016-12-01

New York City is an ultra-urban region, with combined sewers and buried stream channels. Traditional flood studies rely on the presence of stream gages to detect flood stage and discharge, but ultra-urban regions frequently lack the surface stream channels and gages necessary for this approach. In this study we aggregate multiple non-traditional data for detecting flash flood events. These data including phone call reports, city records, and, for one particular flood event, news reports and social media reports. These data are compared with high-resolution bias-corrected radar rainfall fields to study flash flood events in New York City. We seek to determine if these non-traditional data will allow for a comprehensive study of rainfall-runoff relationships in New York City. We also seek to map warm season rainfall heterogeneities in the city and to compare them to spatial distribution of reported flood occurrence.

Sea-level Rise Increases the Frequency of Nuisance Flooding in Coastal Regions

NASA Astrophysics Data System (ADS)

Moftakhari Rostamkhani, H.; Aghakouchak, A.; Sanders, B. F.; Feldman, D.; Sweet, W.; Matthew, R.; Luke, A.

2015-12-01

The global warming-drivensea-level rise (SLR) posesa serious threat for population and assets in flood-prone coastal zones over the next century. The rate of SLR is accelerated in recent decades and is expected to increase based on current trajectories of anthropogenic activities and greenhouse gas emissions. Over the 20th century, an increase in the frequency of nuisance (minor) flooding has been reported due to the reduced gap between tidal datum and flood stage. Nuisance flooding (NF), however non-destructive, causes public inconvenience, business interruption, and substantial economic losses due to impacts such as road closures and degradation of infrastructure. It also portends an increased risk in severe floods. Here we report substantial increases in NF along the coasts of United States due to SLR over the past decades. We then take the projected SLR under the least and the most extreme representative concentration pathways (e.gRCP2.6 and RCP 8.5) to estimate the increase in NF in the near- (2030) and mid-term (2050) future. The results suggest that projected SLR will cause up to two-fold more frequent NF by 2050, compared with the 20th century. The projected increase in NF will have significant socio-economic impacts and pose public health risks especially in rapidly urbanized coastal regions.

An integrated simulation method for flash-flood risk assessment: 2. Effects of changes in land-use under a historical perspective

NASA Astrophysics Data System (ADS)

Rosso, R.; Rulli, M. C.

The influence of land use changes on flood occurrence and severity in the Bisagno River (Thyrrenian Liguria, N.W. Italy is investigated using a Monte Carlo simulation approach (Rulli and Rosso, 2002). High resolution land-use maps for the area were reconstructed and scenario simulations were made for a pre-industrial (1878), an intermediate (1930) and a current (1980) year. Land-use effects were explored to assess the consequences of distributed changes in land use due to agricultural practice and urbanisation. Hydraulic conveyance effects were considered, to assess the consequences of channel modifications associated with engineering works in the lower Bisagno River network. Flood frequency analyses of the annual flood series, retrieved from the simulations, were used to examine the effect of land-use change and river conveyance on flood regime. The impact of these effects proved to be negligible in the upper Bisagno River, moderate in the downstream river and severe in the small tributaries in the lower Bisagno valley that drain densely populated urban areas. The simulation approach is shown to be capable of incorporating historical data on landscape and river patterns into quantitative methods for risk assessment.

Changing Perceptions of Flooding and Stormwater as a Driver of Urban Hydrology and Biogeochemistry

NASA Astrophysics Data System (ADS)

Hale, R. L.

2015-12-01

Urbanization can have detrimental impacts on downstream ecosystems due to its effects on hydrological and biogeochemical cycles. In particular, how urban stormwater systems are designed have implications for flood regimes and biogeochemical transformations. Flood and stormwater management paradigms have shifted over time at large scales, but patterns and drivers of local stormwater infrastructure designs are unknown. We describe patterns of infrastructure design and use over the 20th century in three cities along an urbanization gradient in Utah: Salt Lake, Logan, and Heber City. To understand changes in stormwater management paradigms we conducted a historical media content analysis of newspaper articles related to flooding and stormwater in Salt Lake City from 1900 to 2012. Stormwater infrastructure design varied spatially and temporally, both within and among cities. All three cities transitioned from agriculture to urban land use, and legacies were evident in the use of agricultural canals for stormwater conveyance. Salt Lake City infrastructure transitioned from centralized storm sewers during early urbanization to decentralized detention systems in the 1970's. In contrast, newer cities, Logan and Heber, saw parallel increases in conveyance and detention systems with urbanization. The media analysis revealed significant changes in flood and stormwater management paradigms over the 20th century that were driven by complex factors including top-down regulations, local disturbances, and funding constraints. Early management paradigms focused on infrastructural solutions to address problems with private and public property damage, whereas more recent paradigms focus on behavioral solutions to flooding and green infrastructure solutions to prevent negative impacts of urban stormwater on local ecosystems. Changes in human perceptions of the environment can affect how we design urban ecosystems, with important implications for ecological functions.

The Study on Flood Reduction and Securing Instreamflow by applying Decentralized Rainwater Retention Facilities for Chunggyechun in Seoul of Korea

NASA Astrophysics Data System (ADS)

Park, J. H.; Jun, S. M.; Park, C. G.

2014-12-01

Recently abnormal climate phenomena and urbanization recently causes the changes of the hydrological environment. To restore the hydrological cycle in urban area some fundamental solutions such as decentralized rainwater management system and Low Impact Development (LID) techniques may be choosed. In this study, SWMM 5 was used to analyze the effects of decentralized stormwater retention for preventing the urban flood and securing the instreamflow. The Chunggyechun stream watershed(21.29㎢) which is located in Seoul city(Korea) and fully developed as urban area was selected as the study watershed, and the runoff characteristics of urban stream with various methods of LID techniques (Permeable pavement, small rainwater storage tank, large rainwater storage tank) were analyzed. By the simulation results, the permeability of pavement materials and detention storage at the surface soil layer make high effect to the flood discharge, and the initial rainfall retention at the rainwater storage tank effected to reduce the flood peak. The peak discharge was decreased as 22% for the design precipitation. Moreover the instreamflow was increased as 55% by using adequate LID techniques These kind of data could be used as the basis data for designing urban flood prevention facilities, urban regeneration planning in the view of the integrated watershed management.

Policy Implications and Suggestions on Administrative Measures of Urban Flood

NASA Astrophysics Data System (ADS)

Lee, S. V.; Lee, M. J.; Lee, C.; Yoon, J. H.; Chae, S. H.

2017-12-01

The frequency and intensity of floods are increasing worldwide as recent climate change progresses gradually. Flood management should be policy-oriented in urban municipalities due to the characteristics of urban areas with a lot of damage. Therefore, the purpose of this study is to prepare a flood susceptibility map by using data mining model and make a policy suggestion on administrative measures of urban flood. Therefore, we constructed a spatial database by collecting relevant factors including the topography, geology, soil and land use data of the representative city, Seoul, the capital city of Korea. Flood susceptibility map was constructed by applying the data mining models of random forest and boosted tree model to input data and existing flooded area data in 2010. The susceptibility map has been validated using the 2011 flood area data which was not used for training. The predictor importance value of each factor to the results was calculated in this process. The distance from the water, DEM and geology showed a high predictor importance value which means to be a high priority for flood preparation policy. As a result of receiver operating characteristic (ROC), random forest model showed 78.78% and 79.18% accuracy of regression and classification and boosted tree model showed 77.55% and 77.26% accuracy of regression and classification, respectively. The results show that the flood susceptibility maps can be applied to flood prevention and management, and it also can help determine the priority areas for flood mitigation policy by providing useful information to policy makers.

Modeling urban coastal flood severity from crowd-sourced flood reports using Poisson regression and Random Forest

NASA Astrophysics Data System (ADS)

Sadler, J. M.; Goodall, J. L.; Morsy, M. M.; Spencer, K.

2018-04-01

Sea level rise has already caused more frequent and severe coastal flooding and this trend will likely continue. Flood prediction is an essential part of a coastal city's capacity to adapt to and mitigate this growing problem. Complex coastal urban hydrological systems however, do not always lend themselves easily to physically-based flood prediction approaches. This paper presents a method for using a data-driven approach to estimate flood severity in an urban coastal setting using crowd-sourced data, a non-traditional but growing data source, along with environmental observation data. Two data-driven models, Poisson regression and Random Forest regression, are trained to predict the number of flood reports per storm event as a proxy for flood severity, given extensive environmental data (i.e., rainfall, tide, groundwater table level, and wind conditions) as input. The method is demonstrated using data from Norfolk, Virginia USA from September 2010 to October 2016. Quality-controlled, crowd-sourced street flooding reports ranging from 1 to 159 per storm event for 45 storm events are used to train and evaluate the models. Random Forest performed better than Poisson regression at predicting the number of flood reports and had a lower false negative rate. From the Random Forest model, total cumulative rainfall was by far the most dominant input variable in predicting flood severity, followed by low tide and lower low tide. These methods serve as a first step toward using data-driven methods for spatially and temporally detailed coastal urban flood prediction.

NEW STUDIES OF URBAN FLOOD FREQUENCY IN THE SOUTHEASTERN UNITED STATES.

USGS Publications Warehouse

Sauer, Vernon B.

1986-01-01

Five reports dealing with flood magnitude and frequency in urban areas in the southeastern United States have been published during the past 2 years by the U. S. Geological Survey (USGS). These reports are based on data collected in Tampa and Tallahassee, Florida; Atlanta, Georgia; and several cities in Alabama and Tennessee. Each report contains regression equations useful for estimating flood peaks for selected recurrence intervals at ungauged urban sites. A nationwide study of urban flood characteristics by the USGS published in 1983 contains equations for estimating urban peak discharges for ungauged sites. At the time that the nationwide study was conducted, data from only 35 sites in the southeastern United States were available. The five new reports contain data for 88 additional sites. These new data show that the seven-parameter estimating equations developed in the nationwide study are unbiased and have prediction errors less than those described in the nationwide report.

Geostatistical analysis of the flood risk perception queries in the village of Navaluenga (Central Spain)

NASA Astrophysics Data System (ADS)

Guardiola-Albert, Carolina; Díez-Herrero, Andrés; Amérigo, María; García, Juan Antonio; María Bodoque, José; Fernández-Naranjo, Nuria

2017-04-01

Flash floods provoke a high average mortality as they are usually unexpected events which evolve rapidly and affect relatively small areas. The short time available for minimizing risks requires preparedness and response actions to be put into practice. Therefore, it is necessary the development of emergency response plans to evacuate and rescue people in the context of a flash-flood hazard. In this framework, risk management has to integrate the social dimension of flash-flooding and its spatial distribution by understanding the characteristics of local communities in order to enhance community resilience during a flash-flood. In this regard, the flash-flood social risk perception of the village of Navaluenga (Central Spain) has been recently assessed, as well as the level of awareness of civil protection and emergency management strategies (Bodoque et al., 2016). This has been done interviewing 254 adults, representing roughly 12% of the population census. The present study wants to go further in the analysis of the resulting questionnaires, incorporating in the analysis the location of home spatial coordinates in order to characterize the spatial distribution and possible geographical interpretation of flood risk perception. We apply geostatistical methods to analyze spatial relations of social risk perception and level of awareness with distance to the rivers (Alberche and Chorrerón) or to the flood-prone areas (50-year, 100-year and 500-year flood plains). We want to discover spatial patterns, if any, using correlation functions (variograms). Geostatistical analyses results can help to either confirm the logical pattern (i.e., less awareness further to the rivers or high return period of flooding) or reveal departures from expected. It can also be possible to identify hot spots, cold spots, and spatial outliers. The interpretation of these spatial patterns can give valuable information to define strategies to improve the awareness regarding preparedness and response actions, such as designing optimal evacuation routes during flood emergencies. Geostatistical tools also provide a set of interpolation techniques for the prediction of the variable value at unstudied similar locations, basing on the sample point values and other variables related with the measured variable. We attempt different geostatistical interpolation methods to obtain continuous surfaces of the risk perception and level of awareness in the study area. The use of these maps for future extensions and actualizations of the Civil Protection Plan is evaluated. References Bodoque, J. M., Amérigo, M., Díez-Herrero, A., García, J. A., Cortés, B., Ballesteros-Cánovas, J. A., & Olcina, J. (2016). Improvement of resilience of urban areas by integrating social perception in flash-flood risk management.Journal of Hydrology.

Climate change impacts on urban wildfire and flooding policy in Idaho: a comparative policy network perspective

NASA Astrophysics Data System (ADS)

Lindquist, E.; Pierce, J. L.

2013-12-01

Numerous frameworks and models exist for understanding the dynamics of the public policy process. A policy network approach considers how and why stakeholders and interests pay attention to and engage in policy problems, such as flood control or developing resilient and fire resistant landscapes. Variables considered in this approach include what the relationships are between these stakeholders, how they influence the process and outcomes, communication patterns within and between policy networks, and how networks change as a result of new information, science, or public interest and involvement with the problem. This approach is useful in understanding the creation of natural hazards policy as new information or situations, such as projected climate change impacts, influence and disrupt the policy process and networks. Two significant natural hazard policy networks exist in the semi-arid Treasure Valley region of Southwest Idaho, which includes the capitol city of Boise and the surrounding metropolitan area. Boise is situated along the Boise River and adjacent to steep foothills; this physiographic setting makes Boise vulnerable to both wildfires at the wildland-urban interface (WUI) and flooding. Both of these natural hazards have devastated the community in the past and floods and fires are projected to occur with more frequency in the future as a result of projected climate change impacts in the region. While both hazards are fairly well defined problems, there are stark differences lending themselves to comparisons across their respective networks. The WUI wildfire network is large and well developed, includes stakeholders from all levels of government, the private sector and property owner organizations, has well defined objectives, and conducts promotional and educational activities as part of its interaction with the public in order to increase awareness and garner support for its policies. The flood control policy network, however, is less defined, dominated by a few historically strong interests and is constrained (and supported) by the complex legal and management foundations of Western water rights, as well as federal and state regulatory practices for flood control and water provision. Overlap between these networks does occur as many of the stakeholders are the same, adding another dimension to the comparative approach presented here. It is the physical and natural sciences that bind these two networks, however, and create opportunities for convergence as hydrological inputs (snowmelt and rain) and summer drought simultaneously inform and impact efforts to increase resilience and reduce vulnerability and risk from both fire and flood. For example, early spring snowmelt can both increase risks of flooding and contribute to later severe fire conditions, and fires greatly increase the risk of catastrophic floods and debris flows in burned basins. Contributing to both of these potential hazards are changes in the climate in the region. This paper will present findings from a comparative study of these two policy networks and discuss the implications from how climate change is defined, understood, accepted, and integrated in both networks and the policy processes associated with these urban hazards.

Combining Satellite Measurements and Numerical Flood Prediction Models to Save Lives and Property from Flooding

NASA Astrophysics Data System (ADS)

Saleh, F.; Garambois, P. A.; Biancamaria, S.

2017-12-01

Floods are considered the major natural threats to human societies across all continents. Consequences of floods in highly populated areas are more dramatic with losses of human lives and substantial property damage. This risk is projected to increase with the effects of climate change, particularly sea-level rise, increasing storm frequencies and intensities and increasing population and economic assets in such urban watersheds. Despite the advances in computational resources and modeling techniques, significant gaps exist in predicting complex processes and accurately representing the initial state of the system. Improving flood prediction models and data assimilation chains through satellite has become an absolute priority to produce accurate flood forecasts with sufficient lead times. The overarching goal of this work is to assess the benefits of the Surface Water Ocean Topography SWOT satellite data from a flood prediction perspective. The near real time methodology is based on combining satellite data from a simulator that mimics the future SWOT data, numerical models, high resolution elevation data and real-time local measurement in the New York/New Jersey area.

Blue-Green Solutions in Urban Development

NASA Astrophysics Data System (ADS)

Karlsson, Caroline; Kalantari, Zahra

2017-04-01

With the ongoing urbanisation and increasing pressure for new housing and infrastructure, the nexus of developing compact, energy-efficient and yet liveable and sustainable cities is urgent to address. In this context, blue-green spaces and related ecosystem services (ES) are critical resources that need to be integrated in policy and planning of urban. Among the ES provided by blue-green spaces, regulating ES such as water retention and purification are particularly important in urban areas, affecting water supply and quality, related cultural ES and biodiversity, as well as cities potential to adapt to climate change. Blue-green infrastructure management is considered a sustainable way to reducing negative effects of urbanisation, such as decreasing flood risks, as well as adapting to climate change for example by controlling increasing flood and drought risks. Blue-green infrastructure management can for example create multifunctional surfaces with valuable environmental and social functions and generally handle greenways and ecological networks as important ecosystem service components, for example for stormwater regulation in a sustainable urban drainage system. The Norrström drainage basin (22,000 km2) is a large demonstrator for Blue-green infrastructure management. Both urbanisation and agriculture are extensive within this basin, which includes the Swedish capital Stockholm and is part of the fertile Swedish belt. Together, the relatively high population density combined with agricultural and industrial activities in this region imply large eutrophication and pollution pressures, not least transferred through storm runoff to both inland surface waters and the coastal waters of the Baltic Sea. The ecosystems of this basin provide highly valued but also threatened services. For example, Lake Mälaren is the single main freshwater supply for the Swedish capital Stockholm, as well as a key nutrient retention system that strongly mitigates waterborne nutrient loads to the Baltic Sea a function that is in turn threatened by climate change. Large socio-economic values are also at stake here with regard to ecosystem regulation of both flood and drought risks, again threatened by both climate change and human development activities within the Norrström basin itself.

Human Leptospirosis Infection in Fiji: An Eco-epidemiological Approach to Identifying Risk Factors and Environmental Drivers for Transmission

PubMed Central

Lau, Colleen L.; Watson, Conall H.; Lowry, John H.; David, Michael C.; Craig, Scott B.; Wynwood, Sarah J.; Kama, Mike; Nilles, Eric J.

2016-01-01

Leptospirosis is an important zoonotic disease in the Pacific Islands. In Fiji, two successive cyclones and severe flooding in 2012 resulted in outbreaks with 576 reported cases and 7% case-fatality. We conducted a cross-sectional seroprevalence study and used an eco-epidemiological approach to characterize risk factors and drivers for human leptospirosis infection in Fiji, and aimed to provide an evidence base for improving the effectiveness of public health mitigation and intervention strategies. Antibodies indicative of previous or recent infection were found in 19.4% of 2152 participants (81 communities on the 3 main islands). Questionnaires and geographic information systems data were used to assess variables related to demographics, individual behaviour, contact with animals, socioeconomics, living conditions, land use, and the natural environment. On multivariable logistic regression analysis, variables associated with the presence of Leptospira antibodies included male gender (OR 1.55), iTaukei ethnicity (OR 3.51), living in villages (OR 1.64), lack of treated water at home (OR 1.52), working outdoors (1.64), living in rural areas (OR 1.43), high poverty rate (OR 1.74), living <100m from a major river (OR 1.41), pigs in the community (OR 1.54), high cattle density in the district (OR 1.04 per head/sqkm), and high maximum rainfall in the wettest month (OR 1.003 per mm). Risk factors and drivers for human leptospirosis infection in Fiji are complex and multifactorial, with environmental factors playing crucial roles. With global climate change, severe weather events and flooding are expected to intensify in the South Pacific. Population growth could also lead to more intensive livestock farming; and urbanization in developing countries is often associated with urban and peri-urban slums where diseases of poverty proliferate. Climate change, flooding, population growth, urbanization, poverty and agricultural intensification are important drivers of zoonotic disease transmission; these factors may independently, or potentially synergistically, lead to enhanced leptospirosis transmission in Fiji and other similar settings. PMID:26820752

Methods for estimating the magnitude and frequency of floods for urban and small, rural streams in Georgia, South Carolina, and North Carolina, 2011

USGS Publications Warehouse

Feaster, Toby D.; Gotvald, Anthony J.; Weaver, J. Curtis

2014-01-01

Reliable estimates of the magnitude and frequency of floods are essential for the design of transportation and water-conveyance structures, flood-insurance studies, and flood-plain management. Such estimates are particularly important in densely populated urban areas. In order to increase the number of streamflow-gaging stations (streamgages) available for analysis, expand the geographical coverage that would allow for application of regional regression equations across State boundaries, and build on a previous flood-frequency investigation of rural U.S Geological Survey streamgages in the Southeast United States, a multistate approach was used to update methods for determining the magnitude and frequency of floods in urban and small, rural streams that are not substantially affected by regulation or tidal fluctuations in Georgia, South Carolina, and North Carolina. The at-site flood-frequency analysis of annual peak-flow data for urban and small, rural streams (through September 30, 2011) included 116 urban streamgages and 32 small, rural streamgages, defined in this report as basins draining less than 1 square mile. The regional regression analysis included annual peak-flow data from an additional 338 rural streamgages previously included in U.S. Geological Survey flood-frequency reports and 2 additional rural streamgages in North Carolina that were not included in the previous Southeast rural flood-frequency investigation for a total of 488 streamgages included in the urban and small, rural regression analysis. The at-site flood-frequency analyses for the urban and small, rural streamgages included the expected moments algorithm, which is a modification of the Bulletin 17B log-Pearson type III method for fitting the statistical distribution to the logarithms of the annual peak flows. Where applicable, the flood-frequency analysis also included low-outlier and historic information. Additionally, the application of a generalized Grubbs-Becks test allowed for the detection of multiple potentially influential low outliers. Streamgage basin characteristics were determined using geographical information system techniques. Initial ordinary least squares regression simulations reduced the number of basin characteristics on the basis of such factors as statistical significance, coefficient of determination, Mallow’s Cp statistic, and ease of measurement of the explanatory variable. Application of generalized least squares regression techniques produced final predictive (regression) equations for estimating the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probability flows for urban and small, rural ungaged basins for three hydrologic regions (HR1, Piedmont–Ridge and Valley; HR3, Sand Hills; and HR4, Coastal Plain), which previously had been defined from exploratory regression analysis in the Southeast rural flood-frequency investigation. Because of the limited availability of urban streamgages in the Coastal Plain of Georgia, South Carolina, and North Carolina, additional urban streamgages in Florida and New Jersey were used in the regression analysis for this region. Including the urban streamgages in New Jersey allowed for the expansion of the applicability of the predictive equations in the Coastal Plain from 3.5 to 53.5 square miles. Average standard error of prediction for the predictive equations, which is a measure of the average accuracy of the regression equations when predicting flood estimates for ungaged sites, range from 25.0 percent for the 10-percent annual exceedance probability regression equation for the Piedmont–Ridge and Valley region to 73.3 percent for the 0.2-percent annual exceedance probability regression equation for the Sand Hills region.

Unraveling the impact of built-environmental self-modification of the local inhabitants in their attempt to reduce the urban flood impact in Grogol, Sukoharjo*

NASA Astrophysics Data System (ADS)

Wanabakti, M. J.; Susilo, C. R.; Nathania, M.; Putri, C. Y.

2018-05-01

Due in part to climate change impact and the lack of environmental awareness of urban societies, urban flood disasters have increased in both frequency and impacted areas. The inevitable destructive impact is also experienced by urban inhabitants within Grogol District, Sukoharjo, Central Java. Situated within the fast-growing peri-urban area of Surakarta, the geographical condition of the district, which is located in the convergence of Bengawan Solo River and four different streamlet rivers is undoubtedly critical to flood. Since the position of the peri-urban area is along the border of Surakarta City and Sukoharjo Regency, the site is a strategic locus of the main city’s urban expansion. However, its border location has made flood-reduction programs challenging to be implemented, due to unclear territorial admiration and distribution. Because of the absence of flood-reduction programs in the area, local inhabitants have been independently developing physical and built environmental modification of their settlements. By analyzing the two-months built environmental fieldwork research in Grogol Sukoharjo, this paper unravels both the success and the conflicting impact of local self-initiative modification in Grogol Sukoharjo. By combining the two-month field observation with the semi-structured interviews in three sub-districts of Grogol, this paper finds that the very pragmatic self-modification taken by the inhabitants results in short-term reductions of flood impact and increases the secure feelings of inhabitants to continue living in their neighborhoods. However, the lack of proper technical supervision from experts and the absence of inter-neighborhood coordination leads to future additional damage on the flood-prone areas of Grogol. The paper also reveals that one pragmatic physical self-modification solution taken by one neighborhood may lead to an extra flood-threat to other neighborhoods.

Integrated flood damage modelling in the Ebro river basin under hydrodynamic, socio-economic and environmental factors

NASA Astrophysics Data System (ADS)

Foudi, S.; Galarraga, I.; Osés, N.

2012-04-01

This paper presents a model of flood damage measurement. It studies the socio-economic and environmental potential damage of floods in the Ebro river basin. We estimate the damage to the urban, rural and environmental sectors. In these sectors, we make distinctions between residential, non residential, cultural, agricultural, public facilities and utilities, environmental and human subsectors. We focus on both the direct, indirect, tangible and intangible impacts. The residential damages refer to the damages on housing, costs of repair and cleaning as direct effects and the re-housing costs as an indirect effect. The non residential and agricultural impacts concern the losses to the economic sectors (industry, business, agricultural): production, capital losses, costs of cleaning and repairs for the direct costs and the consequences of the suspension of activities for the indirect costs. For the human sector, we refer to the physical impacts (injuries and death) in the direct tangible effects and to the posttraumatic stress as indirect intangible impact. The environmental impacts focus on a site of Community Interests (pSCIs) in the case study area. The case study is located the Ebro river basin, Spain. The Ebro river basin is the larger river basin in term of surface and water discharge. The Ebro river system is subject to Atlantic and Mediterranean climatic influences. It gathers most of its water from the north of Spain (in the Pyrenees Mountains) and is the most important river basin of Spain in term of water resources. Most of the flooding occurs during the winter period. Between 1900- 2010, the National Catalogue of Historical Floods identifies 372 events: meanly 33 events every 10 years and up to 58 during the 1990-2000. Natural floods have two origins: (i) persistent rainfalls in large sub basins raised up by high temperature giving rise to a rapid thaw in the Pyrenees, (ii) local rainfalls of short duration and high intensity that gives rise to rapid and wrenching floods. Our integrated model combines hydrologic, land use, environmental and economic data. The combination of the cadastral data with the flood characteristics (flow, depth, duration) for various periods of return enables to draw damage maps expressed as function of flood characteristics (Penning-Rowsell et al. 2005). This methodology also enables to illustrate consequences of risk prevention measures. We can thus measure the value of information in the alert system of Civil Protection Agency, give information on risks for urban development plans and simulate the consequences of hydraulic interventions like river bed cleaning. This methodology would then contribute to match with the requirements of the 2007 EU flood risk Management Directive (2007/60/CE).

Delivery of Ecosystem Benefits at the Urban-Suburban Interface: A Case Study of Flood Protection in the Woonasquatucket River Watershed

EPA Science Inventory

Urbanization exacerbates flooding by increasing surface runoff and decreasing surface roughness. Restoring wetlands can enhance flood protection while providing a suite of co-benefits such as temperature regulation and access to open space. Spatial modeling of the delivery of flo...

Flood hazards in the Seattle-Tacoma urban complex and adjacent areas, Washington

USGS Publications Warehouse

Foxworthy, B.L.; Nassar, E.G.

1975-01-01

Floods are natural hazards that have complicated man's land-use planning for as long as we have had a history. Although flood hzards are a continuing danger, the year-to-year threat cannot be accurately predicted. Also, on any one stream, the time since the last destructive flood might be so long that most people now living near the stream have not experienced such a flood. Because of the unpredictability and common infrequency of disastrous flooding, or out of ignorance about the danger, or perhaps because of an urge to gamble, man tends to focus his attention on only the advantages of the flood-prone areas, rather than the risk due to the occasional major flood. The purposes of this report are to: (1) briefly describe flood hazards in this region, including some that may be unique to the Puget Sound basin, (2) indicate the parts of the area for which flood-hazard data are available, and (3) list the main sources of hydrologic information that is useful for flood-hazard analysis in conjuction with long-range planning. This map-type report is one of a series being prepared by the U.S. Geological Survey to present basic environmental information and interpretations to assist land-use planning in the Puget Sound region.

Monitoring and Risk Identification Caused by High Water, Floods and Erosion Processes in Urban Part of Sava Riverbed

NASA Astrophysics Data System (ADS)

Oskoruš, D.; Miković, N.; Ljevar, I.

2012-04-01

Riverbed erosion and bottom deepening are part of natural fluvial processes in the upper stream of Sava River. The increasing gradient of those changes is interconnected with the level of human influence in the river basin and riverbed as well. In time period of last forty years the consequences of riverbed erosion are become serious as well as dangerous and they threaten the stability of hydro technical structures. The increasing value of flow velocity in riverbed in urban part of river section during high water level, mud and debris flow during the floods as well, is especially dangerous for old bridges. This paper contains result of velocity measurements during high waters taken by Hydrological Service of Republic Croatia, load transport monitoring during such events and cross sections in some vulnerable location. In this paper is given one example of Jakuševac railway bridge in Zagreb, heavily destroyed during high water event on the 30 March 2009., recently reconstructed by "Croatian Railways" company. Keywords: Riverbed erosion, flow velocity, mud and debris flow, risk identification, stability of bridges

Coupling Analysis of Heat Island Effects, Vegetation Coverage and Urban Flood in Wuhan

NASA Astrophysics Data System (ADS)

Liu, Y.; Liu, Q.; Fan, W.; Wang, G.

2018-04-01

In this paper, satellite image, remote sensing technique and geographic information system technique are main technical bases. Spectral and other factors comprehensive analysis and visual interpretation are main methods. We use GF-1 and Landsat8 remote sensing satellite image of Wuhan as data source, and from which we extract vegetation distribution, urban heat island relative intensity distribution map and urban flood submergence range. Based on the extracted information, through spatial analysis and regression analysis, we find correlations among heat island effect, vegetation coverage and urban flood. The results show that there is a high degree of overlap between of urban heat island and urban flood. The area of urban heat island has buildings with little vegetation cover, which may be one of the reasons for the local heavy rainstorms. Furthermore, the urban heat island has a negative correlation with vegetation coverage, and the heat island effect can be alleviated by the vegetation to a certain extent. So it is easy to understand that the new industrial zones and commercial areas which under constructions distribute in the city, these land surfaces becoming bare or have low vegetation coverage, can form new heat islands easily.

A comparative analysis: storm water pollution policy in California, USA and Victoria, Australia.

PubMed

Swamikannu, X; Radulescu, D; Young, R; Allison, R

2003-01-01

Urban drainage systems historically were developed on principles of hydraulic capacity for the transport of storm water to reduce the risk of flooding. However, with urbanization the percent of impervious surfaces increases dramatically resulting in increased flood volumes, peak discharge rates, velocities and duration, and a significant increase in pollutant loads. Storm water and urban runoff are the leading causes of the impairment of receiving waters and their beneficial uses in Australia and the United States today. Strict environmental and technology controls on wastewater treatment facilities and industry for more than three decades have ensured that these sources are less significant today as the cause of impairment of receiving waters. This paper compares the approach undertaken by the Environmental Protection Authority Victoria for the Melbourne metropolitan area with the approach implemented by the California Environmental Protection Agency for the Los Angeles area to control storm water pollution. Both these communities are largely similar in population size and the extent of urbanization. The authors present an analysis of the different approaches contrasting Australia with the USA, comment on their comparative success, and discuss the relevance of the two experiences for developed and developing nations in the context of environmental policy making to control storm water and urban runoff pollution.

Benefit Assessment for Urban Rainwater Measure Configuration Mode in Beijing Based on PROMETHEE Method

NASA Astrophysics Data System (ADS)

Tian, L.; Shu, A. P.; Huang, L.

2017-12-01

Along with accelerating in Chinese urbanization, a increasing number of urban construction projects have been built, which cause the growth of impervious surface ratio in cities. Large areas of impervious surface hinders city normal natural water cycles, increases surface runoff coefficient, brings flood peak forward, and increases risk of flooding . Therefore, with the view of reducing risk of urban waterlogging disaster, improving water resource cyclic utilization, and maximizing recovery of urban eco-hydrological process, China begins to promote Sponge city construction using LID as core idea. The paper take five kinds of collecting and utilization rainwater measure as research example, analysis their characteristic ,take investment cost, economic benefit and enviromental benefit as principle of assessment. The weight of the evaluation criterion are gained by entropy method. The final evaluation of urban stormwater measures configuration mode based on the low impact development with PROMETHEE method . The sensitivity of evaluation criterion are analysised by GAIA. Finally, the examples are given to explain the feasibility . The result shows that comprehensive benefit of the mode containing green roof, permeable pavement, Sunken green space and rainwater harvesting tank is the highest. It turn out that reasonable and various types rainwater measures and high land utilization is significant for increasing the its comprehensive efficiency. Besides, the environmental benefit of urban rainwater measures is significantly greater than the economic benefit. There is a positive correlation between plant significantly greater than the economic benefit. There is a positive correlation between plant shallow groove, sunken green space and comprehensive benefit of rainwater measure. Because they can effectively removes water pollutants in stormwater. The studies not only have a great significance in optimizing configuration mode of urban rainwater measures, but also push development of the sponge city construction and propel exploration in developmental model of ideal city forward.

The development of manufactured flood risk: New Orleans' mid-century growth machine and the hurricane of 1947.

PubMed

Youngman, Nicole

2015-10-01

Much of the flood risk faced by coastal and riparian populations worldwide is manufactured rather than strictly natural--the outcome of human development projects involving municipal growth machines. This paper details the impacts of the hurricane of September 1947 on New Orleans, Louisiana, United States, and its relationship with the urban development and expansion efforts undertaken during and after the Second World War of 1939-45. New Orleans' newest drainage and shipping canals, which were a major part of its mid-twentieth century development initiative, funnelled the storm surge into the city, a pattern that would repeat itself in subsequent years. Unlike more infamous hurricanes, such as Betsy and Katrina of 1965 and 2005, respectively, the 1947 event is not well-known among disaster researchers. Yet, it provides a fundamental example of how local elites have continuously exacerbated flood risk throughout the city and surrounding area, leaving it simultaneously dependent on and endangered by its embedded system of drainage and shipping canals. © 2015 The Author(s). Disasters © Overseas Development Institute, 2015.

Return period curves for extreme 5-min rainfall amounts at the Barcelona urban network

NASA Astrophysics Data System (ADS)

Lana, X.; Casas-Castillo, M. C.; Serra, C.; Rodríguez-Solà, R.; Redaño, A.; Burgueño, A.; Martínez, M. D.

2018-03-01

Heavy rainfall episodes are relatively common in the conurbation of Barcelona and neighbouring cities (NE Spain), usually due to storms generated by convective phenomena in summer and eastern and south-eastern advections in autumn. Prevention of local flood episodes and right design of urban drainage have to take into account the rainfall intensity spread instead of a simple evaluation of daily rainfall amounts. The database comes from 5-min rain amounts recorded by tipping buckets in the Barcelona urban network along the years 1994-2009. From these data, extreme 5-min rain amounts are selected applying the peaks-over-threshold method for thresholds derived from both 95% percentile and the mean excess plot. The return period curves are derived from their statistical distribution for every gauge, describing with detail expected extreme 5-min rain amounts across the urban network. These curves are compared with those derived from annual extreme time series. In this way, areas in Barcelona submitted to different levels of flood risk from the point of view of rainfall intensity are detected. Additionally, global time trends on extreme 5-min rain amounts are quantified for the whole network and found as not statistically significant.

Development of river flood model in lower reach of urbanized river basin

NASA Astrophysics Data System (ADS)

Yoshimura, Kouhei; Tajima, Yoshimitsu; Sanuki, Hiroshi; Shibuo, Yoshihiro; Sato, Shinji; Lee, SungAe; Furumai, Hiroaki; Koike, Toshio

2014-05-01

Japan, with its natural mountainous landscape, has demographic feature that population is concentrated in lower reach of elevation close to the coast, and therefore flood damage with large socio-economic value tends to occur in low-lying region. Modeling of river flood in such low-lying urbanized river basin is complex due to the following reasons. In upstream it has been experienced urbanization, which changed land covers from natural forest or agricultural fields to residential or industrial area. Hence rate of infiltration and runoff are quite different from natural hydrological settings. In downstream, paved covers and construct of sewerage system in urbanized areas affect direct discharges and it enhances higher and faster flood peak arrival. Also tidal effect from river mouth strongly affects water levels in rivers, which must be taken into account. We develop an integrated river flood model in lower reach of urbanized areas to be able to address above described complex feature, by integrating model components: LSM coupled distributed hydrological model that models anthropogenic influence on river discharges to downstream; urban hydrological model that simulates run off response in urbanized areas; Saint Venant's equation approximated river model that integrates upstream and urban hydrological models with considering tidal effect from downstream. These features are integrated in a common modeling framework so that model interaction can be directly performed. The model is applied to the Tsurumi river basin, urbanized low-lying river basin in Yokohama and model results show that it can simulate water levels in rivers with acceptable model errors. Furthermore the model is able to install miscellaneous water planning constructs, such as runoff reduction pond in urbanized area, flood control field along the river channel, levee, etc. This can be a useful tool to investigate cost performance of hypothetical water management plan against impact of climate change in the region.

Quantification of flash flood economic risk using ultra-detailed stage-damage functions and 2-D hydraulic models

NASA Astrophysics Data System (ADS)

Garrote, J.; Alvarenga, F. M.; Díez-Herrero, A.

2016-10-01

The village of Pajares de Pedraza (Segovia, Spain) is located in the floodplain of the Cega River, a left bank tributary of the Douro River. Repeated flash flood events occur in this small village because of its upstream catchment area, mountainous character and impermeable lithology, which reduce concentration time to just a few hours. River overbank flow has frequently caused flooding and property damage to homes and rural properties, most notably in 1927, 1991, 1996, 2001, 2013 and 2014. Consequently, a detailed analysis was carried out to quantify the economic risk of flash floods in peri-urban and rural areas. Magnitudes and exceedance probabilities were obtained from a flood frequency analysis of maximum discharges. To determine the extent and characteristics of the flooded area, we performed 2D hydraulic modeling (Iber 2.0 software) based on LIDAR (1 m) topography and considering three different scenarios associated with the initial construction (1997) and subsequent extension (2013) of a linear defense structure (rockfill dike or levee) to protect the population. Specific stage-damage functions were expressly developed using in situ data collection for exposed elements, with special emphasis on urban-type categories. The average number of elements and their unit value were established. The relationship between water depth and the height at which electric outlets, furniture, household goods, etc. were located was analyzed; due to its effect on the form of the function. Other nonspecific magnitude-damage functions were used in order to compare both economic estimates. The results indicate that the use of non-specific magnitude-damage functions leads to a significant overestimation of economic losses, partly linked to the use of general economic cost data. Furthermore, a detailed classification and financial assessment of exposed assets is the most important step to ensure a correct estimate of financial losses. In both cases, this should include a consideration of the socio-economic and cultural conditions prevailing in the area, as well as the types of flood that affect it.

We have the technology, but can we use it? Building flood risk capacity amongst property owners in England.

NASA Astrophysics Data System (ADS)

White, Iain; Connelly, Angela; O'Hare, Paul; Lawson, Nigel

2013-04-01

The UK's Meteorological Office has provisionally confirmed 2012 to be the second wettest recorded in the country (The Met Office, 2013). Volatile weather patterns resulted in much social and economic disruption and damage from floods. The UK's Flood and Water Management Act (2010) has placed responsibility for flood risk management primarily at local level. In reality, various agencies are responsible for managing flood risk resulting in a fragmented system that communities struggle to make sense of. Strengthening emergency response during a flood event is one strategy to build capacity. However, resilience has emerged as an operative policy, and points to a need for anticipatory approaches. These should extend beyond large-scale flood defenses or measures that reduce the vulnerability of infrastructures and buildings in order to incorporate social vulnerability through the establishment of warning systems and capacity building (White 2010). To this, small-scale, innovative technologies - from automatic door guards and 'smart' air bricks - hold the potential to manage the uncertainty around flood risk before an event occurs. However, innovative technologies are often resisted by institutions, technical systems, cultural preferences, and legislation, which require a multifaceted approach that addresses the social, cultural, economic and technical domains (De Graaf 2009). We present a case study that explores the barriers that inhibit the uptake of property level technologies in England by various actors: from property owners and manufacturers, to municipal authorities and built environment professionals. Through the case study, we demonstrate how these various stakeholders were involved in identifying the procedural principles to overcome these barriers and to integrate property level technologies more fully into an overall flood risk management system. Following this, best practice guidance was designed and we show the means by which such guidance can improve social capacity even where there is much uncertainty. The paper ends by describing the transferable lessons learned through the development of this tool and concludes on the potential of property level protection to manage flood risk across Europe. References de Graaf, R. E. (2009). Urban water innovations to reduce the vulnerability of cities. Feasibility and mainstreaming of technologies in society, Ph. D thesis, Delft University of Technology. Available at: www.deltasync.nl/reports/De_Graaf_thesis.pdf [Accessed 29 December 2012]. The Met Office. (2013) Statistics for December and 2012 - is the UK getting wetter? [Online resource]. Available at: http://www.metoffice.gov.uk/news/releases/archive/2013/2012-weather-statistics [Accessed 6 January 2012]. White, I. (2010). Water and the city: Risk resilience and planning for a sustainable future. London: Routledge.

Flash flood hazard assessment through modelling in small semi-arid watersheds. The example of the Beni Mellal watershed in Morocco

NASA Astrophysics Data System (ADS)

Werren, G.; Balin, D.; Reynard, E.; Lane, S. N.

2012-04-01

Flood modelling is essential for flood hazard assessment. Modelling becomes a challenge in small, ungauged watersheds prone to flash floods, like the ones draining the town of Beni Mellal (Morocco). Four temporary streams meet in the urban area of Beni Mellal, producing every year sheet floods, harmful to infrastructure and to people. Here, statistical analysis may not give realistic results, but the study of these repeated real flash flood events may provide a better understanding of watershed specific hydrology. This study integrates a larger cooperation project between Switzerland and Morroco, aimed at knowledge transfer in disaster risk reduction, especially through hazard mapping and land-use planning, related to implementation of hazard maps. Hydrologic and hydraulic modelling was carried out to obtain hazard maps. An important point was to find open source data and methods that could still produce a realistic model for the area concerned, in order to provide easy-to-use, cost-effective tools for risk management in developing countries like Morocco, where routine data collection is largely lacking. The data used for modelling is the Web available TRMM 3-Hour 0.25 degree rainfall data provided by the Tropical Rainfall Measurement Mission Project (TRMM). Hydrologic modelling for discharge estimation was undertaken using methods available in the HEC-HMS software provided by the US Army Corps of Engineers® (USACE). Several transfer models were used, so as to choose the best-suited method available. As no model calibration was possible for no measured flow data was available, a one-at-the-time sensitivity analysis was performed on the parameters chosen, in order to detect their influence on the results. But the most important verification method remained field observation, through post-flood field campaigns aimed at mapping water surfaces and depths in the flooded areas, as well as river section monitoring, where rough discharge estimates could be obtained using empirical equations. Another information source was local knowledge, as people could give a rough estimation of concentration time by describing flood evolution. Finally, hydraulic modelling of the flooded areas in the urban perimeter was performed using the USACE HEC-RAS® software capabilities. A specific challenge at this stage was field morphology, as the flooded areas form large alluvial fans, with very different flood behaviour compared to flood plains. Model "calibration" at this stage was undertaken using the mapped water surfaces and depths. Great care was taken for field geometry design, where field observations, measured cross sections and field images were used to improve the existing DTM data. The model included protection dikes already built by local authorities in their flood-fight effort. Because of flash-flood specific behaviour, only maximal flooded surfaces and flow velocities were simulated through steady flow analysis in HEC-RAS. The discharge estimates obtained for the chosen event were comparable to 10-year return periods as estimated by the watershed authorities. Times of concentration correspond to this previous estimation and to local people descriptions. The modelled water surfaces reflect field reality. Flash-flood modelling demands extensive knowledge of the studied field in order to compensate data scarcity. However, more precise data, like radar rainfall estimates available in Morocco, would definitely improve outputs. In this perspective, better data access at the local level and good use of the available methods could benefit the disaster risk reduction effort as a whole.

Assessment of stormwater runoff management practices and BMPs under soil sealing: A study case in a peri-urban watershed of the metropolitan area of Rome (Italy).

PubMed

Recanatesi, Fabio; Petroselli, Andrea; Ripa, Maria Nicolina; Leone, Antonio

2017-10-01

By 2006, almost 100,000 km 2 of EU soil (2.3% of the whole territory) had been sealed, with a per capita quota of 200 m 2 of sealed surface for each EU citizen. Italy, in 2016, recorded a soil sealing rate of 2.8% of the entire territory. In this context, the urban expansion which occurred in past decades is considered one of the main causes of the increase in flood frequency and intensity in small catchments, causing both social and financial damage. In the present paper, the positive impact of introducing Best Management Practices (BMPs) at urban scale is assessed, with particular regard to the decreasing of flood prone areas. A suburban watershed of the metropolitan area of Rome has been selected for a study case, as its soil sealing rate can be considered paradigmatic at this scale. Starting from the analysis of rainfall events occurring between 2008 and 2011 which caused millions of euros worth of damage, and using a high resolution data set in a GIS environment, two scenarios, with and without BMP introduction, are evaluated applying a rainfall-runoff model and a bidimensional hydraulic model. From a comparison of the flood maps with and without the introduction of BMPs, it was determined that in 90% of the circumstances the employment of the BMPs would completely remove the hydraulic risk, while in the remaining 10% the BMP would at least reduce the areas subjected to flooding. Copyright © 2017 Elsevier Ltd. All rights reserved.

Two dimensional modelling of flood flows and suspended sediment transport: the case of Brenta River

NASA Astrophysics Data System (ADS)

D'Alpaos, L.; Martini, P.; Carniello, L.

2003-04-01

The paper deals with numerical modelling of flood waves and suspended sediment in plain river basins. The two dimensional depth integrated momentum and continuity equations, modified to take into account of the bottom irregularities that strongly affect the hydrodynamic and the continuity in partially dry areas (for example, during the first stages of a plain flooding and in tidal flows), are solved with a standard Galerkin finite element method using a semi-implicit numerical scheme and considering the role both of the small channel network and the regulation dispositive on the flooding wave propagation. Transport of suspended sediment and bed evolution are coupled with the flood propagation through the convection-dispersion equation and the Exner's equation. Results of a real case study are presented in which the effects of extreme flood of Brenta River (Italy) are examinated. The flooded areas (urban and rural areas) are identified and a mitigation solution based on a diversion channel flowing into Venice Lagoon is proposed. We show that this solution strongly reduces the flood risk in the downstream areas and can provide an important sediment source to the Venice Lagoon. Finally, preliminary results of the sediment dispersion in the Venice Lagoon are presented.

Impact of altered land use on urban hydrology and strategic management practices on flooding problems

USDA-ARS?s Scientific Manuscript database

This paper describes the impact of altered land use on urban flooding in Northwest Indiana over a 10-year time span between 1992 and 2001. The studied watershed, Great Calumet Basin, is located on the south shore of Lake Michigan, which is well known as a highly industrialized area. The flood peaks ...

Telling and measuring urban floods: event reconstruction by means of public-domain media

NASA Astrophysics Data System (ADS)

Macchia, S.; Gallo, E.; Claps, P.

2012-04-01

In the last decade, the diffusion of mobile telephones and ond of low-cost digital cameras have changed the public approach to catastrophes. As regards floods, it has become widespread the availability of images and videos taken in urban areas. Searching into Youtube or Youreporter, for example, one can understand how often citizen are considering to report even scary events. Nowadays these amateurs videos are often used in news world reports, which often increase or dampen the public perception of flood risk. More importantly, these amateur videos can play a crucial role in a didactic and technical representation of media flooding problems. The question so arise: why don't use the amateur videos for civil protection purposes? This work shows a new way to use flood images and videos to obtain technical data and spread safety information. Specifically, we show how to determine the height and speed of water flow, which have been achieved in some places during Genoa flood - 4th November 2011 - For this event we have downloaded more than 50 videos from different websites, where the authors have provided information about the time of recording, the geographical coordinates and the height above ground of the point of recording. The support by Google tools, such as Google maps and StreetWiew © has allowed us to geographically locate the recording points, so to put together shots and slides necessary to put together a whole reconstruction of the event. Future research will be in the direction of using these videos to generate a tool for the Google platforms, in order to address an easily achievable, yet accurate, information to the public, so to warn people on how to behave in front of imminent floods.

Land cover change impact on urban flood modeling (case study: Upper Citarum watershed)

NASA Astrophysics Data System (ADS)

Siregar, R. I.

2018-03-01

The upper Citarum River watershed utilizes remote sensing technology in Geographic Information System to provide information on land coverage by interpretation of objects in the image. Rivers that pass through urban areas will cause flooding problems causing disadvantages, and it disrupts community activities in the urban area. Increased development in a city is related to an increase in the number of population growth that added by increasing quality and quantity of life necessities. Improved urban lifestyle changes have an impact on land cover. The impact in over time will be difficult to control. This study aims to analyze the condition of flooding in urban areas caused by upper Citarum watershed land-use change in 2001 with the land cover change in 2010. This modeling analyzes with the help of HEC-RAS to describe flooded inundation urban areas. Land cover change in upper Citarum watershed is not very significant; it based on the results of data processing of land cover has the difference of area that changed is not enormous. Land cover changes for the floods increased dramatically to a flow coefficient for 2001 is 0.65 and in 2010 at 0.69. In 2001, the inundation area about 105,468 hectares and it were about 92,289 hectares in 2010.

Investigation of Flood Risk Assessment in Inaccessible Regions using Multiple Remote Sensing and Geographic Information Systems

NASA Astrophysics Data System (ADS)

Lim, J.; Lee, K. S.

2017-12-01

Flooding is extremely dangerous when a river overflows to inundate an urban area. From 1995 to 2016, North Korea (NK) experienced annual extensive damage to life and property almost each year due to a levee breach resulting from typhoons and heavy rainfall during the summer monsoon season. Recently, Hoeryeong City (2016) experienced heavy rainfall during typhoon Lionrock and the resulting flood killed and injured many people (68,900) and destroyed numerous buildings and settlements (11,600). The NK state media described it as the biggest national disaster since 1945. Thus, almost all annual repeat occurrences of floods in NK have had a serious impact, which makes it necessary to figure out the extent of floods in restoring the damaged environment. In addition, traditional hydrological model is impractical to delineate Flood Damaged Areas (FDAs) in NK due to the inaccessibility. Under such a situation, multiple optical Remote Sensing (RS) and radar RS along with a Geographic Information System (GIS)-based spatial analysis were utilized in this study (1) to develop modelling FDA delineation using multiple RS and GIS methods and (2) to conduct flood risk assessment in NK. Interpreting high-resolution web-based satellite imagery were also implemented to confirm the results of the study. From the study result, it was found that (1) on August 30th, 2016, an area of 117.2 km2 (8.6%) at Hoeryeong City was inundated. Most floods occurred in flat areas with a lower and middle stream order. (2) In the binary logistic regression model applied in this study, the distance from the nearest stream map and landform map variables are important factors to delineate FDAs because these two factors reflect heterogeneous mountainous NK topography. (3) Total annual flood risk of study area is estimated to be ₩454.13 million NKW ($504,417.24 USD, and ₩576.53 million SKW). The risk of the confluence of the Tumen River and Hoeryeong stream appears to be the highest. (4) High resolution satellite images can be used to confirm study results as ground truth data in this study, which shows the possibility of further application in environmental research of NK. Ultimately, this study provides recommendations to improve flood risk management in NK upon reunification.

Urban RoGeR: Merging process-based high-resolution flash flood model for urban areas with long-term water balance predictions

NASA Astrophysics Data System (ADS)

Weiler, M.

2016-12-01

Heavy rain induced flash floods are still a serious hazard and generate high damages in urban areas. In particular in the spatially complex urban areas, the temporal and spatial pattern of runoff generation processes at a wide spatial range during extreme rainfall events need to be predicted including the specific effects of green infrastructure and urban forests. In addition, the initial conditions (soil moisture pattern, water storage of green infrastructure) and the effect of lateral redistribution of water (run-on effects and re-infiltration) have to be included in order realistically predict flash flood generation. We further developed the distributed, process-based model RoGeR (Runoff Generation Research) to include the relevant features and processes in urban areas in order to test the effects of different settings, initial conditions and the lateral redistribution of water on the predicted flood response. The uncalibrated model RoGeR runs at a spatial resolution of 1*1m² (LiDAR, degree of sealing, landuse), soil properties and geology (1:50.000). In addition, different green infrastructures are included into the model as well as the effect of trees on interception and transpiration. A hydraulic model was included into RoGeR to predict surface runoff, water redistribution, and re-infiltration. During rainfall events, RoGeR predicts at 5 min temporal resolution, but the model also simulates evapotranspiration and groundwater recharge during rain-free periods at a longer time step. The model framework was applied to several case studies in Germany where intense rainfall events produced flash floods causing high damage in urban areas and to a long-term research catchment in an urban setting (Vauban, Freiburg), where a variety of green infrastructures dominates the hydrology. Urban-RoGeR allowed us to study the effects of different green infrastructures on reducing the flood peak, but also its effect on the water balance (evapotranspiration and groundwater recharge). We could also show that infiltration of surface runoff from areas with a low infiltration (lateral redistribution) reduce the flood peaks by over 90% in certain areas and situations. Finally, we also evaluated the model to long-term runoff observations (surface runoff, ET, roof runoff) and to flood marks in the selected case studies.

Two dimensional modelling of flood flows and suspended sedimenttransport: the case of the Brenta River, Veneto (Italy)

NASA Astrophysics Data System (ADS)

Martini, P.; Carniello, L.; Avanzi, C.

2004-03-01

The paper presents a numerical model for the simulation of flood waves and suspended sediment transport in a lowland river basin of North Eastern Italy. The two dimensional depth integrated momentum and continuity equations are modified to take into account the bottom irregularities that strongly affect the hydrodynamics in partially dry areas, as for example, in the first stages of an inundation process or in tidal flow. The set of equations are solved with a standard Galerkin finite element method using a semi-implicit numerical scheme where the effects of both the small channel network and the regulation devices on the flood wave propagation are accounted for. Transport of suspended sediment and bed evolution are coupled with the hydrodynamics using an appropriate form of the advection-dispersion equation and Exner's equation. Applications to a case study are presented in which the effects of extreme flooding on the Brenta River (Italy) are examined. Urban and rural flood risk areas are identified and the effects of a alleviating action based on a diversion channel flowing into Venice Lagoon are simulated. The results show that this solution strongly reduces the flood risk in the downstream areas and can provide an important source of sediment for the Venice Lagoon. Finally, preliminary results of the sediment dispersion due to currents and waves in the Venice Lagoon are presented.

Results of rapid needs assessments in rural and urban Iowa following large-scale flooding events in 2008.

PubMed

Quinlisk, Patricia; Jones, Mary J; Bostick, Nathan A; Walsh, Lauren E; Curtiss, Rebecca; Walker, Robert; Mercer, Steve; Subbarao, Italo

2011-12-01

On June 8 and 9, 2008, more than 4 inches of rain fell in the Iowa-Cedars River Basin causing widespread flooding along the Cedar River in Benton, Linn, Johnson, and Cedar Counties. As a result of the flooding, there were 18 deaths, 106 injuries, and over 38,000 people displaced from their homes; this made it necessary for the Iowa Department of Health to conduct a rapid needs assessment to quantify the scope and effect of the floods on human health. In response, the Iowa Department of Public Health mobilized interview teams to conduct rapid needs assessments using Geographic Information Systems (GIS)-based cluster sampling techniques. The information gathered was subsequently employed to estimate the public health impact and significant human needs that resulted from the flooding. While these assessments did not reveal significant levels of acute injuries resulting from the flood, they did show that many households had been temporarily displaced and that future health risks may emerge as the result of inadequate access to prescription medications or the presence of environmental health hazards. This exercise highlights the need for improved risk communication measures and ongoing surveillance and relief measures. It also demonstrates the utility of rapid needs assessment survey tools and suggests that increasing use of such surveys can have significant public health benefits.

iSPUW: integrated sensing and prediction of urban water for sustainable cities

NASA Astrophysics Data System (ADS)

Noh, S. J.; Nazari, B.; Habibi, H.; Norouzi, A.; Nabatian, M.; Seo, D. J.; Bartos, M. D.; Kerkez, B.; Lakshman, L.; Zink, M.; Lee, J.

2016-12-01

Many cities face tremendous water-related challenges in this Century of the City. Urban areas are particularly susceptible not only to excesses and shortages of water but also to impaired water quality. To addresses these challenges, we synergistically integrate advances in computing and cyber-infrastructure, environmental modeling, geoscience, and information science to develop integrative solutions for urban water challenges. In this presentation, we describe the various efforts that are currently ongoing in the Dallas-Fort Worth Metroplex (DFW) area for iSPUW: real-time high-resolution flash flood forecasting, inundation mapping for large urban areas, crowdsourcing of water observations in urban areas, real-time assimilation of crowdsourced observations for street and river flooding, integrated control of lawn irrigation and rainwater harvesting for water conservation and stormwater management, feature mining with causal discovery for flood prediction, and development of the Arlington Urban Hydroinformatics Testbed. Analyzed is the initial data of sensor network for water level and lawn monitoring, and cellphone applications for crowdsourcing flood reports. New data assimilation approaches to deal with categorical and continuous observations are also evaluated via synthetic experiments.

Risk to a Changing Climate in the Mexico City Metropolitan Area

NASA Astrophysics Data System (ADS)

Vargas, N. D.

2016-12-01

The issue of climate change has dominated the atmospheric sciences agenda in recent decades. The concern about an increase in climate related disasters, mainly in large population centers, has led to ask whether they are mainly due to changes in climate or in vulnerability.The Mexico City Metropolitan Area (MCMA) is an example of megalopolis under high climate risk, where floods, landslides, health problems, high air pollution events, socioeconomic droughts are becoming important environmental and social problems. As urbanization spreads and population increases exposure to natural hazards increases, and so the magnitude of risk to a changing climate and the negative impacts. Since the late nineteenth century, in the MCMA an average maximum temperature could be around 22°C, whereas today it is about 24.5ºC. That is, the increase in the average temperature in Mexico City is around 3°C in a hundred years. But there are areas where an increase in the average temperature is similar in only thirty years. The heating rate of the city can vary depending on the change in land use. Areas that conserve forested regions in the process of urbanization tend to warm less than areas where the transformation into concrete and cement is almost complete. Thus, the climate of the MCMA shows important changes mainly in relation to land use changes. Global warming and natural climate variability were also analyzed as possible forcing factors of the observed warming by comparing low frequency variations in local temperature and indices for natural forcing. The hydrological cycle of the MCMA has also changed with urbanization. The "bubble of hot air" over the urban area has more capacity to hold moisture now than before the UHI. However, the increased risk to floods, heat or drought appears to be related not only to more frequent intense climatic hazards induced by the urbanization effect. This process also induces increased vulnerability to a changing climate. The establishment of areas with trees, water parks or green infrastructure can recover some ecosystem services and therefore, reduce climate risk in cities, with co-benefits that costly infrastructure does not always provide. Contemplating the services of urban ecosystems in the management of cities would lead to lower impacts of climate change for residents of cities.

Basin-Scale Reconstruction of Flood Characteristics in a Small Urban Waterhsed

NASA Astrophysics Data System (ADS)

Miller, A. J.; Smith, J. A.; Baeck, M. L.

2006-05-01

Intense short-duration summer thunderstorms are primarily responsible for the occurrence of extreme floods in small, highly urban watersheds. In these systems hydrologic response is rapid and the role of urban infrastructure (impervious cover, storm drain networks, stormwater retention facilities, engineered channels, road embankments, bridges and culverts, and floodplain fill and regrading) has potentially important consequences for runoff generation and for flood-wave propagation. The occurrence of even a single well- documented extreme event provides an opportunity to improve our understanding of the relationships between temporal and spatial patterns of precipitation, natural and anthropogenic landscape features, and the dynamics of flood behavior. We report on combined field and modeling studies of a record flood (Qpk ~ 250 m3s-1) that occurred on 7 July 2004 in the 14.3 km2 Dead Run watershed in suburban Baltimore, Maryland. Flood peaks were reconstructed for nine locations in the watershed and streamflow hydrographs were derived for four locations where complete or partial stage records were recovered; these were compared with precipitation mass-balance estimates using bias-corrected radar rainfall data in order to examine the spatial pattern of runoff ratios, lag times, and cumulative properties of the flood wave as it advanced downstream. Flood behavior in part reflects the role of capacity constraints in the storm drain network and of ponding and storage of overbank flow by physical barriers such as road embankments and culverts. The results can be used to improve predictions of flood response to other hydrometeorological events and provide insight on sensitivity of flood behavior to patterns of urban development and infrastructure.

Improved Gradation for Rain Garden of Low Impact Development

NASA Astrophysics Data System (ADS)

Lee, Sandra; Chang, Fu-Ming

2016-04-01

With rapid urban and economic development, living standard improves in urban areas but urban ecological environments deteriorate rapidly. Urban waterlogging and flooding have become a serious problem for urban water security. As urbanization continues, sustainability is the key to balance between urban development and healthy environment. Rain garden is recommended to be one of the best ways to reduce urban pollutants. It not only diminishes runoff flooding but also purify water in the urban area. The studies on rain gardens are mainly about how to incorporate rain garden to purify water quality, but lack of researches on runoff control. This project focuses on rain garden under Low Impact Development using indoor laboratory to test and quantify the water holding capacities of two different Taiwan indigenous rain garden plants, Taiwan Cyclosorus and Sour Grass. The results show that the water holding capacity of Sour Grass (10%-37%) is better than that of Taiwan Cyclosorus (6.8%-17.3%). The results could be a helpful reference for Low Impact Development in urban flood prevention and urban planning. Keywords: Low Impact Development; rain garden; indoor laboratory experiments; water holding capacity; porosity

Urban land use and geohazards in the Itanagar Capital city, Arunachal Pradesh, India: Need for geoethics in urban disaster resilience governance in a changing climate

NASA Astrophysics Data System (ADS)

Acharjee, Swapna

2013-04-01

The capital city, Itanagar, Arunachal Pradesh, India is exposed to the multiple geohazards as the city is located in the region which experiences extreme physical phenomenon due to changing climate in the tectonically active North-Eastern Himalayas. The geohazards in Itanagar includes landslides, floods, soil erosion and earthquakes. The high decadal growth rate of 111.36% in 1991-2001 census has brought in many challenges with respect to the capital city developmental planning. Due to rapid and haphazard growth in urban land use the people residing in the city are gradually becoming more vulnerable to the geohazards in the past decades. The city condition at present has raised issues of grave concern related to effective hazard management. It is observed that geoscientific approach is violated at many places in the urban developmental activities along the central spine, the National Highway-52A of the capital city. There is an urgent need of geoscientists to apprise the urban populace about land suitability and stability in terms of rock types, soil, slope, geomorphology, groundwater condition etc. and the vulnerability of the existing urban land use to landslides, flood, soil erosion and earthquakes. In this paper major issue, critical issues and elements at risk are discussed in the context of ethics in geohazard management and developmental planning for urban disaster resilience governance in a changing climate.

Study of flood defense structural measures priorities using Compromise Programming technique

NASA Astrophysics Data System (ADS)

Lim, D.; Jeong, S.

2017-12-01

Recent climate change of global warming has led to the frequent occurrence of heavy regional rainfalls. As such, inundation vulnerability increases in urban areas with high population density due to the low runoff carrying capacity. This study selects a sample area (Janghang-eup, the Republic of Korea), which is one of the most vulnerable areas to flooding, analyzing the urban flood runoff model (XP-SWMM) and using the MCDM (Multi-Criteria Decision Making) technique to establish flood protection structural measures. To this end, we compare the alternatives and choose the optimal flood defense measure: our model is utilized with three flood prevention structural measures; (i) drainage pipe construction; (ii) water detention; and (iii) flood pumping station. Dividing the target area into three small basins, we propose flood evaluations for an inundation decrease by studying the flooded area, the maximum inundation depth, the damaged residential area, and the construction cost. In addition, Compromise Programming determines the priority of the alternatives. As a consequent, this study suggests flood pumping station for Zone 1 and drainage pipe construction for Zone 2 and Zone 3, respectively, as the optimal flood defense alternative. Keywords : MCDM; Compromise Programming; Urban Flood Prevention; This research was supported by a grant [MPSS-DP-2013-62] through the Disaster and Safety Management Institute funded by Ministry of Public Safety and Security of Korean government.

Estimating flood hydrographs for urban basins in North Carolina

USGS Publications Warehouse

Mason, R.R.; Bales, J.D.

1996-01-01

A dimensionless hydrograph for North Carolina was developed from data collected in 29 urban and urbanizing basins in the State. The dimen- sionless hydrograph can be used with an estimate of peak flow and basin lagtime to synthesize a design flood hydrograph for urban basins in North Carolina. Peak flows can be estimated from a number of avail- able techniques; a procedure for estimating basin lagtime from main channel length, stream slope, and percentage of impervious area was developed from data collected at 50 sites and is presented in this report. The North Carolina dimensionless hydrograph provides satis- factory predictions of flood hydrographs in all regions of the State except for basins in or near Asheville where the method overestimated 11 of 12 measured hydrographs. A previously developed dimensionless hydrograph for urban basins in the Piedmont and upper Coastal Plain of South Carolina provides better flood-hydrograph predictions for the Asheville basins and has a standard error of 21 percent as compared to 41 percent for the North Carolina dimensionless hydrograph.

Overview of historical recurring low-amplitude floods in Lower Provence, Southeastern France (1700-1950)

NASA Astrophysics Data System (ADS)

Maughan, Nicolas

2015-04-01

In the Mediterranean world, water plays a prominent role as a « prime mover » in the development of urban and rural spaces. But, the specificities of the typical climate require a management of a natural resource that varies permanently between scarcity and abundance. Since Antiquity, the chronic lack of freshwater could be limited thanks to large hydraulic infrastructures while the flood risk management has always been a recurring problem for rural and urban communities. Because of brief, intense and irregularly distributed rain, amplified by a mountainous topography, stream floods often are heavy and flash with catastrophic consequences. However, often only past extremefloods were studied because both their consequences and available archival materials they have left while many recurring low-amplitude floodshave resulted in severe damagesto hydraulic and road infrastructures, in loss of agricultural soils and inconflicts between citizens and administration. Indeed, these ones were a central problem for rural and urban settlements and for the managementof water bodies.It seems interesting to present adetailed overview of historical recurring low-amplitude floods and consider how local societies have chosen to manage these questions and how these small hydrological events have contributed to shape existing current hydrological and geomorphologicalstructure of hydrosystems. In this context, the Lower Provence area (especially the Bouches-du-Rhône district, southeastern France), subject to recurring floods for centuries, appears to be a perfect place to explore and understand these questions. The decision to start the study at the dawn of the Eighteenth Century is especially interesting because it's a turning point for economic, scientific and engineering development in many European countries during whichdisasters and environmental health risks, including flooding, begin to become a real social and technical problem for authorities and citizens. Moreover, from this time, archives related to rivers begin to be numerous and easily usable. The analysis of archival materials, but also of articles from the local press reporting environmental disasters, provides a rich data set to attempt to understand evolution of both perceptions and responses of local societies to flooding risks. Therefore, our work is based both on the study of local archives- municipal and regional - (especially debates and reports from the municipal council of Marseilles, from the general council of the Bouches-du-Rhône district and from a local engineering office named the "Service hydraulique", created in 1848 and dedicated to the management of water courses) and on a large corpus of articles from newspapers. First, after presenting a short panorama of the economic and social role played by rivers in the Provence area during the early modern period, we'll analyze, on the one hand, thefrequency and intensity oflow-amplitude floodsfor seven different small-scale urban and rural streams flowing in the Bouches-du-Rhône district (the Huveaune, Touloubre, Arc, Cadière, Raumartin, Aygalades and Jarretrivers; all having a channel length less than 90 km) during the last three centuries and, on the other hand,their potential environmental, social and economic impact. Second, we will also show how, at the same time,local societies have coped and managed these daily events together with the progressive evolution of most uses of the river's water.

Flood Risk Vulnerability Assessment: What are the Main Factors? Hierarchization of The Main Factors at a Regional Scale

NASA Astrophysics Data System (ADS)

Jouannic, G.; Kolli, Z.; Legendre, T.; Marchetti, M.; Gastaud, P.; Gargani, J.; Lermet, R.; Augeard, C.; Felts, D.; Arki, F.

2015-12-01

Recent studies have shown that the national flood risk exposure is high in France, with one fourth of the total population and a third of jobs located in risk areas. In this context, a global vulnerability assessment methodology is currently being developed in France to bring adequate tools for local territories to manage flood risk. This study addresses the question of the quantification, the qualification and the choice of these vulnerability indicators for a given territory. This work aims to propose a classification of nearly 40 of these indicators in terms of their relative impacts on the risk level estimated on two territories: Chalon-sur-Saône (Saône river) Garonne estuary (Garonne and Dordogne rivers, and Atlantic ocean) Through these cases study, 3 different spatial scales have been compared: the Prés-Saint-Jean district inside Chalon (0.6 km²), the city of Ambès (28.8 km²) and Chalon with its suburbs (72.2 km²). A principal component analysis (PCA) was applied and indicated a threshold in terms of urban impacts between the different flood scenarios. On Chalon, the PCA discriminates 2 groups of flood and highlighted a threshold between T20 and T50. A partial least-square regression (PLS) was computed to make predictions on vulnerability indicators values modelled on new flood scenarios. Their results were is useful to identify the most relevant vulnerability indicators as a function of their flood exposure. These statistical analysis aims to highlight the relationship between a variable of exposure level (hydrologic impact: water levels and flow velocity) with spatialized vulnerability indicators in a 100 m grid (e.g., population, job, etc.). Finally, to get a hierarchy of variables depending on their impact on the risk level, an ANOVA was computed. The selection of variables was performed with a stepwise selection to assess contributions of each dependant variable on the F-statistic as they are added to or removed from the model.

Remote Sensing Technologies and Geospatial Modelling Hierarchy for Smart City Support

NASA Astrophysics Data System (ADS)

Popov, M.; Fedorovsky, O.; Stankevich, S.; Filipovich, V.; Khyzhniak, A.; Piestova, I.; Lubskyi, M.; Svideniuk, M.

2017-12-01

The approach to implementing the remote sensing technologies and geospatial modelling for smart city support is presented. The hierarchical structure and basic components of the smart city information support subsystem are considered. Some of the already available useful practical developments are described. These include city land use planning, urban vegetation analysis, thermal condition forecasting, geohazard detection, flooding risk assessment. Remote sensing data fusion approach for comprehensive geospatial analysis is discussed. Long-term city development forecasting by Forrester - Graham system dynamics model is provided over Kiev urban area.

Regional flood impact assessment for Kiel and Eckernförde, Germany

NASA Astrophysics Data System (ADS)

Shustikova, Iuliia; Viavattene, Christophe; Seiß, Guntram

2017-04-01

It is well-observed that extreme flood events bring considerable destruction to coastal communities. The estimates of damage increases when direct and indirect losses are both considered in the assessment. This study applied the INtegrated DisRuption Assessment (INDRA) model which is designed to estimate and compare not only tangible but also intangible losses such as risk to life, recovery mechanisms and household displacement. Multi-criteria analysis (MCA) was performed in order to compare hotspots of high flood risk on the regional scale and detect which impact indicators influence results the most. INDRA allowed assessing the following impact indicators: direct damages to buildings and roads, transport disruption, risk to life and financial recovery mechanisms of private households and businesses. The focus was on two hotspots of flood risk, where direct and indirect impacts from 200 years flood were assessed and analyzed in terms of relative importance to the region. The region here was defined as municipalities located on the Baltic Sea coast within the Schleswig-Holstein state, Germany. The hotspots are the towns of Kiel and Eckernförde. They are urban areas with a high concentration of people and assets, which previously experienced extreme flood events. From the performed investigation it was found out that modeled flood differently impacts Kiel and Eckernförde. The results produced by MCA show that the scores of direct and indirect damage are slightly higher in Eckernförde than in Kiel. Transport disruption is a compelling element in the performed regional impact assessment and demonstrated immense weight. Extreme events may pose significant direct and indirect impacts on the coastal roads, obstructing not only the access to important landmarks such as hospitals, train stations, harbors, etc. but also to contiguous municipalities. Yet, the analysis showed that other impact indicators are rather of local importance and would not cause vast damage on a regional scale. Nonetheless, the study suggests, that these effects should not be underestimated in terms of losses.

Using an extended 2D hydrodynamic model for evaluating damage risk caused by extreme rain events: Flash-Flood-Risk-Map (FFRM) Upper Austria

NASA Astrophysics Data System (ADS)

Humer, Günter; Reithofer, Andreas

2016-04-01

Using an extended 2D hydrodynamic model for evaluating damage risk caused by extreme rain events: Flash-Flood-Risk-Map (FFRM) Upper Austria Considering the increase in flash flood events causing massive damage during the last years in urban but also rural areas [1-4], the requirement for hydrodynamic calculation of flash flood prone areas and possible countermeasures has arisen to many municipalities and local governments. Besides the German based URBAS project [1], also the EU-funded FP7 research project "SWITCH-ON" [5] addresses the damage risk caused by flash floods in the sub-project "FFRM" (Flash Flood Risk Map Upper Austria) by calculating damage risk for buildings and vulnerable infrastructure like schools and hospitals caused by flash-flood driven inundation. While danger zones in riverine flooding are established as an integral part of spatial planning, flash floods caused by overland runoff from extreme rain events have been for long an underrated safety hazard not only for buildings and infrastructure, but man and animals as well. Based on the widespread 2D-model "hydro_as-2D", an extension was developed, which calculates the runoff formation from a spatially and temporally variable precipitation and determines two dimensionally the land surface area runoff and its concentration. The conception of the model is to preprocess the precipitation data and calculate the effective runoff-volume for a short time step of e.g. five minutes. This volume is applied to the nodes of the 2D-model and the calculation of the hydrodynamic model is started. At the end of each time step, the model run is stopped, the preprocessing step is repeated and the hydraulic model calculation is continued. In view of the later use for the whole of Upper Austria (12.000 km²) a model grid of 25x25 m² was established using digital elevation data. Model parameters could be estimated for the small catchment of river Ach, which was hit by an intense rain event with up to 109 mm per hour at 20th of June 2012, based on open data sources of geology, soil and land use. The aim of FFRM is to provide an estimation of the damage risk caused by flash-floods for the whole of Upper Austria. To address the hazard, inundation depths were calculated with the extended 2D-model using design rains with an 100-year return period provided by the Environmental Ministry [7]. The potential damage was calculated using damage functions, which were derived from our experience from damage surveys of past events in Austria and according to guidelines for determination of cost-benefit-ratios for flood protection measures [8]. The greatest difficulty was to get appropriate data for the distribution of houses and industrial plants. Zoning plans provide good information on spatial distribution of residential, commercial and industrial areas, but does not contain information on the kind of industry, which is essential for estimating absolute damage values. To get a first idea detailed information from surveyed areas was intersected with the zoning plan, which provides an average damage in the respective zones. The first results can be found on www.waterviewer.com and will be updated with the further development of the project. [1] URBAS, risk management of extreme flooding events - prediction and management of flash floods in urban areas, www.urbanesturzfluten.de, prompted on 13th of November 2014 [2] Società Meteorologica Italiana (SMI), http://www.nimbus.it/eventi/2013/130624flashfloodRimini.pdf, prompted on 13th of November 2014 [3]Newspaper "Österreich", http://www.oe24.at/oesterreich/chronik/Sturzflut-Regen-legt-Ost-Oesterreich-lahm/1509113, prompted on 13th of November 2014 [4] Newspaper "Oberösterreichische Nachrichten", http://www.nachrichten.at/oberoesterreich/Unwetter-Mure-riss-Strasse-mit-Wohnhaus-in-Gosau-gefaehrdet;art4,911288 , prompted on 13th of November 2014 [5] Sharing Water-related Information to Tackle Changes in the Hydrosphere - for Operational Needs (SWITCH-ON), http://water-switch-on.eu [6] European Commission, directive 2007/60/EC of the European Parliament and the Council of 23rd October 2007 on the assessment and management of flood risks: http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2007:288:0027:0034:en:PDF [7] http://ehyd.gv.at [8] Austrian Federal Ministry of Agriculture, Forestry, Environment and Water Management: „Kosten-Nutzen-Untersuchungen im Schutzwaserbau", July 2009

Flood Hazards - A National Threat

USGS Publications Warehouse

,

2006-01-01

In the late summer of 2005, the remarkable flooding brought by Hurricane Katrina, which caused more than $200 billion in losses, constituted the costliest natural disaster in U.S. history. However, even in typical years, flooding causes billions of dollars in damage and threatens lives and property in every State. Natural processes, such as hurricanes, weather systems, and snowmelt, can cause floods. Failure of levees and dams and inadequate drainage in urban areas can also result in flooding. On average, floods kill about 140 people each year and cause $6 billion in property damage. Although loss of life to floods during the past half-century has declined, mostly because of improved warning systems, economic losses have continued to rise due to increased urbanization and coastal development.

The Estimation of Future Pump Capacity for the Urban Drainage System under Climate Change

NASA Astrophysics Data System (ADS)

Kang, Narae; Noh, Huiseong; Kim, Yonsoo; Lee, Jongso; Kim, Hungsoo

2013-04-01

In the recent years, flash flood and local heavy rainfall have been frequently occurred in Korea and this may be due to the climate change. Korea Meteorological Administration(KMA) and IPCC AR5 reported new greenhouse gas scenario called RCPs(Representative concentration pathways) which are becoming an interesting subject in the field of water resources. These days, the urban areas in the Korean Peninsula have been suffered from the floods, almost every year, by the localized heavy rainfall and this abnormal rainfall may be due to the climate change. Also, the runoff in the urban area has increased due to the rapid urbanization and so the current design rainfall could not be proper any more for accommodating the abnormal runoff capacity. When we determine the frequency of drainage facilities, the maximum flood discharge from the recorded rainfall intensity is used as the design capacity of the facilities. However, there is a need to examine the future rainfall tendency for the re-establishment of the design criteria of the facilities under the climate change, since the recorded rainfall intensity does not reflect the trend of the abnormal rainfall which can be occurred. This study tries to analyze the variability and trend of future rainfall using RCP scenarios and estimate the future capacity at existing pumping station for the urban drainage system. The future projection periods are set to the next 90 years(2011-2100) and are divided into three cases; Target I : 2011~2040 yrs, Target II : 2041~2070 yrs, and Target III : 2071~2100 yrs. The study area is Incheon-city, Korea which has 9 pumping stations. According to the RCP 8.5 scenario which is the worst scenario of RCPs, the Target I design rainfall is increased by 20%, Target II increased by 33%, and Target III increased by 74% compared with the reference period(1970-2010). When considering the impact of climate change, 3 of 9 pumping stations are expected to have no difficulty in the future rainfall. But, the capacities of 6 pumping stations will not be sufficient for the future rainfall and runoff. Therefore, it is expected to construct more pumping stations allowable 6 times of existing pump capacity especially for Target III(2071-2100). ACKNOWLEDGMENT This research was supported by a grant 'The development of disaster risk assessment technique for flood prevention facilities considering the multi risk factors' [NEMA-NH-2010-33] from the Natural Hazard Mitigation Research Group, National Emergency Management Agency of Korea.

Determinants of the lethality of climate-related disasters in the Caribbean Community (CARICOM): a cross-country analysis

PubMed Central

Andrewin, Aisha N.; Rodriguez-Llanes, Jose M.; Guha-Sapir, Debarati

2015-01-01

Floods and storms are climate-related hazards posing high mortality risk to Caribbean Community (CARICOM) nations. However risk factors for their lethality remain untested. We conducted an ecological study investigating risk factors for flood and storm lethality in CARICOM nations for the period 1980–2012. Lethality - deaths versus no deaths per disaster event- was the outcome. We examined biophysical and social vulnerability proxies and a decadal effect as predictors. We developed our regression model via multivariate analysis using a generalized logistic regression model with quasi-binomial distribution; removal of multi-collinear variables and backward elimination. Robustness was checked through subset analysis. We found significant positive associations between lethality, percentage of total land dedicated to agriculture (odds ratio [OR] 1.032; 95% CI: 1.013–1.053) and percentage urban population (OR 1.029, 95% CI 1.003–1.057). Deaths were more likely in the 2000–2012 period versus 1980–1989 (OR 3.708, 95% CI 1.615–8.737). Robustness checks revealed similar coefficients and directions of association. Population health in CARICOM nations is being increasingly impacted by climate-related disasters connected to increasing urbanization and land use patterns. Our findings support the evidence base for setting sustainable development goals (SDG). PMID:26153115

Assessing the Value of Information for Identifying Optimal Floodplain Management Portfolios

NASA Astrophysics Data System (ADS)

Read, L.; Bates, M.; Hui, R.; Lund, J. R.

2014-12-01

Floodplain management is a complex portfolio problem that can be analyzed from an integrated perspective incorporating traditionally structural and nonstructural options. One method to identify effective strategies for preparing, responding to, and recovering from floods is to optimize for a portfolio of temporary (emergency) and permanent floodplain management options. A risk-based optimization approach to this problem assigns probabilities to specific flood events and calculates the associated expected damages. This approach is currently limited by: (1) the assumption of perfect flood forecast information, i.e. implementing temporary management activities according to the actual flood event may differ from optimizing based on forecasted information and (2) the inability to assess system resilience across a range of possible future events (risk-centric approach). Resilience is defined here as the ability of a system to absorb and recover from a severe disturbance or extreme event. In our analysis, resilience is a system property that requires integration of physical, social, and information domains. This work employs a 3-stage linear program to identify the optimal mix of floodplain management options using conditional probabilities to represent perfect and imperfect flood stages (forecast vs. actual events). We assess the value of information in terms of minimizing damage costs for two theoretical cases - urban and rural systems. We use portfolio analysis to explore how the set of optimal management options differs depending on whether the goal is for the system to be risk-adverse to a specified event or resilient over a range of events.

Urban nuisance flooding and topographic wetness index: does excess runoff collect where we think it should in urban landscapes?

NASA Astrophysics Data System (ADS)

Kelleher, C.; McPhillips, L. E.

2017-12-01

Urban landscapes translate water in a variety of ways that diverge from more natural systems. In particular, due to the presence of impervious surfaces and alteration of topography, they are prone to nuisance flooding when it rains. To track the locations of areas of minor flooding and other complaints, many cities are now facilitating nuisance reports from residents via information technology services like 311. These reports provide useful information for tracking where in the landscape water may collect during rain events; we sought to use this information to test potential geospatial indices for predictively identifying locations prone to nuisance flooding in urban areas. In this study, we utilized a tool commonly applied in natural systems, topographic indices, to create spatially contiguous estimates of topographic wetness index (TWI), a value that can be used to identify areas within a watershed expected to be preferentially wetter or drier based on topographic slope and surface flow pathways. For several watersheds across Baltimore and New York City (USA), we tested three different resolutions of LiDAR-derived topography and two different methods of flow routing to calculate continuous distributions of TWI. When comparing these values to nuisance flooding locations, we found that distributions of TWI values within a radius of reported nuisance floods were higher, on average, than the distribution of TWI values across each watershed. We also employed a spatial Monte Carlo sampling strategy, randomly selecting grid cells within each watershed to determine if these randomly selected grid cells have preferentially lower TWI values than those near nuisance flooding locations. Overall, we demonstrate that topographic indices may be useful predictors of localized flooding within urban environments.

Stormwater Volume Control to Prevent Increases in Lake Flooding and Dam Failure Risk

NASA Astrophysics Data System (ADS)

Potter, K. W.

2017-12-01

Urban expansion is not often considered a major factor contributing to dam failure. But if urbanization occurs without mitigation of the hydrologic impacts, the risk of dam failure will increase. Of particular concern are increases in the volume of storm runoff resulting from increases in the extent of impervious surfaces. Storm runoff volumes are not regulated for much the U.S, and where they are, the required control is commonly less than 100%. Unmitigated increases in runoff volume due to urbanization can pose a risk to dams. A recent technical advisory committee of Dane County has recommended that the county require 100% control of stormwater volumes for new developments. The primary motivation was to prevent increases in the water levels in the Yahara Lakes, slowly draining lakes that are highly sensitive to runoff volume. The recommendations included the use of "volume trading" to achieve efficient compliance. Such recommendations should be considered for other slowly draining lakes, including those created by artificial structures.

The use of LiDAR-derived high-resolution DSM and intensity data to support modelling of urban flooding

NASA Astrophysics Data System (ADS)

Aktaruzzaman, Md.; Schmitt, Theo G.

2011-11-01

This paper addresses the issue of a detailed representation of an urban catchment in terms of hydraulic and hydrologic attributes. Modelling of urban flooding requires a detailed knowledge of urban surface characteristics. The advancement in spatial data acquisition technology such as airborne LiDAR (Light Detection and Ranging) has greatly facilitated the collection of high-resolution topographic information. While the use of the LiDAR-derived Digital Surface Model (DSM) has gained popularity over the last few years as input data for a flood simulation model, the use of LiDAR intensity data has remained largely unexplored in this regard. LiDAR intensity data are acquired along with elevation data during the data collection mission by an aircraft. The practice of using of just aerial images with RGB (Red, Green and Blue) wavebands is often incapable of identifying types of surface under the shadow. On the other hand, LiDAR intensity data can provide surface information independent of sunlight conditions. The focus of this study is the use of intensity data in combination with aerial images to accurately map pervious and impervious urban areas. This study presents an Object-Based Image Analysis (OBIA) framework for detecting urban land cover types, mainly pervious and impervious surfaces in order to improve the rainfall-runoff modelling. Finally, this study shows the application of highresolution DSM and land cover maps to flood simulation software in order to visualize the depth and extent of urban flooding phenomena.

Socio-economic Impact Analysis for Near Real-Time Flood Detection in the Lower Mekong River Basin

NASA Astrophysics Data System (ADS)

Oddo, P.; Ahamed, A.; Bolten, J. D.

2017-12-01

Flood events pose a severe threat to communities in the Lower Mekong River Basin. The combination of population growth, urbanization, and economic development exacerbate the impacts of these flood events. Flood damage assessments are frequently used to quantify the economic losses in the wake of storms. These assessments are critical for understanding the effects of flooding on the local population, and for informing decision-makers about future risks. Remote sensing systems provide a valuable tool for monitoring flood conditions and assessing their severity more rapidly than traditional post-event evaluations. The frequency and severity of extreme flood events are projected to increase, further illustrating the need for improved flood monitoring and impact analysis. In this study we implement a socio-economic damage model into a decision support tool with near real-time flood detection capabilities (NASA's Project Mekong). Surface water extent for current and historical floods is found using multispectral Moderate-resolution Imaging Spectroradiometer (MODIS) 250-meter imagery and the spectral Normalized Difference Vegetation Index (NDVI) signatures of permanent water bodies (MOD44W). Direct and indirect damages to populations, infrastructure, and agriculture are assessed using the 2011 Southeast Asian flood as a case study. Improved land cover and flood depth assessments result in a more refined understanding of losses throughout the Mekong River Basin. Results suggest that rapid initial estimates of flood impacts can provide valuable information to governments, international agencies, and disaster responders in the wake of extreme flood events.

Visual Sensing for Urban Flood Monitoring

PubMed Central

Lo, Shi-Wei; Wu, Jyh-Horng; Lin, Fang-Pang; Hsu, Ching-Han

2015-01-01

With the increasing climatic extremes, the frequency and severity of urban flood events have intensified worldwide. In this study, image-based automated monitoring of flood formation and analyses of water level fluctuation were proposed as value-added intelligent sensing applications to turn a passive monitoring camera into a visual sensor. Combined with the proposed visual sensing method, traditional hydrological monitoring cameras have the ability to sense and analyze the local situation of flood events. This can solve the current problem that image-based flood monitoring heavily relies on continuous manned monitoring. Conventional sensing networks can only offer one-dimensional physical parameters measured by gauge sensors, whereas visual sensors can acquire dynamic image information of monitored sites and provide disaster prevention agencies with actual field information for decision-making to relieve flood hazards. The visual sensing method established in this study provides spatiotemporal information that can be used for automated remote analysis for monitoring urban floods. This paper focuses on the determination of flood formation based on image-processing techniques. The experimental results suggest that the visual sensing approach may be a reliable way for determining the water fluctuation and measuring its elevation and flood intrusion with respect to real-world coordinates. The performance of the proposed method has been confirmed; it has the capability to monitor and analyze the flood status, and therefore, it can serve as an active flood warning system. PMID:26287201

Sea Level Rise, Rainfall and Coastal Flooding in Northeastern U.S. Cities Vivien Gornitz, Radley Horton, Philip Orton, Nickitas Georgas, Alan Blumberg, and Cynthia Rosenzweig

NASA Astrophysics Data System (ADS)

Gornitz, V.; Horton, R. M.; Orton, P. M.; Georgas, N.; Blumberg, A. F.; Rosenzweig, C.

2012-12-01

Populations and infrastructure along much of the northeastern coast of the United States will become increasingly vulnerable to the impacts of rising sea level and storm surges over the coming century. This vulnerability is amplified by regional land subsidence and likely also by shifts in ocean circulation. Building upon recent studies for the New York City Panel on Climate Change (NPCC), New York State ClimAid assessment, and the latest U.S. National Climate Assessment, we report new regional sea level rise projections based on the latest CMIP-5 global climate models (GCMs) and RCP emission scenarios, adjusted for revised glacial ice melt contributions, and other factors such as gravitational effects, land water storage, and changes in the Atlantic Meriodional Overturning Circulation (AMOC). Over the coming two years, GCM-derived sea level outputs for future decades will be utilized in risk assessments for coastal flooding in New York City, Boston, and Philadelphia, as part of the Consortium for Climate Risk in the Urban Northeast-RISA project. The Stevens Institute Estuarine and Coastal Ocean Model (sECOM) will be used to produce best estimates (including uncertainty ranges) of sea level rise impacts for a wide range of tropical and extra-tropical cyclones for the 2010s, 2050s, and 2080s. Major improvements over prior studies include (a) the use of a detailed, extensively validated ocean model, and (b) inclusion of rainfall and river flow influences on coastal flooding, which affect flood levels in enclosed tidal waterways (e.g., the Hudson and Delaware Rivers), and which are also likely important in coastal confluence zones of impermeable urbanized watersheds. In addition to the sea level rise results, we present initial model validation results for historical storms.

An examination of land use impacts of flooding induced by sea level rise

NASA Astrophysics Data System (ADS)

Song, Jie; Fu, Xinyu; Gu, Yue; Deng, Yujun; Peng, Zhong-Ren

2017-03-01

Coastal regions become unprecedentedly vulnerable to coastal hazards that are associated with sea level rise. The purpose of this paper is therefore to simulate prospective urban exposure to changing sea levels. This article first applied the cellular-automaton-based SLEUTH model (Project Gigalopolis, 2016) to calibrate historical urban dynamics in Bay County, Florida (USA) - a region that is greatly threatened by rising sea levels. This paper estimated five urban growth parameters by multiple-calibration procedures that used different Monte Carlo iterations to account for modeling uncertainties. It then employed the calibrated model to predict three scenarios of urban growth up to 2080 - historical trend, urban sprawl, and compact development. We also assessed land use impacts of four policies: no regulations; flood mitigation plans based on the whole study region and on those areas that are prone to experience growth; and the protection of conservational lands. This study lastly overlaid projected urban areas in 2030 and 2080 with 500-year flooding maps that were developed under 0, 0.2, and 0.9 m sea level rise. The calibration results that a substantial number of built-up regions extend from established coastal settlements. The predictions suggest that total flooded area of new urbanized regions in 2080 would be more than 25 times that under the flood mitigation policy, if the urbanization progresses with few policy interventions. The joint model generates new knowledge in the domain between land use modeling and sea level rise. It contributes to coastal spatial planning by helping develop hazard mitigation schemes and can be employed in other international communities that face combined pressure of urban growth and climate change.

Floods and human health: a systematic review.

PubMed

Alderman, Katarzyna; Turner, Lyle R; Tong, Shilu

2012-10-15

Floods are the most common type of disaster globally, responsible for almost 53,000 deaths in the last decade alone (23:1 low- versus high-income countries). This review assessed recent epidemiological evidence on the impacts of floods on human health. Published articles (2004-2011) on the quantitative relationship between floods and health were systematically reviewed. 35 relevant epidemiological studies were identified. Health outcomes were categorized into short- and long-term and were found to depend on the flood characteristics and people's vulnerability. It was found that long-term health effects are currently not well understood. Mortality rates were found to increase by up to 50% in the first year post-flood. After floods, it was found there is an increased risk of disease outbreaks such as hepatitis E, gastrointestinal disease and leptospirosis, particularly in areas with poor hygiene and displaced populations. Psychological distress in survivors (prevalence 8.6% to 53% two years post-flood) can also exacerbate their physical illness. There is a need for effective policies to reduce and prevent flood-related morbidity and mortality. Such steps are contingent upon the improved understanding of potential health impacts of floods. Global trends in urbanization, burden of disease, malnutrition and maternal and child health must be better reflected in flood preparedness and mitigation programs. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Flood characteristics of urban watersheds in the United States

USGS Publications Warehouse

Sauer, Vernon B.; Thomas, W.O.; Stricker, V.A.; Wilson, K.V.

1983-01-01

A nationwide study of flood magnitude and frequency in urban areas was made for the purpose of reviewing available literature, compiling an urban flood data base, and developing methods of estimating urban floodflow characteristics in ungaged areas. The literature review contains synopses of 128 recent publications related to urban floodflow. A data base of 269 gaged basins in 56 cities and 31 States, including Hawaii, contains a wide variety of topographic and climatic characteristics, land-use variables, indices of urbanization, and flood-frequency estimates. Three sets of regression equations were developed to estimate flood discharges for ungaged sites for recurrence intervals of 2, 5, 10, 25, 50, 100, and 500 years. Two sets of regression equations are based on seven independent parameters and the third is based on three independent parameters. The only difference in the two sets of seven-parameter equations is the use of basin lag time in one and lake and reservoir storage in the other. Of primary importance in these equations is an independent estimate of the equivalent rural discharge for the ungaged basin. The equations adjust the equivalent rural discharge to an urban condition. The primary adjustment factor, or index of urbanization, is the basin development factor, a measure of the extent of development of the drainage system in the basin. This measure includes evaluations of storm drains (sewers), channel improvements, and curb-and-gutter streets. The basin development factor is statistically very significant and offers a simple and effective way of accounting for drainage development and runoff response in urban areas. Percentage of impervious area is also included in the seven-parameter equations as an additional measure of urbanization and apparently accounts for increased runoff volumes. This factor is not highly significant for large floods, which supports the generally held concept that imperviousness is not a dominant factor when soils become more saturated during large storms. Other parameters in the seven-parameter equations include drainage area size, channel slope, rainfall intensity, lake and reservoir storage, and basin lag time. These factors are all statistically significant and provide logical indices of basin conditions. The three-parameter equations include only the three most significant parameters: rural discharge, basin-development factor, and drainage area size. All three sets of regression equations provide unbiased estimates of urban flood frequency. The seven-parameter regression equations without basin lag time have average standard errors of regression varying from ? 37 percent for the 5-year flood to ? 44 percent for the 100-year flood and ? 49 percent for the 500-year flood. The other two sets of regression equations have similar accuracy. Several tests for bias, sensitivity, and hydrologic consistency are included which support the conclusion that the equations are useful throughout the United States. All estimating equations were developed from data collected on drainage basins where temporary in-channel storage, due to highway embankments, was not significant. Consequently, estimates made with these equations do not account for the reducing effect of this temporary detention storage.

A Study on the Assessment of Multi-Factors Affecting Urban Floods Using Satellite Image: A Case Study in Nakdong Basin, S. Korea

NASA Astrophysics Data System (ADS)

Kwak, Youngjoo; Kondoh, Akihiko

2010-05-01

Floods are also related to the changes in social economic conditions and land use. Recently, floods increased due to rapid urbanization and human activity in the lowland. Therefore, integrated management of total basin system is necessary to get the secure society. Typhoon ‘Rusa’ swept through eastern and southern parts of South Korea in the 2002. This pity experience gave us valuable knowledge that could be used to mitigate the future flood hazards. The purpose of this study is to construct the digital maps of the multi-factors related to urban flood concerning geomorphologic characteristics, land cover, and surface wetness. Parameters particularly consider geomorphologic functional unit, geomorphologic parameters derived from DEM (digital elevation model), and land use. The research area is Nakdong River Basin in S. Korea. As a result of preliminary analysis for Pusan area, the vulnerability map and the flood-prone areas can be extracted by applying spatial analysis on GIS (geographic information system).

Assessing the role of urban developments on storm runoff response through multi-scale catchment experiments

NASA Astrophysics Data System (ADS)

Wilkinson, Mark; Owen, Gareth; Geris, Josie; Soulsby, Chris; Quinn, Paul

2015-04-01

Many communities across the world face the increasing challenge of balancing water quantity and quality issues with accommodating new growth and urban development. Urbanisation is typically associated with detrimental changes in water quality, sediment delivery, and effects on water storage and flow pathways (e.g. increases in flooding). In particular for mixed rural and urban catchments where the spatio-temporal variability of hydrological responses is high, there remains a key research challenge in evaluating the timing and magnitude of storage and flow pathways at multiple scales. This is of crucial importance for appropriate catchment management, for example to aid the design of Green Infrastructure (GI) to mitigate the risk of flooding, among other multiple benefits. The aim of this work was to (i) explore spatio-temporal storm runoff generation characteristics in multi-scale catchment experiments that contain rural and urban land use zones, and (ii) assess the (preliminary) impact of Sustainable Drainage (SuDs) as GI on high flow and flood characteristics. Our key research catchment, the Ouseburn in Northern England (55km2), has rural headwaters (15%) and an urban zone (45%) concentrated in the lower catchment area. There is an intermediate and increasingly expanding peri-urban zone (currently 40%), which is defined here as areas where rural and urban features coexist, alongside GIs. Such a structure is typical for most catchments with urban developments. We monitored spatial precipitation and multiscale nested (five gauges) runoff response, in addition to the storage dynamics in GIs for a period of 6 years (2007-2013). For a range of events, we examined the multiscale nested runoff characteristics (lag time and magnitude) of the rural and urban flow components, assessed how these integrated with changing land use and increasing scale, and discussed the implications for flood management in the catchment. The analyses indicated three distinctly different patterns in the timing and magnitude of the contributions of the different land use zones and their nested integrated runoff response at increasing scales. These can be clearly linked to variations in antecedent conditions and precipitation patterns. For low antecedent flow conditions, the main flood peak is dominated by urban origins (faster responding and larger in relative magnitude); for high antecedent flow conditions, rural (and peri-urban) sources are most dominant. A third type of response involves mixed events, where both rural and urban contributions interact and reinforce the peak flow response. Our analyses showed that the effectiveness of the GIs varied substantially between the different events, suggesting that their design could be improved by introducing variable drainage rates and strategic placements to allow for interactions with the stream network. However, more information is needed on the spatio-temporal variability in water sources, flow pathways and residence times. This is of particular importance to also assess other multiple benefits of GIs, including the impacts on water quality. These challenges are currently addressed in two new case study catchment in the North East of Scotland (10km2) which are undergoing major land use change from rural to urban. Here, integrated tracer and hydrometric data are being collected to characterise the integrated impacts of urbanisation and GIs on flow pathways (nature and length) and associated water quality.

High-resolution Rainfall Mapping in Dallas-Fort Worth (DFW) Urban Network of Radars at Multiple Frequencies

NASA Astrophysics Data System (ADS)

Chandra, Chandrasekar V.; Chen*, Haonan

2015-04-01

Urban flash flood is one of the most commonly encountered hazardous weather phenomena. Unfortunately, the rapid urbanization has made the densely populated areas even more vulnerable to flood risks. Hence, accurate and timely monitoring of rainfall at high spatiotemporal resolution is critical to severe weather warning and civil defense, especially in urban areas. However, it is still challenging to produce high-resolution products based on the large S-band National Weather Service (NWS) Next-Generation Weather Radar (NEXRAD), due to the sampling limitations and Earth curvature effect. Since 2012, the U.S. National Science Foundation Engineering Research Center (NSF-ERC) for Collaborative Adaptive Sensing of the Atmosphere (CASA) has initiated the development of Dallas-Fort Worth (DFW) radar remote sensing network for urban weather hazards mitigation. The DFW urban radar network consists of a combination of high-resolution X-band radars and a standard NWS NEXRAD radar operating at S-band frequency. High-resolution quantitative precipitation estimation (QPE) is one of the major research goals in the deployment of this urban radar network. It has been shown in the literature that the dual-polarization radar techniques can improve the QPE accuracy over traditional single-polarization radars by rendering more measurements to enhance the data quality, providing more information about rain drop size distribution (DSD), and implying more characteristics of different hydrometeor types. This paper will present the real-time dual-polarization CASA DFW QPE system, which is developed via fusion of observations from both the high-resolution X band radar network and the S-band NWS radar. The specific dual-polarization rainfall algorithms at different frequencies (i.e., S- and X-band) will be described in details. In addition, the fusion methodology combining observations at different temporal resolution will be presented. In order to demonstrate the capability of rainfall estimation of the CASA DFW QPE system, rainfall measurements from ground rain gauges will be used for evaluation purposes. This high-resolution QPE system is used for urban flash flood forecasting when coupled with hydrological models.

Urban flood return period assessment through rainfall-flood response modelling

NASA Astrophysics Data System (ADS)

Murla Tuyls, Damian; Thorndahl, Søren

2017-04-01

Intense rainfall can often cause severe floods, especially in urbanized areas, where population density or large impermeable areas are found. In this context, floods can generate a direct impact in a social-environmental-economic viewpoint. Traditionally, in design of Urban Drainage Systems (UDS), correlation between return period (RP) of a given rainfall and RP of its consequent flood has been assumed to be linear (e.g. DS/EN752 (2008)). However, this is not always the case. Complex UDS, where diverse hydraulic infrastructures are often found, increase the heterogeneity of system response, which may cause an alteration of the mentioned correlation. Consequently, reliability on future urban planning, design and resilience against floods may be also affected by this misassumption. In this study, an assessment of surface flood RP across rainfall RP has been carried out at Lystrup, a urbanized catchment area of 440ha and 10.400inhab. located in Jutland (Denmark), which has received the impact of several pluvial flooding in the last recent years. A historical rainfall dataset from the last 35 years from two different rain gauges located at 2 and 10 km from the study area has been provided by the Danish Wastewater Pollution Committee and the Danish Meteorological Institute (DMI). The most extreme 25 rainfall events have been selected through a two-step multi-criteria procedure, ensuring an adequate variability of rainfall, from extreme high peak storms with a short duration to moderate rainfall with longer duration. In addition, a coupled 1D/2D surface and network UDS model of the catchment area developed in an integrated MIKE URBAN and MIKE Flood model (DHI 2014), considering both permeable and impermeable areas, in combination with a DTM (2x2m res.) has been used to study and assess in detail flood RP. Results show an ambiguous relation between rainfall RP and flood response. Local flood levels, flood area and volume RP estimates should therefore not be neglected in order to guarantee quality of the assessment, especially in design of complex UDS, where features as the main slope, hydraulic capacity, permeability, etc. can play an important role. In addition, a novel approach has been applied to map the response time (Tc) of the flood prone areas of the system under study. Together with the flood area and volume RP estimates this provides valuable knowledge suggesting to consider the different subareas of the UDS for design purposes and to establish a robust database that allows urban areas to be resilient against the severe impact of rainfall. Acknowledgement to ERA-NET Cofund Water Works 2014 (project MUFFIN) for the partial funding of this research; to the Danish Wastewater Pollution Committee and the Danish Meteorological Institute (DMI) for providing the rainfall dataset; to the Danish Geodata Agency for providing the DTM data and to DHI for providing license to MIKE software packages. The applied model has been made available for this study by Aarhus Water Utility Services. References DHI, 2014. MIKE by DHI software package 2014. Hørsholm, DK. DS/EN 752, 2008. Drain and sewer systems outside buildings.

Evacuation planning for plausible worst case inundation scenarios in Honolulu, Hawaii.

PubMed

Kim, Karl; Pant, Pradip; Yamashita, Eric

2015-01-01

Honolulu is susceptible to coastal flooding hazards. Like other coastal cities, Honolulu&s long-term economic viability and sustainability depends on how well it can adapt to changes in the natural and built environment. While there is a disagreement over the magnitude and extent of localized impacts associated with climate change, it is widely accepted that by 2100 there will be at least a meter in sea level rise (SLR) and an increase in extreme weather events. Increased exposure and vulnerabilities associated with urbanization and location of human activities in coastal areas warrants serious consideration by planners and policy makers. This article has three objectives. First, flooding due to the combined effects of SLR and episodic hydro-meteorological and geophysical events in Honolulu are investigated and the risks to the community are quantified. Second, the risks and vulnerabilities of critical infrastructure and the surface transportation system are described. Third, using the travel demand software, travel distances and travel times for evacuation from inundated areas are modeled. Data from three inundation models were used. The first model simulated storm surge from a category 4 hurricane similar to Hurricane Iniki which devastated the island of Kauai in 1992. The second model estimates inundation based on five tsunamis that struck Hawaii. A 1-m increase in sea level was included in both the hurricane storm surge and tsunami flooding models. The third model used in this article generated a 500-year flood event due to riverine flooding. Using a uniform grid cell structure, the three inundation maps were used to assess the worst case flooding scenario. Based on the flood depths, the ruling hazard (hurricane, tsunami, or riverine flooding) for each grid cell was determined. The hazard layer was analyzed with socioeconomic data layers to determine the impact on vulnerable populations, economic activity, and critical infrastructure. The analysis focused both on evacuation needs and the critical elements of the infrastructure system that are needed to ensure effective response and recovery in the advent of flooding. This study shows that the coastal flooding will seriously affect the economy and employment. Extreme flooding events could affect 38 percent of the freeways, 44 percent of the highways, 69 percent of the arterial roads, and 40 percent of the local streets in the area examined. Approximately 80 percent of the economy and 76 percent of the total employment in the urban core of Honolulu is exposed to flooding. Evacuation modeling, shelter accessibility, and travel time to shelter analyses revealed that there is a significant shortage in sheltering options, as well as increases in travel times and distances as inundation depth increases. The findings are useful for evacuation and shelter planning for extreme coastal events, as well as for climate change adaptation planning in Honolulu. Recommendations for emergency responders as well as those interested in the integration of long-term SLR and low probability, high consequence coastal hazards are included. The study shows how to integrate travel demand modeling across multiple hazards and threats related to evacuating, sheltering, and disaster risk reduction.

Hydraulic and hydrologic aspects of flood-plain planning

USGS Publications Warehouse

Wiitala, S.W.; Jetter, K.R.; Sommerville, Alan J.

1961-01-01

The valid incentives compelling occupation of the flood plain, up to and eve n into the stream channel, undoubtedly have contributed greatly to the development of the country. But the result has been a heritage of flood disaster, suffering, and enormous costs. Flood destruction awakened a consciousness toward reduction and elimination of flood hazards, originally manifested in the protection of existing developments. More recently, increased knowledge of the problem has shown the impracticability of permitting development that requires costly flood protect/on. The idea of flood zoning, or flood-plain planning, has received greater impetus as a result of this realization. This study shows how hydraulic and hydrologic data concerning the flood regimen of a stream can be used in appraising its flood potential and the risk inherent in occupation of its flood plain. The approach involves the study of flood magnitudes as recorded or computed; flood frequencies based1 on experience shown by many years of gaging-station record; use of existing or computed stagedischarge relations and flood profiles; and, where required, the preparation of flood-zone maps to show the areas inundated by floods of several magnitudes and frequencies. The planner can delineate areas subject to inundation by floods o* specific recurrence intervals for three conditions: (a) for the immediate vicinity of a gaging station; (b) for a gaged stream at a considerable distance from a gaging station; and (c) for an ungaged stream. The average depth for a flood of specific frequency can be estimated on the basis of simple measurements of area of drainage basin, width of channel, and slope of streambed. This simplified approach should be useful in the initial stages of flood-plain planning. Brief discussions are included on various types of flood hazards, the effects of urbanization on flood runoff, and zoning considerations.

Impacts of Changing Climate, Hydrology and Land Use on the Stormwater Runoff of Urbanizing Central Florida

NASA Astrophysics Data System (ADS)

Huq, E.; Abdul-Aziz, O. I.

2017-12-01

We computed the historical and future storm runoff scenarios for the Shingle Creek Basin, including the growing urban centers of central Florida (e.g., City of Orlando). Storm Water Management Model (SWMM 5.1) of US EPA was used to develop a mechanistic hydrologic model for the basin by incorporating components of urban hydrology, hydroclimatological variables, and land use/cover features. The model was calibrated and validated with historical streamflow of 2004-2013 near the outlet of the Shingle Creek. The calibrated model was used to compute the sensitivities of stormwater budget to reference changes in hydroclimatological variables (rainfall and evapotranspiration) and land use/cover features (imperviousness, roughness). Basin stormwater budgets for the historical (2010s = 2004-2013) and future periods (2050s = 2030-2059; 2080s = 2070-2099) were also computed based on downscaled climatic projections of 20 GCMs-RCMs representing the coupled model intercomparison project (CMIP5), and anticipated changes in land use/cover. The sensitivity analyses indicated the dominant drivers of urban runoff in the basin. Comparative assessment of the historical and future stormwater runoff scenarios helped to locate basin areas that would be at a higher risk of future stormwater flooding. Importance of the study lies in providing valuable guidelines for managing stormwater flooding in central Florida and similar growing urban centers around the world.

A Study on the Land Use Characteristics of Urban Medium and Small stream Depending on the Width of stream

NASA Astrophysics Data System (ADS)

Seok, Song Young; Ho, Song Yang; Ho, Lee Jung; Moo Jong, Park

2015-04-01

Due to the increase of impervious layers caused by increased rainfall and urbanization which were brought about by the climate change after the late 1990s, the flood damage in urban watersheds is rising. The recent flood damage is occurring in medium and small stream rather than in large stream. Particularly, in medium stream which pass the cities, sudden flood occurs due to the short concentration of rainfall and urban areas suffer large damage, even though the flood damage is small, since residential areas and social infrastructures are concentrated. In spite of the importance of medium and small stream to pass the cities, there is no certain standard for classification of natural or urban stream and existing studies are mostly focused on the impervious area among the land use characteristics of watersheds. Most of existing river studies are based on the watershed scale, but in most urban watersheds where stream pass, urban areas are concentrated in the confluence, so urban areas only occupy less than 10% of the whole watershed and there is a high uncertainty in the classification of urban areas, based the watershed of stream. This study aims to suggest a classification standard of medium and small stream between local stream and small stream where suffer flood damage. According to the classified medium and small stream, this study analyzed the stream area to the stream width and distance using Arcgis Buffer tool, based on the stream line, not the existing watershed scale. This study then chose urban watersheds by analyzing the river area at certain intervals from the center of the chosen medium and small stream, in different ways. Among the land use characteristics in urban areas, the impervious area was applied to the selection standard of urban watersheds and the characteristics of urban watersheds were presented by calculating the ratio of the stream area to the impervious area using the Buffer tool. Acknowledgement "This research was supported by a grant [NEMA-NH-2011-45] from the Natural Hazard Mitigation Research Group, National Emergency Management Agency of Korea." Keywords: land use, urban watershed, medium and smaill stream, impervious area

Post-fire, rainfall intensity-peak discharge relations for three mountainous watersheds in the Western USA

USGS Publications Warehouse

Moody, J.A.; Martin, D.A.

2001-01-01

Wildfire alters the hydrologic response of watersheds, including the peak discharges resulting from subsequent rainfall. Improving predictions of the magnitude of flooding that follows wildfire is needed because of the increase in human population at risk in the wildland-urban interface. Because this wildland-urban interface is typically in mountainous terrain, we investigated rainfall-runoff relations by measuring the maximum 30 min rainfall intensity and the unit-area peak discharge (peak discharge divided by the area burned) in three mountainous watersheds (17-26.8 km2) after a wildfire. We found rainfall-runoff relations that relate the unit-area peak discharges to the maximum 30 min rainfall intensities by a power law. These rainfall-runoff relations appear to have a threshold value for the maximum 30 min rainfall intensity (around 10 mm h-1) such that, above this threshold, the magnitude of the flood peaks increases more rapidly with increases in intensity. This rainfall intensity could be used to set threshold limits in rain gauges that are part of an early-warning flood system after wildfire. The maximum unit-area peak discharges from these three burned watersheds ranged from 3.2 to 50 m3 s-1 km-2. These values could provide initial estimates of the upper limits of runoff that can be used to predict floods after wildfires in mountainous terrain. Published in 2001 by John Wiley and Sons, Ltd.

Communication on urban resilience to extreme weather: challenges and achievements in the dialogue between the international scientific community and local stakeholders

NASA Astrophysics Data System (ADS)

Vicari, Rosa; Gires, Auguste; Tchiguirinskaia, Ioulia; Schertzer, Daniel

2014-05-01

The frequency and damages caused by pluvial floods in European cities are expected to increase as a consequence of climate change and urban development. New solutions are needed at local level to cope with extreme storm events and to reduce risks and costs on populations and infrastructures, in particular in disadvantaged urban areas. The HM&Co team (LEESU & Chair 'Hydrology for Resilient Cities' sponsored by Veolia) aims to develop resilient urban systems with the help of innovative technologies, tools and practices based in particular on the use of high-resolution data, simulations, forecasts and management. Indeed, the availability of fine-scale rainfall data, due to the improved reliability of recent low-cost weather radars, opens up prospects for new forms of local urban flood risk management, which requires exchange of information with local actors and their full cooperation with researchers. This demands a large collaboration ranging from regional to international levels, e.g. the RadX@IdF project (Regional Council of Paris Region), the RainGain project (EU Interreg programme) and Blue Green Dream project (Climate-KIC programme), TOMACS (World Meteorological Organisation). These research projects and programmes include awareness raising and capacity building activities aimed to stimulate cooperation between scientists, professionals (e.g. water managers, urban planners) and beneficiaries (e.g. concerned citizens, policy makers). A dialogue between these actors is indeed needed to bring together the know-how from different countries and areas of expertise, avoid fragmentation and link it to the needs of the local stakeholders. Without this "conductive environment", research results risk to remain unexploited. After a general description of the background communication needs, this presentation will illustrate the outreach practices that are carried out by the HM&Co team. The major challenges will be also discussed, some examples are: narrating research uncertainty and its open issues as a virtuous process, aligning diverging objectives and approaches in a common vision, making an innovative technology visible to the public and managing rumours on security issues, bridging the gap between scientific discourses from an international academic community and operational discourses from local communities.

Prioritising watersheds on the basis of regional flood susceptibility and vulnerability in mountainous areas through the use of indicators

NASA Astrophysics Data System (ADS)

Rogelis, Carolina; Werner, Micha

2013-04-01

Settlements in peri-urban areas of many cities in mountainous areas such as in the Andes are susceptible to hazards such as flash floods and debris flows. Additionally these settlements are in many cases informal and thus vulnerable to such hazards, resulting in significant risk. Such watersheds are often quiet small, and generally there is little or no information from gauges to help characterise risk. To help identify watersheds in which flood management measures are to be targeted, a rapid assessment of risk is required. In this paper a novel approach is presented where indicators of susceptibility and vulnerability to flash floods were used to prioritize 106 mountain watersheds in Bogotá (Colombia). Variables recognized in literature to determine the dominant processes both in susceptibility and vulnerability to flash floods were used to construct the indicators. Susceptibility was considered to increase with flashiness and the possibility of debris flow events occurring. This was assessed through the use of an indicator composed of a morphometric indicator and a land use indicator. The former was constructed using morphological variables recognized in literature to significantly influence flashiness and occurrence of debris flows; the latter was constructed in terms of percentage of vegetation cover, urban area and bare soil. The morphometric indicator was compared with the results of a debris flow propagation algorithm to assess its capacity in indentifying the morphological conditions of a watershed that make it able to transport debris flows. Propagation was carried out through the use of the Modified Single Flow Direction algorithm, following previous identification of source areas by applying thresholds identified in the area-slope curve of the watersheds and empirical thresholds. Results show that the morphometric variables can be grouped in four categories: size, shape, hypsometry and energy, with the energy the component found to best explain the capability of the watershed to transport debris flows. The combination of the morphometric and land use indicators resulted in a susceptibility indicator that was compared with the available records of past floods in the area. This showed that the use of the land use indicator significantly improves the susceptibility assessment. Vulnerability was assessed in terms of indicators representing physical exposure, fragility of the socio-economic system and lack of resilience to cope and recover. Principal component analysis was subsequently applied to reduce variables and provide a representation of each of their facets by a component. This resulted in a composite indicator of susceptibility and vulnerability for each of the 106 watersheds. The indicator was compared with the history of flash flood damage in the watersheds. Results show that the indicator is useful in applications at regional scales for preliminary assessment to differentiate at spatial level the degree of flood susceptibility and vulnerability. This provides an initial and qualitative risk outlook in the study area and can be used for planning and prioritization of further more detailed studies.

A new approach for river flood extent delineation in rural and urban areas combining RADARSAT-2 imagery and flood recurrence interval data

NASA Astrophysics Data System (ADS)

Tanguy, Marion; Bernier, Monique; Chokmani, Karem

2015-04-01

When a flood hits an inhabited area, managers and services responsible for public safety need precise, reliable and up to date maps of the areas affected by the flood, in order to quickly roll out and to coordinate the adequate intervention and assistance plans required to limit the human and material damages caused by the disaster. Synthetic aperture radar (SAR) sensors are now considered as one of the most adapted tool for flood detection and mapping in a context of crisis management. Indeed, due to their capacity to acquire data night and day, in almost all meteorological conditions, SAR sensors allow the acquisition of synoptic but detailed views of the areas affected by the flood, even during the active phases of the event. Moreover, new generation sensors such as RADARSAT-2, TerraSAR-X, COSMO-SkyMed, are providing very high resolution images of the disaster (down to 1m ground resolution). Further, critical improvements have been made on the temporal repetitivity of acquisitions and on data availability, through the development of satellite constellations (i.e the four COSMO-Skymed or the Sentinel-1A and 1B satellites) and thanks to the implementation of the International Charter "Space and Major Disasters", which guarantees high priority images acquisition and delivery with 4 to 12 hours. If detection of open water flooded areas is relatively straightforward with SAR imagery, flood detection in built-up areas is often associated with important issues. Indeed, because of the side looking geometry of the SAR sensors, structures such as tall vegetation and structures parallel to the satellite direction of travel may produce shadow and layover effects, leading to important over and under-detections of flooded pixels. Besides, the numerous permanent water-surfaces like radar response areas present in built-up environments, such as parking lots, roads etc., may be mixed up with flooded areas, resulting in substantial inaccuracies in the final flood map. In spite of the many efforts recently done toward the improvements of the accuracy of the processing algorithms for flood detection in urban areas with high resolution SAR imagery, these algorithms still encounter difficulties to detect urban flooded pixels with precision. The difficulties do not seem to be only ascribable to the choice of SAR image processing methods, but can also be imputed to the limitations of the SAR imaging technique itself in urban areas. We propose a fully automatic and effective approach for near-real time delineation of urban and rural flooded areas, which combines the capacity of SAR imagery to detect open water areas, and explicit hydrodynamic characteristics of the region affected by the flood, expressed through flood recurrence interval data. This innovative approach has been tested with RADARSAT-2 Fine and Ultrafine Mode images acquired during the 2011 Richelieu River flooding, in Canada. It proved successful in accurately delineating flooding in urban and rural areas, with a RMSE inferior to 2 pixels.

Urban infrastructure and water management—Science capabilities of the U.S. Geological Survey

USGS Publications Warehouse

Fisher, Shawn C.; Fanelli, Rosemary M.; Selbig, William R.

2016-04-29

Managing the urban-water cycle has increasingly become a challenge for water-resources planners and regulators faced with the problem of providing clean drinking water to urban residents. Sanitary and combined sanitary and storm sewer networks convey wastewater to centralized treatment plants. Impervious surfaces, which include roads, parking lots, and buildings, increase stormwater runoff and the efficiency by which runoff is conveyed to nearby stream channels; therefore, impervious surfaces increase the risk of urban flooding and alteration of natural ecosystems. These challenges will increase with the expansion of urban centers and the probable effects of climate change on precipitation patterns. Understanding the urban-water cycle is critical to effectively manage water resources and to protect people, infrastructure, and urban-stream ecosystems. As a leader in water-supply, wastewater, and stormwater assessments, the U.S. Geological Survey has the expertise and resources needed to monitor, model, and interpret data related to the urban-water cycle and thereby enable water-resources managers to make informed decisions.

Challenges for tree officers to enhance the provision of regulating ecosystem services from urban forests.

PubMed

Davies, Helen J; Doick, Kieron J; Hudson, Malcolm D; Schreckenberg, Kate

2017-07-01

Urbanisation and a changing climate are leading to more frequent and severe flood, heat and air pollution episodes in Britain's cities. Interest in nature-based solutions to these urban problems is growing, with urban forests potentially able to provide a range of regulating ecosystem services such as stormwater attenuation, heat amelioration and air purification. The extent to which these benefits are realized is largely dependent on urban forest management objectives, the availability of funding, and the understanding of ecosystem service concepts within local governments, the primary delivery agents of urban forests. This study aims to establish the extent to which British local authorities actively manage their urban forests for regulating ecosystem services, and identify which resources local authorities most need in order to enhance provision of ecosystem services by Britain's urban forests. Interviews were carried out with staff responsible for tree management decisions in fifteen major local authorities from across Britain, selected on the basis of their urban nature and high population density. Local authorities have a reactive approach to urban forest management, driven by human health and safety concerns and complaints about tree disservices. There is relatively little focus on ensuring provision of regulating ecosystem services, despite awareness by tree officers of the key role that urban forests can play in alleviating chronic air pollution, flood risk and urban heat anomalies. However, this is expected to become a greater focus in future provided that existing constraints - lack of understanding of ecosystem services amongst key stakeholders, limited political support, funding constraints - can be overcome. Our findings suggest that the adoption of a proactive urban forest strategy, underpinned by quantified and valued urban forest-based ecosystem services provision data, and innovative private sector funding mechanisms, can facilitate a change to a proactive, ecosystem services approach to urban forest management. Copyright © 2017. Published by Elsevier Inc.

What Is Driving the Observed Changes in Flooding in the Turkey River in Iowa?

NASA Astrophysics Data System (ADS)

Smith, C.; Yu, G.; Wright, D.

2017-12-01

Flooding can have severe societal, economic, and environmental consequences. In the United States-and worldwide-flooding causes fatalities and billions of dollars in economic loss. Recent research has pointed to changing flood risks in the Midwestern United States. However, we have a limited understanding of what natural and human factors are driving these changes. Researchers have proposed several possible explanations. Increasing intensity of short-duration summertime rainfall, reduced snow cover and earlier snow and soil thaw, changes in land surface evapotranspiration, and the effects of urbanization and agricultural management practices may all play roles in the shifts seen in the hydrologic cycle and flooding in Midwest. This study intends to look at the changes in the region on a smaller scale, whereas most previous research has examined at broad regional trends. Our focus will be on the agricultural Turkey River watershed in northeastern Iowa, where the flood hydroclimatology shows an abrupt shift around the year 1990 toward lower mean annual floods and dramatic increases in the magnitude and frequency of the largest floods. Analyses of land use, temperature, rainfall, river flow, and atmospheric properties, as well as simple continuous hydrologic simulations will aid in our understanding of the flood behavior of Turkey River and its drivers. In doing so, we hope to shed light on the causes of the changes in flooding and hydrology more generally that are taking place throughout the region.

Frequency analysis of urban runoff quality in an urbanizing catchment of Shenzhen, China

NASA Astrophysics Data System (ADS)

Qin, Huapeng; Tan, Xiaolong; Fu, Guangtao; Zhang, Yingying; Huang, Yuefei

2013-07-01

This paper investigates the frequency distribution of urban runoff quality indicators using a long-term continuous simulation approach and evaluates the impacts of proposed runoff control schemes on runoff quality in an urbanizing catchment in Shenzhen, China. Four different indicators are considered to provide a comprehensive assessment of the potential impacts: total runoff depth, event pollutant load, Event Mean Concentration, and peak concentration during a rainfall event. The results obtained indicate that urban runoff quantity and quality in the catchment have significant variations in rainfall events and a very high rate of non-compliance with surface water quality regulations. Three runoff control schemes with the capacity to intercept an initial runoff depth of 5 mm, 10 mm, and 15 mm are evaluated, respectively, and diminishing marginal benefits are found with increasing interception levels in terms of water quality improvement. The effects of seasonal variation in rainfall events are investigated to provide a better understanding of the performance of the runoff control schemes. The pre-flood season has higher risk of poor water quality than other seasons after runoff control. This study demonstrates that frequency analysis of urban runoff quantity and quality provides a probabilistic evaluation of pollution control measures, and thus helps frame a risk-based decision making for urban runoff quality management in an urbanizing catchment.

Recent changes in stream flashiness and flooding, and effects of flood management in North Carolina and Virginia

USGS Publications Warehouse

Mogollón, Beatriz; Frimpong, Emmanuel A.; Hoegh, Andrew B.; Angermeier, Paul L.

2016-01-01

The southeastern United States has undergone anthropogenic changes in landscape structure, with the potential to increase (e.g., urbanization) and decrease (e.g., reservoir construction) stream flashiness and flooding. Assessment of the outcome of such change can provide insight into the efficacy of current strategies and policies to manage water resources. We (1) examined trends in precipitation, floods, and stream flashiness and (2) assessed the relative influence of land cover and flow-regulating features (e.g., best management practices and artificial water bodies) on stream flashiness from 1991 to 2013. We found mean annual precipitation decreased, which coincided with decreasing trends in floods. In contrast, stream flashiness, overall, showed an increasing trend during the period of study. However, upon closer examination, 20 watersheds showed stable stream flashiness, whereas 5 increased and 6 decreased in flashiness. Urban watersheds were among those that increased or decreased in flashiness. Watersheds that increased in stream flashiness gained more urban cover, lost more forested cover and had fewer best management practices installed than urban watersheds that decreased in stream flashiness. We found best management practices are more effective than artificial water bodies in regulating flashy floods. Flashiness index is a valuable and straightforward metric to characterize changes in streamflow and help to assess the efficacy of management interventions.

Future heat-waves, droughts and floods in 571 European cities

NASA Astrophysics Data System (ADS)

Guerreiro, Selma B.; Dawson, Richard J.; Kilsby, Chris; Lewis, Elizabeth; Ford, Alistair

2018-03-01

Cities are particularly vulnerable to climate risks due to their agglomeration of people, buildings and infrastructure. Differences in methodology, hazards considered, and climate models used limit the utility and comparability of climate studies on individual cities. Here we assess, for the first time, future changes in flood, heat-waves (HW), and drought impacts for all 571 European cities in the Urban Audit database using a consistent approach. To capture the full range of uncertainties in natural variability and climate models, we use all climate model runs from the Coupled Model Inter-comparison Project Phase 5 (CMIP5) for the RCP8.5 emissions scenario to calculate Low, Medium and High Impact scenarios, which correspond to the 10th, 50th and 90th percentiles of each hazard for each city. We find that HW days increase across all cities, but especially in southern Europe, whilst the greatest HW temperature increases are expected in central European cities. For the low impact scenario, drought conditions intensify in southern European cities while river flooding worsens in northern European cities. However, the high impact scenario projects that most European cities will see increases in both drought and river flood risks. Over 100 cities are particularly vulnerable to two or more climate impacts. Moreover, the magnitude of impacts exceeds those previously reported highlighting the substantial challenge cities face to manage future climate risks.

Influence of model reduction on uncertainty of flood inundation predictions

NASA Astrophysics Data System (ADS)

Romanowicz, R. J.; Kiczko, A.; Osuch, M.

2012-04-01

Derivation of flood risk maps requires an estimation of the maximum inundation extent for a flood with an assumed probability of exceedence, e.g. a 100 or 500 year flood. The results of numerical simulations of flood wave propagation are used to overcome the lack of relevant observations. In practice, deterministic 1-D models are used for flow routing, giving a simplified image of a flood wave propagation process. The solution of a 1-D model depends on the simplifications to the model structure, the initial and boundary conditions and the estimates of model parameters which are usually identified using the inverse problem based on the available noisy observations. Therefore, there is a large uncertainty involved in the derivation of flood risk maps. In this study we examine the influence of model structure simplifications on estimates of flood extent for the urban river reach. As the study area we chose the Warsaw reach of the River Vistula, where nine bridges and several dikes are located. The aim of the study is to examine the influence of water structures on the derived model roughness parameters, with all the bridges and dikes taken into account, with a reduced number and without any water infrastructure. The results indicate that roughness parameter values of a 1-D HEC-RAS model can be adjusted for the reduction in model structure. However, the price we pay is the model robustness. Apart from a relatively simple question regarding reducing model structure, we also try to answer more fundamental questions regarding the relative importance of input, model structure simplification, parametric and rating curve uncertainty to the uncertainty of flood extent estimates. We apply pseudo-Bayesian methods of uncertainty estimation and Global Sensitivity Analysis as the main methodological tools. The results indicate that the uncertainties have a substantial influence on flood risk assessment. In the paper we present a simplified methodology allowing the influence of that uncertainty to be assessed. This work was supported by National Science Centre of Poland (grant 2011/01/B/ST10/06866).

Crowdsourcing detailed flood data

NASA Astrophysics Data System (ADS)

Walliman, Nicholas; Ogden, Ray; Amouzad*, Shahrzhad

2015-04-01

Over the last decade the average annual loss across the European Union due to flooding has been 4.5bn Euros, but increasingly intense rainfall, as well as population growth, urbanisation and the rising costs of asset replacements, may see this rise to 23bn Euros a year by 2050. Equally disturbing are the profound social costs to individuals, families and communities which in addition to loss of lives include: loss of livelihoods, decreased purchasing and production power, relocation and migration, adverse psychosocial effects, and hindrance of economic growth and development. Flood prediction, management and defence strategies rely on the availability of accurate information and flood modelling. Whilst automated data gathering (by measurement and satellite) of the extent of flooding is already advanced it is least reliable in urban and physically complex geographies where often the need for precise estimation is most acute. Crowdsourced data of actual flood events is a potentially critical component of this allowing improved accuracy in situations and identifying the effects of local landscape and topography where the height of a simple kerb, or discontinuity in a boundary wall can have profound importance. Mobile 'App' based data acquisition using crowdsourcing in critical areas can combine camera records with GPS positional data and time, as well as descriptive data relating to the event. This will automatically produce a dataset, managed in ArcView GIS, with the potential for follow up calls to get more information through structured scripts for each strand. Through this local residents can provide highly detailed information that can be reflected in sophisticated flood protection models and be core to framing urban resilience strategies and optimising the effectiveness of investment. This paper will describe this pioneering approach that will develop flood event data in support of systems that will advance existing approaches such as developed in the in the UK in the more generalised RASP project (DEFRA and the Environment Agency), and in line with the expressed needs of the ABI (Association of British Insurers) and National Flood Forum. The detailed data produced will also support improved flood risk assessment for the provision of affordable insurance.

High-resolution marine flood modelling coupling overflow and overtopping processes: framing the hazard based on historical and statistical approaches

NASA Astrophysics Data System (ADS)

Nicolae Lerma, Alexandre; Bulteau, Thomas; Elineau, Sylvain; Paris, François; Durand, Paul; Anselme, Brice; Pedreros, Rodrigo

2018-01-01

A modelling chain was implemented in order to propose a realistic appraisal of the risk in coastal areas affected by overflowing as well as overtopping processes. Simulations are performed through a nested downscaling strategy from regional to local scale at high spatial resolution with explicit buildings, urban structures such as sea front walls and hydraulic structures liable to affect the propagation of water in urban areas. Validation of the model performance is based on hard and soft available data analysis and conversion of qualitative to quantitative information to reconstruct the area affected by flooding and the succession of events during two recent storms. Two joint probability approaches (joint exceedance contour and environmental contour) are used to define 100-year offshore conditions scenarios and to investigate the flood response to each scenario in terms of (1) maximum spatial extent of flooded areas, (2) volumes of water propagation inland and (3) water level in flooded areas. Scenarios of sea level rise are also considered in order to evaluate the potential hazard evolution. Our simulations show that for a maximising 100-year hazard scenario, for the municipality as a whole, 38 % of the affected zones are prone to overflow flooding and 62 % to flooding by propagation of overtopping water volume along the seafront. Results also reveal that for the two kinds of statistic scenarios a difference of about 5 % in the forcing conditions (water level, wave height and period) can produce significant differences in terms of flooding like +13.5 % of water volumes propagating inland or +11.3 % of affected surfaces. In some areas, flood response appears to be very sensitive to the chosen scenario with differences of 0.3 to 0.5 m in water level. The developed approach enables one to frame the 100-year hazard and to characterize spatially the robustness or the uncertainty over the results. Considering a 100-year scenario with mean sea level rise (0.6 m), hazard characteristics are dramatically changed with an evolution of the overtopping / overflowing process ratio and an increase of a factor 4.84 in volumes of water propagating inland and 3.47 in flooded surfaces.

Perception of Urban Environmental Risks and the Effects of Urban Green Infrastructures (UGIs) on Human Well-being in Four Public Green Spaces of Guangzhou, China.

PubMed

Duan, Junya; Wang, Yafei; Fan, Chen; Xia, Beicheng; de Groot, Rudolf

2018-05-28

Cities face many challenging environmental problems that affect human well-being. Environmental risks can be reduced by Urban Green Infrastructures (UGIs). The effects of UGIs on the urban environment have been widely studied, but less attention has been given to the public perception of these effects. This paper presents the results of a study in Guangzhou, China, on UGI users' perceptions of these effects and their relationship with sociodemographic variables. A questionnaire survey was conducted in four public green spaces. Descriptive statistics, a binary logistic regression model and cross-tabulation analysis were applied on the data from 396 valid questionnaires. The results show that UGI users were more concerned about poor air quality and high temperature than about flooding events. Their awareness of environmental risks was partly in accordance with official records. Regarding the perception of the impacts of environmental risks on human well-being, elderly and female respondents with higher education levels were the most sensitive to these impacts. The respondents' perceptions of these impacts differed among the different green spaces. The effects of UGIs were well perceived and directly observed by the UGI users, but were not significantly influenced by most sociodemographic variables. Moreover, tourists had a lower perception of the impacts of environmental risks and the effects of UGI than residents did. This study provides strong support for UGIs as an effective tool to mitigate environmental risks. Local governments should consider the role of UGIs in environmental risk mitigation and human well-being with regard to urban planning and policy making.

Flood damage curves for consistent global risk assessments

NASA Astrophysics Data System (ADS)

de Moel, Hans; Huizinga, Jan; Szewczyk, Wojtek

2016-04-01

Assessing potential damage of flood events is an important component in flood risk management. Determining direct flood damage is commonly done using depth-damage curves, which denote the flood damage that would occur at specific water depths per asset or land-use class. Many countries around the world have developed flood damage models using such curves which are based on analysis of past flood events and/or on expert judgement. However, such damage curves are not available for all regions, which hampers damage assessments in those regions. Moreover, due to different methodologies employed for various damage models in different countries, damage assessments cannot be directly compared with each other, obstructing also supra-national flood damage assessments. To address these problems, a globally consistent dataset of depth-damage curves has been developed. This dataset contains damage curves depicting percent of damage as a function of water depth as well as maximum damage values for a variety of assets and land use classes (i.e. residential, commercial, agriculture). Based on an extensive literature survey concave damage curves have been developed for each continent, while differentiation in flood damage between countries is established by determining maximum damage values at the country scale. These maximum damage values are based on construction cost surveys from multinational construction companies, which provide a coherent set of detailed building cost data across dozens of countries. A consistent set of maximum flood damage values for all countries was computed using statistical regressions with socio-economic World Development Indicators from the World Bank. Further, based on insights from the literature survey, guidance is also given on how the damage curves and maximum damage values can be adjusted for specific local circumstances, such as urban vs. rural locations, use of specific building material, etc. This dataset can be used for consistent supra-national scale flood damage assessments, and guide assessment in countries where no damage model is currently available.

Estimating flood magnitude and frequency for urban and small, rural streams in Georgia, South Carolina, and North Carolina, 2011

USGS Publications Warehouse

Feaster, Toby D.; Gotvald, Anthony J.; Weaver, J. Curtis

2014-01-01

Reliable estimates of the magnitude and frequency of floods are essential for the design of transportation and water-conveyance structures, flood insurance studies, and flood-plain management. Flood-frequency estimates are particularly important in densely populated urban areas. The U.S. Geological Survey (USGS) used a multistate approach to update methods for determining the magnitude and frequency of floods in urban and small, rural streams that are not substantially affected by regulation or tidal fluctuations in Georgia, South Carolina, and North Carolina (Feaster and others, 2014). The multistate approach has the advantage over a single state approach of increasing the number of streamflow-gaging station (streamgages) available for analysis, expanding the geographical coverage that would allow for application of regional regression equations across state boundaries, and building on a previous flood-frequency investigation of rural streamgages in the Southeastern United States. This investigation was funded as part of a cooperative program of water-resources investigations between the USGS, the South Carolina Department of Transportation, and the North Carolina Department of Transportation. In addition, much of the data and information for the Georgia streamgages was funded through a similar cooperative program with the Georgia Department of Transportation.

Effects of an Extreme Flood on Trace Elements in River Water-From Urban Stream to Major River Basin.

PubMed

Barber, Larry B; Paschke, Suzanne S; Battaglin, William A; Douville, Chris; Fitzgerald, Kevin C; Keefe, Steffanie H; Roth, David A; Vajda, Alan M

2017-09-19

Major floods adversely affect water quality through surface runoff, groundwater discharge, and damage to municipal water infrastructure. Despite their importance, it can be difficult to assess the effects of floods on streamwater chemistry because of challenges collecting samples and the absence of baseline data. This study documents water quality during the September 2013 extreme flood in the South Platte River, Colorado, USA. Weekly time-series water samples were collected from 3 urban source waters (municipal tap water, streamwater, and wastewater treatment facility effluent) under normal-flow and flood conditions. In addition, water samples were collected during the flood at 5 locations along the South Platte River and from 7 tributaries along the Colorado Front Range. Samples were analyzed for 54 major and trace elements. Specific chemical tracers, representing different natural and anthropogenic sources and geochemical behaviors, were used to compare streamwater composition before and during the flood. The results differentiate hydrological processes that affected water quality: (1) in the upper watershed, runoff diluted most dissolved constituents, (2) in the urban corridor and lower watershed, runoff mobilized soluble constituents accumulated on the landscape and contributed to stream loading, and (3) flood-induced groundwater discharge mobilized soluble constituents stored in the vadose zone.

Flood modelling with global precipitation measurement (GPM) satellite rainfall data: a case study of Dehradun, Uttarakhand, India

NASA Astrophysics Data System (ADS)

Sai Krishna, V. V.; Dikshit, Anil Kumar; Pandey, Kamal

2016-05-01

Urban expansion, water bodies and climate change are inextricably linked with each other. The macro and micro level climate changes are leading to extreme precipitation events which have severe consequences on flooding in urban areas. Flood simulations shall be helpful in demarcation of flooded areas and effective flood planning and preparedness. The temporal availability of satellite rainfall data at varying spatial scale of 0.10 to 0.50 is helpful in near real time flood simulations. The present research aims at analysing stream flow and runoff to monitor flood condition using satellite rainfall data in a hydrologic model. The satellite rainfall data used in the research was NASA's Integrated Multi-satellite Retrievals for Global Precipitation Measurement (IMERG), which is available at 30 minutes temporal resolution. Landsat data was used for mapping the water bodies in the study area. Land use land cover (LULC) data was prepared using Landsat 8 data with maximum likelihood technique that was provided as an input to the HEC-HMS hydrological model. The research was applied to one of the urbanized cities of India, viz. Dehradun, which is the capital of Uttarakhand State. The research helped in identifying the flood vulnerability at the basin level on the basis of the runoff and various socio economic parameters using multi criteria analysis.

Effects of an extreme flood on trace elements in river water—From urban stream to major river basin

USGS Publications Warehouse

Barber, Larry B.; Paschke, Suzanne; Battaglin, William A.; Douville, Chris; Fitzgerald, Kevin C.; Keefe, Steffanie H.; Roth, David A.; Vajda, Alan M.

2017-01-01

Major floods adversely affect water quality through surface runoff, groundwater discharge, and damage to municipal water infrastructure. Despite their importance, it can be difficult to assess the effects of floods on streamwater chemistry because of challenges collecting samples and the absence of baseline data. This study documents water quality during the September 2013 extreme flood in the South Platte River, Colorado, USA. Weekly time-series water samples were collected from 3 urban source waters (municipal tap water, streamwater, and wastewater treatment facility effluent) under normal-flow and flood conditions. In addition, water samples were collected during the flood at 5 locations along the South Platte River and from 7 tributaries along the Colorado Front Range. Samples were analyzed for 54 major and trace elements. Specific chemical tracers, representing different natural and anthropogenic sources and geochemical behaviors, were used to compare streamwater composition before and during the flood. The results differentiate hydrological processes that affected water quality: (1) in the upper watershed, runoff diluted most dissolved constituents, (2) in the urban corridor and lower watershed, runoff mobilized soluble constituents accumulated on the landscape and contributed to stream loading, and (3) flood-induced groundwater discharge mobilized soluble constituents stored in the vadose zone.

Use of surrogate indicators for the evaluation of potential health risks due to poor urban water quality: A Bayesian Network approach.

PubMed

Wijesiri, Buddhi; Deilami, Kaveh; McGree, James; Goonetilleke, Ashantha

2018-02-01

Urban water pollution poses risks of waterborne infectious diseases. Therefore, in order to improve urban liveability, effective pollution mitigation strategies are required underpinned by predictions generated using water quality models. However, the lack of reliability in current modelling practices detrimentally impacts planning and management decision making. This research study adopted a novel approach in the form of Bayesian Networks to model urban water quality to better investigate the factors that influence risks to human health. The application of Bayesian Networks was found to enhance the integration of quantitative and qualitative spatially distributed data for analysing the influence of environmental and anthropogenic factors using three surrogate indicators of human health risk, namely, turbidity, total nitrogen and fats/oils. Expert knowledge was found to be of critical importance in assessing the interdependent relationships between health risk indicators and influential factors. The spatial variability maps of health risk indicators developed enabled the initial identification of high risk areas in which flooding was found to be the most significant influential factor in relation to human health risk. Surprisingly, population density was found to be less significant in influencing health risk indicators. These high risk areas in turn can be subjected to more in-depth investigations instead of the entire region, saving time and resources. It was evident that decision making in relation to the design of pollution mitigation strategies needs to account for the impact of landscape characteristics on water quality, which can be related to risk to human health. Copyright © 2017 Elsevier Ltd. All rights reserved.

Unstructured mesh adaptivity for urban flooding modelling

NASA Astrophysics Data System (ADS)

Hu, R.; Fang, F.; Salinas, P.; Pain, C. C.

2018-05-01

Over the past few decades, urban floods have been gaining more attention due to their increase in frequency. To provide reliable flooding predictions in urban areas, various numerical models have been developed to perform high-resolution flood simulations. However, the use of high-resolution meshes across the whole computational domain causes a high computational burden. In this paper, a 2D control-volume and finite-element flood model using adaptive unstructured mesh technology has been developed. This adaptive unstructured mesh technique enables meshes to be adapted optimally in time and space in response to the evolving flow features, thus providing sufficient mesh resolution where and when it is required. It has the advantage of capturing the details of local flows and wetting and drying front while reducing the computational cost. Complex topographic features are represented accurately during the flooding process. For example, the high-resolution meshes around the buildings and steep regions are placed when the flooding water reaches these regions. In this work a flooding event that happened in 2002 in Glasgow, Scotland, United Kingdom has been simulated to demonstrate the capability of the adaptive unstructured mesh flooding model. The simulations have been performed using both fixed and adaptive unstructured meshes, and then results have been compared with those published 2D and 3D results. The presented method shows that the 2D adaptive mesh model provides accurate results while having a low computational cost.

Distribution of uncertainties at the municipality level for flood risk modelling along the river Meuse: implications for policy-making

NASA Astrophysics Data System (ADS)

Pirotton, Michel; Stilmant, Frédéric; Erpicum, Sébastien; Dewals, Benjamin; Archambeau, Pierre

2016-04-01

Flood risk modelling has been conducted for the whole course of the river Meuse in Belgium. Major cities, such as Liege (200,000 inh.) and Namur (110,000 inh.), are located in the floodplains of river Meuse. Particular attention has been paid to uncertainty analysis and its implications for decision-making. The modelling chain contains flood frequency analysis, detailed 2D hydraulic computations, damage modelling and risk calculation. The relative importance of each source of uncertainty to the overall results uncertainty has been estimated by considering several alternate options for each step of the analysis: different distributions were considered in the flood frequency analysis; the influence of modelling assumptions and boundary conditions (e.g., steady vs. unsteady) were taken into account for the hydraulic computation; two different landuse classifications and two sets of damage functions were used; the number of exceedance probabilities involved in the risk calculation (by integration of the risk-curves) was varied. In addition, the sensitivity of the results with respect to increases in flood discharges was assessed. The considered increases are consistent with a "wet" climate change scenario for the time horizons 2021-2050 and 2071-2100 (Detrembleur et al., 2015). The results of hazard computation differ significantly between the upper and lower parts of the course of river Meuse in Belgium. In the former, inundation extents grow gradually as the considered flood discharge is increased (i.e. the exceedance probability is reduced), while in the downstream part, protection structures (mainly concrete walls) prevent inundation for flood discharges corresponding to exceedance probabilities of 0.01 and above (in the present climate). For higher discharges, large inundation extents are obtained in the floodplains. The highest values of risk (mean annual damage) are obtained in the municipalities which undergo relatively frequent flooding (upper part of the river), as well as in those of the downstream part of the Meuse in which flow depths in the urbanized floodplains are particularly high when inundation occurs. This is the case of the city of Liege, as a result of a subsidence process following former mining activities. For a given climate scenario, the uncertainty ranges affecting flood risk estimates are significant; but not so much that the results for the different municipalities would overlap substantially. Therefore, these uncertainties do not hamper prioritization in terms of allocation of risk reduction measures at the municipality level. In the present climate, the uncertainties arising from flood frequency analysis have a negligible influence in the upper part of the river, while they have a considerable impact on risk modelling in the lower part, where a threshold effect was observed due to the flood protection structures (sudden transition from no inundation to massive flooding when a threshold discharge is exceeded). Varying the number of exceedance probabilities in the integration of the risk curve has different effects for different municipalities; but it does not change the ranking of the municipalities in terms of flood risk. For the other scenarios, damage estimation contributes most to the overall uncertainties. As shown by this study, the magnitude of the uncertainty and its main origin vary in space and in time. This emphasizes the paramount importance of conducting distributed uncertainty analyses. In the considered study area, prioritization of risk reduction means can be reliably performed despite the modelling uncertainties. Reference Detrembleur, S., Stilmant, F., Dewals, B., Erpicum, S., Archambeau, P., & Pirotton, M. (2015). Impacts of climate change on future flood damage on the river Meuse, with a distributed uncertainty analysis. Natural Hazards, 77(3), 1533-1549. Acknowledgement Part of this research was funded through the ARC grant for Concerted Research Actions, financed by the Wallonia-Brussels Federation. It was also supported by the NWE Interreg IVB Program.

Advances in urban-drainage management and flood protection.

PubMed

Verworn, Hans-Reinhard

2002-07-15

Since the beginning of modern urban drainage in the 19th century, the sole objective has been to get rid of sewage and storm water in the best possible way and design the systems according to accepted standards. In recent decades, advanced methods have been developed not only to refine the design but also especially to enable the assessment of hydraulic performance and pollutant emissions. Consequently, urban drainage has become part of an integrated approach concerning flood protection as well as ecological aspects for whole watersheds. Another major change concerns the management of urban systems: simple structural maintenance has been replaced by interactive operational management and control of the systems in order to make better use of the facilities. Rehabilitation has become a multi-objective task. This paper looks at today's basic principles of urban drainage and tomorrow's potential advances, and deals with their relevance to flood protection.

Estimating the magnitude and frequency of floods in urban basins in Missouri

USGS Publications Warehouse

Southard, Rodney E.

2010-01-01

Streamgage flood-frequency analyses were done for 35 streamgages on urban streams in and adjacent to Missouri for estimation of the magnitude and frequency of floods in urban areas of Missouri. A log-Pearson Type-III distribution was fitted to the annual series of peak flow data retrieved from the U.S. Geological Survey National Water Information System. For this report, the flood frequency estimates are expressed in terms of percent annual exceedance probabilities of 50, 20, 10, 4, 2, 1, and 0.2. Of the 35 streamgages, 30 are located in Missouri. The remaining five non-Missouri streamgages were added to the dataset to improve the range and applicability of the regression analyses from the streamgage frequency analyses. Ordinary least-squares was used to determine the best set of independent variables for the regression equations. Basin characteristics selected for independent variables into the ordinary least-squares regression analyses were based on theoretical relation to flood flows, literature review of possible basin characteristics, and the ability to measure the basin characteristics using digital datasets and geographic information system technology. Results of the ordinary least-squares were evaluated on the basis of Mallow's Cp statistic, the adjusted coefficient of determination, and the statistical significance of the independent variables. The independent variables of drainage area and percent impervious area were determined to be statistically significant and readily determined from existing digital datasets. The drainage area variable was computed using the best elevation data available, either from a statewide 10-meter grid or high-resolution elevation data from urban areas. The impervious area variable was computed from the National Land Cover Dataset 2001 impervious area dataset. The National Land Cover Dataset 2001 impervious area data for each basin was compared to historical imagery and 7.5-minute topographic maps to verify the national dataset represented the urbanization of the basin at the time streamgage data were collected. Eight streamgages had less urbanization during the period of time streamflow data were collected than was shown on the 2001 dataset. The impervious area values for these eight urban basins were adjusted downward as much as 23 percent to account for the additional urbanization since the streamflow data were collected. Weighted least-squares regression techniques were used to determine the final regression equations for the statewide urban flood-frequency equations. Weighted least-squares techniques improve regression equations by adjusting for different and varying lengths in streamflow records. The final flood-frequency equations for the 50-, 20-, 10-, 4-, 2-, 1-, and 0.2-percent annual exceedance probability floods for Missouri provide a technique for estimating peak flows on urban streams at gaged and ungaged sites. The applicability of the equations is limited by the range in basin characteristics used to develop the regression equations. The range in drainage area is 0.28 to 189 square miles; range in impervious area is 2.3 to 46.0 percent. Seven of the 35 selected streamgages were used to compare the results of the existing rural and urban equations to the urban equations presented in this report for the 1-percent annual exceedance probability. Results of the comparison indicate that the estimated peak flows for the urban equation in this report ranged from 3 to 52 percent higher than the results from the rural equations. Comparing the estimated urban peak flows from this report to the existing urban equation developed in 1986 indicated the range was 255 percent lower to 10 percent higher. The overall comparison between the current (2010) and 1986 urban equations indicates a reduction in estimated peak flow values for the 1-percent annual exceedance probability flood.

A Global Geospatial Database of 5000+ Historic Flood Event Extents

NASA Astrophysics Data System (ADS)

Tellman, B.; Sullivan, J.; Doyle, C.; Kettner, A.; Brakenridge, G. R.; Erickson, T.; Slayback, D. A.

2017-12-01

A key dataset that is missing for global flood model validation and understanding historic spatial flood vulnerability is a global historical geo-database of flood event extents. Decades of earth observing satellites and cloud computing now make it possible to not only detect floods in near real time, but to run these water detection algorithms back in time to capture the spatial extent of large numbers of specific events. This talk will show results from the largest global historical flood database developed to date. We use the Dartmouth Flood Observatory flood catalogue to map over 5000 floods (from 1985-2017) using MODIS, Landsat, and Sentinel-1 Satellites. All events are available for public download via the Earth Engine Catalogue and via a website that allows the user to query floods by area or date, assess population exposure trends over time, and download flood extents in geospatial format.In this talk, we will highlight major trends in global flood exposure per continent, land use type, and eco-region. We will also make suggestions how to use this dataset in conjunction with other global sets to i) validate global flood models, ii) assess the potential role of climatic change in flood exposure iii) understand how urbanization and other land change processes may influence spatial flood exposure iv) assess how innovative flood interventions (e.g. wetland restoration) influence flood patterns v) control for event magnitude to assess the role of social vulnerability and damage assessment vi) aid in rapid probabilistic risk assessment to enable microinsurance markets. Authors on this paper are already using the database for the later three applications and will show examples of wetland intervention analysis in Argentina, social vulnerability analysis in the USA, and micro insurance in India.

Effects of Urbanization and Climate Change on Hydrological Processes over the San Antonio River Basin, Texas

NASA Astrophysics Data System (ADS)

Zhao, G.; Gao, H.; Cuo, L.

2014-12-01

With the rapid population growth and economic development in the State of Texas, a fast urbanization process has occurred over the past several decades. The direct consequences of the increased impervious area are greater surface runoff and higher flood peaks. Meanwhile, climate change has led to more frequent extreme events. Therefore, a thorough understanding of the hydrological processes under urbanization and climate change is indispensable for sustainable water management. In this investigation, a case study was conducted by applying the Distributed Hydrology Soil Vegetation Model (DHSVM) to the San Antonio River Basin (SARB), Texas. Hosting the seventh largest city in the U.S. (i.e., City of San Antonio), the SARB is vulnerable to both floods and droughts. A set of historical and future land cover maps were assembled to represent the urbanization process. Two forcing datasets were employed to drive the DHSVM model. The first is a long-term observation based dataset (1915-2011), which was used as inputs for calibrating and validating DHSVM, as well as evaluating the urbanization effect. The second is the statistically downscaled climate simulations (1950-2099) from the Coupled Model Intercomparison Project Phase 5 (CMIP5), which were applied for understanding impacts related to climate change. Results show that urbanization exerts a much larger influence on streamflow than climate change does. Under the same observed forcings, annual average streamflow increased from 993.0 cfs (with 1929 land cover) to 1777.7 cfs (with 2011 land cover). As for climate change, results suggest that it will exacerbate the drought severity — with reduced evapotranspiration and soil moisture caused by decreased precipitation. However, the projected future streamflow does not show a clear increasing or decreasing trend. Regarding the combined effect from urbanization and climate change, the results indicate that the seasonal streamflow pattern will be notably changed (i.e., streamflow in October will be significantly increased, which makes it a second flow peak in addition to May). Furthermore, with significantly decreased evapotranspiration and slightly increased soil moisture, more water will be available for streamflow, increasing the possibility of flood risk in the region.

Flood Extent Mapping Using Dual-Polarimetric SENTINEL-1 Synthetic Aperture Radar Imagery

NASA Astrophysics Data System (ADS)

Jo, M.-J.; Osmanoglu, B.; Zhang, B.; Wdowinski, S.

2018-04-01

Rapid generation of synthetic aperture radar (SAR) based flood extent maps provide valuable data in disaster response efforts thanks to the cloud penetrating ability of microwaves. We present a method using dual-polarimetric SAR imagery acquired on Sentinel-1a/b satellites. A false-colour map is generated using pre- and post- disaster imagery, allowing operators to distinguish between existing standing water pre-flooding, and recently flooded areas. The method works best in areas of standing water and provides mixed results in urban areas. A flood depth map is also estimated by using an external DEM. We will present the methodology, it's estimated accuracy as well as investigations into improving the response in urban areas.

Intestinal parasite infections and associated risk factors in communities exposed to wastewater in urban and peri-urban transition zones in Hanoi, Vietnam.

PubMed

Fuhrimann, Samuel; Winkler, Mirko S; Pham-Duc, Phuc; Do-Trung, Dung; Schindler, Christian; Utzinger, Jürg; Cissé, Guéladio

2016-10-10

Infections with intestinal parasites (helminths and intestinal protozoa) are endemic in Southeast Asia and inappropriate management and reuse of wastewater might exacerbate the risk of human infections. In rapidly growing urban settings, little is known about the extent of intestinal parasite infections. We assessed the point-prevalence and risk factors of intestinal parasite infections in population groups differently exposed to wastewater in urban and peri-urban transition zones in Hanoi, the capital of Vietnam. A cross-sectional survey was carried out between April and June 2014 in people aged ≥ 18 years at risk of wastewater exposure from To Lich River: workers maintaining wastewater treatment facilities; urban farmers reusing wastewater; and urban dwellers at risk of flooding events. For comparison, two peri-urban population groups living in close proximity to the Red River were chosen: farmers using river water for irrigation purposes; and people living in the same communities. A single stool sample was subjected to Kato-Katz and formalin-ether concentration methods for the diagnosis of helminth and intestinal protozoa infections. A questionnaire was administered to determine risk factors and self-reported signs and symptoms. A total of 681 individuals had complete data records. Highest point-prevalence rates of intestinal parasite infections were observed for peri-urban farmers (30 %). Hookworm and Trichuris trichiura were the predominant helminth species (25 % and 5 %, respectively). Peri-urban farmers were at higher odds of infection with intestinal parasites than any other groups (adjusted odds ratio 5.8, 95 % confidence interval 2.5 to 13.7). Lack of access to improved sanitation and not receiving deworming within the past 12 months were associated with higher infection risk, while higher educational attainment and socioeconomic status were negatively associated with intestinal parasite infections. Our results suggest that exposure to wastewater was not directly associated with infection with helminths and intestinal protozoa in different population groups in Hanoi. These findings might be explained by a high level of awareness of health risks and access to safe sanitary infrastructure in urban areas. The high prevalence rates observed in peri-urban farmers call for specific interventions targeting this population group.

Estimating flood hydrographs and volumes for Alabama streams

USGS Publications Warehouse

Olin, D.A.; Atkins, J.B.

1988-01-01

The hydraulic design of highway drainage structures involves an evaluation of the effect of the proposed highway structures on lives, property, and stream stability. Flood hydrographs and associated flood volumes are useful tools in evaluating these effects. For design purposes, the Alabama Highway Department needs information on flood hydrographs and volumes associated with flood peaks of specific recurrence intervals (design floods) at proposed or existing bridge crossings. This report will provide the engineer with a method to estimate flood hydrographs, volumes, and lagtimes for rural and urban streams in Alabama with drainage areas less than 500 sq mi. Existing computer programs and methods to estimate flood hydrographs and volumes for ungaged streams have been developed in Georgia. These computer programs and methods were applied to streams in Alabama. The report gives detailed instructions on how to estimate flood hydrographs for ungaged rural or urban streams in Alabama with drainage areas less than 500 sq mi, without significant in-channel storage or regulations. (USGS)

To what extent can green infrastructure mitigate downstream flooding in a peri-urban catchment?

NASA Astrophysics Data System (ADS)

Schubert, J. E.; Burns, M.; Sanders, B. F.; Flethcher, T.

2016-12-01

In this research, we couple an urban hydrologic model (MUSIC, eWater, AUS) with a fine resolution 2D hydrodynamic model (BreZo, UC Irvine, USA) to test to what extent retrofitting an urban watershed with stormwater control measures (SCMs) can propagate flood management benefits downstream. Our study site is the peri-urban Little Stringybark Creek (LSC) catchment in eastern Melbourne, AUS, with an area of 4.5 km2 and connected impervious area of 9%. Urban development is mainly limited to the upper 2 km2of the catchment. Since 2009 the LSC catchment has been the subject of a large-scale experiment aiming to restore morenatural flow by implementing over 300 SCMs, such as rain tanks and infiltration trenches, resulting in runoff from 50% of connected impervious areas now being intercepted by some form of SCM. For our study we calibrated the hydrologic and hydraulic models based on current catchment conditions, then we developed models representing alternative SCM scenarios including a complete lack of SCMs versus a full implementation of SCMs. Flow in the hydrologic/hydraulic models is forced using a range of synthetic rainfall events with annual exceedance probabilities (AEPs) between 63-1% and durations between 10 min to 24 hr. Metrics of SCM efficacy in changing flood regime include flood depths and extents, flow intensity (m2/s), flood duration, and critical storm duration leading to maximum flood conditions. Results indicate that across the range of AEPs tested and for storm durations equal or less than 3 hours, current SCM conditions reduce downstream flooded area on average by 29%, while a full implementation of SCMs would reduce downstream flooded area on average by 91%. A full implementation of SCMs could also lower maximum flow intensities by 83% on average, reducing damage potential to structures in the flow path and increasing the ability for vehicles to evacuate flooded streets. We also found that for storm durations longer than 3 hours, the SCMs capacity to retain rainfall runoff volumes is much decreased, with a full implementation of SCMs only reducing flooded area by 8% and flow intensity by 5.5%. Therefore additional measures are required for downstream flood hazard mitigation from long duration events.

Long-term Strategic Planning for a Resilient Metro Colombo: An Economic Case for Wetland Conservation and Management

NASA Astrophysics Data System (ADS)

Rozenberg, J.

2015-12-01

Colombo faces recurrent floods that threaten its long-term economic development. Its urban wetlands have been identified by local agencies as a critical component of its flood reduction system, but they have declined rapidly in recent years due to continuous infilling, unmanaged land development and dredging to create lakes. In collaboration with government agencies, NGOs and local universities, the World Bank has carried out a Robust Decision Making analysis to examine the value of Colombo urban wetlands, both in the short-term and long-term, and identify what are the most viable strategies available to increase the city's flood resilience in an unclear future (in terms of climate change and patterns of urban development). This has involved the use of numerous hydrological and socio-economic scenarios as well as the evaluation of some wetlands benefits, like ecosystem services, wastewater treatment, or recreational services. The analysis has determined that if all urban wetlands across the Colombo catchment were lost, in some scenarios the metropolitan area would have to cope with an annual average flood loss of approximately 1% of Colombo GDP in the near future. For long-term strategies, trade-offs between urban development, lake creation and wetland conservation were analyzed and it was concluded that an active management of urban wetlands was the lowest regret option. Finally, the analysis also revealed that in the future, with climate change and fast urban development, wetlands will not be sufficient to protect Colombo against severe floods. Pro-active urban planning and land-use management are therefore necessary, both to protect existing wetlands and to reduce future exposure. The use of many different scenarios, the consideration of several policy options, and the open participatory process ensured policy-makers' buy-in and lead to the decision to actively protect urban wetlands in Colombo.

Magnitude and Frequency of Floods for Urban and Small Rural Streams in Georgia, 2008

USGS Publications Warehouse

Gotvald, Anthony J.; Knaak, Andrew E.

2011-01-01

A study was conducted that updated methods for estimating the magnitude and frequency of floods in ungaged urban basins in Georgia that are not substantially affected by regulation or tidal fluctuations. Annual peak-flow data for urban streams from September 2008 were analyzed for 50 streamgaging stations (streamgages) in Georgia and 6 streamgages on adjacent urban streams in Florida and South Carolina having 10 or more years of data. Flood-frequency estimates were computed for the 56 urban streamgages by fitting logarithms of annual peak flows for each streamgage to a Pearson Type III distribution. Additionally, basin characteristics for the streamgages were computed by using a geographical information system and computer algorithms. Regional regression analysis, using generalized least-squares regression, was used to develop a set of equations for estimating flows with 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities for ungaged urban basins in Georgia. In addition to the 56 urban streamgages, 171 rural streamgages were included in the regression analysis to maintain continuity between flood estimates for urban and rural basins as the basin characteristics pertaining to urbanization approach zero. Because 21 of the rural streamgages have drainage areas less than 1 square mile, the set of equations developed for this study can also be used for estimating small ungaged rural streams in Georgia. Flood-frequency estimates and basin characteristics for 227 streamgages were combined to form the final database used in the regional regression analysis. Four hydrologic regions were developed for Georgia. The final equations are functions of drainage area and percentage of impervious area for three of the regions and drainage area, percentage of developed land, and mean basin slope for the fourth region. Average standard errors of prediction for these regression equations range from 20.0 to 74.5 percent.

The index-flood and the GRADEX methods combination for flood frequency analysis.

NASA Astrophysics Data System (ADS)

Fuentes, Diana; Di Baldassarre, Giuliano; Quesada, Beatriz; Xu, Chong-Yu; Halldin, Sven; Beven, Keith

2017-04-01

Flood frequency analysis is used in many applications, including flood risk management, design of hydraulic structures, and urban planning. However, such analysis requires of long series of observed discharge data which are often not available in many basins around the world. In this study, we tested the usefulness of combining regional discharge and local precipitation data to estimate the event flood volume frequency curve for 63 catchments in Mexico, Central America and the Caribbean. This was achieved by combining two existing flood frequency analysis methods, the regionalization index-flood approach with the GRADEX method. For up to 10-years return period, similar shape of the scaled flood frequency curve for catchments with similar flood behaviour was assumed from the index-flood approach. For return periods larger than 10-years the probability distribution of rainfall and discharge volumes were assumed to be asymptotically and exponential-type functions with the same scale parameter from the GRADEX method. Results showed that if the mean annual flood (MAF), used as index-flood, is known, the index-flood approach performed well for up to 10 years return periods, resulting in 25% mean relative error in prediction. For larger return periods the prediction capability decreased but could be improved by the use of the GRADEX method. As the MAF is unknown at ungauged and short-period measured basins, we tested predicting the MAF using catchments climate-physical characteristics, and discharge statistics, the latter when observations were available for only 8 years. Only the use of discharge statistics resulted in acceptable predictions.

A Database of Historical Information on Landslides and Floods in Italy

NASA Astrophysics Data System (ADS)

Guzzetti, F.; Tonelli, G.

2003-04-01

For the past 12 years we have maintained and updated a database of historical information on landslides and floods in Italy, known as the National Research Council's AVI (Damaged Urban Areas) Project archive. The database was originally designed to respond to a specific request of the Minister of Civil Protection, and was aimed at helping the regional assessment of landslide and flood risk in Italy. The database was first constructed in 1991-92 to cover the period 1917 to 1990. Information of damaging landslide and flood event was collected by searching archives, by screening thousands of newspaper issues, by reviewing the existing technical and scientific literature on landslides and floods in Italy, and by interviewing landslide and flood experts. The database was then updated chiefly through the analysis of hundreds of newspaper articles, and it now covers systematically the period 1900 to 1998, and non-systematically the periods 1900 to 1916 and 1999 to 2002. Non systematic information on landslide and flood events older than 20th century is also present in the database. The database currently contains information on more than 32,000 landslide events occurred at more than 25,700 sites, and on more than 28,800 flood events occurred at more than 15,600 sites. After a brief outline of the history and evolution of the AVI Project archive, we present and discuss: (a) the present structure of the database, including the hardware and software solutions adopted to maintain, manage, use and disseminate the information stored in the database, (b) the type and amount of information stored in the database, including an estimate of its completeness, and (c) examples of recent applications of the database, including a web-based GIS systems to show the location of sites historically affected by landslides and floods, and an estimate of geo-hydrological (i.e., landslide and flood) risk in Italy based on the available historical information.

The land morphology approach to flood risk mapping: An application to Portugal.

PubMed

Cunha, N S; Magalhães, M R; Domingos, T; Abreu, M M; Küpfer, C

2017-05-15

In the last decades, the increasing vulnerability of floodplains is linked to societal changes such as population density growth, land use changes, water use patterns, among other factors. Land morphology directly influences surface water flow, transport of sediments, soil genesis, local climate and vegetation distribution. Therefore, the land morphology, the land used and management directly influences flood risks genesis. However, attention is not always given to the underlying geomorphological and ecological processes that influence the dynamic of rivers and their floodplains. Floodplains are considered a part of a larger system called Wet System (WS). The WS includes permanent and temporary streams, water bodies, wetlands and valley bottoms. Valley bottom is a broad concept which comprehends not only floodplains but also flat and concave areas, contiguous to streams, in which slope is less than 5%. This will be addressed through a consistent method based on a land morphology approach that classifies landforms according to their hydrological position in the watershed. This method is based on flat areas (slopes less than 5%), surface curvature and hydrological features. The comparison between WS and flood risk data from the Portuguese Environmental Agency for the main rivers of mainland Portugal showed that in downstream areas of watersheds, valley bottoms are coincident with floodplains modelled by hydrological methods. Mapping WS has a particular interest in analysing river ecosystems position and function in the landscape, from upstream to downstream areas in the watershed. This morphological approach is less demanding data and time-consuming than hydrological methods and can be used as the preliminary delimitation of floodplains and potential flood risk areas in situations where there is no hydrological data available. The results were also compared with the land use/cover map at a national level and detailed in Trancão river basin, located in Lisbon metropolitan area, an urbanized basin that suffered heavy flooding in the last decades. This study also contributes to a better understanding of the basin morphology at a local-scale and the effects of soil sealing in downstream flood risks. This work will contribute to the understanding of the morphology, ecology and land use of watersheds that could be used to reduce runoff and downstream flood risk. This can be accomplished by using natural water retention and infiltration methods or higher-level based planning instead of a reaction to local decisions on flood hazards. This morphological approach to map landforms, including wet system, is a valuable tool to assist policy makers and planners in flood risk and land use management, floodplain restoration, agricultural land management practices, and location of human activities according to ecological suitability. Copyright © 2017 Elsevier Ltd. All rights reserved.

Towards improved prediction and mitigation of beach overwash: Terrestrial LiDAR observation of dynamic beach berm erosion

NASA Astrophysics Data System (ADS)

Schubert, J. E.; Gallien, T.; Shakeri Majd, M.; Sanders, B. F.

2012-12-01

Globally, over 20 million people currently reside below high tide levels and 200 million are below storm tide levels. Future climate change along with the pressures of urbanization will exacerbate flooding in low lying coastal communities. In Southern California, coastal flooding is triggered by a combination of high tides, storm surge, and waves and recent research suggests that a current 100 year flood event may be experienced on a yearly basis by 2050 due to sea level rise adding a positive offset to return levels. Currently, Southern California coastal communities mitigate the threat of beach overwash, and consequent backshore flooding, with a combination of planning and operational activities such as protective beach berm construction. Theses berms consist of temporary alongshore sand dunes constructed days or hours before an extreme tide or wave event. Hydraulic modeling in urbanized embayments has shown that coastal flooding predictions are extremely sensitive to the presence of coastal protective infrastructure, requiring parameterization of the hard infrastructure elevations at centimetric accuracy. Beach berms are an example of temporary dynamic structures which undergo severe erosion during extreme events and are typically not included in flood risk assessment. Currently, little is known about the erosion process and performance of these structures, which adds uncertainty to flood hazard delineation and flood forecasts. To develop a deeper understanding of beach berm erosion dynamics, three trapezoidal shaped berms, approximately 35 m long and 1.5 m high, were constructed and failure during rising tide conditions was observed using terrestrial laser scanning. Concurrently, real-time kinematic GPS, high-definition time lapse photography, a local tide gauge and wave climate data were collected. The result is a rich and unique observational dataset capturing berm erosion dynamics. This poster highlights the data collected and presents methods for processing and leveraging multi-sensor field observation data. The data obtained from this study will be used to support the development and validation of a numerical beach berm overtopping and overwash model that will allow for improved predictions of coastal flood damage during winter storms and large swells.

Forecasting Flood Hazard on Real Time: Implementation of a New Surrogate Model for Hydrometeorological Events in an Andean Watershed.

NASA Astrophysics Data System (ADS)

Contreras Vargas, M. T.; Escauriaza, C. R.; Westerink, J. J.

2017-12-01

In recent years, the occurrence of flash floods and landslides produced by hydrometeorological events in Andean watersheds has had devastating consequences in urban and rural areas near the mountains. Two factors have hindered the hazard forecast in the region: 1) The spatial and temporal variability of climate conditions, which reduce the time range that the storm features can be predicted; and 2) The complexity of the basin morphology that characterizes the Andean region, and increases the velocity and the sediment transport capacity of flows that reach urbanized areas. Hydrodynamic models have become key tools to assess potential flood risks. Two-dimensional (2D) models based on the shallow-water equations are widely used to determine with high accuracy and resolution, the evolution of flow depths and velocities during floods. However, the high-computational requirements and long computational times have encouraged research to develop more efficient methodologies for predicting the flood propagation on real time. Our objective is to develop new surrogate models (i.e. metamodeling) to quasi-instantaneously evaluate floods propagation in the Andes foothills. By means a small set of parameters, we define storms for a wide range of meteorological conditions. Using a 2D hydrodynamic model coupled in mass and momentum with the sediment concentration, we compute on high-fidelity the propagation of a flood set. Results are used as a database to perform sophisticated interpolation/regression, and approximate efficiently the flow depth and velocities in critical points during real storms. This is the first application of surrogate models to evaluate flood propagation in the Andes foothills, improving the efficiency of flood hazard prediction. The model also opens new opportunities to improve early warning systems, helping decision makers to inform citizens, enhancing the reslience of cities near mountain regions. This work has been supported by CONICYT/FONDAP grant 15110017, and by the Vice Chancellor of Research of the Pontificia Universidad Catolica de Chile, through the Research Internationalization Grant, PUC1566 funded by MINEDUC.

Modelling the Impacts of Changing Land Cover/Land Use and Climate on Flooding in the Elk River Watershed, British Columbia

NASA Astrophysics Data System (ADS)

Barnes, C. C.; Byrne, J. M.; Hopkinson, C.; MacDonald, R. J.; Johnson, D. L.

2015-12-01

The Elk River is a mountain watershed located along the eastern border of British Columbia, Canada. The Elk River is confined by railway bridges, roads, and urban areas. Flooding has been a concern in the valley for more than a century. The most recent major flood event occurred in 2013 affecting several communities. River modifications such as riprapped dykes, channelization, and dredging have occurred in an attempt to reduce inundation, with limited success. Significant changes in land cover/land use (LCLU) such as natural state to urban, forestry practices, and mining from underground to mountaintop/valley fill have changed terrain and ground surfaces thereby altering water infiltration and runoff processes in the watershed. Future climate change in this region is expected to alter air temperature and precipitation as well as produce an earlier seasonal spring freshet potentially impacting future flood events. The objective of this research is to model historical and future hydrological conditions to identify flood frequency and risk under a range of climate and LCLU change scenarios in the Elk River watershed. Historic remote sensing data, forest management plans, and mining industry production/post-mining reclamation plans will be used to create a predictive past and future LCLU time series. A range of future air temperature and precipitation scenarios will be developed based on accepted Global Climate Modelling (GCM) research to examine how the hydrometeorological conditions may be altered under a range of future climate scenarios. The GENESYS (GENerate Earth SYstems Science input) hydrometeorological model will be used to simulate climate and LCLU to assess historic and potential future flood frequency and magnitude. Results will be used to create innovative flood mitigation, adaptation, and management strategies for the Elk River with the intent of being wildlife friendly and non-destructive to ecosystems and habitats for native species.

High Resolution Flash Flood Forecasting Using a Wireless Sensor Network in the Dallas-Fort Worth Metroplex

NASA Astrophysics Data System (ADS)

Bartos, M. D.; Kerkez, B.; Noh, S.; Seo, D. J.

2017-12-01

In this study, we develop and evaluate a high resolution urban flash flood monitoring system using a wireless sensor network (WSN), a real-time rainfall-runoff model, and spatially-explicit radar rainfall predictions. Flooding is the leading cause of natural disaster fatalities in the US, with flash flooding in particular responsible for a majority of flooding deaths. While many riverine flood models have been operationalized into early warning systems, there is currently no model that is capable of reliably predicting flash floods in urban areas. Urban flash floods are particularly difficult to model due to a lack of rainfall and runoff data at appropriate scales. To address this problem, we develop a wide-area flood-monitoring wireless sensor network for the Dallas-Fort Worth metroplex, and use this network to characterize rainfall-runoff response over multiple heterogeneous catchments. First, we deploy a network of 22 wireless sensor nodes to collect real-time stream stage measurements over catchments ranging from 2-80 km2 in size. Next, we characterize the rainfall-runoff response of each catchment by combining stream stage data with gage and radar-based precipitation measurements. Finally, we demonstrate the potential for real-time flash flood prediction by joining the derived rainfall-runoff models with real-time radar rainfall predictions. We find that runoff response is highly heterogeneous among catchments, with large variabilities in runoff response detected even among nearby gages. However, when spatially-explicit rainfall fields are included, spatial variability in runoff response is largely captured. This result highlights the importance of increased spatial coverage for flash flood prediction.

Modeling multi-source flooding disaster and developing simulation framework in Delta

NASA Astrophysics Data System (ADS)

Liu, Y.; Cui, X.; Zhang, W.

2016-12-01

Most Delta regions of the world are densely populated and with advanced economies. However, due to impact of the multi-source flooding (upstream flood, rainstorm waterlogging, storm surge flood), the Delta regions is very vulnerable. The academic circles attach great importance to the multi-source flooding disaster in these areas. The Pearl River Delta urban agglomeration in south China is selected as the research area. Based on analysis of natural and environmental characteristics data of the Delta urban agglomeration(remote sensing data, land use data, topographic map, etc.), hydrological monitoring data, research of the uneven distribution and process of regional rainfall, the relationship between the underlying surface and the parameters of runoff, effect of flood storage pattern, we use an automatic or semi-automatic method for dividing spatial units to reflect the runoff characteristics in urban agglomeration, and develop an Multi-model Ensemble System in changing environment, including urban hydrologic model, parallel computational 1D&2D hydrodynamic model, storm surge forecast model and other professional models, the system will have the abilities like real-time setting a variety of boundary conditions, fast and real-time calculation, dynamic presentation of results, powerful statistical analysis function. The model could be optimized and improved by a variety of verification methods. This work was supported by the National Natural Science Foundation of China (41471427); Special Basic Research Key Fund for Central Public Scientific Research Institutes.

Landslide and flood hazard assessment in urban areas of Levoča region (Eastern Slovakia)

NASA Astrophysics Data System (ADS)

Magulova, Barbora; Caporali, Enrica; Bednarik, Martin

2010-05-01

The case study presents the use of statistical methods and analysis tools, for hazard assessment of "urbanization units", implemented in a Geographic Information Systems (GIS) environment. As a case study, the Levoča region (Slovakia) is selected. The region, with a total area of about 351 km2, is widely affected by landslides and floods. The problem, for small urbanization areas, is nowadays particularly significant from the socio-economic point of view. It is considered, presently, also an increasing problem, mainly because of climate change and more frequent extreme rainfall events. The geo-hazards are evaluated using a multivariate analysis. The landslide hazard assessment is based on the comparison and subsequent statistical elaboration of territorial dependence among different input factors influencing the instability of the slopes. Particularly, five factors influencing slope stability are evaluated, i.e. lithology, slope aspect, slope angle, hypsographic level and present land use. As a result a new landslide susceptibility map is compiled and different zones of stable, dormant and non-stable areas are defined. For flood hazard map a detailed digital elevation model is created. A compose index of flood hazard is derived from topography, land cover and pedology related data. To estimate flood discharge, time series of stream flow and precipitation measurements are used. The assessment results are prognostic maps of landslide hazard and flood hazard, which presents the optimal base for urbanization planning.

Debris flood hazard documentation and mitigation on the Tilcara alluvial fan (Quebrada de Humahuaca, Jujuy province, North-West Argentina)

NASA Astrophysics Data System (ADS)

Marcato, G.; Bossi, G.; Rivelli, F.; Borgatti, L.

2012-06-01

For some decades, mass wasting processes such as landslides and debris floods have been threatening villages and transportation routes in the Rio Grande Valley, named Quebrada de Humauhuaca. One of the most significant examples is the urban area of Tilcara, built on a large alluvial fan. In recent years, debris flood phenomena have been triggered in the tributary valley of the Huasamayo Stream and reached the alluvial fan on a decadal basis. In view of proper development of the area, hazard and risk assessment together with risk mitigation strategies are of paramount importance. The need is urgent also because the Quebrada de Humahuaca was recently included in the UNESCO World Cultural Heritage. Therefore, the growing tourism industry may lead to uncontrolled exploitation and urbanization of the valley, with a consequent increase of the vulnerability of the elements exposed to risk. In this context, structural and non structural mitigation measures not only have to be based on the understanding of natural processes, but also have to consider environmental and sociological factors that could hinder the effectiveness of the countermeasure works. The hydrogeological processes are described with reference to present-day hazard and risk conditions. Considering the socio-economic context, some possible interventions are outlined, which encompass budget constraints and local practices. One viable solution would be to build a protecting dam upstream of the fan apex and an artificial channel, in order to divert the floodwaters in a gully that would then convey water and sediments into the Rio Grande, some kilometers downstream of Tilcara. The proposed remedial measures should employ easily available and relatively cheap technologies and local workers, incorporating low environmental and visual impacts issues, in order to ensure both the future conservation of the site and its safe exploitation for inhabitants and tourists.

The Atlas of Natural Hazards and Risks of Austria: first results for fluvial and pluvial floods

NASA Astrophysics Data System (ADS)

Mergili, Martin; Tader, Andreas; Glade, Thomas; Neuhold, Clemens; Stiefelmeyer, Heinz

2015-04-01

Incoherent societal adaptation to natural processes results in significant losses every year. A better knowledge of the spatial and temporal distribution of hazards and risks, and of particular hot spots in a given region or period, is essential for reducing adverse impacts. Commonly, different hazard and risk estimations are performed within individual approaches based on tailor-made concepts. This works well as long as specific cases are considered. The advantage of such a procedure is that each individual hazard and risk is addressed in the best possible manner. The drawback, however, consists in the fact that the results differ significantly in terms of quality and accuracy and therefore cannot be compared. Hence, there is a need to develop a strategy and concept which uses similar data sources of equivalent quality in order to adequately analyze the different natural hazards and risks at broader scales. The present study is aiming to develop such a platform. The project Risk:ATlas focuses on the design of an atlas visualizing the most relevant natural hazards and, in particular, possible consequences for the entire territory of Austria. Available as a web-based tool and as a printed atlas, it is seen as a key tool to improve the basis for risk reduction, risk adaptation and risk transfer. The atlas is founded on those data sets available for the entire territory of Austria at a consistent resolution and quality. A 1 m resolution DEM and the official cadastre and building register represent the core, further data sets are employed according to the requirements for each natural hazard and risk. In this contribution, the methodology and the preliminary results for fluvial and pluvial floods and their consequences to buildings for three selected test areas in different types of landscapes (rural, urban and mountainous) are presented. Flooding depths expected for annualities of 30, 100 and 300 are derived from existing data sets for fluvial floods and are computed using the model FloodArea for pluvial floods. Land cover parameters necessary for flood routing are deduced from the official cadastre. The values exposed to each flood scenario are quantified on the basis of objects. In this study, the focus is on buildings, thus the official building register is employed as a major data source. The same register is used to derive the vulnerability of each building with regard to floods. Combining exposed values and vulnerability, the risk for each building, expressed as the expected damage per unit of time, is derived. Furthermore, a methodology to automatically regionalize the object-based hazards, exposures, vulnerabilities and risks to any spatial unit desired is presented. This enables us (i) to adapt the web-based atlas to different zooming levels and to flexibly react to (ii) the needs of the users of the atlas and (iii) the availability of reference data for validation of the analyses. The next steps will include (1) extending the analyses for fluvial and pluvial floods to the entire territory of Austria, employing advanced computational techniques such as the use of a cluster; (2) deriving hazards, exposures, vulnerabilities and risks related to a variety of other hazardous processes as well as to chains and combinations of processes (multi-hazard); (3) considering the consequences of hazardous processes not only for buildings, but also for infrastructures and even humans; and (4) elaborating future scenarios, based on possible environmental (including climatic) and socio-economic changes.

Relative importance of impervious area, drainage density, width function, and subsurface storm drainage on flood runoff from an urbanized catchment

NASA Astrophysics Data System (ADS)

Ogden, Fred L.; Raj Pradhan, Nawa; Downer, Charles W.; Zahner, Jon A.

2011-12-01

The literature contains contradictory conclusions regarding the relative effects of urbanization on peak flood flows due to increases in impervious area, drainage density and width function, and the addition of subsurface storm drains. We used data from an urbanized catchment, the 14.3 km2 Dead Run watershed near Baltimore, Maryland, USA, and the physics-based gridded surface/subsurface hydrologic analysis (GSSHA) model to examine the relative effect of each of these factors on flood peaks, runoff volumes, and runoff production efficiencies. GSSHA was used because the model explicitly includes the spatial variability of land-surface and hydrodynamic parameters, including subsurface storm drains. Results indicate that increases in drainage density, particularly increases in density from low values, produce significant increases in the flood peaks. For a fixed land-use and rainfall input, the flood magnitude approaches an upper limit regardless of the increase in the channel drainage density. Changes in imperviousness can have a significant effect on flood peaks for both moderately extreme and extreme storms. For an extreme rainfall event with a recurrence interval in excess of 100 years, imperviousness is relatively unimportant in terms of runoff efficiency and volume, but can affect the peak flow depending on rainfall rate. Changes to the width function affect flood peaks much more than runoff efficiency, primarily in the case of lower density drainage networks with less impermeable area. Storm drains increase flood peaks, but are overwhelmed during extreme rainfall events when they have a negligible effect. Runoff in urbanized watersheds with considerable impervious area shows a marked sensitivity to rainfall rate. This sensitivity explains some of the contradictory findings in the literature.

Importance of Integrating High-Resoultion 2D Flood Hazard Maps in the Flood Disaster Management of Marikina City, Philippines

NASA Astrophysics Data System (ADS)

Tapales, Ben Joseph; Mendoza, Jerico; Uichanco, Christopher; Mahar Francisco Amante Lagmay, Alfredo; Moises, Mark Anthony; Delmendo, Patricia; Eneri Tingin, Neil

2015-04-01

Flooding has been a perennial problem in the city of Marikina. These incidences result in human and economic losses. In response to this, the city has been investing in their flood disaster mitigation program in the past years. As a result, flooding in Marikina was reduced by 31% from 1992 to 2004. [1] However, these measures need to be improved so as to mitigate the effects of floods with more than 100 year return period, such as the flooding brought by tropical storm Ketsana in 2009 which generated 455mm of rains over a 24-hour period. Heavy rainfall caused the streets to be completely submerged in water, leaving at least 70 people dead in the area. In 2012, the Southwest monsoon, enhanced by a typhoon, brought massive rains with an accumulated rainfall of 472mm for 22-hours, a number greater than that which was experienced during Ketsana. At this time, the local government units were much more prepared in mitigating the risk with the use of early warning and evacuation measures, resulting to zero casualty in the area. Their urban disaster management program, however, can be further improved through the integration of high-resolution 2D flood hazard maps in the city's flood disaster management. The use of these maps in flood disaster management is essential in reducing flood-related risks. This paper discusses the importance and advantages of integrating flood maps in structural and non-structural mitigation measures in the case of Marikina City. Flood hazard maps are essential tools in predicting the frequency and magnitude of floods in an area. An information that may be determined with the use of these maps is the locations of evacuation areas, which may be accurately positioned using high-resolution 2D flood hazard maps. Evacuation of people in areas that are not vulnerable of being inundated is one of the unnecessary measures that may be prevented and thus optimizing mitigation efforts by local government units. This paper also discusses proposals for a more efficient exchange of information, allowing for flood simulations to be utilized in local flood disaster management programs. The success of these systems relies heavily on the knowledge of the people involved. As environmental changes create more significant impacts, the need to adapt to these is vital for man's safety. [1] Pacific Disaster Center

Importance of Integrating High-Resoultion 2D Flood Hazard Maps in the Flood Disaster Management of Marikina City, Philippines

NASA Astrophysics Data System (ADS)

Tapales, B. J. M.; Mendoza, J.; Uichanco, C.; Lagmay, A. M. F. A.; Moises, M. A.; Delmendo, P.; Tingin, N. E.

2014-12-01

Flooding has been a perennial problem in the city of Marikina. These incidences result in human and economic losses. In response to this, the city has been investing in their flood disaster mitigation program in the past years. As a result, flooding in Marikina was reduced by 31% from 1992 to 2004. [1] However, these measures need to be improved so as to mitigate the effects of floods with more than 100 year return period, such as the flooding brought by tropical storm Ketsana in 2009 which generated 455mm of rains over a 24-hour period. Heavy rainfall caused the streets to be completely submerged in water, leaving at least 70 people dead in the area. In 2012, the Southwest monsoon, enhanced by a typhoon, brought massive rains with an accumulated rainfall of 472mm for 22-hours, a number greater than that which was experienced during Ketsana. At this time, the local government units were much more prepared in mitigating the risk with the use of early warning and evacuation measures, resulting to zero casualty in the area. Their urban disaster management program, however, can be further improved through the integration of high-resolution 2D flood hazard maps in the city's flood disaster management. The use of these maps in flood disaster management is essential in reducing flood-related risks. This paper discusses the importance and advantages of integrating flood maps in structural and non-structural mitigation measures in the case of Marikina City. Flood hazard maps are essential tools in predicting the frequency and magnitude of floods in an area. An information that may be determined with the use of these maps is the locations of evacuation areas, which may be accurately positioned using high-resolution 2D flood hazard maps. Evacuation of areas that are not vulnerable of being inundated is one of the unnecessary measures that may be prevented and thus optimizing mitigation efforts by local government units. This paper also discusses proposals for a more efficient exchange of information, allowing for flood simulations to be utilized in local flood disaster management programs. The success of these systems relies heavily on the knowledge of the people involved. As environmental changes create more significant impacts, the need to adapt to these is vital for man's safety. [1] Pacific Disaster Center

Protection of Urban Water body Infrastructure - Policy Requirements

NASA Astrophysics Data System (ADS)

Neelakantan, T. R.; Ramakrishnan, K.

2017-07-01

Water body is an important infrastructure of urban landscape. Water bodies like tanks and ponds are constructed to harvest rainwater for local use. Such water bodies serve many environmental functions including flood and soil erosion control and are useful for irrigation, drinking water supply and groundwater recharge. A large number of water bodies recently have been lost due to anthropogenic activities and the remaining water bodies are under stress due to risk of degradation. There are many phases to solve or control the problem; starting from stopping the abuse, to restoration to monitoring and maintenance. In this situation, the existing urban and peri-urban water bodies are to be preserved and rehabilitated. In this study, policy requirements for the protection (preservation and rehabilitation) of water bodies are analyzed with special reference to Thanjavur city. Thanjavur city has many water bodies and moat around the Big-Temple and the palace, and stands as an evidence for water management in ancient days. These water bodies are to be protected and used properly for sustainable growth of the city. This paper envisages the following three: (a) need for evaluation of hydraulic and hydrologic properties of the water bodies for conserving rainwater and controlling flood water in the existing urban water bodies; (b) need for evaluation of potential of socio-environmental services by the water bodies, and (c) need for developing a relative importance index for protection of water bodies to prioritize the remedial actions.

Flooding from Intense Rainfall: an overview of project SINATRA

NASA Astrophysics Data System (ADS)

Cloke, Hannah

2014-05-01

Project SINATRA (Susceptibility of catchments to INTense RAinfall and flooding) is part of the UK NERC's Flooding From Intense Rainfall (FFIR) research programme which aims to reduce the risks of damage and loss of life caused by surface water and flash floods through improved identification, characterisation and prediction of interacting meteorological, hydrological and hydro-morphological processes that contribute to flooding associated with high-intensity rainfall events. Extreme rainfall events may only last for a few hours at most, but can generate terrifying and destructive floods. Their impact can be affected by a wide range factors (or processes) such as the location and intensity of the rainfall, the shape and steepness of the catchment it falls on, how much sediment is moved by the water and the vulnerability of the communities in the flood's path. Furthermore, FFIR are by their nature rapid, making it very difficult for researchers to 'capture' measurements during events. The complexity, speed and lack of field measurements on FFIR make it difficult to create computer models to predict flooding and often we are uncertain as to their accuracy. In addition there is no consensus on how to identify how particular catchments may be vulnerable to FFIR, due to factors such as catchment area, shape, geology and soil type as well as land-use. Additionally, the catchments most susceptible to FFIR are often small and un-gauged. Project SINATRA will: (1) Increase our understanding of what factors cause FFIR and gathering new, high resolution measurements of FFIR by: assembling an archive of past FFIR events in Britain and their impacts, as a prerequisite for improving our ability to predict future occurrences of FFIR; making real time observations of flooding during flood events as well as post-event surveys and historical event reconstruction, using fieldwork and crowd-sourcing methods; and characterizing the physical drivers for UK summer flooding events by identifying the large-scale atmospheric conditions associated with FFIR events, and linking them to catchment type. (2) Use this new understanding and data to improve models of FFIR so we can predict where they may happen nationwide by: employing an integrated catchment/urban scale modelling approach to FFIR at high spatial and temporal scales, modelling rapid catchment response to flash floods and their impacts in urban areas; scaling up to larger catchments by improving the representation of fast riverine and surface water flooding and hydromorphic change (including debris flow) in regional scale models of FFIR; improving the representation of FFIR in the JULES land surface model by integrating river routing and fast runoff processes, and performing assimilation of soil moisture and river discharge into the model run (3) Use these new findings and predictions to provide the Environment Agency and other professionals with information and software they can use to manage FFIR, reducing their damage and impact to communities by: developing tools to enable prediction of future FFIR impacts to support the Flood Forecasting Centre in issuing new 'impacts-based' warnings about their occurrence; developing a FFIR analysis tool to assess risks associated with rare events in complex situations involving incomplete knowledge, analogous to those developed for safety assessment in radioactive waste management.

Interactions between soil consumption and archaeological heritage: spatial analysis for hydrogeological risk evaluation and urban sprawl in the Tavoliere di Puglia (southern Italy)

NASA Astrophysics Data System (ADS)

Danese, Maria; Gioia, Dario; Masini, Nicola

2015-04-01

The soil consumption is a complex phenomenon because it is due to different causes and it also produces many consequences on landscape and related human activities. In low-relief areas of the Mediterranean regions such as the foredeep of the southern Italian chain, alluvional processes and flooding can play an important role on the amount of available soil, especially if one consider the recent climate changes and the recurrence of extreme events. Moreover the uncontrolled growth of the cities is a cause of soil consumption too. Consequently occurrence of flood events in low-relief areas, erosion processes and urban sprawl have a strong impact on agricultural activities and real estate market, but also in research activities about archaeological heritage, with the risk to loose signs of the past. To consider this phenomenon from a spatial point of view is essential to determine protection policies, but it is nowadays still a problem. In this contribution, we performed a detailed study of the geological and geomorphological features of the drainage network of the Tavoliere di Puglia plain in order to investigate erosional and depositional processes. GIS-supported statistical analysis of the drainage network features allow us to compile a map of the hydrogeological hazard [1]. The map has been used as a basic tool useful to consider areal distribution in soil consumption coming from alluvional processes, erosional phenomena and the urban sprawl of the Tavoliere di Puglia plain (Southern Italy). Moreover, we investigated the relationships between sectors of the Tavoliere di Puglia plain featured by higher hydrogeological risk and archaeological sensibility areas, such as places with existing or with not yet discovered archaeological sites or areas characterized by crop marks [2]. [1] Danese M., Gioia D., Biscione M., Masini N. 2014. Spatial Methods for Archaeological Flood Risk: The Case Study of the Neolithic Sites in the Apulia Region (Southern Italy). Computational Science and Its Applications - ICCSA 2014 Lecture Notes in Computer Science, Volume 579, 2014, pp 423-439, doi: 10.1007/978-3-319-09144-0_29. [2] Danese M., Masini N., Biscione M., Lasaponara R. 2014. Predictive modeling for preventive Archaeology: Overview and case study. Central European Journal of Geosciences. March 2014,Volume 6, Issue 1, 42-55, doi: 10.2478/s13533-012-0160-5

24 CFR 3285.302 - Flood hazard areas.

Code of Federal Regulations, 2010 CFR

2010-04-01

... loads associated with design flood and wind events or combined wind and flood events, and homes must be installed on foundation supports that are designed and anchored to prevent floatation, collapse, or lateral... URBAN DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Foundations § 3285.302 Flood hazard...

Detection and attribution of flood change across the United States

NASA Astrophysics Data System (ADS)

Archfield, Stacey

2017-04-01

In the United States, there have a been an increasing number of studies quantifying trends in the annual maximum flood; yet, few studies examine trends in floods that may occur more than once in a given year and even fewer assess trends in floods on rivers that have undergone substantial changes due to urbanization, land-cover change, and agricultural drainage practices. Previous research has shown that, for streamgages having minimal direct human intervention, trends in the peak magnitude, frequency, duration and volume of frequent floods (floods occurring at an average of two events per year relative to a base period) across the United States show large changes; however, few trends are found to be statistically significant. This study extends previous research to provide a comprehensive assessment of flood change across the United States that includes streamgages having experienced confounding alterations to streamflow (urbanization, storage, and land-cover changes) that provides a comprehensive assessment of flood change. Attribution of these changes is also explored.

A twenty-first century California observing network for monitoring extreme weather events

USGS Publications Warehouse

White, A.B.; Anderson, M.L.; Dettinger, M.D.; Ralph, F.M.; Hinojosa, A.; Cayan, D.R.; Hartman, R.K.; Reynolds, D.W.; Johnson, L.E.; Schneider, T.L.; Cifelli, R.; Toth, Z.; Gutman, S.I.; King, C.W.; Gehrke, F.; Johnston, P.E.; Walls, C.; Mann, Dorte; Gottas, D.J.; Coleman, T.

2013-01-01

During Northern Hemisphere winters, the West Coast of North America is battered by extratropical storms. The impact of these storms is of paramount concern to California, where aging water supply and flood protection infrastructures are challenged by increased standards for urban flood protection, an unusually variable weather regime, and projections of climate change. Additionally, there are inherent conflicts between releasing water to provide flood protection and storing water to meet requirements for water supply, water quality, hydropower generation, water temperature and flow for at-risk species, and recreation. In order to improve reservoir management and meet the increasing demands on water, improved forecasts of precipitation, especially during extreme events, is required. Here we describe how California is addressing their most important and costliest environmental issue – water management – in part, by installing a state-of-the-art observing system to better track the area’s most severe wintertime storms.

Nogales flood detention study

USGS Publications Warehouse

Norman, Laura M.; Levick, Lainie; Guertin, D. Phillip; Callegary, James; Guadarrama, Jesus Quintanar; Anaya, Claudia Zulema Gil; Prichard, Andrea; Gray, Floyd; Castellanos, Edgar; Tepezano, Edgar; Huth, Hans; Vandervoet, Prescott; Rodriguez, Saul; Nunez, Jose; Atwood, Donald; Granillo, Gilberto Patricio Olivero; Ceballos, Francisco Octavio Gastellum

2010-01-01

Flooding in Ambos Nogales often exceeds the capacity of the channel and adjacent land areas, endangering many people. The Nogales Wash is being studied to prevent future flood disasters and detention features are being installed in tributaries of the wash. This paper describes the application of the KINEROS2 model and efforts to understand the capacity of these detention features under various flood and urbanization scenarios. Results depict a reduction in peak flow for the 10-year, 1-hour event based on current land use in tributaries with detention features. However, model results also demonstrate that larger storm events and increasing urbanization will put a strain on the features and limit their effectiveness.

Methods for estimating the magnitude and frequency of floods for urban and small, rural streams in Georgia, South Carolina, and North Carolina, 2011.

DOT National Transportation Integrated Search

2014-03-01

The central purpose of this report is to present methods : for estimating the magnitude and frequency of floods on : urban and small, rural streams in the Southeast United States : with particular focus on Georgia, South Carolina, and North : Carolin...

Tropical stormwater floods: a sustainable solution

NASA Astrophysics Data System (ADS)

Molinie, Jack; Bade, Francois; Nagau, Jimmy; Nuiro, Paul

2017-04-01

Stormwater management is one of the most difficult problem of urban and suburban area. The urban runoff volume related to rain intensity and surfaces properties can lead to flood. Thereby, urban flooding creates considerable infrastructure problem, economics and human damages. In tropical countries, burgeoning human population coupled with unplanned urbanization altered the natural drainage. Consequently, classical intense rain around 100 cm/h produces frequent street flooding. In our case, we study the management of intense tropical rain, by using a network of individual rain storage tanks. The study area is economical and industrial zone installed in a coastal plain , with seventy per cent of impermeable surface (roads, parking lots, building roof, …) and thirty per cent of wetland (mangrove, …). Our solution is to delay the routes and parking lots runoff to the roof one. We propose sustainable individual water storage and a real time dynamical management, which permit to control the roof water arrival in the stormwater culvert. During the remaining time, the stored rainwater can be used for domestic activities instead of the use of drinking water.

Application of Shuffled Frog Leaping Algorithm and Genetic Algorithm for the Optimization of Urban Stormwater Drainage

NASA Astrophysics Data System (ADS)

Kumar, S.; Kaushal, D. R.; Gosain, A. K.

2017-12-01

Urban hydrology will have an increasing role to play in the sustainability of human settlements. Expansion of urban areas brings significant changes in physical characteristics of landuse. Problems with administration of urban flooding have their roots in concentration of population within a relatively small area. As watersheds are urbanized, infiltration decreases, pattern of surface runoff is changed generating high peak flows, large runoff volumes from urban areas. Conceptual rainfall-runoff models have become a foremost tool for predicting surface runoff and flood forecasting. Manual calibration is often time consuming and tedious because of the involved subjectivity, which makes automatic approach more preferable. The calibration of parameters usually includes numerous criteria for evaluating the performances with respect to the observed data. Moreover, derivation of objective function assosciat6ed with the calibration of model parameters is quite challenging. Various studies dealing with optimization methods has steered the embracement of evolution based optimization algorithms. In this paper, a systematic comparison of two evolutionary approaches to multi-objective optimization namely shuffled frog leaping algorithm (SFLA) and genetic algorithms (GA) is done. SFLA is a cooperative search metaphor, stimulated by natural memetics based on the population while, GA is based on principle of survival of the fittest and natural evolution. SFLA and GA has been employed for optimizing the major parameters i.e. width, imperviousness, Manning's coefficient and depression storage for the highly urbanized catchment of Delhi, India. The study summarizes the auto-tuning of a widely used storm water management model (SWMM), by internal coupling of SWMM with SFLA and GA separately. The values of statistical parameters such as, Nash-Sutcliffe efficiency (NSE) and Percent Bias (PBIAS) were found to lie within the acceptable limit, indicating reasonably good model performance. Overall, this study proved promising for assessing risk in urban drainage systems and should prove useful to improve integrity of the urban system, its reliability and provides guidance for inundation preparedness.Keywords: Hydrologic model, SWMM, Urbanization, SFLA and GA.

Belford proactive flood solutions: scientific evidence to influence local and national policy by multi-purpose runoff management

NASA Astrophysics Data System (ADS)

Wilkinson, M.; Quinn, P. F.; Jonczyk, J.

2010-12-01

The increased risk from flooding continues to be of concern to governments all around the world and flood protection is becoming more of a challenge. In the UK, climate change projections indicate more extremes within the weather systems. In addition, there is an increased demand for using land in urban areas beside channels. These developments both put pressure on our flood defences and there is a need for new solutions to managing flood risk. There is currently support within the England and Wales Environment Agency for sustainable flood management solutions such as storage ponds, wetlands, beaver dams and willow riparian features (referred to here as Runoff Attenuation Features, or RAFs). However the effectiveness of RAFs are not known at the catchment scale since they have only really been trailed at the plot scale. These types of mitigation measure can offer benefits to water quality and create ecological habitats. The village of Belford, situated in the Belford Burn catchment (6km2), northern England, has suffered from numerous flood events. In addition, the catchment suffers from water quality issues within the channel and high sediment loads are having an impact on the ecology of the nearby estuary. There was a desire by the Local Environment Agency Flood Levy team to deliver an alternative catchment-based solution to the problem. With funding from the Northumbria Regional Flood Defence Committee, the Environment Agency North East Local Levy team and Newcastle University have created a partnership to address the flood problem trailing soft engineered RAF’s at the catchment scale. The partnership project, “Belford proactive flood solutions” is testing novel techniques in reducing flood risk in small sub-catchments for the Environment Agency. The project provides the information needed to understand whether the multi-functional mitigation measures are working at the sub-catchment scale. Data suggest that the mitigation measures present have delayed the overall travel time of the flood peak in the catchment by 33%. The current maximum flood storage capacity of all the features stands at around 15,000 m3. The evidence also suggests that a dam like in-stream mitigation measure can significantly reduce sediment load. Other benefits of some mitigation features include large increase in the population of water voles over the past two years. The scheme also acts as a demonstration site for interested stakeholders where they can learn about this approach to flood risk management and see the multipurpose benefits. As the project has progressed and lessons have been learnt, it has been possible to develop a runoff management toolkit for implementing these mitigation measures in other catchments of similar size. Already, the local Environment Agency has utilised the tools and recently applied similar mitigation measures to other catchments. On-going modelling exercises in the project are using the data to explore the up-scaling of the features to larger catchments.

Multi-dimensional perspectives of flood risk - using a participatory framework to develop new approaches to flood risk communication

NASA Astrophysics Data System (ADS)

Rollason, Edward; Bracken, Louise; Hardy, Richard; Large, Andy

2017-04-01

Flooding is a major hazard across Europe which, since, 1998 has caused over €52 million in damages and displaced over half a million people. Climate change is predicted to increase the risks posed by flooding in the future. The 2007 EU Flood Directive cemented the use of flood risk maps as a central tool in understanding and communicating flood risk. Following recent flooding in England, an urgent need to integrate people living at risk from flooding into flood management approaches, encouraging flood resilience and the up-take of resilient activities has been acknowledged. The effective communication of flood risk information plays a major role in allowing those at risk to make effective decisions about flood risk and increase their resilience, however, there are emerging concerns over the effectiveness of current approaches. The research presented explores current approaches to flood risk communication in England and the effectiveness of these methods in encouraging resilient actions before and during flooding events. The research also investigates how flood risk communications could be undertaken more effectively, using a novel participatory framework to integrate the perspectives of those living at risk. The research uses co-production between local communities and researchers in the environmental sciences, using a participatory framework to bring together local knowledge of flood risk and flood communications. Using a local competency group, the research explores what those living at risk from flooding want from flood communications in order to develop new approaches to help those at risk understand and respond to floods. Suggestions for practice are refined by the communities to co-produce recommendations. The research finds that current approaches to real-time flood risk communication fail to forecast the significance of predicted floods, whilst flood maps lack detailed information about how floods occur, or use scientific terminology which people at risk find confusing or lacking in realistic grounding. This means users do not have information they find useful to make informed decisions about how to prepare for and respond to floods. Working together with at-risk participants, the research has developed new approaches for communicating flood risk. These approaches focus on understanding flood mechanisms and dynamics, to help participants imagine their flood risk and link potential scenarios to reality, and provide forecasts of predicted flooding at a variety of scales, allowing participants to assess the significance of predicted flooding and make more informed judgments on what action to take in response. The findings presented have significant implications for the way in which flood risk is communicated, changing the focus of mapping from probabilistic future scenarios to understanding flood dynamics and mechanisms. Such ways of communicating flood risk embrace how people would like to see risk communicated, and help those at risk grow their resilience. Communicating in such a way has wider implications for flood modelling and data collection. However, these represent potential opportunities to build more effective local partnerships for assessing and managing flood risks.

Sinking coastal cities

NASA Astrophysics Data System (ADS)

Erkens, Gilles; Bucx, Tom; Dam, Rien; De Lange, Ger; Lambert, John

2014-05-01

In many coastal and delta cities land subsidence now exceeds absolute sea level rise up to a factor of ten. Without action, parts of Jakarta, Ho Chi Minh City, Bangkok and numerous other coastal cities will sink below sea level. Land subsidence increases flood vulnerability (frequency, inundation depth and duration of floods), with floods causing major economic damage and loss of lives. In addition, differential land movement causes significant economic losses in the form of structural damage and high maintenance costs. This effects roads and transportation networks, hydraulic infrastructure - such as river embankments, sluice gates, flood barriers and pumping stations -, sewage systems, buildings and foundations. The total damage worldwide is estimated at billions of dollars annually. Excessive groundwater extraction after rapid urbanization and population growth is the main cause of severe land subsidence. In addition, coastal cities are often faced with larger natural subsidence, as they are built on thick sequences of soft soil. Because of ongoing urbanization and population growth in delta areas, in particular in coastal megacities, there is, and will be, more economic development in subsidence-prone areas. The impacts of subsidence are further exacerbated by extreme weather events (short term) and rising sea levels (long term).Consequently, detrimental impacts will increase in the near future, making it necessary to address subsidence related problems now. Subsidence is an issue that involves many policy fields, complex technical aspects and governance embedment. There is a need for an integrated approach in order to manage subsidence and to develop appropriate strategies and measures that are effective and efficient on both the short and long term. Urban (ground)water management, adaptive flood risk management and related spatial planning strategies are just examples of the options available. A major rethink is needed to deal with the 'hidden' but urgent threat of subsidence. As subsidence is spatially different and can be caused by multi processes, an assessment of subsidence in delta cities needs to answer questions such as: what are the main causes, how much is the current subsidence rate and what are future scenarios (and interaction with other major environmental issues), where are the vulnerable areas, what are the impacts and risks, how can adverse impacts can be mitigated or compensated for, and who is involved and responsible to act? In this study a quick-assessment of subsidence is performed on the following mega-cities: Jakarta, Ho Chi Minh City, Dhaka, New Orleans and Bangkok. Results of these case studies will be presented and compared, and a (generic) approach how to deal with subsidence in current and future subsidence-prone areas is provided.

The notions of resilience in spatial planning for drought - flood coexistence (DFC) at regional scale

NASA Astrophysics Data System (ADS)

Trong Hoa, Nguyen; Vinh, Nguyen Quoc

2018-04-01

The notions of urban resilience and resilient city has been developed in the 2000s [1], four decades since the first concept of ecological resilience was originally introduced in the 1970s by ecologist C.S. Holling [2]. However, they have attracted great attentions and interests, in both academia and urban governance, then in planning practice over recent years. The first two sections of this paper examine the term resilience in ecological systems, urban systems, in spatial planning and in urban design. Specific attention of the paper, introduced in the third part, is to investigate resilience in the context of drought-flood coexistence (DFC), revolving two key objects and their interactions: DFC and urban at regional scale. Flood and drought events, in their turns intertwine in natural correlation, which is also reviewed. These relationships are literally investigated, to prove that they interplay mutually with each other, and that once a city develops in relation with water cycle at a regional context, in arid zone, not only hydrological drought could be regionally decreased, but human-induced floods could be ecologically regulated. The study concludes in the fourth, together with lessons from relevant case studies in America, China, with some principles on spatial planning, resilient/adaptive to DFC, which could be ecologically managed in correlation with urban development on a sustainable pathway.

Urban pluvial flood prediction: a case study evaluating radar rainfall nowcasts and numerical weather prediction models as model inputs.

PubMed

Thorndahl, Søren; Nielsen, Jesper Ellerbæk; Jensen, David Getreuer

2016-12-01

Flooding produced by high-intensive local rainfall and drainage system capacity exceedance can have severe impacts in cities. In order to prepare cities for these types of flood events - especially in the future climate - it is valuable to be able to simulate these events numerically, both historically and in real-time. There is a rather untested potential in real-time prediction of urban floods. In this paper, radar data observations with different spatial and temporal resolution, radar nowcasts of 0-2 h leadtime, and numerical weather models with leadtimes up to 24 h are used as inputs to an integrated flood and drainage systems model in order to investigate the relative difference between different inputs in predicting future floods. The system is tested on the small town of Lystrup in Denmark, which was flooded in 2012 and 2014. Results show it is possible to generate detailed flood maps in real-time with high resolution radar rainfall data, but rather limited forecast performance in predicting floods with leadtimes more than half an hour.

A comparative study of European insurance schemes for extreme weather risks and incentives for risk reduction

NASA Astrophysics Data System (ADS)

de Ruiter, Marleen; Hudson, Paul; de Ruig, Lars; Kuik, Onno; Botzen, Wouter

2017-04-01

This paper provides an analysis of the insurance schemes that cover extreme weather events in twelve different EU countries and the risk reduction incentives offered by these schemes. Economic impacts of extreme weather events in many regions in Europe and elsewhere are on the rise due to climate change and increasing exposure as driven by urban development. In an attempt to manage impacts from extreme weather events, natural disaster insurance schemes can provide incentives for taking measures that limit weather-related risks. Insurance companies can influence public risk management policies and risk-reducing behaviour of policyholders by "rewarding behaviour that reduces risks and potential damages" (Botzen and Van den Bergh, 2008, p. 417). Examples of insurance market systems that directly or indirectly aim to incentivize risk reduction with varying degrees of success are: the U.S. National Flood Insurance Programme; the French Catastrophes Naturelles system; and the U.K. Flood Re program which requires certain levels of protection standards for properties to be insurable. In our analysis, we distinguish between four different disaster types (i.e. coastal and fluvial floods, droughts and storms) and three different sectors (i.e. residential, commercial and agriculture). The selected case studies also provide a wide coverage of different insurance market structures, including public, private and public-private insurance provision, and different methods of coping with extreme loss events, such as re-insurance, governmental aid and catastrophe bonds. The analysis of existing mechanisms for risk reduction incentives provides recommendations about incentivizing adaptive behaviour, in order to assist policy makers and other stakeholders in designing more effective insurance schemes for extreme weather risks.

Nontraditional Settlement Patterns and Typhoon Hazard on Contemporary Majuro Atoll, Republic of the Marshall Islands

PubMed

Spennemann

1996-05-01

Low-lying islands and atolls are particularly prone to storm surges created by tropical depressions and typhoons. This paper presents a case study of traditional and contemporary settlement patterns of Majuro, the capital of the Republic of the Marshall Islands, and discusses its vulnerability to such storm surges. The paper shows that the application of traditional knowledge extends to the realm of urban planning and that, in fact, ignoring this traditional knowledge as expressed in pre-World War II settlement patterns, exposes urban development to increased flood hazards, a risk which may exact a price too high in life and property.

Household Adaptive Behavior in Response to Coastal Flood Risk and External Stressors

NASA Astrophysics Data System (ADS)

Buchanan, M. K.

2017-12-01

Approximately forty percent of the world's population sits along ocean coastlines. This urban exposure to flooding is increasing due to population growth and sea level rise resulting from anthropogenic climate change. Recent research improving the characterization of physical hazards from climate change on the coastal zone has helped cities assess their risks. This work includes improving our understanding of the rate and magnitude of sea level rise, the change in distribution of tropical cyclones, and the resulting frequency and severity of flooding on global to local scales. However, the ability of settlements to cope or thrive under changing climate conditions will likely depend on the cooperation and initiative of households, regardless of any governmental efforts to reduce risk. Understanding individuals' likely responses to changing coastal hazards is thus critical for decision-makers to plan for a sustainable future. Individuals may be motivated not only by information regarding emerging flood hazards, but also by cognitive and contextual factors. For governments to develop effective adaptation policies, it is important to understand what factors tend to motivate household adaptation. We apply principles from economics and psychology to investigate how people respond to various existing adaptation options and policies, using a household survey with experiments in New York City neighborhoods affected by Hurricane Sandy. We investigate a comprehensive set of factors that may influence household adaptive behavior. A striking 64% of homeowners and 83% of renters intend to relocate among different plausible future conditions, such as frequent nuisance flooding and the adaptation of peers. This amount is substantial considering the political sensitivity of `retreat' and the lack of regional and federal preparation for large-scale climate-induced migration.

Flood frequency analysis for nonstationary annual peak records in an urban drainage basin

USGS Publications Warehouse

Villarini, G.; Smith, J.A.; Serinaldi, F.; Bales, J.; Bates, P.D.; Krajewski, W.F.

2009-01-01

Flood frequency analysis in urban watersheds is complicated by nonstationarities of annual peak records associated with land use change and evolving urban stormwater infrastructure. In this study, a framework for flood frequency analysis is developed based on the Generalized Additive Models for Location, Scale and Shape parameters (GAMLSS), a tool for modeling time series under nonstationary conditions. GAMLSS is applied to annual maximum peak discharge records for Little Sugar Creek, a highly urbanized watershed which drains the urban core of Charlotte, North Carolina. It is shown that GAMLSS is able to describe the variability in the mean and variance of the annual maximum peak discharge by modeling the parameters of the selected parametric distribution as a smooth function of time via cubic splines. Flood frequency analyses for Little Sugar Creek (at a drainage area of 110 km2) show that the maximum flow with a 0.01-annual probability (corresponding to 100-year flood peak under stationary conditions) over the 83-year record has ranged from a minimum unit discharge of 2.1 m3 s- 1 km- 2 to a maximum of 5.1 m3 s- 1 km- 2. An alternative characterization can be made by examining the estimated return interval of the peak discharge that would have an annual exceedance probability of 0.01 under the assumption of stationarity (3.2 m3 s- 1 km- 2). Under nonstationary conditions, alternative definitions of return period should be adapted. Under the GAMLSS model, the return interval of an annual peak discharge of 3.2 m3 s- 1 km- 2 ranges from a maximum value of more than 5000 years in 1957 to a minimum value of almost 8 years for the present time (2007). The GAMLSS framework is also used to examine the links between population trends and flood frequency, as well as trends in annual maximum rainfall. These analyses are used to examine evolving flood frequency over future decades. ?? 2009 Elsevier Ltd.

Study on the Potential Development of Rainwater Utilization in the Hilly City of Southern China

NASA Astrophysics Data System (ADS)

Fu, Xiaoran; Liu, Jiahong; Shao, Weiwei; Zhang, Haixing

2017-12-01

Aimed at the current flood problems and the contradiction between supply and demand of water resources in the southern cities of China, the comprehensive utilization of Urban Rainwater Resources (URRs) is a significant solution. At present, the research on the comprehensive utilization system of urban rainwater resources in China is still immature, especially the lack of a comprehensive method for the comprehensive utilization of the rainwater and flood resources in the south. Based on the current mode for utilization of URRs at home and abroad, Fenghuang County in Hunan Province was taken as a case of study, which is a typical mountainous city in the southern China. And the potential development of URRs was simulated and evaluated with a comparison of before and after the exploitation and utilization of URRs in this paper. The reduction effect of flood and waterlogging on the ancient city area is analyzed from SWMM. The simulation results show that the potential of exploitation and utilization of URRs in Fenghuang county is remarkable under the mode of exploitation and utilization which is given priority to flood prevention and control, and the annual development potential is 4.865×105 m3. The rainwater utilization measures of flood control effect is obvious with this mode, and the relevant research results can provide theoretical and technical support for enhancing urban water security capability, water conservation capacity, and disaster mitigation of urban flood.

Making Space for Water: A review of SUstainable Drainage systems (SUDs) in a rural/urban area of Newcastle upon Tyne, UK.

NASA Astrophysics Data System (ADS)

Quinn, Paul; Tellier, Sebastien; Wilkinson, Mark

2010-05-01

Expansion of the city of Newcastle included a new development of over 3000 houses and an associated commercial area on agricultural land. The development firmly signed up to the notion that the new estate should adhere to full SUDs design and implementation. In essence there should be no loss of floodplain capacity, the total runoff from the new housing should not increase flood risk downstream and benefits to ecology, recreation and amenity should be fully maximised. Credit must be given to Newcastle City Council, the Environment Agency, the local water company and the developers themselves as a full set of large scale SUDs now exist and they are clearly an asset to the city. However, such a large scale landscape engineering endeavour has not been without direct and indirect problems. This paper reviews some of the experiences, problems and lessons learnt from SUDs implementation, the function of SUDs during flood events and the perception of SUDs by the public. During the life of the project several older estates close to the new development suffered from two major flood events; including foul water inundation, the drowning out of sewer overflows and intense flash flooding. These floods at first gave rise to the public perception that the new development had caused the flooding. During a research project entitled 'making space for water', the instrumentation of the river in the area and the SUDs took place. The hydrological data this produced has given rise to a mixture of positive and negative aspects of SUDs implementation. The cause of one flood was due to the drowning out of key sewer overflows by locally generated by urban flood flow arising from an upstream estate. The second flood was caused by a 48 hour storm event giving rise to high runoff from the rural area again drowning out key sewer overflows. The SUDs were found to perform well during storm events and do not increase runoff from the new estates. The main fundamental complaint is that despite such a large investment in the Newcastle area, the older estates continue to be flooded. There is at this time no capability to think about holistic solutions to flooding in a catchment and the 'development' in the town gives rise to local solution only. A proposal to use the new SUDs and the floodplain to help lower flood risk for the older estates has met with a wall regulatory objections. The ability to manage runoff sources arising from rural areas could be addressed by investing in SUDs on agricultural land. Equally, putting SUDs into older estates could be very beneficial to the whole of the city. Holistic options and catchment management has to be at the heart of future planning considerations. The whole experience is great example of hydrology, engineering, planning and politics in action. The role of solid hydrological evidence in the debate has been significant. The most reassuring aspect of the work is that all the partners are endeavouring to learn and improve the flood management in the area and holistic thinking is now occurring.

Data-Driven Geospatial Visual Analytics for Real-Time Urban Flooding Decision Support

NASA Astrophysics Data System (ADS)

Liu, Y.; Hill, D.; Rodriguez, A.; Marini, L.; Kooper, R.; Myers, J.; Wu, X.; Minsker, B. S.

2009-12-01

Urban flooding is responsible for the loss of life and property as well as the release of pathogens and other pollutants into the environment. Previous studies have shown that spatial distribution of intense rainfall significantly impacts the triggering and behavior of urban flooding. However, no general purpose tools yet exist for deriving rainfall data and rendering them in real-time at the resolution of hydrologic units used for analyzing urban flooding. This paper presents a new visual analytics system that derives and renders rainfall data from the NEXRAD weather radar system at the sewershed (i.e. urban hydrologic unit) scale in real-time for a Chicago stormwater management project. We introduce a lightweight Web 2.0 approach which takes advantages of scientific workflow management and publishing capabilities developed at NCSA (National Center for Supercomputing Applications), streaming data-aware semantic content management repository, web-based Google Earth/Map and time-aware KML (Keyhole Markup Language). A collection of polygon-based virtual sensors is created from the NEXRAD Level II data using spatial, temporal and thematic transformations at the sewershed level in order to produce persistent virtual rainfall data sources for the animation. Animated color-coded rainfall map in the sewershed can be played in real-time as a movie using time-aware KML inside the web browser-based Google Earth for visually analyzing the spatiotemporal patterns of the rainfall intensity in the sewershed. Such system provides valuable information for situational awareness and improved decision support during extreme storm events in an urban area. Our further work includes incorporating additional data (such as basement flooding events data) or physics-based predictive models that can be used for more integrated data-driven decision support.

High Resolution Sensing and Control of Urban Water Networks

NASA Astrophysics Data System (ADS)

Bartos, M. D.; Wong, B. P.; Kerkez, B.

2016-12-01

We present a framework to enable high-resolution sensing, modeling, and control of urban watersheds using (i) a distributed sensor network based on low-cost cellular-enabled motes, (ii) hydraulic models powered by a cloud computing infrastructure, and (iii) automated actuation valves that allow infrastructure to be controlled in real time. This platform initiates two major advances. First, we achieve a high density of measurements in urban environments, with an anticipated 40+ sensors over each urban area of interest. In addition to new measurements, we also illustrate the design and evaluation of a "smart" control system for real-world hydraulic networks. This control system improves water quality and mitigates flooding by using real-time hydraulic models to adaptively control releases from retention basins. We evaluate the potential of this platform through two ongoing deployments: (i) a flood monitoring network in the Dallas-Fort Worth metropolitan area that detects and anticipates floods at the level of individual roadways, and (ii) a real-time hydraulic control system in the city of Ann Arbor, MI—soon to be one of the most densely instrumented urban watersheds in the United States. Through these applications, we demonstrate that distributed sensing and control of water infrastructure can improve flash flood predictions, emergency response, and stormwater contaminant mitigation.

The economic value of the flow regulation environmental service in a Brazilian urban watershed

NASA Astrophysics Data System (ADS)

Marques, Guilherme F.; de Souza, Verônica B. F. S.; Moraes, Natália V.

2017-11-01

Urban flood management have often focused either on the capacity expansion of drainage systems or on artificial detention storage. While flood control should take part early on urban planning, not enough is known to guide such plans and provide incentive to land use decisions that minimize the vulnerability to localized floods. In this paper, we offer a broader perspective on flood protection, by treating the original hydrologic flow regulation as an environmental service, and exploring how the value of this environmental service drives economic land use decisions that convert original (permeable) land into urbanized (impermeable). We investigate the relationship between land use decisions and their hydrologic consequences explicitly, and use this relationship to simulate resulting land use scenarios depending on the value attached to the environmental service of flow regulation. Rainfall-runoff simulation model results are combined to an optimization model based on two-stage stochastic programming approach to model economic land use decisions. The objective function maximizes the total expected land use benefit in an urban area, considering the opportunity cost of permeable areas in the first stage and the resulting loss of the environmental service of flow regulation on the second stage, under several probable hydrological events. A watershed in the city of Belo Horizonte, Brazil, is used to demonstrate the approach. Different values attached to the environmental service were tested, from zero to higher than the opportunity cost of land, and artificial detention infrastructure was included to calculate the resulting land use change and the loss in the environmental service value. Results indicate that by valuing the environmental service loss and discounting it from the economic benefits of land use, alternative solutions to land use are found, with decreased peak flows and lower flood frequency. Combined solutions including structural and non-structural techniques provide more cost effective results, avoiding both the depletion of the environmental service and the high opportunity cost associated to valuable commercial urban areas. Urban development under such premises will be more resilient and adapted to local flooding, instead of relying on increasingly expensive infrastructure.

Evaluation of Urban Drainage Infrastructure: New York City Case Study

NASA Astrophysics Data System (ADS)

Hamidi, A.; Grossberg, M.; Khanbilvardi, R.

2017-12-01

Flood response in an urban area is the product of interactions of spatially and temporally varying rainfall and infrastructures. In urban areas, however, the complex sub-surface networks of tunnels, waste and storm water drainage systems are often inaccessible, pose challenges for modeling and prediction of the drainage infrastructure performance. The increased availability of open data in cities is an emerging information asset for a better understanding of the dynamics of urban water drainage infrastructure. This includes crowd sourced data and community reporting. A well-known source of this type of data is the non-emergency hotline "311" which is available in many US cities, and may contain information pertaining to the performance of physical facilities, condition of the environment, or residents' experience, comfort and well-being. In this study, seven years of New York City 311 (NYC311) call during 2010-2016 is employed, as an alternative approach for identifying the areas of the city most prone to sewer back up flooding. These zones are compared with the hydrologic analysis of runoff flooding zones to provide a predictive model for the City. The proposed methodology is an example of urban system phenomenology using crowd sourced, open data. A novel algorithm for calculating the spatial distribution of flooding complaints across NYC's five boroughs is presented in this study. In this approach, the features that represent reporting bias are separated from those that relate to actual infrastructure system performance. The sewer backup results are assessed with the spatial distribution of runoff in NYC during 2010-2016. With advances in radar technologies, a high spatial-temporal resolution data set for precipitation is available for most of the United States that can be implemented in hydrologic analysis of dense urban environments. High resolution gridded Stage IV radar rainfall data along with the high resolution spatially distributed land cover data are employed to investigate the urban pluvial flooding. The monthly results of excess runoff are compared with the sewer backup in NYC to build a predictive model of flood zones according to the 311 phone calls.

Land use change in the last century in the Veneto floodplain: effects on network drainage density, water storage, and related consequences on flood risk

NASA Astrophysics Data System (ADS)

Prosdocimi, Massimo; Sofia, Giulia; Dalla Fontana, Giancarlo; Tarolli, Paolo

2013-04-01

In a high-density populated country such as Italy, the anthropic pressure plays a fundamental role in the alteration and the modification of the landscape. Among the most evident anthropic alterations, the most important are the urbanization processes that have been occurring since the end of the second world war. Agricultural activities, housing and other land uses have shifted due to the progressive spreading of urban areas. These modifications affect the hydrologic regimes, but municipalities often are not aware of the real impact of land cover changes on such processes and, consequently, an increase of the elements at risk of flooding is generally registered. The main objective of this work is to evaluate the impact of land cover changes in the Veneto region (north-east Italy), from 1954 to 2006, on the minor drainage network system and on its capacity to attenuate the direct runoff. The major flood event occurred between October and November 2010. The study is a typical agrarian landscape and it has been chosen considering its involvement inthe major flood of 2010 and considering also the availability of high-resolution topographic data (LiDAR-derived DTMs) and historical aerial photographs. Aerial photographs dated back to 1954 and 1981, in particular, have been used either to classify the land cover in five categories according to the first level of the CORINE land cover classification and to identify the minor drainage network. A semi-automatic approach based on the high-resolution DTM (Cazorzi et al., 2012), was also considered to identify the minor drainage network and estimate its water storage capacity. The results underline how land cover variation over the last 50 years has strongly increased the propension of the soil to produce direct runoff (increase of the Curve Number value) and it has also reduced the extent of the minor network system. As a consequence, the capacity of the agrarian minor network to attenuate and laminate a flood event is decreased as well. These analysis can be considered useful tools for a suitable land use planning in flood prone areas. References Cazorzi, F., Dalla Fontana, G., De Luca, A., Sofia, G., Tarolli, P. (2012). Drainage network detection and assessment of network storage capacity in agrarian landscape, Hydrological Processes, ISSN: 0885-6087, doi:10.1002/hyp.9224

Assessing increasing susceptibility to wildfire at the wildland-urban fringe in the western United States

NASA Astrophysics Data System (ADS)

Kinoshita, A. M.; Hogue, T. S.

2013-05-01

Much of the western U.S. is increasingly susceptible to wildfire activity due to drier conditions, elevated fuel loads, and expanding urbanization. As population increases, development pushes the urban boundary further into wildlands, creating more potential for human interaction at the wildland-urban interface (WUI), primarily from human ignitions and fire suppression policies. The immediate impacts of wildfires include vulnerability to debris flows, flooding, and impaired water quality. Fires also alter longer-term hydrological and ecosystem behavior. The current study utilizes geospatial datasets to investigate historical wildfire size and frequency relative to the WUI for a range of cities across western North America. California, the most populous state in the U.S., has an extensive fire history. The decennial population and acres burned for four major counties (Los Angeles, San Bernardino, San Diego, and Shasta) in California show that increasing wildfire size and frequency follow urbanization trends, with high correlation between the last decade of burned area, urban-fringe proximity, and increasing population. Ultimately, results will provide information on urban fringe communities that are most vulnerable to the risks associated with wildfire and post-fire impacts. In light of evolving land use policies (i.e. forest management and treatment, development at the urban-fringe) and climate change, it is critical to advance our knowledge of the implications that these conditions pose to urban centers, communicate risks to the public, and ultimately provide guidance for wildfire management.

Hydrogeological challenges through gender approaches

NASA Astrophysics Data System (ADS)

Di Lorenzo, Maria Rosaria; Saltari, Davide; Di Giacomo, Tullia Valeria

2017-04-01

Women and Men play a different role in the society, tied from the differences (physical, biological, somatic, etc…) typical of each one. In the last decades, more gender approach has been introduced in a number of fields including the hydrogeological risk. Experiences, needs and potential of each one, women and men, covers both the risk reduction before the occurrence of extreme events (vulnerability assessment and prediction of the expected risk), then in the next emergency and intervention in follow-up actions to the overcoming of the event for the return to everyday life. The response of the extreme hydrological events are also subordinated from gender participation and it is closely related from other aspects, as natural disasters (flood events), gender inequalities and urban floodings. These aspects are also scheduled by the different approaches: a woman focuses different primary and social aspects than a man. How women can help organizations offering new 'policies' and government is the main aspect to be considered and how a gender approach can mitigate disasters to hydrological risk. It depends on some factors: gender inequalities (gender perception and sensibility), importance of natural disasters and urban floodings. Gender inequalities can match both in the natural disasters and urban floodings in a relevant way. ICT solutions can also give a helpful framework to accelerate and focus the quicker condition to get the better approach and solution. Gender has a particular significant, explanatory variable in disaster research. Many studies, show how women have higher mortality and morbidity rates than men during natural disasters, especially in lower income countries. In the aftermath disasters, at the same time, specific responsibilities on women are imposed from the gendered division of labour. Furthermore gender differences are sometimes attributed to traditional women's roles, discrimination, lower physical strength, nutritional deficiencies, etc. as demonstrated in Bangladesh Cyclone, named Cyclone Gorky, occurred in 1991, where an emblematic gender-biased was represented: women outnumbered men by 14:1 . The causes of female's greater mortality in this lower income countries, as appear from some researches, works where they have a good insight, arriving at the following verifications: • many women perished with their children at home, waiting both their husbands return at home and make the evacuation decision; • many women died because of their dress, the saree, which limited their ability to move. Many girls died while their brothers were rescued "to carry on the family lines", This two example shows badly targeted disaster communication can increase gender inequalities. According the previous points, three points seem important:  disaster communication is important to be sensitive to gender-targeted and to culture and context;  women and men have different risk perceptions, different access to information and communication styles:  a new successful relationships with genders communicate and thus adapting communication style is goal to achieve to help the institutions to save more habitants. The different behaviors, between women and men, will do the best in order to fit how minimize the effects of the hydrogeological disasters.

Living more safely in the chaparral-urban interface

Treesearch

Klaus W. H. Radtke

1983-01-01

Urban encroachment into chaparral areas has accelerated the fire-flood-erosion cycle. Preventative maintenance measures can help reduce the damage from fire and flood. This report describes the chaparral environment; how to cope with problems in watershed management, how to landscape for fire and soil erosion control, how to plan for home safety from fire, how to treat...

Hispanic health disparities after a flood disaster: results of a population-based survey of individuals experiencing home site damage in El Paso (Texas, USA).

PubMed

Collins, Timothy W; Jimenez, Anthony M; Grineski, Sara E

2013-04-01

In 2006, El Paso County, a predominantly Hispanic urban area, was affected by a flood disaster; 1,500 homes were damaged. We assessed the health impacts of the disaster upon 475 individuals whose homes were flood-damaged using mail survey data and logistic regression. Substantial proportions of individuals had one or more physical (43 %) or mental (18 %) health problem in the four months following the floods; 28 % had one or more injury or acute effect related to post-flood cleanup. Adverse event experiences, older age, and lower socioeconomic status were significantly associated with negative post-flood health outcomes in all three logistic regression models. A lack of access to healthcare, non-US citizenship, and English proficiency were significant predictors of negative outcomes in both the physical and mental health models, while Hispanic ethnicity (physical), native-birth (mental), and more serious home damage (cleanup) were significant predictors in one model each. The disaster had disproportionate negative health impacts on those who were more exposed, poorer, older, and with constrained resource-access. While a lack of US citizenship and Hispanic ethnicity were associated with higher risks, being less acculturated (i.e., English-deficient, foreign-born) may have protected against health impacts.

Medium range forecasting of Hurricane Harvey flash flooding using ECMWF and social vulnerability data

NASA Astrophysics Data System (ADS)

Pillosu, F. M.; Jurlina, T.; Baugh, C.; Tsonevsky, I.; Hewson, T.; Prates, F.; Pappenberger, F.; Prudhomme, C.

2017-12-01

During hurricane Harvey the greater east Texas area was affected by extensive flash flooding. Their localised nature meant they were too small for conventional large scale flood forecasting systems to capture. We are testing the use of two real time forecast products from the European Centre for Medium-range Weather Forecasts (ECMWF) in combination with local vulnerability information to provide flash flood forecasting tools at the medium range (up to 7 days ahead). Meteorological forecasts are the total precipitation extreme forecast index (EFI), a measure of how the ensemble forecast probability distribution differs from the model-climate distribution for the chosen location, time of year and forecast lead time; and the shift of tails (SOT) which complements the EFI by quantifying how extreme an event could potentially be. Both products give the likelihood of flash flood generating precipitation. For hurricane Harvey, 3-day EFI and SOT products for the period 26th - 29th August 2017 were used, generated from the twice daily, 18 km, 51 ensemble member ECMWF Integrated Forecast System. After regridding to 1 km resolution the forecasts were combined with vulnerable area data to produce a flash flood hazard risk area. The vulnerability data were floodplains (EU Joint Research Centre), road networks (Texas Department of Transport) and urban areas (Census Bureau geographic database), together reflecting the susceptibility to flash floods from the landscape. The flash flood hazard risk area forecasts were verified using a traditional approach against observed National Weather Service flash flood reports, a total of 153 reported flash floods have been detected in that period. Forecasts performed best for SOT = 5 (hit ratio = 65%, false alarm ratio = 44%) and EFI = 0.7 (hit ratio = 74%, false alarm ratio = 45%) at 72 h lead time. By including the vulnerable areas data, our verification results improved by 5-15%, demonstrating the value of vulnerability information within natural hazard forecasts. This research shows that flash flooding from hurricane Harvey was predictable up to 4 days ahead and that filtering the forecasts to vulnerable areas provides a more focused guidance to civil protection agencies planning their emergency response.

Analysis of flood vulnerability in urban area; a case study in deli watershed

NASA Astrophysics Data System (ADS)

Indrawan, I.; Siregar, R. I.

2018-03-01

Based on the National Disaster Management Agency of Indonesia, the distribution of disasters and victims died until the year 2016 is the largest flood disaster. Deli River is a river that has the greatest flood potential through Medan City. In Deli Watershed, flow discharge affected by the discharge from its tributaries, the high rainfall intensity and human activity. We should anticipate reducing and preventing the occurrence of losses due to flood damage. One of the ways to anticipate flood disaster is to predict which part of urban area is would flood. The objective of this study is to analyze the flood inundation areas due to overflow of Deli River through Medan city. Two-dimensional modeling by HEC-RAS 5.0.3 is a widely used hydraulic software tool developed by the U.S Army Corps of Engineers, which combined with the HEC-HMS for hydrological modeling. The result shows flood vulnerability in Medan by a map to present the spot that vulnerable about flood. The flooded area due to the overflowing of Deli River consists of seven sub districts, namely Medan Johor, Medan Selayang, Medan Kota, Medan Petisah, Medan Maimun, Medan Perjuangan and Medan Barat.

Green-blue water in the city: quantification of impact of source control versus end-of-pipe solutions on sewer and river floods.

PubMed

De Vleeschauwer, K; Weustenraad, J; Nolf, C; Wolfs, V; De Meulder, B; Shannon, K; Willems, P

2014-01-01

Urbanization and climate change trends put strong pressures on urban water systems. Temporal variations in rainfall, runoff and water availability increase, and need to be compensated for by innovative adaptation strategies. One of these is stormwater retention and infiltration in open and/or green spaces in the city (blue-green water integration). This study evaluated the efficiency of three adaptation strategies for the city of Turnhout in Belgium, namely source control as a result of blue-green water integration, retention basins located downstream of the stormwater sewers, and end-of-pipe solutions based on river flood control reservoirs. The efficiency of these options is quantified by the reduction in sewer and river flood frequencies and volumes, and sewer overflow volumes. This is done by means of long-term simulations (100-year rainfall simulations) using an integrated conceptual sewer-river model calibrated to full hydrodynamic sewer and river models. Results show that combining open, green zones in the city with stormwater retention and infiltration for only 1% of the total city runoff area would lead to a 30 to 50% reduction in sewer flood volumes for return periods in the range 10-100 years. This is due to the additional surface storage and infiltration and consequent reduction in urban runoff. However, the impact of this source control option on downstream river floods is limited. Stormwater retention downstream of the sewer system gives a strong reduction in peak discharges to the receiving river. However due to the difference in response time between the sewer and river systems, this does not lead to a strong reduction in river flood frequency. The paper shows the importance of improving the interface between urban design and water management, and between sewer and river flood management.

Potentialities of ensemble strategies for flood forecasting over the Milano urban area

NASA Astrophysics Data System (ADS)

Ravazzani, Giovanni; Amengual, Arnau; Ceppi, Alessandro; Homar, Víctor; Romero, Romu; Lombardi, Gabriele; Mancini, Marco

2016-08-01

Analysis of ensemble forecasting strategies, which can provide a tangible backing for flood early warning procedures and mitigation measures over the Mediterranean region, is one of the fundamental motivations of the international HyMeX programme. Here, we examine two severe hydrometeorological episodes that affected the Milano urban area and for which the complex flood protection system of the city did not completely succeed. Indeed, flood damage have exponentially increased during the last 60 years, due to industrial and urban developments. Thus, the improvement of the Milano flood control system needs a synergism between structural and non-structural approaches. First, we examine how land-use changes due to urban development have altered the hydrological response to intense rainfalls. Second, we test a flood forecasting system which comprises the Flash-flood Event-based Spatially distributed rainfall-runoff Transformation, including Water Balance (FEST-WB) and the Weather Research and Forecasting (WRF) models. Accurate forecasts of deep moist convection and extreme precipitation are difficult to be predicted due to uncertainties arising from the numeric weather prediction (NWP) physical parameterizations and high sensitivity to misrepresentation of the atmospheric state; however, two hydrological ensemble prediction systems (HEPS) have been designed to explicitly cope with uncertainties in the initial and lateral boundary conditions (IC/LBCs) and physical parameterizations of the NWP model. No substantial differences in skill have been found between both ensemble strategies when considering an enhanced diversity of IC/LBCs for the perturbed initial conditions ensemble. Furthermore, no additional benefits have been found by considering more frequent LBCs in a mixed physics ensemble, as ensemble spread seems to be reduced. These findings could help to design the most appropriate ensemble strategies before these hydrometeorological extremes, given the computational cost of running such advanced HEPSs for operational purposes.

Adapting Reservoir Operations to Reduce the Multi-Sectoral Impacts of Flood Intensification in the Lower Susquehanna

NASA Astrophysics Data System (ADS)

Zatarain-Salazar, J.; Reed, P. M.; Quinn, J.

2017-12-01

This study characterizes how changes in reservoir operations can be used to better balance growing flood intensities and the conflicting multi-sectorial demands in the Lower Susequehanna River Basin (LSRB), USA. Tensions in the LSRB are increasing with urban population pressures, evolving energy demands, and growing flood-based infrastructure vulnerabilities. This study explores how re-operation of the Conowingo Reservoir, located in the LSRB, can improve the balance between competing demands for hydropower production, urban water supply to Chester, PA and Baltimore, MD, cooling water supply for the Peach Bottom Atomic Power Plant, recreation, federal environmental flow requirements and improved mitigation of growing flood hazards. The LSRB is also one of the most flood prone basins in the US, impacted by hurricanes and rain-on-snow induced flood events causing on average $100 million in economic losses and infrastructure damages to downstream settlements every year. The purpose of this study is to evaluate the consequences of mathematical formulation choices, uncertainty characterization and the value of information when defining the Conowingo reservoir's multi-purpose operations. This work seeks to strike a balance between the complexity and the efficacy of rival framings for the problem formulations used to discover effective operating policies. More broadly, the problem of intensifying urban floods in reservoir systems with complex multi-sectoral demands is broadly relevant to developed river basins globally.

Attenuating reaches and the regional flood response of an urbanizing drainage basin

NASA Astrophysics Data System (ADS)

Turner-Gillespie, Daniel F.; Smith, James A.; Bates, Paul D.

The Charlotte, North Carolina metropolitan area has experienced extensive urban and suburban growth and sharply increasing trends in the magnitude and frequency of flooding. The hydraulics and hydrology of flood response in the region are examined through a combination of numerical modeling studies and diagnostic analyses of paired discharge observations from upstream-downstream gaging stations. The regional flood response is shown to strongly reflect urbanization effects, which increase flood peaks and decrease response times, and geologically controlled attenuating reaches, which decrease flood peaks and increase lag times. Attenuating reaches are characterized by systematic changes in valley bottom geometry and longitudinal profile. The morphology of the fluvial system is controlled by the bedrock geology, with pronounced changes occurring at or near contacts between intrusive igneous and metamorphic rocks. Analyses of wave celerity and flood peak attenuation over a range of discharge values for an 8.3 km valley bottom section of Little Sugar Creek are consistent with Knight and Shiono's characterization of the variation of flood wave velocity from in-channel conditions to valley bottom full conditions. The cumulative effect of variation in longitudinal profile, expansions and contractions of the valley bottom, floodplain roughness and sub-basin flood response is investigated using a two-dimensional, depth-averaged, finite element hydrodynamic model coupled with a distributed hydrologic model. For a 10.1 km stream reach of Briar Creek, with drainage area ranging from 13 km 2 at the upstream end of the reach to 49 km 2 at the downstream end, it is shown that flood response reflects a complex interplay of hydrologic and hydraulic processes on hillslopes and valley bottoms.

Flood damage in Italy: towards an assessment model of reconstruction costs

NASA Astrophysics Data System (ADS)

Sterlacchini, Simone; Zazzeri, Marco; Genovese, Elisabetta; Modica, Marco; Zoboli, Roberto

2016-04-01

Recent decades in Italy have seen a very rapid expansion of urbanisation in terms of physical assets, while demographics have remained stable. Both the characteristics of Italian soil and anthropic development, along with repeated global climatic stress, have made the country vulnerable to floods, the intensity of which is increasingly alarming. The combination of these trends will contribute to large financial losses due to property damage in the absence of specific mitigation strategies. The present study focuses on the province of Sondrio in Northern Italy (area of about 3,200 km²), which is home to more than 180,000 inhabitants and the population is growing slightly. It is clearly a hot spot for flood exposure, as it is primarily a mountainous area where floods and flash floods hit frequently. The model we use for assessing potential flood damage determines risk scenarios by overlaying flood hazard maps and economic asset data. In Italy, hazard maps are provided by Regional Authorities through the Hydrogeological System Management Plan (PAI) based on EU Flood Directive guidelines. The PAI in the study area includes both the large plain and the secondary river system and considers three hazard scenarios of Low, Medium and High Frequency associated with return periods of 20, 200 and 500 years and related water levels. By an overlay of PAI maps and residential areas, visualized on a GIS, we determine which existing built-up areas are at risk for flood according to each scenario. Then we investigate the value of physical assets potentially affected by floods in terms of market values, using the database of the Italian Property Market Observatory (OMI), and in terms of reconstruction costs, by considering synthetic cost indexes of predominant building types (from census information) and PAI water height. This study illustrates a methodology to assess flood damage in urban settlements and aims to determine general guidelines that can be extended throughout Italy. The final objective will be to analyse how the loss prospective can change when mitigation measures, including actions to reduce the flood hazard and strategies to prevent potential consequences, are implemented. Flood impacts and the corresponding value of mitigation measures will be assessed by means of a cost-benefit analysis in accordance with the EU Floods Directive.

Integration of social vulnerability into emergency management plans: designing of evacuation routes against flood disasters

NASA Astrophysics Data System (ADS)

Aroca-Jimenez, Estefanía; Bodoque, Jose Maria; Garcia, Juan Antonio; Diez-Herrero, Andres

2017-04-01

Flash floods are highly spatio-temporal localized flood events characterized by reaching a high peak flow in a very short period of time, i.e., generally with times of concentration lower than six hours. Its short duration, which limits or even voids any warning time, means that flash floods are considered to be one of the most destructive natural hazards with the greatest capacity to generate risk, either in terms of the number of people affected globally or the proportion of individual fatalities. The above highlights the importance of a realistic and appropriate design of evacuation strategies in order to reduce flood-related losses, being evacuation planning considered of critical importance for disaster management. Traditionally, evacuation maps have been based on flood-prone areas, shelters or emergency residences location and evacuation routes information. However, evacuation plans rarely consider the spatial distribution of vulnerable population (i.e., people with special needs, mobility constraints or economic difficulties), which usually require assistance from emergency responders. The goal of this research is to elaborate an evacuation map against the occurrence of flash floods by combining geographic information (e.g. roads, health facilities location, sanitary helicopters) and social vulnerability patterns, which are previously obtained from socioeconomic variables (e.g. population, unemployment, dwelling characteristics). To do this, ArcGis Network Analyst tool is used, which allows to calculate the optimal evacuation routes. The methodology proposed here is implemented in the region of Castilla y León (94,230 km2). Urban areas prone to flash flooding are identified taking into account the following requirements: i) city centers are crossed by rivers or streams with a longitudinal slope higher than 0.01 m m-1; ii) city centers are potentially affected by flash floods; and iii) city centers are affected by an area with low or exceptional probability of flooding (i.e., 500-year flood). A total of 3 evacuation routes were designed and automatically traced for each of the 39 urban areas identified as interest, considering the nearest: i) health facility, ii) hospital; and iii) evacuation area (i.e. sports halls or any other). The suitable elaboration of evacuation plans is really important in small mountainous areas prone to flash flooding as they are managed by local organisms where available economic resources are often limited. Furthermore, the short response time obliges emergency responders to act efficiently, which requires the design of evacuation plans taking into account certain social characteristics for evacuation routes designing.

A continuation of the Asia-Pacific Risk Index for natural disasters: extending the record for an updated analysis from 1900-2015

NASA Astrophysics Data System (ADS)

Daniell, James; Daniell, Trevor; Daniell, Katherine; Khazai, Bijan; Schaefer, Andreas; Wenzel, Friedemann

2016-04-01

In 2010, an Asia-Pacific risk index was created for the CECAR5 (Civil Engineering Conference for the Asia-Pacific Region) by Daniell et al. (2010a) for floods and earthquakes, using empirical and analytical risk data for direct as well as socio-economic community vulnerability. The socio-economic situation of countries can aggravate the physical risk of natural disaster impacts, as demonstrated by the impacts of earthquakes in Christchurch and Tohoku 2011; add to this a number of deadly typhoon (Haiyan 2013), cyclone (Yasi 2011), flood (Thailand 2011), bushfire and weather effects, and significant changes to the index in 2010 have been seen. At least 10,000 historical events have been recorded since 1900 across the Asia-Pacific region (western Pacific). The database for global socio-economic indicators was produced to allow comparison of countries in terms of their socio-economic situation for use in risk studies. In addition, a global damaging natural disasters database (CATDAT) has been created over the last 14 years to better understand the historical impact of natural disasters on the Asia-Pacific region as well as globally. Simplified hazard models have been used in conjunction with historical damage data added to human exposure. Post-flood and post-typhoon loss models have been produced this methodology. The relative country level rural and urban building inventories and historical building trends are used to define levels of vulnerability, exposure and hazard. From this, physical and community risk indices are derived for the countries of the Asia-Pacific region. It was found that the vulnerabilities in communities of developing countries such as Indonesia and the Philippines can further intensify the impact from direct damages by many times, showing the increased need for earthquake and flood risk reduction policy. Trends based on HDI and other indicators within the fields of economy, poverty, demographics, governance and environment are also presented, showing the influence of these factors on country-level fragility and resilience showing Philippines and Japan to be the highest at risk countries in absolute and relative terms. (a) Daniell, J.E., Daniell, K.A., Daniell, T.M. & B. Khazai: A country level physical and community risk index in the Asia-Pacific region for earthquakes and floods, Paper No. 0392, 5th CECAR Conference Proceedings, Sydney, Australia, 2010.

The CLUVA project: Climate-change scenarios and their impact on urban areas in Africa

NASA Astrophysics Data System (ADS)

Di Ruocco, Angela; Weets, Guy; Gasparini, Paolo; Jørgensen, Gertrud; Lindley, Sarah; Pauleit, Stephan; Vahed, Anwar; Schiano, Pasquale; Kabisch, Sigrun; Vedeld, Trond; Coly, Adrien; Tonye, Emmanuel; Touré, Hamidou; Kombe, Wilbard; Yeshitela, Kumelachew

2013-04-01

CLUVA (CLimate change and Urban Vulnerability in Africa; http://www.cluva.eu/) is a 3 years project, funded by the European Commission in 2010. Its main objective is the estimate of the impacts of climate changes in the next 40 years at urban scale in Africa. The mission of CLUVA is to develop methods and knowledge to assess risks cascading from climate-changes. It downscales IPCC climate projections to evaluate threats to selected African test cities; mainly floods, sea-level rise, droughts, heat waves and desertification. The project evaluates and links: social vulnerability; vulnerability of in-town ecosystems and urban-rural interfaces; vulnerability of urban built environment and lifelines; and related institutional and governance dimensions of adaptation. A multi-scale and multi-disciplinary quantitative, probabilistic, modelling is applied. CLUVA brings together climate experts, risk management experts, urban planners and social scientists with their African counterparts in an integrated research effort focusing on the improvement of the capacity of scientific institutions, local councils and civil society to cope with climate change. The CLUVA approach was set-up in the first year of the project and developed as follows: an ensemble of eight global projections of climate changes is produced for east and west Africa until 2050 considering the new IPCC (International Panel on Climate Changes; http://www.ipcc.ch/) scenarios. These are then downscaled to urban level, where territorial modeling is required to compute hazard effects on the vulnerable physical system (urban ecosystems, informal settlements, lifelines such as transportation and sewer networks) as well as on the social context, in defined time frames, and risk analysis is then employed to assess expected consequences. An investigation of the existing urban planning and governance systems and its interface with climate risks is performed. With the aid of the African partners, the developed approach is currently being applied to selected African case studies: Addis Ababa - Ethiopia; Dar es Salaam - Tanzania, Douala - Cameroun; Ouagadougou - Burkina Faso, St. Louis - Senegal. The poster will illustrate the CLUVA's framework to assess climate-change-related risks at an urban scale in Africa, and will report on the progresses of selected case studies to demonstrate feasibility of a multi-scale and multi-risk quantitative approach for risk management.

24 CFR 574.640 - Flood insurance protection.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 24 Housing and Urban Development 3 2010-04-01 2010-04-01 false Flood insurance protection. 574.640... Requirements § 574.640 Flood insurance protection. No property to be assisted under this part may be located in... flood hazards, unless: (a)(1) The community in which the area is situated is participating in the...

24 CFR 203.16a - Mortgagor and mortgagee requirement for maintaining flood insurance coverage.

Code of Federal Regulations, 2010 CFR

2010-04-01

... for maintaining flood insurance coverage. 203.16a Section 203.16a Housing and Urban Development... requirement for maintaining flood insurance coverage. (a) If the mortgage is to cover property improvements (dwelling and related structures/equipment essential to the value of the property and subject to flood...

24 CFR 570.605 - National Flood Insurance Program.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 24 Housing and Urban Development 3 2010-04-01 2010-04-01 false National Flood Insurance Program... Requirements § 570.605 National Flood Insurance Program. Notwithstanding the date of HUD approval of the... accordance with 24 CFR part 91), section 202(a) of the Flood Disaster Protection Act of 1973 (42 U.S.C. 4106...