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.

Fargo-Moorhead Urban Study. Flood Control Appendix.

DTIC Science & Technology

1985-05-01

area is Fargo clay locally known as gumbo. Crops best grown in the soil include wheat, barley, flax, rye , alfalfa, sweet clover and corn. Potatoes do...land as possible and reduce the amount of sediment and pollutants entering waterways. 8 0 Apply more cover crops and utilize minimum tillage practices to...3. RECIPIENT’S CATALOG NUMBER 4. TITLE (and Subtitle) 5. TYPE OF REPORT & PERIOD COVERED FARGO-MOORHEAD URBAN STUDY; Flood Control FINAL, ?- 8-20

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...

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.

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.

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

Control Scheme of River-lake System from the View of Ecological Sponge Basin aiming at Sponge City Construction

NASA Astrophysics Data System (ADS)

Ding, X.; Liu, J.; Yang, Z.

2017-12-01

China is in the rapid advance of urbanization, and is promoting the Sponge City Construction (SCC) with the characteristics of natural accumulation, natural infiltration and natural purification. The Chinese government selected 16 and 14 cities as pilot cities in 2015 and 2016 respectively to carry out SCC taking Low Impact Development (LID) as the concept. However, in 2015 and 2016, water-logging occurred in 10 cities and 9 cities respectively during the pilot cities. Therefore, relying solely on LID can not solve the problem of urban flood and waterlogging. Except for a series of LID measures during the process of SCC, corresponding control scheme of river-lake system should be established to realize water-related targets. From the view of ecological sponge basin, this study presents the general idea of SCC both in and out of the unban built-up area and the corresponding control scheme of river-lake system: for the regions outside the built-up area, the main aim of SCC is to carry out the top-level design of urban flood control and waterlogging, establish the water security system outside the city for solving the problems including flood control, water resources, water environment and water ecology; for the built-up area, the main aim of SCC is to construct different kinds of urban sponge according to local conditions and develop multi-scale drainage system responding to different intensities of rainfall taking the river-lake system as the core. Taking Fenghuang County of Hunan Province as an example for the application research, the results indicate that, after the implementation of the control scheme of river-lake system: 1) together with other SCC measures including LID, the control rate of total annual runoff in Fenghuang County is expected to be 82.9% which meets the target requirement of 80%; 2) flood control and drainage standards in Fenghuang County can be increased from the current 10-year return to 20-year return; 3) urban and rural water supply guarantee rate is expected to be 98% which meets the target requirement of 95%. Therefore, the control scheme of urban river-lake system in the county is technically feasible, and can effectively solve the problems including flood control, water resources shortage and ecological water demand in the county, thus may provide strong support and guarantee for SCC.

Sustainable Improvement of Urban River Network Water Quality and Flood Control Capacity by a Hydrodynamic Control Approach-Case Study of Changshu City

NASA Astrophysics Data System (ADS)

Xie, Chen; Yang, Fan; Liu, Guoqing; Liu, Yang; Wang, Long; Fan, Ziwu

2017-01-01

Water environment of urban rivers suffers degradation with the impacts of urban expansion, especially in Yangtze River Delta. The water area in cites decreased sharply, and some rivers were cut off because of estate development, which brings the problems of urban flooding, flow stagnation and water deterioration. The approach aims to enhance flood control capability and improve the urban river water quality by planning gate-pump stations surrounding the cities and optimizing the locations and functions of the pumps, sluice gates, weirs in the urban river network. These gate-pump stations together with the sluice gates and weirs guarantee the ability to control the water level in the rivers and creating hydraulic gradient artificially according to mathematical model. Therefore the flow velocity increases, which increases the rate of water exchange, the DO concentration and water body self-purification ability. By site survey and prototype measurement, the river problems are evaluated and basic data are collected. The hydrodynamic model of the river network is established and calibrated to simulate the scenarios. The schemes of water quality improvement, including optimizing layout of the water distribution projects, improvement of the flow discharge in the river network and planning the drainage capacity are decided by comprehensive Analysis. Finally the paper introduces the case study of the approach in Changshu City, where the approach is successfully implemented.

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.

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.

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.

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.

Autonomous watersheds: Reducing flooding and stream erosion through real-time control

NASA Astrophysics Data System (ADS)

Kerkez, B.; Wong, B. P.

2017-12-01

We introduce an analytical toolchain, based on dynamical system theory and feedback control, to determine how many control points (valves, gates, pumps, etc.) are needed to transform urban watersheds from static to adaptive. Advances and distributed sensing and control stand to fundamentally change how we manage urban watersheds. In lieu of new and costly infrastructure, the real-time control of stormwater systems will reduce flooding, mitigate stream erosion, and improve the treatment of polluted runoff. We discuss the how open source technologies, in the form of wireless sensor nodes and remotely-controllable valves (open-storm.org), have been deployed to build "smart" stormwater systems in the Midwestern US. Unlike "static" infrastructure, which cannot readily adapt to changing inputs and land uses, these distributed control assets allow entire watersheds to be reconfigured on a storm-by-storm basis. Our results show how the control of even just a few valves within urban catchments (1-10km^2) allows for the real-time "shaping" of hydrographs, which reduces downstream erosion and flooding. We also introduce an equivalence framework that can be used by decision-makers to objectively compare investments into "smart" system to more traditional solutions, such as gray and green stormwater infrastructure.

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.

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.

Risk assessment of urban flood disaster in Jingdezhen City based on analytic hierarchy process and geographic information system

NASA Astrophysics Data System (ADS)

Sun, D. C.; Huang, J.; Wang, H. M.; Wang, Z. Q.; Wang, W. Q.

2017-08-01

The research of urban flood risk assessment and management are of great academic and practical importance, which has become a widespread concern throughout the world. It’s significant to understand the spatial-temporal distribution of the flood risk before making the risk response measures. In this study, the urban region of Jingdezhen City is selected as the study area. The assessment indicators are selected from four aspects: disaster-causing factors, disaster-pregnant environment, disaster-bearing body and the prevention and mitigation ability, by consideration of the formation process of urban flood risk. And then, a small-scale flood disaster risk assessment model is developed based on Analytic Hierarchy Process(AHP) and Geographic Information System(GIS), and the spatial-temporal distribution of flood risk in Jingdezhen City is analysed. The results show that the risk decreases gradually from the centre line of Changjiang River to the surrounding, and the areas of high flood disaster risk is decreasing from 2010 to 2013 while the risk areas are more concentred. The flood risk of the areas along the Changjiang River is the largest, followed by the low-lying areas in Changjiang District. And the risk is also large in Zhushan District where the population, the industries and commerce are concentrated. The flood risk in the western part of Changjiang District and the north-eastern part of the study area is relatively low. The results can provide scientific support for flood control construction and land development planning in Jingdezhen City.

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.

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.

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.

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.

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.

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.

Urban construction and safety project

NASA Technical Reports Server (NTRS)

Hogarth, P. T.

1976-01-01

Technology utilization projects in the area of urban construction and safety included the following: development of undercarpet and baseboard flat conductor cables, flood insurance studies, tornado safety engineering, the Project TECH house at the Langley Research Center, assistance to the City of Atlanta in their environmental habitability and resource allocation program, and market assessment of a solid state diesel engine controller. The flat conductor cable and the flood insurance studies are given particular attention.

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.

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.

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.

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.

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.

Modeling flood reduction effects of low impact development at a watershed scale.

PubMed

Ahiablame, Laurent; Shakya, Ranish

2016-04-15

Low impact development (LID) is a land development approach that seeks to mimic a site's pre-development hydrology. This study is a case study that assessed flood reduction capabilities of large-scale adoption of LID practices in an urban watershed in central Illinois using the Personal Computer Storm Water Management Model (PCSWMM). Two flood metrics based on runoff discharge were developed to determine action flood (43 m(3)/s) and major flood (95 m(3)/s). Four land use scenarios for urban growth were evaluated to determine the impacts of urbanization on runoff and flooding. Flood attenuation effects of porous pavement, rain barrel, and rain garden at various application levels were also evaluated as retrofitting technologies in the study watershed over a period of 30 years. Simulation results indicated that increase in urban land use from 50 to 94% between 1992 and 2030 increased average annual runoff and flood events by more than 30%, suggesting that urbanization without sound management would increase flood risks. The various implementation levels of the three LID practices resulted in 3-47% runoff reduction in the study watershed. Flood flow events that include action floods and major floods were also reduced by 0-40%, indicating that LID practices can be used to mitigate flood risk in urban watersheds. The study provides an insight into flood management with LID practices in existing urban areas. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

Mapping technological and biophysical capacities of watersheds to regulate floods

USGS Publications Warehouse

Mogollón, Beatriz; Villamagna, Amy M.; Frimpong, Emmanuel A.; Angermeier, Paul

2016-01-01

Flood regulation is a widely valued and studied service provided by watersheds. Flood regulation benefits people directly by decreasing the socio-economic costs of flooding and indirectly by its positive impacts on cultural (e.g., fishing) and provisioning (e.g., water supply) ecosystem services. Like other regulating ecosystem services (e.g., pollination, water purification), flood regulation is often enhanced or replaced by technology, but the relative efficacy of natural versus technological features in controlling floods has scarcely been examined. In an effort to assess flood regulation capacity for selected urban watersheds in the southeastern United States, we: (1) used long-term flood records to assess relative influence of technological and biophysical indicators on flood magnitude and duration, (2) compared the widely used runoff curve number (RCN) approach for assessing the biophysical capacity to regulate floods to an alternative approach that acknowledges land cover and soil properties separately, and (3) mapped technological and biophysical flood regulation capacities based on indicator importance-values derived for flood magnitude and duration. We found that watersheds with high biophysical (via the alternative approach) and technological capacities lengthened the duration and lowered the peak of floods. We found the RCN approach yielded results opposite that expected, possibly because it confounds soil and land cover processes, particularly in urban landscapes, while our alternative approach coherently separates these processes. Mapping biophysical (via the alternative approach) and technological capacities revealed great differences among watersheds. Our study improves on previous mapping of flood regulation by (1) incorporating technological capacity, (2) providing high spatial resolution (i.e., 10-m pixel) maps of watershed capacities, and (3) deriving importance-values for selected landscape indicators. By accounting for technology that enhances or replaces natural flood regulation, our approach enables watershed managers to make more informed choices in their flood-control investments.

The link between land use and flood risk assessment in urban areas

NASA Astrophysics Data System (ADS)

Sörensen, Johanna; Kalantari, Zahra

2017-04-01

Densification of urban areas rises a concern for increased pluvial flooding. Flood risk in urban areas might rise under impact of land use changes. Urbanisation involves conversion of natural areas to impermeable areas giving lower infiltration rates and increased runoff. When high-intense rainfall excess the capacity of the drainage system in a city, high runoff causes pluvial flooding in low-laying areas. In the present study, a long time series (20 years) of geo-referenced flood claims from property owners has been collected and analysed in detail to assess flood risk under impact of land use changes in urban areas. The flood claim data come from property owners with flood insurance that covers property loss from overland flooding, groundwater intrusion through basement walls, as well as flooding from the drainage system, and are used as a proxy for flood severity. The spatial relationships between land use change and flood occurrences in different urban areas were analysed. Special emphasis were put on how nature-based solutions and blue-green infrastructure relates to flood risk. The relationships defined by a statistical method explaining the tendencies where the land use change contributes to flood risk changes and others engaged factors.

Measuring the past 20 years of urban-rural land growth in flood-prone areas in the developed Taihu Lake watershed, China

NASA Astrophysics Data System (ADS)

Su, Weizhong

2017-03-01

There is growing interest in using the urban landscape for stormwater management studies, where land patterns and processes can be important controls for the sustainability of urban development and planning. This paper proposes an original index of Major Hazard Oriented Level (MHOL) and investigates the structure distribution, driving factors, and controlling suggestions of urban-rural land growth in flood-prone areas in the Taihu Lake watershed, China. The MHOL of incremental urban-rural land increased from M 31.51 during the years 1985-1995 to M 38.37 during the years 1995-2010 (M for medium structure distribution, and the number for high-hazard value). The index shows that urban-rural land was distributed uniformly in flood hazard levels and tended to move rapidly to high-hazard areas, where 72.68% of incremental urban-rural land was aggregated maximally in new urban districts along the Huning traffic line and the Yangtze River. Thus, the current accelerating growth of new urban districts could account for the ampliative exposure to high-hazard areas. New districts are driven by the powerful link between land financial benefits and political achievements for local governments and the past unsustainable process of "single objective" oriented planning. The correlation categorical analysis of the current development intensity and carrying capacity of hydrological ecosystems for sub-basins was used to determine four types of development areas and provide decision makers with indications on the future watershed-scale subdivision of Major Function Oriented Zoning implemented by the Chinese government.

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

A new methodology for dynamic modelling of health risks arising from wastewater influenced urban flooding

NASA Astrophysics Data System (ADS)

Jørgensen, Claus; Mark, Ole; Djordjevic, Slobodan; Hammond, Michael; Khan, David M.; Erichsen, Anders; Dorrit Enevoldsen, Ann; Heinicke, Gerald; Helwigh, Birgitte

2015-04-01

Indroduction Urban flooding due to rainfall exceeding the design capacity of drainage systems is a global problem and it has significant economic and social consequences. While the cost of the direct flood damages of urban flooding is well understood, the indirect damages, like the water borne diseases is in general still poorly understood. Climate changes are expected to increase the frequency of urban flooding in many countries which is likely to increase water borne diseases. Diarrheal diseases are most prevalent in developing countries, where poor sanitation, poor drinking water and poor surface water quality causes a high disease burden and mortality, especially during floods. The level of water borne diarrhea in countries with well-developed water and waste water infrastructure has been reduced to an acceptable level, and the population in general do not consider waste water as being a health risk. Hence, exposure to wastewater influenced urban flood water still has the potential to cause transmission of diarrheal diseases. When managing urban flooding and planning urban climate change adaptations, health risks are rarely taken into consideration. This paper outlines a novel methodology for linking dynamic urban flood modelling with Quantitative Microbial Risk Assessment (QMRA). This provides a unique possibility for understanding the interaction between urban flooding and the health risks caused by direct human contact with flood water and provides an option for reducing the burden of disease in the population through the use of intelligent urban flood risk management. Methodology We have linked hydrodynamic urban flood modelling with quantitative microbial risk assessment (QMRA) to determine the risk of infection caused by exposure to wastewater influenced urban flood water. The deterministic model MIKE Flood, which integrates the sewer network model in MIKE Urban and the 2D surface model MIKE21, was used to calculate the concentration of pathogens in the flood water, based on either measured waste water pathogen concentrations or on assumptions regarding the prevalence of infections in the population. The exposure (dosage) to pathogens was estimated by multiplying the concentration with literature values for the ingestion of water for different exposure groups (e.g. children, adults). The probability of infection was determined by applying dose response relations and MonteCarlo simulation. The methodology is demonstrated on two cases, i.e one case from a developing country with poor sanitation and one case from a developed country, where climate adaptation is the main issue: The risk of cholera in the City of Dhaka, Bangladesh during a flood event 2004, and the risk of bacterial and viral infections of during a flood event in Copenhagen, Denmark in 2011. Results PIC The historical flood events in Dhaka (2004) and Copenhagen (2011) were successfully modelled. The urban flood model was successfully coupled to QMRA. An example of the results of the quantitative microbial risk assessment given as the average estimated risk of cholera infection for children below 5 years living in slum areas in Dhaka is shown in the figure. Similarly, the risk of infection during the flood event in Copenhagen will be presented in the article. Conclusions We have developed a methodology for the dynamic modeling of the risk of infection during waste water influenced urban flooding. The outcome of the modelling exercise indicates that direct contact with polluted flood water is a likely route of transmission of cholera in Dhaka, and bacterial and viral infectious diseases in Copenhagen. It demonstrates the applicability and the potential for linking urban flood models with QMRA in order to identify interventions to reduce the burden of disease on the population in Dhaka City and Copenhagen.

The Impact of Drainage Network Structure on Flooding in a Small Urban Watershed in Metropolitan Baltimore, MD

NASA Astrophysics Data System (ADS)

Meierdiercks, K. L.; Smith, J. A.; Miller, A. J.

2006-12-01

The impact of urban development on watershed-scale hydrology is examined in a small urban watershed in the Metropolitan Baltimore area. Analyses focus on Dead Run, a 14.3 km2 tributary of the Gwynns Falls, which is the principal study watershed of the Baltimore Ecosystem Study. Field observations of rainfall and discharge have been collected for storms occurring in the 2003, 2004, and 2005 warm seasons including the flood of record for the USGS Dead Run at Franklintown gage (7 July 2004), in which 5 inches of rain fell in less than 4 hours. Dead Run has stream gages at 6 locations with drainage areas ranging from 1.2 to 14.3 km2. Hydrologic response to storm events varies greatly in each of the subwatersheds due to the diverse development types located there. These subwatersheds range in land use from medium-density residential, with and without stormwater management control, to commercial/light industrial with large impervious lots and an extensive network of stormwater management ponds. The unique response of each subwatershed is captured using field observations in conjunction with the EPA Stormwater Management Model (SWMM), which routes storm runoff over the land surface and through the drainage network of a watershed. Of particular importance to flood response is the structure of the drainage network (both surface channels and storm drain network) and its connectivity to preferential flow paths within the watershed. The Dead Run drainage network has been delineated using geospatial data derived from aerial photography and engineering planning drawings. Model analyses are used to examine the characteristics of flow paths that control flood response in urban watersheds. These analyses aim to identify patterns in urban flow pathways and use those patterns to predict response in other urban watersheds.

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

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...

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.

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.

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.

Assessment of urban pluvial flood risk and efficiency of adaptation options through simulations - A new generation of urban planning tools

NASA Astrophysics Data System (ADS)

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

2017-07-01

We present a new framework for flexible testing of flood risk adaptation strategies in a variety of urban development and climate scenarios. This framework couples the 1D-2D hydrodynamic simulation package MIKE FLOOD with the agent-based urban development model DAnCE4Water and provides the possibility to systematically test various flood risk adaptation measures ranging from large infrastructure changes over decentralised water management to urban planning policies. We have tested the framework in a case study in Melbourne, Australia considering 9 scenarios for urban development and climate and 32 potential combinations of flood adaptation measures. We found that the performance of adaptation measures strongly depended on the considered climate and urban development scenario and the other implementation measures implemented, suggesting that adaptive strategies are preferable over one-off investments. Urban planning policies proved to be an efficient means for the reduction of flood risk, while implementing property buyback and pipe increases in a guideline-oriented manner was too costly. Random variations in location and time point of urban development could have significant impact on flood risk and would in some cases outweigh the benefits of less efficient adaptation strategies. The results of our setup can serve as an input for robust decision making frameworks and thus support the identification of flood risk adaptation measures that are economically efficient and robust to variations of climate and urban layout.

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.

Evaluating the impact and risk of pluvial flash flood on intra-urban road network: A case study in the city center of Shanghai, China

NASA Astrophysics Data System (ADS)

Yin, Jie; Yu, Dapeng; Yin, Zhane; Liu, Min; He, Qing

2016-06-01

Urban pluvial flood are attracting growing public concern due to rising intense precipitation and increasing consequences. Accurate risk assessment is critical to an efficient urban pluvial flood management, particularly in transportation sector. This paper describes an integrated methodology, which initially makes use of high resolution 2D inundation modeling and flood depth-dependent measure to evaluate the potential impact and risk of pluvial flash flood on road network in the city center of Shanghai, China. Intensity-Duration-Frequency relationships of Shanghai rainstorm and Chicago Design Storm are combined to generate ensemble rainfall scenarios. A hydrodynamic model (FloodMap-HydroInundation2D) is used to simulate overland flow and flood inundation for each scenario. Furthermore, road impact and risk assessment are respectively conducted by a new proposed algorithm and proxy. Results suggest that the flood response is a function of spatio-temporal distribution of precipitation and local characteristics (i.e. drainage and topography), and pluvial flash flood is found to lead to proportionate but nonlinear impact on intra-urban road inundation risk. The approach tested here would provide more detailed flood information for smart management of urban street network and may be applied to other big cities where road flood risk is evolving in the context of climate change and urbanization.

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.

REAL-TIME high-resolution urban surface water flood mapping to support flood emergency management

NASA Astrophysics Data System (ADS)

Guan, M.; Yu, D.; Wilby, R.

2016-12-01

Strong evidence has shown that urban flood risks will substantially increase because of urbanisation, economic growth, and more frequent weather extremes. To effectively manage these risks require not only traditional grey engineering solutions, but also a green management solution. Surface water flood risk maps based on return period are useful for planning purposes, but are limited for application in flood emergencies, because of the spatiotemporal heterogeneity of rainfall and complex urban topography. Therefore, a REAL-TIME urban surface water mapping system is highly beneficial to increasing urban resilience to surface water flooding. This study integrated numerical weather forecast and high-resolution urban surface water modelling into a real-time multi-level surface water mapping system for Leicester City in the UK. For rainfall forecast, the 1km composite rain radar from the Met Office was used, and we used the advanced rainfall-runoff model - FloodMap to predict urban surface water at both city-level (10m-20m) and street-level (2m-5m). The system is capable of projecting 3-hour urban surface water flood, driven by rainfall derived from UK Met Office radar. Moreover, this system includes real-time accessibility mapping to assist the decision-making of emergency responders. This will allow accessibility (e.g. time to travel) from individual emergency service stations (e.g. Fire & Rescue; Ambulance) to vulnerable places to be evaluated. The mapping results will support contingency planning by emergency responders ahead of potential flood events.

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.

Variable Streamflow Contributions in Nested Subwatersheds of a US Midwestern Urban Watershed

DOE PAGES

Wei, Liang; Hubbart, Jason A.; Zhou, Hang

2017-09-09

Quantification of runoff is critical to estimate and control water pollution in urban regions, but variation in impervious area and land-use type can complicate the quantification of runoff. We quantified the streamflow contributions of subwatersheds and the historical changes in streamflow in a flood prone urbanizing watershed in US Midwest to guide the establishment of a future pollution-control plan. Streamflow data from five nested hydrological stations enabled accurate estimations of streamflow contribution from five subwatersheds with variable impervious areas (from 0.5% to 26.6%). We corrected the impact of Missouri river backwatering at the most downstream station by comparing its streamflowmore » with an upstream station using double-mass analysis combined with Bernaola-Galvan Heuristic Segmentation approach. We also compared the streamflow of the urbanizing watershed with seven surrounding rural watersheds to estimate the cumulative impact of urbanization on the streamflow regime. The two most urbanized subwatersheds contributed >365 mm streamflow in 2012 with 657 mm precipitation, which was more than fourfold greater than the two least urbanized subwatersheds. Runoff occurred almost exclusively over the most urbanized subwatersheds during the dry period. The frequent floods occurred and the same amount of precipitation produced ~100 mm more streamflow in 2008–2014 than 1967–1980 in the urbanizing watershed; such phenomena did not occur in surrounding rural watersheds. Our approaches provide comprehensive information for planning on runoff control and pollutant reduction in urban watersheds.« less

Variable Streamflow Contributions in Nested Subwatersheds of a US Midwestern Urban Watershed

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

Wei, Liang; Hubbart, Jason A.; Zhou, Hang

Quantification of runoff is critical to estimate and control water pollution in urban regions, but variation in impervious area and land-use type can complicate the quantification of runoff. We quantified the streamflow contributions of subwatersheds and the historical changes in streamflow in a flood prone urbanizing watershed in US Midwest to guide the establishment of a future pollution-control plan. Streamflow data from five nested hydrological stations enabled accurate estimations of streamflow contribution from five subwatersheds with variable impervious areas (from 0.5% to 26.6%). We corrected the impact of Missouri river backwatering at the most downstream station by comparing its streamflowmore » with an upstream station using double-mass analysis combined with Bernaola-Galvan Heuristic Segmentation approach. We also compared the streamflow of the urbanizing watershed with seven surrounding rural watersheds to estimate the cumulative impact of urbanization on the streamflow regime. The two most urbanized subwatersheds contributed >365 mm streamflow in 2012 with 657 mm precipitation, which was more than fourfold greater than the two least urbanized subwatersheds. Runoff occurred almost exclusively over the most urbanized subwatersheds during the dry period. The frequent floods occurred and the same amount of precipitation produced ~100 mm more streamflow in 2008–2014 than 1967–1980 in the urbanizing watershed; such phenomena did not occur in surrounding rural watersheds. Our approaches provide comprehensive information for planning on runoff control and pollutant reduction in urban watersheds.« less

OPPORTUNITY COSTS OF RESIDENTIAL BEST MANAGEMENT PRACTICES FOR STORMWATER RUNOFF CONTROL

EPA Science Inventory

Excess stormwater runoff is a serious problem in a large number of urban areas, causing flooding, water pollution, groundwater recharge deficits and ecological damage to urban streams. Solutions currently proposed to deal with this problem often involve large centralized infrastr...

Characterizing Microbial Water Quality of Extreme Tide Floodwaters Discharged from an Urbanized Subtropical Beach: Case Study of Miami Beach with Implications for Sea Level Rise and Public Health

NASA Astrophysics Data System (ADS)

Gidley, M. L.

2016-02-01

With the advent of rising sea levels and increasing incidents of extreme tidal flooding events and stormwater flooding events, there is increasing probability of mobilization of land-based sources of pollution (LBSP) from highly urbanized beach environments and potential transport of these contaminants to coastal waters where they may have negative impacts on ecosystems and public health. A case in point is the situation facing the City of Miami Beach, where urban tidal flooding has become routine for extreme tidal events such as King Tide. To deal with the increasing problem of tidal flooding and other potential sources of coastal inundation, the City of Miami Beach has installed a system of floodwater/stormwater pumping stations to collect and discharge such floodwaters. This system appears to control the extent and duration of coastal inundation, however, the floodwater is discharged directly into Biscayne Bay without any treatment , which may potentially carry a variety of pollutants acquired during inundation of this urbanized coast. We report a case study examining the microbial water quality of floodwaters discharged by this pumping system back into Biscayne Bay following the inundation by King Tide floodwaters from September 2014 and 2015. The presence and abundance of both general and host-specific fecal indicating bacteria (FIB), including enterococci and human-host Bacteriodales were measured by traditional culture methods and by molecular microbial source tracking (MST) qPCR methods. While the results from different locations did vary substantially, several discharge samples demonstrated high elevations of fecal indicator bacteria and high levels of human fecal marker by MST. This study suggests that while such flood control measures may improve resiliency of urbanized coastal communities to tidal flooding and/or stormwater, the water quality of such floodwater discharges need to be monitored and potentially treated to mediate the transport of LBSP contaminants to the coastal zone, thus better protecting both ecosystem and public health in an era of sea level rise and more frequent inundation events.

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.

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.

TRADING ALLOWANCES FOR STORMWATER CONTROL: HYDROLOGY AND OPPORTUNITY COSTS

EPA Science Inventory

Excess stormwater runoff is a serious problem in a large number of urban areas, causing flooding, water pollution, groundwater recharge deficits and ecological damage to urban streams. It has been posited that to mitigate the effects of excess stormwater runoff, policy makers...

TRADING ALLOWANCES FOR STORMWATER CONTROL: HYDROLOGY AND OPPORTUNITY COSTS

EPA Science Inventory

Excess stormwater runoff is a serious problem in a large number of urban areas, causing flooding, water pollution, groundwater recharge deficits and ecological damage to urban streams. It has been posited that to mitigate the effects of excess stormwater runoff, policy makers cou...

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.

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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.

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.

TRADING ALLOWANCES FOR STORMWATER CONTROL: ACCOUNTING FOR CONTINUOUS HYDROLOGY AND OPPORTUNITY COSTS

EPA Science Inventory

Excess stormwater runoff is a serious problem in a large number of urban areas, causing flooding, water pollution, groundwater recharge deficits and ecological damage to urban streams. It has been posited that to mitigate the effects of excess stormwater runoff, policy makers cou...

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.

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.

Evaluating the anthropogenic impacts on fluvial flood risks in a coastal mega-city during its transitional economy (1979-2009): the interaction between land subsidence, urbanization and structural measures

NASA Astrophysics Data System (ADS)

Yu, Dapeng; Yin, Jie

2014-05-01

Flood risk in a specific geographical location is a function of the interaction between various natural (e.g. rainfall, sea-level rise) and anthropogenic processes (e.g. land subsidence and urbanization). These processes, whether a driver or an alleviating factor, often encompass a large degree of spatial and temporal variability. Looking at a specific process in isolation is likely to provide an incomplete picture of the risks. This paper describes a novel approach to the evaluation of anthropogenic impacts on flood risks in coastal mega-cities by incorporating three anthropogenic variables (land subsidence, urbanization and flood defence) within a scenario-based framework where numerical modelling was undertaken to quantify the risks. The evolving risks at four time points (1979, 1990, 2000 and 2009) were assessed for the Huangpu River floodplain where the City of Shanghai is located. Distributed data of land subsidence rate, urbanization rate and flood defence heights were obtained. Scenarios were designed by representing the rate of land subsidence and flood defence height through the modification of DEM. Effect of urbanization is represented by a roughness parameter in the model simulations. A 2D hydrodynamic model (FloodMap-Inertial) was used to estimate the flood risks associated with each scenario. Flood events with various return periods (10-, 100- and 1000-year) were designed based on a one in 50 year flood event occurred in Shanghai in August 1997. Results demonstrate the individual as well as the combined impacts of the three anthropogenic factors on the changing fluvial flood risks in the Huangpu River basin over the last three decades during the city's transitional economy (1979-2009). Land subsidence and urbanization were found to lead to proportionate but non-linear impact on flood risks due to their complex spatial and temporal interaction. The impacts and their sensitivity are the function of the rate & spatial distribution of each evolving factor. They also manifest differently in floods of different magnitude. While the pattern of response to individual anthropogenic variables is largely expected, the combined impacts demonstrate greater spatial and temporal variation. Flood defences offer considerable benefits in reducing the total inundated areas in the Huangpu River basin over the periods considered, for all magnitude floods. This, to a large extent, alleviates the adverse impacts arising from land subsidence and urbanization. However, even with an enclosed and completed defence system in 2009, extensive flood inundation is still expected for a 10-year event, albeit largely restricted to the upstream of the river where urban settlements are limited. The scenario-based approach described herein could be adopted for applications in other urbanized and subsided coastal floodplains, especially in places where the rate of land subsidence is still accelerating, urbanization is still undergoing and the local sea level keeps rising. Risk scenarios that encompass probable future anthropogenic projections may assist decision makers and other concerned stakeholders in better understanding the underlying drivers of changing flood risks, and thus help to design proper adaptation options for sustainable flood risk management and urban planning.

A National Assessment of Changes in Flood Exposure in the United States

NASA Astrophysics Data System (ADS)

Lam, N.; Qiang, Y.; Cai, H.; Zou, L.

2017-12-01

Analyzing flood exposure and its temporal trend is the first step toward understanding flood risk, flood hazard, and flood vulnerability. This presentation is based on a national, county-based study assessing the changes in population and urban areas in high-risk flood zones from 2001-2011 in the contiguous United States. Satellite land use land cover data, Federal Emergency Management Agency (FEMA)'s 100-year flood maps, and census data were used to extract the proportion of developed (urban) land in flood zones by county in the two time points, and indices of difference were calculated. Local Moran's I statistic was applied to identify hotspots of increase in urban area in flood zones, and geographically weighted regression was used to estimate the population in flood zones from the land cover data. Results show that in 2011, an estimate of about 25.3 million people (8.3% of the total population) lived in the high-risk flood zones. Nationally, the ratio of urban development in flood zones is less than the ratio of land in flood zones, implying that Americans were responsive to flood hazards by avoiding development in flood zones. However, this trend varied from place to place, with coastal counties having less urban development in flood zones than the inland counties. Furthermore, the contrast between coastal and inland counties increased during 2001-2011. Finally, several exceptions from the trend (hotspots) were detected, most notably New York City and Miami where significant increases in urban development in flood zones were found. This assessment provides important baseline information on the spatial patterns of flood exposure and their changes from 2001-2011. The study pinpoints regions that may need further investigations and better policy to reduce the overall flood risks. Methodologically, the study demonstrates that pixelated land cover data can be integrated with other natural and human data to investigate important societal problems. The same methodology can be easily extended worldwide to assess the overall trend as well as identify hotspots that need further attention.

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.

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...

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.

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.

Sensitivity analysis of urban flood flows to hydraulic controls

NASA Astrophysics Data System (ADS)

Chen, Shangzhi; Garambois, Pierre-André; Finaud-Guyot, Pascal; Dellinger, Guilhem; Terfous, Abdelali; Ghenaim, Abdallah

2017-04-01

Flooding represents one of the most significant natural hazards on each continent and particularly in highly populated areas. Improving the accuracy and robustness of prediction systems has become a priority. However, in situ measurements of floods remain difficult while a better understanding of flood flow spatiotemporal dynamics along with dataset for model validations appear essential. The present contribution is based on a unique experimental device at the scale 1/200, able to produce urban flooding with flood flows corresponding to frequent to rare return periods. The influence of 1D Saint Venant and 2D Shallow water model input parameters on simulated flows is assessed using global sensitivity analysis (GSA). The tested parameters are: global and local boundary conditions (water heights and discharge), spatially uniform or distributed friction coefficient and or porosity respectively tested in various ranges centered around their nominal values - calibrated thanks to accurate experimental data and related uncertainties. For various experimental configurations a variance decomposition method (ANOVA) is used to calculate spatially distributed Sobol' sensitivity indices (Si's). The sensitivity of water depth to input parameters on two main streets of the experimental device is presented here. Results show that the closer from the downstream boundary condition on water height, the higher the Sobol' index as predicted by hydraulic theory for subcritical flow, while interestingly the sensitivity to friction decreases. The sensitivity indices of all lateral inflows, representing crossroads in 1D, are also quantified in this study along with their asymptotic trends along flow distance. The relationship between lateral discharge magnitude and resulting sensitivity index of water depth is investigated. Concerning simulations with distributed friction coefficients, crossroad friction is shown to have much higher influence on upstream water depth profile than street friction coefficients. This methodology could be applied to any urban flood configuration in order to better understand flow dynamics and repartition but also guide model calibration in the light of flow controls.

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.

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.

Flood risks in urbanized areas - multi-sensoral approaches using remotely sensed data for risk assessment

NASA Astrophysics Data System (ADS)

Taubenböck, H.; Wurm, M.; Netzband, M.; Zwenzner, H.; Roth, A.; Rahman, A.; Dech, S.

2011-02-01

Estimating flood risks and managing disasters combines knowledge in climatology, meteorology, hydrology, hydraulic engineering, statistics, planning and geography - thus a complex multi-faceted problem. This study focuses on the capabilities of multi-source remote sensing data to support decision-making before, during and after a flood event. With our focus on urbanized areas, sample methods and applications show multi-scale products from the hazard and vulnerability perspective of the risk framework. From the hazard side, we present capabilities with which to assess flood-prone areas before an expected disaster. Then we map the spatial impact during or after a flood and finally, we analyze damage grades after a flood disaster. From the vulnerability side, we monitor urbanization over time on an urban footprint level, classify urban structures on an individual building level, assess building stability and quantify probably affected people. The results show a large database for sustainable development and for developing mitigation strategies, ad-hoc coordination of relief measures and organizing rehabilitation.

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.

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.

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...

Landsat Earth Monitor.

ERIC Educational Resources Information Center

Haggerty, James J.

1979-01-01

The uses of NASA's Landsat in the areas of cartography, flood control, agricultural inventory, land use mapping, water runoff, urban planning, erosion, geology, and water quality monitoring are illustrated. (BB)

Exploring storage and runoff generation processes for urban flooding through a physically based watershed model

NASA Astrophysics Data System (ADS)

Smith, B. K.; Smith, J. A.; Baeck, M. L.; Miller, A. J.

2015-03-01

A physically based model of the 14 km2 Dead Run watershed in Baltimore County, MD was created to test the impacts of detention basin storage and soil storage on the hydrologic response of a small urban watershed during flood events. The Dead Run model was created using the Gridded Surface Subsurface Hydrologic Analysis (GSSHA) algorithms and validated using U.S. Geological Survey stream gaging observations for the Dead Run watershed and 5 subbasins over the largest 21 warm season flood events during 2008-2012. Removal of the model detention basins resulted in a median peak discharge increase of 11% and a detention efficiency of 0.5, which was defined as the percent decrease in peak discharge divided by percent detention controlled area. Detention efficiencies generally decreased with increasing basin size. We tested the efficiency of detention basin networks by focusing on the "drainage network order," akin to the stream order but including storm drains, streams, and culverts. The detention efficiency increased dramatically between first-order detention and second-order detention but was similar for second and third-order detention scenarios. Removal of the soil compacted layer, a common feature in urban soils, resulted in a 7% decrease in flood peak discharges. This decrease was statistically similar to the flood peak decrease caused by existing detention. Current soil storage within the Dead Run watershed decreased flood peak discharges by a median of 60%. Numerical experiment results suggested that detention basin storage and increased soil storage have the potential to substantially decrease flood peak discharges.

Forest cover, socioeconomics, and reported flood frequency in developing countries

NASA Astrophysics Data System (ADS)

Ferreira, Susana; Ghimire, Ramesh

2012-08-01

In this paper, we analyze the determinants of the number of large floods reported since 1990. Using the same sample of countries as Bradshaw et al. (2007), and, like them, omitting socioeconomic characteristics from the analysis, we found that a reduction in natural forest cover is associated with an increase in the reported count of large floods. This result does not hold in any of three new analyses we perform. First, we expand the sample to include all the developing countries and all countries for which data were available but were omitted in their study. Second, and more importantly, since forest management is just one possible channel through which humans can influence reported flood frequency, we account for other important human-flood interactions. People are typically responsible for deforestation, but they are also responsible for other land use changes (e.g., urbanization), for floodplain and flood emergency management, and for reporting the floods. Thus, in our analysis we account for population, urban population growth, income, and corruption. Third, we exploit the panel nature of the data to control for unobserved country and time heterogeneity. We conclude that not only is the link between forest cover and reported flood frequency at the country level not robust, it also seems to be driven by sample selection and omitted variable bias. The human impact on the reported frequency of large floods at the country level is not through deforestation.

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.

Influence of solid waste and topography on urban floods: The case of Mexico City.

PubMed

Zambrano, Luis; Pacheco-Muñoz, Rodrigo; Fernández, Tania

2018-02-24

Floods in cities are increasingly common as a consequence of multifactor watershed dynamics, including geomorphology, land-use changes and land subsidence. However, urban managers have focused on infrastructure to address floods by reducing blocked sewage infrastructure, without significant success. Using Mexico City as a case study, we generated a spatial flood risk model with geomorphology and anthropogenic variables. The results helped contrast the implications of different public policies in land use and waste disposal, and correlating them with flood hazards. Waste disposal was only related to small floods. 58% of the city has a high risk of experiencing small floods, and 24% of the city has a risk for large floods. Half of the population with the lowest income is located in the high-risk areas for large floods. These models are easy to build, generate fast results and are able to help to flood policies, by understanding flood interactions in urban areas within the watershed.

A methodology for urban flood resilience assessment

NASA Astrophysics Data System (ADS)

Lhomme, Serge; Serre, Damien; Diab, Youssef; Laganier, Richard

2010-05-01

In Europe, river floods have been increasing in frequency and severity [Szöllösi-Nagy and Zevenbergen, 2005]. Moreover, climate change is expected to exacerbate the frequency and intensity of hydro meteorological disaster [IPCC, 2007]. Despite efforts made to maintain the flood defense assets, we often observe levee failures leading to finally increase flood risk in protected area. Furthermore, flood forecasting models, although benefiting continuous improvements, remain partly inaccurate due to uncertainties arising all along data calculation processes. In the same time, the year 2007 marks a turning point in history: half of the world population now lives in cities (UN-Habitat, 2007). Moreover, the total urban population is expected to double from two to four billion over the next 30 to 35 years (United Nations, 2006). This growing rate is equivalent to the creation of a new city of one million inhabitants every week, and this during the next four decades [Flood resilience Group]. So, this quick urban development coupled with technical failures and climate change have increased flood risk and corresponding challenges to urban flood risk management [Ashley et al., 2007], [Nie et al., 2009]. These circumstances oblige to manage flood risk by integrating new concepts like urban resilience. In recent years, resilience has become a central concept for risk management. This concept has emerged because a more resilient system is less vulnerable to risk and, therefore, more sustainable [Serre et al., 2010]. But urban flood resilience is a concept that has not yet been directly assessed. Therefore, when decision makers decide to use the resilience concept to manage urban flood, they have no tool to help them. That is why this paper proposes a methodology to assess urban flood resilience in order to make this concept operational. Networks affect the well-being of the people and the smooth functioning of services and, more generally, of economical activities. Yet, multiple networks that innervate the city are particularly sensitive to flooding, through their structures and geographic constraints. Because societal functions are highly dependent on networked systems and the operability of these systems can be vulnerable to disasters, there is a need to understand how networked systems are resilient. That is why, considering that networks can be regarded as the "flood gateway" [Lhomme et al., 2009], we will focus on the resilience assessment of these critical networks before urban resilience assessment. The first part of this paper introduce resilience concept to well understand the importance of this concept to manage flood risk and of assessing this resilience. In a second part, this paper presents the use of safety methods to model network system dysfunctions during flood and then to produce resilience indicators. Finally it presents use of graph theory to assess adaptive capacity of these networks. These researches are the first steps toward the development of a GIS tool to optimize preparedness and recovery after a flood event.

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)

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.

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.

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.

Assessing and optimising flood control options along the Arachthos river floodplain (Epirus, Greece)

NASA Astrophysics Data System (ADS)

Drosou, Athina; Dimitriadis, Panayiotis; Lykou, Archontia; Kossieris, Panagiotis; Tsoukalas, Ioannis; Efstratiadis, Andreas; Mamassis, Nikos

2015-04-01

We present a multi-criteria simulation-optimization framework for the optimal design and setting of flood protection structures along river banks. The methodology is tested in the lower course of the Arachthos River (Epirus, Greece), downstream of the hydroelectric dam of Pournari. The entire study area is very sensitive, particularly because the river crosses the urban area of Arta, which is located just after the dam. Moreover, extended agricultural areas that are crucial for the local economy are prone to floods. In the proposed methodology we investigate two conflicting criteria, i.e. the minimization of flood hazards (due to damages to urban infrastructures, crops, etc.) and the minimization of construction costs of the essential hydraulic structures (e.g. dikes). For the hydraulic simulation we examine two flood routing models, named 1D HEC-RAS and quasi-2D LISFLOOD, whereas the optimization is carried out through the Surrogate-Enhanced Evolutionary Annealing-Simplex (SE-EAS) algorithm that couples the strengths of surrogate modeling with the effectiveness and efficiency of the EAS method.

Urban construction and safety project

NASA Technical Reports Server (NTRS)

1975-01-01

The purpose and functions of NASA technology applications temas (TAT) are described, with emphasis on the activities of the Urban and Construction and Safety Project. The transfer and implementation of technology is discussed in five activities. Topics include: flat conductor cable, NASA house and compendium, flood insurance studies, tornado studies, and the controller for stationary diesels.

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...

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.

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.

"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.

Future trends in flood risk in Indonesia - A probabilistic approach

NASA Astrophysics Data System (ADS)

Muis, Sanne; Guneralp, Burak; Jongman, Brenden; Ward, Philip

2014-05-01

Indonesia is one of the 10 most populous countries in the world and is highly vulnerable to (river) flooding. Catastrophic floods occur on a regular basis; total estimated damages were US 0.8 bn in 2010 and US 3 bn in 2013. Large parts of Greater Jakarta, the capital city, are annually subject to flooding. Flood risks (i.e. the product of hazard, exposure and vulnerability) are increasing due to rapid increases in exposure, such as strong population growth and ongoing economic development. The increase in risk may also be amplified by increasing flood hazards, such as increasing flood frequency and intensity due to climate change and land subsidence. The implementation of adaptation measures, such as the construction of dykes and strategic urban planning, may counteract these increasing trends. However, despite its importance for adaptation planning, a comprehensive assessment of current and future flood risk in Indonesia is lacking. This contribution addresses this issue and aims to provide insight into how socio-economic trends and climate change projections may shape future flood risks in Indonesia. Flood risk were calculated using an adapted version of the GLOFRIS global flood risk assessment model. Using this approach, we produced probabilistic maps of flood risks (i.e. annual expected damage) at a resolution of 30"x30" (ca. 1km x 1km at the equator). To represent flood exposure, we produced probabilistic projections of urban growth in a Monte-Carlo fashion based on probability density functions of projected population and GDP values for 2030. To represent flood hazard, inundation maps were computed using the hydrological-hydraulic component of GLOFRIS. These maps show flood inundation extent and depth for several return periods and were produced for several combinations of GCMs and future socioeconomic scenarios. Finally, the implementation of different adaptation strategies was incorporated into the model to explore to what extent adaptation may be able to decrease future risks. Preliminary results show that the urban extent in Indonesia is projected to increase within 211 to 351% over the period 2000-2030 (5 and 95 percentile). Mainly driven by this rapid urbanization, potential flood losses in Indonesia increase rapidly and are primarily concentrated on the island of Java. The results reveal the large risk-reducing potential of adaptation measures. Since much of the urban development between 2000 and 2030 takes place in flood-prone areas, strategic urban planning (i.e. building in safe areas) may significantly reduce the urban population and infrastructure exposed to flooding. We conclude that a probabilistic risk approach in future flood risk assessment is vital; the drivers behind risk trends (exposure, hazard, vulnerability) should be understood to develop robust and efficient adaptation pathways.

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.

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.

HISTORICAL DEVELOPMENT OF WET-WEATHER FLOW MANAGEMENT

EPA Science Inventory

The management of wet-weather flow (WWF) is necessary to maintain the quality of urban water resources. Throughout history strategies were implemented to control WWF for reasons, e.g., flood and water quality control, aesthetic improvement, waste removal and others. A comprehen...

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.

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.

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.

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.

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

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.

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)

Flood risk and adaptation strategies under climate change and urban expansion: A probabilistic analysis using global data.

PubMed

Muis, Sanne; Güneralp, Burak; Jongman, Brenden; Aerts, Jeroen C J H; Ward, Philip J

2015-12-15

An accurate understanding of flood risk and its drivers is crucial for effective risk management. Detailed risk projections, including uncertainties, are however rarely available, particularly in developing countries. This paper presents a method that integrates recent advances in global-scale modeling of flood hazard and land change, which enables the probabilistic analysis of future trends in national-scale flood risk. We demonstrate its application to Indonesia. We develop 1000 spatially-explicit projections of urban expansion from 2000 to 2030 that account for uncertainty associated with population and economic growth projections, as well as uncertainty in where urban land change may occur. The projections show that the urban extent increases by 215%-357% (5th and 95th percentiles). Urban expansion is particularly rapid on Java, which accounts for 79% of the national increase. From 2000 to 2030, increases in exposure will elevate flood risk by, on average, 76% and 120% for river and coastal floods. While sea level rise will further increase the exposure-induced trend by 19%-37%, the response of river floods to climate change is highly uncertain. However, as urban expansion is the main driver of future risk, the implementation of adaptation measures is increasingly urgent, regardless of the wide uncertainty in climate projections. Using probabilistic urban projections, we show that spatial planning can be a very effective adaptation strategy. Our study emphasizes that global data can be used successfully for probabilistic risk assessment in data-scarce countries. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

The efficiency of asset management strategies to reduce urban flood risk.

PubMed

ten Veldhuis, J A E; Clemens, F H L R

2011-01-01

In this study, three asset management strategies were compared with respect to their efficiency to reduce flood risk. Data from call centres at two municipalities were used to quantify urban flood risks associated with three causes of urban flooding: gully pot blockage, sewer pipe blockage and sewer overloading. The efficiency of three flood reduction strategies was assessed based on their effect on the causes contributing to flood risk. The sensitivity of the results to uncertainty in the data source, citizens' calls, was analysed through incorporation of uncertainty ranges taken from customer complaint literature. Based on the available data it could be shown that increasing gully pot blockage is the most efficient action to reduce flood risk, given data uncertainty. If differences between cause incidences are large, as in the presented case study, call data are sufficient to decide how flood risk can be most efficiently reduced. According to the results of this analysis, enlargement of sewer pipes is not an efficient strategy to reduce flood risk, because flood risk associated with sewer overloading is small compared to other failure mechanisms.

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.

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.

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.

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.

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.

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.

MANAGEMENT OF WET-WEATHER FLOW IN THE URBAN WATERSHED

EPA Science Inventory

This chapter covers the control and treatment of stormwater in relation to the removal or reduction of the stormwater pollutant loads. The control of stormwater to prevent flooding is not the emphasis of this chapter. The pollution abatement technologies discussed will help atte...

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.

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.

Simulation of Urban Rainfall-Runoff in Piedmont Cities: A Case Study in Jinan City, China

NASA Astrophysics Data System (ADS)

Chang, X.; Xu, Z.; Zhao, G.; Li, H.

2017-12-01

During the past decades, frequent flooding disasters in urban areas resulted in catastrophic impacts such as human life casualties and property damages especially in piedmont cities due to its specific topography. In this study, a piedmont urban flooding model was developed in the Huangtaiqiao catchment based on SWMM. The sub-catchments in this piedmont area were divided into mountainous area, plain area and main urban area according to the variations of underlying surface topography. The impact of different routing mode and channel roughness on simulation results was quantitatively analyzed under different types of scenarios, and genetic algorithm was used to optimize model parameters. Results show that the simulation is poor (with a mean Nash coefficient of 0.61) when using the traditional routing mode in SWMM model, which usually ignores terrain variance in piedmont area. However, when the difference of routing mode, percent routed and channel roughness are considered, the prediction precision of model were significantly increased (with a mean Nash coefficient of 0.86), indicating that the difference of surface topography significantly affects the simulation results in piedmont cities. The relevant results would provide the scientific basis and technical support for rainfall-runoff simulation, flood control and disaster alleviation in piedmont cities.

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.

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.

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...

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.

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.

Communicating Flood Risk with Street-Level Data

NASA Astrophysics Data System (ADS)

Sanders, B. F.; Matthew, R.; Houston, D.; Cheung, W. H.; Karlin, B.; Schubert, J.; Gallien, T.; Luke, A.; Contreras, S.; Goodrich, K.; Feldman, D.; Basolo, V.; Serrano, K.; Reyes, A.

2015-12-01

Coastal communities around the world face significant and growing flood risks that require an accelerating adaptation response, and fine-resolution urban flood models could serve a pivotal role in enabling communities to meet this need. Such models depict impacts at the level of individual buildings and land parcels or "street level" - the same spatial scale at which individuals are best able to process flood risk information - constituting a powerful tool to help communities build better understandings of flood vulnerabilities and identify cost-effective interventions. To measure understanding of flood risk within a community and the potential impact of street-level models, we carried out a household survey of flood risk awareness in Newport Beach, California, a highly urbanized coastal lowland that presently experiences nuisance flooding from high tides, waves and rainfall and is expected to experience a significant increase in flood frequency and intensity with climate change. Interviews were completed with the aid of a wireless-enabled tablet device that respondents could use to identify areas they understood to be at risk of flooding and to view either a Federal Emergency Management Agency (FEMA) flood map or a more detailed map prepared with a hydrodynamic urban coastal flood model (UCI map) built with grid cells as fine as 3 m resolution and validated with historical flood data. Results indicate differences in the effectiveness of the UCI and FEMA maps at communicating the spatial distribution of flood risk, gender differences in how the maps affect flood understanding, and spatial biases in the perception of flood vulnerabilities.

Use of real time control modelling on the urban sewage system of Nancy.

PubMed

Zug, M; Faure, D; De Belly, B; Phan, L

2001-01-01

Since 1991, European Legislation on the urban treatment of wastewater requires local authorities to take into account the treatment of polluted water transported by the sewerage system and this during dry and wet weather conditions. In the seventies, the urban Community of Grand Nancy constructed storage tanks in its sewerage system in order to prevent flooding and wish today to use them to reduce and control the pollution discharges into the receiving water. This action is a part of a European LIFE project 1996-2000. The main aim of this project was to assess the effectiveness of reducing pollution of one particular retention basin, the 12,000 m3 Gentilly tank. This one has two operating modes: protection against floods during heavy rain and reduction of pollutant overflows during lighter rain. To assess its effect on the pollutant discharge, the HYDROWORKS DM software and its Real Time Control Module have been used, calibrated and validated. As this study is still in progress, this paper describes the studied site and the modelling results under different weather conditions and shows that the mathematical model can be used to simulate the operation of the catchment area and its associated sewerage system realistically.

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.

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.

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.

Land subsidence caused by ground water withdrawal in urban areas

USGS Publications Warehouse

Holzer, T.L.; Johnson, A.I.

1985-01-01

At least eight urban areas in the world have encountered significant economic impact from land subsidence caused by pumping of ground water from unconsolidated sediment. The areas, most of which are coastal, include Bangkok, Houston, Mexico City, Osaka, San Jose, Shanghai, Tokyo, and Venice. Flooding related to decreased ground elevation is the principal adverse effect of the subsidence. Lesser effects include regional tilting, well-casing failures, "rising" buildings, and ground failure or rupture. Subsidence of most of these urban areas began before the phenomenon was discovered and understood. Thus, the subsidence problems were unanticipated. Methods to arrest subsidence typically have included control of ground water pumping and development of surface water to offset the reductions of ground water pumping. Ground water recharge has also been practiced. Areas threatened by flooding have been protected by extensive networks of dikes and sea walls, locks, and pumping stations to remove storm runoff. ?? 1985 D. Reidel Publishing Company.

Variation of Temperature and Precipitation in Urban Agglomeration and Prevention Suggestion of Waterlogging in Middle and Lower Reaches of Yangtze River

NASA Astrophysics Data System (ADS)

Na, Liu; Youjie, Jin; Jiaqi, Dai

2018-03-01

The variation trend of temperature and precipitation during flood season in the middle and lower reaches of the Yangtze River basin in recent 50 years and change characteristics of rainfall in five typical flood prone cities are analysed. Aiming at waterlogging problems in the urban agglomeration of middle and lower reaches of the Yangtze River, the comprehensive prevention and control suggestions are put forward. The results showed that: the temperature trend in the basin decreased and then increased, and the precipitation showed a downward-rising-downward trend, no mutation occurred; The incidence of heavy rainfall events in the five typical cities with daily rainfall more than 50mm showed an upward trend, and increased significantly after 2002. The intensity of precipitation increased gradually. Climate change makes urban agglomeration waterlogging disasters become increasingly prominent in the middle and lower reaches of the Yangtze River.

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

Application of High-resolution Aerial LiDAR Data in Calibration of a Two-dimensional Urban Flood Simulation

NASA Astrophysics Data System (ADS)

Piotrowski, J.; Goska, R.; Chen, B.; Krajewski, W. F.; Young, N.; Weber, L.

2009-12-01

In June 2008, the state of Iowa experienced an unprecedented flood event which resulted in an economic loss of approximately $2.88 billion. Flooding in the Iowa River corridor, which exceeded the previous flood of record by 3 feet, devastated several communities, including Coralville and Iowa City, home to the University of Iowa. Recognizing an opportunity to capture a unique dataset detailing the impacts of the historic flood, the investigators contacted the National Center for Airborne Laser Mapping (NCALM), which performed an aerial Light Detection and Ranging (LiDAR) survey along the Iowa River. The survey, conducted immediately following the flood peak, provided coverage of a 60-mile reach. The goal of the present research is to develop a process by which flood extents and water surface elevations can be accurately extracted from the LiDAR data set and to evaluate the benefit of such data in calibrating one- and two-dimensional hydraulic models. Whereas data typically available for model calibration include sparsely distributed point observations and high water marks, the LiDAR data used in the present study provide broad-scale, detailed, and continuous information describing the spatial extent and depth of flooding. Initial efforts were focused on a 10-mile, primarily urban reach of the Iowa River extending from Coralville Reservoir, a United States Army Corps of Engineers flood control project, downstream through the Coralville and Iowa City. Spatial extent and depth of flooding were estimated from the LiDAR data. At a given cross-sectional location, river channel and floodplain measurements were compared. When differences between floodplain and river channel measurements were less than a standard deviation of the vertical uncertainty in the LiDAR survey, floodplain measurements were classified as flooded. A flood water surface DEM was created using measurements classified as flooded. A two-dimensional, depth-averaged numerical model of a 10-mile reach of the Iowa River corridor was developed using the United States Bureau of Reclamation SRH-2D hydraulic modeling software. The numerical model uses an unstructured numerical mesh and variable surface roughness, assigned according to observed land use and cover. The numerical model was calibrated using inundation extents and water surface elevations derived from the LiDAR data. It was also calibrated using high water marks and land survey data collected daily during the 2008 flood. The investigators compared the two calibrations to evaluate the benefit of high-resolution LiDAR data in improving the accuracy of a two-dimensional urban flood simulation.

Vegetation composition and structure of woody plant communities along urban interstate corridors in Louisville, KY, U.S.A

Treesearch

Tara L. E. Trammell; Margaret M. Carreiro

2011-01-01

Urban forests adjacent to interstate corridors are understudied ecosystems across cities. Despite their small area, these forests may be strategically located to provide large ecosystem services due to their ability to act as a barrier against air pollutants and noise as well as to provide flood control. The woody vegetation composition and structure of forests...

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 ...

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.

Long-term changes in flood event patterns due to changes in hydrological distribution parameters in a rural-urban catchment, Shikoku, Japan

NASA Astrophysics Data System (ADS)

Mouri, Goro; Kanae, Shinjiro; Oki, Taikan

2011-07-01

This article describes the principal control parameters of flood events and precipitation and the relationships between corresponding hydrologic and climatologic parameters. The long-term generation of runoff and associated processes is important in understanding floods and droughts under changes in climate and land use. This study presents detailed analyses of flood events in a coastal amphitheatre catchment with a total area of 445 km 2 in western Japan, followed by analyses of flood events in both urban and forest areas. Using long-term (1962 to 2002) hydrological and climatological data from the Ministry of Land, Infrastructure and Transport, Japan, the contributions of precipitation, river discharge, temperature, and relative humidity to flood events were analysed. Flood events could be divided into three types with respect to hydrologic and climatologic principal control parameters: the long-term tendency; medium-term changes as revealed by hydrographs and hyetographs of high-intensity events such as the relative precipitation, river discharge, and temperature; and large events, as shown by the flow-duration curve, with each cluster having particular characteristics. River discharge showed a decreasing tendency of flow quantity during small rainfall events of less than 100 mm/event from the 1980s to the present. An approximately 7% decrease from 44.8 to 37.3% occurred in the percentage of river water supplied by precipitation in the years after the 1980s. For the medium-term changes, no marked change occurred in the flow quantity of the peak point over time in event hydrographs. However, flow quantities before and after the peak tended to decrease by 1 to 2 m 3/s after the 1980s. Theoretical considerations with regard to the influence of hydrologic and climatologic parameters on flood discharge are discussed and examined in terms of observational data. These findings provide a sound foundation for use in hydrological catchment modelling.

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.

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.

Flood of July 21, 1975 in Mercer County, New Jersey

USGS Publications Warehouse

Stankowski, Stephen J.; Schopp, Robert D.; Velnich, Anthony J.

1975-01-01

Intense rainfall during the evening of July 20 and early morning hours of July 21, 1975 caused flooding of unprecedented magnitude in highly urbanized Mercer County, New Jersey. Over 6 inches (152 millimetres) of rainfall was recorded during a 10-hour period at Trenton, the capital of New Jersey. No lives were lost but damages to highways and bridges, to industrial, business, and residential buildings, to farmlands and crops, and to water supply systems were severe. This report illustrates the magnitude of the flood and provides hydrologic data needed for planning and design to control or lessen damages from future floods. It includes discussions of the antecedent conditions and meteorological aspects of the storm; a description of the flood and comparison to previous floods; a summary of flood stages and discharges; a discussion of flood frequency; and photomosaics which show inundated areas. More than 200 high-water marks are described as to location and elevation above mean sea level.

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.

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.

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.

The Effects of Urbanization and Flood Control on Sediment Discharge of a Southern California River, Evidence of a Dilution Effect

NASA Astrophysics Data System (ADS)

Warrick, J. A.; Orzech, K. M.; Rubin, D. M.

2004-12-01

The southern California landscape has undergone dramatic urbanization and population growth during the past 60 years and currently supports almost 20 million inhabitants. During this time, rivers of the region have been altered with damming, channel straightening and hardening, and water transfer engineering. These changes have drastically altered water and sediment discharge from most of the region's drainage basins. Here we focus on changes in sediment discharge from the largest watershed of southern California, the Santa Ana River. Order-of-magnitude drops in the suspended sediment rating curves (the relationship between suspended sediment concentration and instantaneous river discharge) are observed between 1967 and 2001, long after the construction of a major flood control dam in 1941. These sediment concentration decreases do not, however, represent alteration of the total sediment flux from the basin (a common interpretation of sediment rating curves), but rather a dilution of suspended sediment by increases (approx. 4x) in stormwater discharge associated with urbanization. Increases in peak and total stormwater discharge are consistent with runoff patterns from urbanizing landscapes, supporting our hypothesis that the diluting water originated from stormwater runoff generated in urban areas both up- and downstream of dams. Our dilution hypothesis is further supported with water and sediment budgets, dilution calculations, and suspended and bed grain size information.

Review article: A review and critical analysis of the efforts towards urban flood risk management in the Lagos region of Nigeria

NASA Astrophysics Data System (ADS)

Nkwunonwo, U. C.; Whitworth, M.; Baily, B.

2016-02-01

Urban flooding has been and will continue to be a significant problem for many cities across the developed and developing world. Crucial to the amelioration of the effects of these floods is the need to formulate a sound flood management policy, which is driven by knowledge of the frequency and magnitude of impacts of these floods. Within the area of flood research, attempts are being made to gain a better understanding of the causes, impacts, and pattern of urban flooding. According to the United Nations office for disaster reduction (UNISDR), flood risk is conceptualized on the basis of three integral components which are frequently adopted during flood damage estimation. These components are: probability of flood hazard, the level of exposure, and vulnerabilities of elements at risk. Reducing the severity of each of these components is the objective of flood risk management under the UNISDR guideline and idea of "living with floods". On the basis of this framework, the present research reviews flood risk within the Lagos area of Nigeria over the period 1968-2012. During this period, floods have caused harm to millions of people physically, emotionally, and economically. Arguably over this period the efforts of stakeholders to address the challenges appear to have been limited by, amongst other things, a lack of reliable data, a lack of awareness amongst the population affected, and a lack of knowledge of flood risk mitigation. It is the aim of this research to assess the current understanding of flood risk and management in Lagos and to offer recommendations towards future guidance.

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.

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.

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.

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.

Combating Flood Crisis with Geographic Information System (GIS): An Example From Akure, Southwest Nigeria

NASA Astrophysics Data System (ADS)

Eludoyin, A. O.; Akinbode, O. M.; Archibong, Ediang Okuku

2007-07-01

Flood is a natural environmental disaster which could be aggravated by man's unguided development. It may subsequently cause destruction of properties and loss of life. Therefore it needs to be controlled and human influences controlled. This study attempts to describe an application of GIS as decision support to flooding problems in an urban area in Nigeria. The objective of the study is to describe the efficacy of GIS in monitoring of development on floodplains in an urban area in Nigeria. Topographic features were digitised from an existing 1:5,000 topographic map of Akure, with some position data collected and map updated using a handheld GPS. A database was created using both cartographic and attributes data collected from these and other sources. Spatial analyses were carried out using a PC based Integrated Land and Water Information System (ILWIS), version 3.2. The results obtained implicated dumpsites within the river channel as well as structural development within the River Ala floodplain as the major causes of inundation in this section of the city, especially, in the wet season. The study concluded that GIS could provide adequate decision support information to policy makers.

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.

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.

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

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.

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).

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 relationship between Urbanisation and changes in flood regimes: the British case.

NASA Astrophysics Data System (ADS)

Prosdocimi, Ilaria; Miller, James; Kjeldsen, Thomas

2013-04-01

This pilot study investigates if long-term changes in observed series of extreme flood events can be attributed to changes in climate and land-use drivers. We investigate, in particular, changes of winter and summer peaks extracted from gauged instantaneous flows records in selected British catchments. Using a Poisson processes framework, the frequency and magnitude of extreme events above a threshold can be modelled simultaneously under the standard stationarity assumptions of constant location and scale. In the case of a non-stationary process, the framework was extended to include covariates to account for changes in the process parameters. By including covariates related to the physical process, such as increased urbanization or North Atlantic Oscillation (NAO) Index levels, rather than just time, an enhanced understanding of the changes in high flows is obtainable. Indeed some variability is expected in any natural process and can be partially explained by large scale measures like NAO Index. The focus of this study is to understand, once natural variability is taken into account, how much of the remaining variability can be explained by increased urbanization levels. For this study, catchments are selected that have experienced significant growth in urbanisation in the past decades, typically 1960s to present, and for which concurrent good quality high flow data are available. Temporal change in the urban extent within catchments is obtained using novel processing of historical mapping sources, whereby the urban, suburban and rural fractions are obtained for decadal periods. Suitable flow data from localised rural catchments are also included as control cases to compare observed changes in the flood regime of urbanised catchments against, and to provide evidence of changes in regional climate. Initial results suggest that the effect of urbanisation can be detected in the rate of occurrence of flood events, especially in summer, whereas the impact on flood magnitude is less pronounced. Further tests across a greater number of catchments are necessary to validate these results.

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.

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.

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.

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.

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.

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.

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

Grand Forks - East Grand Forks Urban Water Resources Study. East Grand Forks Flood Fight Manual.

DTIC Science & Technology

1981-07-01

wastewater management, and flood control) were identified, and a "plan of study" was developed. The plan of study outlined the general approach t~i -tiTd...three parts. Part 1 contains a general description and narrative on the need of the unit, Part 2 identifies the Unit Chief, Deputies, and Unit members...other units are discussed only in general terms. Future revisions will hopefully result in a happy medium between detailed specifics and generalities

[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.

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.

Applications of Polarimetric Radar to the Hydrometeorology of Urban Floods in St. Louis

NASA Astrophysics Data System (ADS)

Chaney, M. M.; Smith, J. A.; Baeck, M. L.

2017-12-01

Predicting and responding to flash flooding requires accurate spatial and temporal representation of rainfall rates. The polarimetric upgrade of all US radars has led to optimism about more accurate rainfall rate estimation from the NEXRAD network of WSR-88D radars in the US. Previous work has proposed different algorithms to do so, but significant uncertainties remain, especially for extreme short-term rainfall rates that control flash floods in urban settings. We will examine the relationship between radar rainfall estimates and gage rainfall rates for a catalog of 30 storms in St. Louis during the period of polarimetric radar measurements, 2012-2016. The storms are selected to provide a large sample of extreme rainfall measurements at the 15-minute to 3-hour time scale. A network of 100 rain gages and a lack of orographic or coastal effects make St. Louis an interesting location to study these relationships. A better understanding of the relationships between polarimetric radar measurements and gage rainfall rates will aid in refining polarimetric radar rainfall algorithms, in turn helping hydrometeorologists predict flash floods and other hazards associated with severe rainfall. Given the fact that St. Louis contains some of the flashiest watersheds in the United States (Smith and Smith, 2015), it is an especially important urban area in which to have accurate, real-time rainfall data. Smith, Brianne K, and James A Smith. "The Flashiest Watersheds in the Contiguous United States." American Meteorological Society (2015): 2365-2381. Web.

Urban-Climate Adaptation Tool: Optimizing Green Infrastructure

NASA Astrophysics Data System (ADS)

Fellows, J. D.; Bhaduri, B. L.

2016-12-01

Cities have an opportunity to become more resilient to future climate change and green through investments made in urban infrastructure today. However, most cities lack access to credible high-resolution climate change projection and other environmental information needed to assess and address potential vulnerabilities from future climate variability. Therefore, we present an integrated framework for developing an urban climate adaptation tool (Urban-CAT). The initial focus of Urban-CAT is to optimize the placement of green infrastructure (e.g., green roofs, porous pavements, retention basins, etc.) to be better control stormwater runoff and lower the ambient urban temperature. Urban-CAT consists of four modules. Firstly, it provides climate projections at different spatial resolutions for quantifying urban landscape. Secondly, this projected data is combined with socio-economic and other environmental data using leading and lagging indicators for assessing landscape vulnerability to climate extremes (e.g., urban flooding). Thirdly, a neighborhood scale modeling approach is presented for identifying candidate areas for adaptation strategies (e.g., green infrastructure as an adaptation strategy for urban flooding). Finally, all these capabilities are made available as a web-based tool to support decision-making and communication at the neighborhood and city levels. This presentation will highlight the methods that drive each of the modules, demo some of the capabilities using Knoxville Tennessee as a case study, and discuss the challenges of working with communities to incorporate climate change into their planning. Next steps on Urban-CAT is to additional capabilities to create a comprehensive climate adaptation tool, including energy, transportation, health, and other key urban services.

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.

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.

Use long short-term memory to enhance Internet of Things for combined sewer overflow monitoring

NASA Astrophysics Data System (ADS)

Zhang, Duo; Lindholm, Geir; Ratnaweera, Harsha

2018-01-01

Combined sewer overflow causes severe water pollution, urban flooding and reduced treatment plant efficiency. Understanding the behavior of CSO structures is vital for urban flooding prevention and overflow control. Neural networks have been extensively applied in water resource related fields. In this study, we collect data from an Internet of Things monitoring CSO structure and build different neural network models for simulating and predicting the water level of the CSO structure. Through a comparison of four different neural networks, namely multilayer perceptron (MLP), wavelet neural network (WNN), long short-term memory (LSTM) and gated recurrent unit (GRU), the LSTM and GRU present superior capabilities for multi-step-ahead time series prediction. Furthermore, GRU achieves prediction performances similar to LSTM with a quicker learning curve.

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.

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.

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.

Sediment traps with guiding channel and hybrid check dams improve controlled sediment retention

NASA Astrophysics Data System (ADS)

Schwindt, Sebastian; Franca, Mário J.; Reffo, Alessandro; Schleiss, Anton J.

2018-03-01

Sediment traps with partially open check dams are crucial elements for flood protection in alpine regions. The trapping of sediment is necessary when intense sediment transport occurs during floods that may endanger urban areas at downstream river reaches. In turn, the unwanted permanent trapping of sediment during small, non-hazardous floods can result in the ecological and morphological degradation of downstream reaches. This study experimentally analyses a novel concept for permeable sediment traps. For ensuring the sediment transfer up to small floods, a guiding channel implemented in the deposition area of a sediment trap was systematically studied. The bankfull discharge of the guiding channel corresponds to a dominant morphological discharge. At the downstream end of the guiding channel, a permeable barrier (check dam) triggers sediment retention and deposition. The permeable barrier consists of a bar screen for mechanical deposition control, superposed to a flow constriction for the hydraulic control. The barrier obstructs hazardous sediment transport for discharges that are higher than the bankfull discharge of the guiding channel without the risk of unwanted sediment flushing (massive self-cleaning).

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.

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.

Is Climate Chang Responsible to Recent Urban Flooding in Devloping Cities in Africa? A Case study of Addis Ababa City, Ethiopia

NASA Astrophysics Data System (ADS)

Moges, Semu; Raschid-Sally, Liqa; Gebremichael, Mekonnen

2013-04-01

Cities in Africa show extraordinary expansion of the built environment and imperviousness of the surface condition. Addis Ababa is a case in point, where over the priod of 1984 to 2002, the city asphalted area has increased from 4.72 sq.km (1984) to 27.7 sq.km (2002). Similarly the paved area has expanded five fold from the original 11.1 sq.km, whilst the built environment expanded from 60.1 to 212.7 sq.km. Using hydrological modeling, we demonstrated due to the surface condition change, runoff generation potential has shown significant increase from 28% (in 1984) to 45% (in 2002), showing over 60% change in the runoff volume. The changing condition of the surface is increasing anabtedly, worsening the flooding condition. Similarly, climate change study shows likely increase of precipitation in and around Addis Ababa by about 13 to 17% and comparative increase in flooding. Unlike many cities in Europe, cities in developing countries are confronted with impact emanating from climate change as well as surface condition change. The impact of flooding caused due to the expansion of built environment is found to be more significant in the short term that the climate change, however, the climate change may dominate the long term future of flooding pattern as cities mature towards 2050. Therefore, It is important to view the impacts expansion of built environment and climate change in tandem in future time horizon since the dominance of the impact is different in different temporal scale. In the case of Addis Ababa, we strongly present the following four suggesions: i) the city adminstration re-estabilish the abandoned flood and drainage department of the city as the main flood regulatory and management body working in tandem with Addis Ababa Roads Authority, Water Supply and Sanitation Authority and Urban Planning Authority; ii) The old design guidlines for palnning and design of urban drainage system is not working any more (assumed stationarity condition), we suggest the planning and design criteria of urban drainage systems be immediately revised and incorporated to reflect the new reality of hydrologial non-stationarity; iii) for Addis Ababa City to be Resilient, we suggest implementation of 'Best Managemnt Practice" that incorporates arresting runoff from the source for benefial use, application of runoff treatment practices (open space, infiltration galleries, retardnat ponds, etc) and flood flow control drainage system based on new design criteria, and iv) instituting improved weather forecasting and early warning system.

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.

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.

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.

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.

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.

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.

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.

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

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.

Historical Evaluation of Groundwater Responses to Underground Injection Controls in an Urban Watershed

NASA Astrophysics Data System (ADS)

Harrison, M.; Haggerty, R.; Santelmann, M. V.

2017-12-01

Underground injection controls (UICs) are drywells designed to recharge stormwater to alleviate flooding events. The development of UICs affect the dynamics of the urban hydrologic setting in which more than half of precipitation can be recharged directly into UICs systems. This study seeks to better understand how the development of UICs affect groundwater levels and streamflows. The Portland, OR metropolitan area consist of well over 10,000 of UICs to mitigate flooding during storm events. This study evaluates historical precipitation, streamflow, and groundwater levels from over 20 monitoring wells within a watershed in the city Portland, OR along with well log data of UICs. UICs within the study area are approximately 30 feet in depth and have noted to contribute to about 12% of recharge. This study evaluates the dynamics of groundwater levels in relation towards the development of UICs. The results of obtained from this analysis is applied to model seasonal groundwater, precipitation, and streamflow relationships within a neighborhood subcatchment.

Consumer demand for green stormwater management technology in an urban setting: The case of Chicago rain barrels

NASA Astrophysics Data System (ADS)

Ando, Amy W.; Freitas, Luiz P. C.

2011-12-01

Hydrological disruption and water pollution from urbanization can be reduced if households in urban areas adopt decentralized storm water controls. We study a citywide municipal subsidized rain-barrel program in the third biggest city in the United States, Chicago, to explore what factors influence whether households purchase this sort of green storm water management technology in an urban setting. Specifically, we regress census-tract level data on the number of rain barrels adopted in different parts of the city on socioeconomic variables, data on local flood frequency, and features of the housing stock. We find that rain-barrel purchases are not correlated with local levels of flooding, even though city residents were told by program managers that rain barrels could alleviate local flooding. Instead, rain barrels are heavily concentrated in places with high-income attitudinally green populations. We do find more rain barrels were adopted in places close to rain-barrel distribution points and near sites of hydrological information campaigns; thus, policy makers might increase green-technology adoption in areas where they can do the most good by reducing transaction costs and providing education programs to those areas. Finally, our results indicate that owner occupancy is positively correlated with green-technology adoption. Low-rise rental housing may have inefficiently low levels of adoption, such that city managers might want to develop programs to encourage storm water management investments by landlords who do not live in their own properties.

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.

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)

Pesticides in surface water measured at select sites in the Sacramento River basin, California, 1996-1998

USGS Publications Warehouse

Domagalski, Joseph L.

2000-01-01

Pesticides were measured in one urban stream, one agricultural stream, one site on the Sacramento River, and one large flood control channel over a period of 18 months during 1996-1998. All sites were located within the Sacramento River Basin of California. Measurements were made on 83 pesticides or pesticide transformation products by either gas chromatography/mass spectrometry or by high performance liquid chromatography with ultraviolet light spectrometry. Some pesticides were detected frequently at the agricultural stream and downstream in the Sacramento River and at the flood control channel of the Sacramento River. These were pesticides related to rice farming (molinate, carbofuran, thiobencarb, and bentazon); herbicides used both agriculturally or for roadside maintenance (diuron, simazine, and metolachlor); or insecticides used on orchards and row corps (diazinon and chlorpyrifos). No pesticide concen-trations above enforceable water quality criteria were measured at either the agricultural site or the Sacramento River sites. In contrast to the agricul-tural site, insecticides used for household, lawn, or garden maintenance were the most frequently detected pesticides at the urban site. Diazinon, an organophosphate insecticide, exceeded recom-mended criteria for the protection of aquatic life, and the diazinon levels were frequently above known toxic levels for certain zooplankton species at the urban site. Because of the low discharge of the urban stream, pesticide concentrations were greatly diluted upon mixing with Sacramento River water.

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.

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.

Impact of anthropogenic development on coastal ground-water hydrology in southeastern Florida, 1900-2000

USGS Publications Warehouse

Renken, Robert A.; Dixon, Joann; Koehmstedt, John A.; Ishman, Scott; Lietz, A.C.; Marella, Richard L.; Telis, Pamela A.; Rodgers, Jeff; Memberg, Steven

2005-01-01

Southeastern Florida is an area that has been subject to widely conflicting anthropogenic stress to the Everglades and coastal ecosystems. This stress is a direct consequence of the 20th century economic competition for limited land and water resources needed to satisfy agricultural development and its expansion, its displacement by burgeoning urban development, and the accompanying growth of the limestone mining industry. The development of a highly controlled water-management system designed to reclaim land for urban and agricultural development has severely impacted the extent, character, and vitality of the historic Everglades and coastal ecosystems. An extensive conveyance system of canals, levees, impoundments, surface- water control structures, and numerous municipal well fields are used to sustain the present-day Everglades hydrologic system, prevent overland flow from moving eastward and flooding urban and agricultural areas, maintain water levels to prevent saltwater intrusion, and provide an adequate water supply. Extractive mining activities expanded considerably in the latter part of the 20th century, largely in response to urban construction needs. Much of the present-day urban-agricultural corridor of southeastern Florida lies within an area that is no more than 15 feet above NGVD 1929 and formerly characterized by freshwater marsh, upland, and saline coastal wetland ecosystems. Miami- Dade, Broward, and Palm Beach Counties have experienced explosive population growth, increasing from less than 4,000 inhabitants in 1900 to more than 5 million in 2000. Ground-water use, the principal source of municipal supply, has increased from about 65 Mgal/d (million gallons per day) obtained from 3 well fields in 1930 to more than 770 Mgal/d obtained from 65 well fields in 1995. Water use for agricultural supply increased from 505 Mgal/d in 1953 to nearly 1,150 Mgal/d in 1988, but has since declined to 764 Mgal/d in 1995, partly as a result of displacement of the agricultural industry by urban growth. Present-day agricultural supplies are obtained largely from surface-water sources in Palm Beach County and ground-water sources in Miami-Dade County, whereas Broward County agricultural growers have been largely displaced. The construction of a complex canal drainage system and large well fields has substantially altered the surface- and ground-water hydrologic systems. The drainage system constructed between 1910 and 1928 mostly failed to transport flood flows, however, and exacerbated periods of low rainfall and drought by overdraining the surficial aquifer system. Following completion of the 1930s Hoover Dike levee system that was designed to reduce Lake Okeechobee flood flows, the Central and Southern Florida Flood Control Project initiated the restructure of the existing conveyance system in 1948 through canal expansion, construction of protective levees and control structures, and greater management of ground-water levels in the surficial aquifer system. Gated canal control structures discharge excess surface water during the wet season and remain closed during the dry season to induce recharge by canal seepage and well withdrawals. Management of surface water through canal systems has successfully maintained lower ground-water levels inland to curb urban and agricultural flooding, and has been used to increase ground-water levels near the coast to impede saltwater intrusion. Coastal discharge, however, appears to have declined, due in part to water being rerouted to secondary canals, and to induced recharge to the surficial aquifer system by large municipal withdrawals. Southeastern Florida is underlain by Holocene- to Tertiary-age karstic limestone deposits that form (in descending order): a highly prolific surficial aquifer system, a poorly permeable intermediate confining system, and a permeable Floridan aquifer system. Prior to construction of a complex drainage netwo

36 CFR 72.56 - Grant program compliance requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., Protection of Wetlands Executive Order 12088, Federal compliance with Pollution Control Standards Executive Order 12185, Conservation of Petroleum and Natural Gas Flood Disaster Protection Act of 1973 (Pub. L. 93... INTERIOR URBAN PARK AND RECREATION RECOVERY ACT OF 1978 Grant Selection, Approval and Administration § 72...

36 CFR 72.56 - Grant program compliance requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., Protection of Wetlands Executive Order 12088, Federal compliance with Pollution Control Standards Executive Order 12185, Conservation of Petroleum and Natural Gas Flood Disaster Protection Act of 1973 (Pub. L. 93... INTERIOR URBAN PARK AND RECREATION RECOVERY ACT OF 1978 Grant Selection, Approval and Administration § 72...

36 CFR 72.56 - Grant program compliance requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., Protection of Wetlands Executive Order 12088, Federal compliance with Pollution Control Standards Executive Order 12185, Conservation of Petroleum and Natural Gas Flood Disaster Protection Act of 1973 (Pub. L. 93... INTERIOR URBAN PARK AND RECREATION RECOVERY ACT OF 1978 Grant Selection, Approval and Administration § 72...

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.

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).

Stochastic characteristics of different duration annual maximum rainfall and its spatial difference in China based on information entropy

NASA Astrophysics Data System (ADS)

Li, X.; Sang, Y. F.

2017-12-01

Mountain torrents, urban floods and other disasters caused by extreme precipitation bring great losses to the ecological environment, social and economic development, people's lives and property security. So there is of great significance to floods prevention and control by the study of its spatial distribution. Based on the annual maximum rainfall data of 60min, 6h and 24h, the paper generate long sequences following Pearson-III distribution, and then use the information entropy index to study the spatial distribution and difference of different duration. The results show that the information entropy value of annual maximum rainfall in the south region is greater than that in the north region, indicating more obvious stochastic characteristics of annual maximum rainfall in the latter. However, the spatial distribution of stochastic characteristics is different in different duration. For example, stochastic characteristics of 60min annual maximum rainfall in the Eastern Tibet is smaller than surrounding, but 6h and 24h annual maximum rainfall is larger than surrounding area. In the Haihe River Basin and the Huaihe River Basin, the stochastic characteristics of the 60min annual maximum rainfall was not significantly different from that in the surrounding area, and stochastic characteristics of 6h and 24h was smaller than that in the surrounding area. We conclude that the spatial distribution of information entropy values of annual maximum rainfall in different duration can reflect the spatial distribution of its stochastic characteristics, thus the results can be an importantly scientific basis for the flood prevention and control, agriculture, economic-social developments and urban flood control and waterlogging.

RIVER LEVEL ESTIMATION USING ARTIFICIAL NEURAL NETWORK FOR URBAN SMALL RIVER IN TIDAL REACH

NASA Astrophysics Data System (ADS)

Takasaki, Tadakatsu; Kawamura, Akira; Amaguchi, Hideo

Prediction of water level in small rivers is great interest for flood control in an urban area located in the river mouth. The tidal river water level is affected by not only flood discharge but also tide, atmospheric pressure, wind direction and speed. We propose a method of estimating river water level considering these factors using an artificial neural network model for the Kanda River located in the center of Tokyo. The effects by those factors are quantitatively investigated. As for the effects by the atmospheric pressure, river water level rises about 7cm per 5hPa increase of the pressure regardless of river discharge under the conditions of 1m/s wind speed and north wind direction. The accurate rating curve for the tidal river is finally obtained.

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.

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.

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.

Remotely Measuring Trash Fluxes in the Flood Canals of Megacities with Time Lapse Cameras and Computer Vision Algorithms - a Case Study from Jakarta, Indonesia.

NASA Astrophysics Data System (ADS)

Sedlar, F.; Turpin, E.; Kerkez, B.

2014-12-01

As megacities around the world continue to develop at breakneck speeds, future development, investment, and social wellbeing are threatened by a number of environmental and social factors. Chief among these is frequent, persistent, and unpredictable urban flooding. Jakarta, Indonesia with a population of 28 million, is a prime example of a city plagued by such flooding. Yet although Jakarta has ample hydraulic infrastructure already in place with more being constructed, the increasingly severity of the flooding it experiences is not from a lack of hydraulic infrastructure but rather a failure of existing infrastructure. As was demonstrated during the most recent floods in Jakarta, the infrastructure failure is often the result of excessive amounts of trash in the flood canals. This trash clogs pumps and reduces the overall system capacity. Despite this critical weakness of flood control in Jakarta, no data exists on the overall amount of trash in the flood canals, much less on how it varies temporally and spatially. The recent availability of low cost photography provides a means to obtain such data. Time lapse photography postprocessed with computer vision algorithms yields a low cost, remote, and automatic solution to measuring the trash fluxes. When combined with the measurement of key hydrological parameters, a thorough understanding of the relationship between trash fluxes and the hydrology of massive urban areas becomes possible. This work examines algorithm development, quantifying trash parameters, and hydrological measurements followed by data assimilation into existing hydraulic and hydrological models of Jakarta. The insights afforded from such an approach allows for more efficient operating of hydraulic infrastructure, knowledge of when and where critical levels of trash originate from, and the opportunity for community outreach - which is ultimately needed to reduce the trash in the flood canals of Jakarta and megacities around the world.

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...

A quantitative flood risk analysis methodology for urban areas with integration of social research data

NASA Astrophysics Data System (ADS)

Escuder-Bueno, I.; Castillo-Rodríguez, J. T.; Zechner, S.; Jöbstl, C.; Perales-Momparler, S.; Petaccia, G.

2012-09-01

Risk analysis has become a top priority for authorities and stakeholders in many European countries, with the aim of reducing flooding risk, considering the population's needs and improving risk awareness. Within this context, two methodological pieces have been developed in the period 2009-2011 within the SUFRI project (Sustainable Strategies of Urban Flood Risk Management with non-structural measures to cope with the residual risk, 2nd ERA-Net CRUE Funding Initiative). First, the "SUFRI Methodology for pluvial and river flooding risk assessment in urban areas to inform decision-making" provides a comprehensive and quantitative tool for flood risk analysis. Second, the "Methodology for investigation of risk awareness of the population concerned" presents the basis to estimate current risk from a social perspective and identify tendencies in the way floods are understood by citizens. Outcomes of both methods are integrated in this paper with the aim of informing decision making on non-structural protection measures. The results of two case studies are shown to illustrate practical applications of this developed approach. The main advantage of applying the methodology herein presented consists in providing a quantitative estimation of flooding risk before and after investing in non-structural risk mitigation measures. It can be of great interest for decision makers as it provides rational and solid information.

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.

Using Minimax Regret Optimization to Search for Multi-Stakeholder Solutions to Deeply Uncertain Flood Hazards under Climate Change

NASA Astrophysics Data System (ADS)

Kirshen, P. H.; Hecht, J. S.; Vogel, R. M.

2015-12-01

Prescribing long-term urban floodplain management plans under the deep uncertainty of climate change is a challenging endeavor. To address this, we have implemented and tested with stakeholders a parsimonious multi-stage mixed integer programming (MIP) model that identifies the optimal time period(s) for implementing publicly and privately financed adaptation measures. Publicly funded measures include reach-scale flood barriers, flood insurance, and buyout programs to encourage property owners in flood-prone areas to retreat from the floodplain. Measures privately funded by property owners consist of property-scale floodproofing options, such as raising building foundations, as well as investments in flood insurance or retreat from flood-prone areas. The objective function to minimize the sum of flood control and damage costs in all planning stages for different property types during floods of different severities. There are constraints over time for flow mass balances, construction of flood management alternatives and their cumulative implementation, budget allocations, and binary decisions. Damages are adjusted for flood control investments. In recognition of the deep uncertainty of GCM-derived climate change scenarios, we employ the minimax regret criterion to identify adaptation portfolios robust to different climate change trajectories. As an example, we identify publicly and privately funded adaptation measures for a stylized community based on the estuarine community of Exeter, New Hampshire, USA. We explore the sensitivity of recommended portfolios to different ranges of climate changes, and costs associated with economies of scale and flexible infrastructure design as well as different municipal budget constraints.

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.

Multimetric Evaluation of Detention Basin Retrofit to Reduce Hydrologic Alteration of Urbanization and Restore Stream Stability

EPA Science Inventory

Abstract: Conventional stormwater detention basins are ubiquitous in the developed portions of U.S., particularly those areas developed since the 1980s. Because most detention basins were designed exclusively for flood control, they are not being utilized to their fullest potent...

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.

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

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...

Analysis of flood-magnitude and flood-frequency data for streamflow-gaging stations in the Delaware and North Branch Susquehanna River Basins in Pennsylvania

USGS Publications Warehouse

Roland, Mark A.; Stuckey, Marla H.

2007-01-01

The Delaware and North Branch Susquehanna River Basins in Pennsylvania experienced severe flooding as a result of intense rainfall during June 2006. The height of the flood waters on the rivers and tributaries approached or exceeded the peak of record at many locations. Updated flood-magnitude and flood-frequency data for streamflow-gaging stations on tributaries in the Delaware and North Branch Susquehanna River Basins were analyzed using data through the 2006 water year to determine if there were any major differences in the flood-discharge data. Flood frequencies for return intervals of 2, 5, 10, 50, 100, and 500 years (Q2, Q5, Q10, Q50, Q100, and Q500) were determined from annual maximum series (AMS) data from continuous-record gaging stations (stations) and were compared to flood discharges obtained from previously published Flood Insurance Studies (FIS) and to flood frequencies using partial-duration series (PDS) data. A Wilcoxon signed-rank test was performed to determine any statistically significant differences between flood frequencies computed from updated AMS station data and those obtained from FIS. Percentage differences between flood frequencies computed from updated AMS station data and those obtained from FIS also were determined for the 10, 50, 100, and 500 return intervals. A Mann-Kendall trend test was performed to determine statistically significant trends in the updated AMS peak-flow data for the period of record at the 41 stations. In addition to AMS station data, PDS data were used to determine flood-frequency discharges. The AMS and PDS flood-frequency data were compared to determine any differences between the two data sets. An analysis also was performed on AMS-derived flood frequencies for four stations to evaluate the possible effects of flood-control reservoirs on peak flows. Additionally, flood frequencies for three stations were evaluated to determine possible effects of urbanization on peak flows. The results of the Wilcoxon signed-rank test showed a significant difference at the 95-percent confidence level between the Q100 computed from AMS station data and the Q100 determined from previously published FIS for 97 sites. The flood-frequency discharges computed from AMS station data were consistently larger than the flood discharges from the FIS; mean percentage difference between the two data sets ranged from 14 percent for the Q100 to 20 percent for the Q50. The results of the Mann-Kendall test showed that 8 stations exhibited a positive trend (i.e., increasing annual maximum peaks over time) over their respective periods of record at the 95-percent confidence level, and an additional 7 stations indicated a positive trend, for a total of 15 stations, at a confidence level of greater than or equal to 90 percent. The Q2, Q5, Q10, Q50, and Q100 determined from AMS and PDS data for each station were compared by percentage. The flood magnitudes for the 2-year return period were 16 percent higher when partial-duration peaks were incorporated into the analyses, as opposed to using only the annual maximum peaks. The discharges then tended to converge around the 5-year return period, with a mean collective difference of only 1 percent. At the 10-, 50-, and 100-year return periods, the flood magnitudes based on annual maximum peaks were, on average, 6 percent higher compared to corresponding flood magnitudes based on partial-duration peaks. Possible effects on flood peaks from flood-control reservoirs and urban development within the basin also were examined. Annual maximum peak-flow data from four stations were divided into pre- and post-regulation periods. Comparisons were made between the Q100 determined from AMS station data for the periods of record pre- and post-regulation. Two stations showed a nearly 60- and 20-percent reduction in the 100-year discharges; the other two stations showed negligible differences in discharges. Three stations within urban basins were compared to 38 stations

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

Changes In Tree Species In Riparian Zones Of Urban Streams May Have Effects On Restoration And Storm Water Control Efforts

EPA Science Inventory

A riparian zone is the land and vegetation within and directly adjacent to surface water ecosystems, such as lakes and streams. The vegetation in riparian zones provides ecosystem services (such as reducing flooding and bank erosion and reducing levels of pollutants in streams) ...

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...

24 CFR 201.28 - Flood and hazard insurance, and Coastal Barriers properties.

Code of Federal Regulations, 2014 CFR

2014-04-01

... Coastal Barriers properties. 201.28 Section 201.28 Housing and Urban Development Regulations Relating to... Disbursement Requirements § 201.28 Flood and hazard insurance, and Coastal Barriers properties. (a) Flood... obtained by the borrower in compliance with section 102 of the Flood Disaster Protection Act of 1973 (42 U...

24 CFR 201.28 - Flood and hazard insurance, and Coastal Barriers properties.

Code of Federal Regulations, 2011 CFR

2011-04-01

... Coastal Barriers properties. 201.28 Section 201.28 Housing and Urban Development Regulations Relating to... Disbursement Requirements § 201.28 Flood and hazard insurance, and Coastal Barriers properties. (a) Flood... obtained by the borrower in compliance with section 102 of the Flood Disaster Protection Act of 1973 (42 U...

24 CFR 201.28 - Flood and hazard insurance, and Coastal Barriers properties.

Code of Federal Regulations, 2013 CFR

2013-04-01

... Coastal Barriers properties. 201.28 Section 201.28 Housing and Urban Development Regulations Relating to... Disbursement Requirements § 201.28 Flood and hazard insurance, and Coastal Barriers properties. (a) Flood... obtained by the borrower in compliance with section 102 of the Flood Disaster Protection Act of 1973 (42 U...

24 CFR 201.28 - Flood and hazard insurance, and Coastal Barriers properties.

Code of Federal Regulations, 2010 CFR

2010-04-01

... Coastal Barriers properties. 201.28 Section 201.28 Housing and Urban Development Regulations Relating to... Disbursement Requirements § 201.28 Flood and hazard insurance, and Coastal Barriers properties. (a) Flood... obtained by the borrower in compliance with section 102 of the Flood Disaster Protection Act of 1973 (42 U...

24 CFR 201.28 - Flood and hazard insurance, and Coastal Barriers properties.

Code of Federal Regulations, 2012 CFR

2012-04-01

... Coastal Barriers properties. 201.28 Section 201.28 Housing and Urban Development Regulations Relating to... Disbursement Requirements § 201.28 Flood and hazard insurance, and Coastal Barriers properties. (a) Flood... obtained by the borrower in compliance with section 102 of the Flood Disaster Protection Act of 1973 (42 U...

Map showing flood-prone areas, greater Denver area, Front Range Urban Corridor, Colorado

USGS Publications Warehouse

McCain, J.F.; Hotchkiss, W.R.

1975-01-01

The rapid growth of population in the Front Range Urban Corridor of Colorado is causing intense competition for available land resources. One form of competition posing serious problems in indiscriminate development on flood plains along creeks and rivers. Flood plains are natural features of the landscape developed by streams in carry water in excess of channel capacity. Although not used as often by the stream, flood plains are as much a part of the stream system as is the channel. Whenever man competes with this natural function of the flood plain he must inevitably pay the price through property damage and varying degrees of human suffering Flood damages in the United States have been estimated to average about \\$1 billion annually (American Public Works Association, 1966.) This tremendous waste of national resources is borne not only by those citizens in direct contact with floods but also to a lesser degree by all citizens through increased cost of public services. Thus, floods are of concern to the entire community, and solutions to existing or potential problems should be a community effort.

Comparison of physical and semi-empirical hydraulic models for flood inundation mapping

NASA Astrophysics Data System (ADS)

Tavakoly, A. A.; Afshari, S.; Omranian, E.; Feng, D.; Rajib, A.; Snow, A.; Cohen, S.; Merwade, V.; Fekete, B. M.; Sharif, H. O.; Beighley, E.

2016-12-01

Various hydraulic/GIS-based tools can be used for illustrating spatial extent of flooding for first-responders, policy makers and the general public. The objective of this study is to compare four flood inundation modeling tools: HEC-RAS-2D, Gridded Surface Subsurface Hydrologic Analysis (GSSHA), AutoRoute and Height Above the Nearest Drainage (HAND). There is a trade-off among accuracy, workability and computational demand in detailed, physics-based flood inundation models (e.g. HEC-RAS-2D and GSSHA) in contrast with semi-empirical, topography-based, computationally less expensive approaches (e.g. AutoRoute and HAND). The motivation for this study is to evaluate this trade-off and offer guidance to potential large-scale application in an operational prediction system. The models were assessed and contrasted via comparability analysis (e.g. overlapping statistics) by using three case studies in the states of Alabama, Texas, and West Virginia. The sensitivity and accuracy of physical and semi-eimpirical models in producing inundation extent were evaluated for the following attributes: geophysical characteristics (e.g. high topographic variability vs. flat natural terrain, urbanized vs. rural zones, effect of surface roughness paratermer value), influence of hydraulic structures such as dams and levees compared to unobstructed flow condition, accuracy in large vs. small study domain, effect of spatial resolution in topographic data (e.g. 10m National Elevation Dataset vs. 0.3m LiDAR). Preliminary results suggest that semi-empericial models tend to underestimate in a flat, urbanized area with controlled/managed river channel around 40% of the inundation extent compared to the physical models, regardless of topographic resolution. However, in places where there are topographic undulations, semi-empericial models attain relatively higher level of accuracy than they do in flat non-urbanized terrain.

Urban flood simulation and prioritization of critical urban sub-catchments using SWMM model and PROMETHEE II approach

NASA Astrophysics Data System (ADS)

Babaei, Sahar; Ghazavi, Reza; Erfanian, Mahdi

2018-06-01

Urban runoff increased due to augment of impervious surfaces. In order to flood mitigation during rainy season, determination of critical urban sub-catchments is very important for urban planners. Due to lack of information, adopting a simulation approach is one of the practical ways to identify the surcharged junctions and critical sub-catchments. Occurrence of destructive floods in the rainy seasons indicates the inappropriateness of the urban drainage system in Urmia. The main aims of this study were to estimate the surface runoff of urban sub-catchments using SWMM, to evaluate the accuracy of the drainage system of the study urban area and to prioritize sub-catchments using PROMETHEE II approach and SWMM. In the present study, the occurrence of rainfall event of the Urmia city (West Azerbaijan province, Iran) used for estimation of runoff depth. The study area was divided into 22 sub-catchments. For calibration and validation of model parameters, 3 rainfall events and their related runoff were measured. According to sensitivity analysis CN was the most sensitive parameter for model calibration. Amount of surcharged conduits and junctions indicates that the drainage system of the study area has not enough capacity for converting of the runoff and. For 10 year return period, depth of channels should increase by 20% for prevention of flooding in these sub-catchments. Sub-catchments were prioritized using PROMETHEE II approach and its results were compared with SWMM simulation outcomes. Based on SWMM simulation, S11, S7, S18, S16 and S1 sub-catchments are more critical sub-catchments respectively, while according to PROMETHEE method, S1, S11, S16, S14 and S18 are determined as the critical areas.

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.

Recharge as an Ecosystem Service and Disservice in a Midwestern, Urbanizing, Agricultural Watershed with an Increasing Precipitation Trend

NASA Astrophysics Data System (ADS)

Booth, E. G.; Zipper, S. C.; Loheide, S. P.; Kucharik, C. J.

2012-12-01

Groundwater recharge is typically viewed as a beneficial ecosystem service as it relates to replenishing groundwater supplies for human use and groundwater-dependent ecosystems that have been diminished due to pumping. However, groundwater flooding - a condition caused by increased groundwater recharge - can cause damages to infrastructure and agricultural crops as elevated water tables lead to surface flooding and oxygen stress for unadapted plants such as corn. The Yahara River watershed - an urbanizing, agricultural watershed in south-central Wisconsin - is an exemplar for such disparate views of recharge. The basin has experienced a significantly increasing trend in annual precipitation since 1930 and groundwater flooding has been especially pervasive in the last decade in the northern rural part of the basin. Agricultural productivity has declined in areas affected by groundwater flooding. At the same time, the expansion of the Madison metropolitan area has led to increased groundwater pumping, more variable baseflows, and likely decreased flow to urban wetlands. Infiltration practices on new developments are required through local municipal ordinances to promote groundwater recharge in urban areas and help offset the effects of pumping. A comprehensive analysis of ecosystem services - which includes provisioning services such as freshwater supply and crop production and regulating services such as flood regulation - must take into account the differential impacts of recharge.

A global analysis approach for investigating structural resilience in urban drainage systems.

PubMed

Mugume, Seith N; Gomez, Diego E; Fu, Guangtao; Farmani, Raziyeh; Butler, David

2015-09-15

Building resilience in urban drainage systems requires consideration of a wide range of threats that contribute to urban flooding. Existing hydraulic reliability based approaches have focused on quantifying functional failure caused by extreme rainfall or increase in dry weather flows that lead to hydraulic overloading of the system. Such approaches however, do not fully explore the full system failure scenario space due to exclusion of crucial threats such as equipment malfunction, pipe collapse and blockage that can also lead to urban flooding. In this research, a new analytical approach based on global resilience analysis is investigated and applied to systematically evaluate the performance of an urban drainage system when subjected to a wide range of structural failure scenarios resulting from random cumulative link failure. Link failure envelopes, which represent the resulting loss of system functionality (impacts) are determined by computing the upper and lower limits of the simulation results for total flood volume (failure magnitude) and average flood duration (failure duration) at each link failure level. A new resilience index that combines the failure magnitude and duration into a single metric is applied to quantify system residual functionality at each considered link failure level. With this approach, resilience has been tested and characterised for an existing urban drainage system in Kampala city, Uganda. In addition, the effectiveness of potential adaptation strategies in enhancing its resilience to cumulative link failure has been tested. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

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.

Parcel-scale urban coastal flood mapping: Leveraging the multi-scale CoSMoS model for coastal flood forecasting

NASA Astrophysics Data System (ADS)

Gallien, T.; Barnard, P. L.; Sanders, B. F.

2011-12-01

California coastal sea levels are projected to rise 1-1.4 meters in the next century and evidence suggests mean tidal range, and consequently, mean high water (MHW) is increasing along portions of Southern California Bight. Furthermore, emerging research indicates wind stress patterns associated with the Pacific Decadal Oscillation (PDO) have suppressed sea level rise rates along the West Coast since 1980, and a reversal in this pattern would result in the resumption of regional sea level rise rates equivalent to or exceeding global mean sea level rise rates, thereby enhancing coastal flooding. Newport Beach is a highly developed, densely populated lowland along the Southern California coast currently subject to episodic flooding from coincident high tides and waves, and the frequency and intensity of flooding is expected to increase with projected future sea levels. Adaptation to elevated sea levels will require flood mapping and forecasting tools that are sensitive to the dominant factors affecting flooding including extreme high tides, waves and flood control infrastructure. Considerable effort has been focused on the development of nowcast and forecast systems including Scripps Institute of Oceanography's Coastal Data Information Program (CDIP) and the USGS Multi-hazard model, the Southern California Coastal Storm Modeling System (CoSMoS). However, fine scale local embayment dynamics and overtopping flows are needed to map unsteady flooding effects in coastal lowlands protected by dunes, levees and seawalls. Here, a recently developed two dimensional Godunov non-linear shallow water solver is coupled to water level and wave forecasts from the CoSMoS model to investigate the roles of tides, waves, sea level changes and flood control infrastructure in accurate flood mapping and forecasting. The results of this study highlight the important roles of topographic data, embayment hydrodynamics, water level uncertainties and critical flood processes required for meaningful prediction of sea level rise impacts and coastal flood forecasting.

Urban hydrology—Science capabilities of the U.S. Geological Survey

USGS Publications Warehouse

Bell, Joseph M.; Simonson, Amy E.; Fisher, Irene J.

2016-04-29

Urbanization affects streamflow characteristics, coastal flooding, and groundwater recharge. Increasing impervious areas, streamflow diversions, and groundwater pumpage are some of the ways that the natural water cycle is affected by urbanization. Assessment of the relations among these factors and changes in land use helps water-resource managers with issues such as stormwater management and vulnerability to flood and drought. Scientists with the U.S. Geological Survey (USGS) have the expertise to monitor and model urban hydrologic systems. Streamflow and groundwater data are available in national databases, and analyses of these data, including identification of long-term streamflow trends and the efficacy of management practices, are published in USGS reports.

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.

Integrated modeling of storm drain and natural channel networks for real-time flash flood forecasting in large urban areas

NASA Astrophysics Data System (ADS)

Habibi, H.; Norouzi, A.; Habib, A.; Seo, D. J.

2016-12-01

To produce accurate predictions of flooding in urban areas, it is necessary to model both natural channel and storm drain networks. While there exist many urban hydraulic models of varying sophistication, most of them are not practical for real-time application for large urban areas. On the other hand, most distributed hydrologic models developed for real-time applications lack the ability to explicitly simulate storm drains. In this work, we develop a storm drain model that can be coupled with distributed hydrologic models such as the National Weather Service Hydrology Laboratory's Distributed Hydrologic Model, for real-time flash flood prediction in large urban areas to improve prediction and to advance the understanding of integrated response of natural channels and storm drains to rainfall events of varying magnitude and spatiotemporal extent in urban catchments of varying sizes. The initial study area is the Johnson Creek Catchment (40.1 km2) in the City of Arlington, TX. For observed rainfall, the high-resolution (500 m, 1 min) precipitation data from the Dallas-Fort Worth Demonstration Network of the Collaborative Adaptive Sensing of the Atmosphere radars is used.

Long-term effects of flooding on mortality in England and Wales, 1994-2005: controlled interrupted time-series analysis

PubMed Central

2011-01-01

Background Limited evidence suggests that being flooded may increase mortality and morbidity among affected householders not just at the time of the flood but for months afterwards. The objective of this study is to explore the methods for quantifying such long-term health effects of flooding by analysis of routine mortality registrations in England and Wales. Methods Mortality data, geo-referenced by postcode of residence, were linked to a national database of flood events for 1994 to 2005. The ratio of mortality in the post-flood year to that in the pre-flood year within flooded postcodes was compared with that in non-flooded boundary areas (within 5 km of a flood). Further analyses compared the observed number of flood-area deaths in the year after flooding with the number expected from analysis of mortality trends stratified by region, age-group, sex, deprivation group and urban-rural status. Results Among the 319 recorded floods, there were 771 deaths in the year before flooding and 693 deaths in the year after (post-/pre-flood ratio of 0.90, 95% CI 0.82, 1.00). This ratio did not vary substantially by age, sex, population density or deprivation. A similar post-flood 'deficit' of deaths was suggested by the analyses based on observed/expected deaths. Conclusions The observed post-flood 'deficit' of deaths is counter-intuitive and difficult to interpret because of the possible influence of population displacement caused by flooding. The bias that might arise from such displacement remains unquantified but has important implications for future studies that use place of residence as a marker of exposure. PMID:21288358

The Potential Role of Urban Forests in Removing Nutrients from Stormwater.

PubMed

Denman, E C; May, P B; Moore, G M

2016-01-01

Biofiltration systems can be used to improve the quality of stormwater by treating runoff using plants grown in a moderately permeable soil. Most biofilters use herbaceous species, but in highly urbanized locations, such as streets, trees may be a more suitable vegetation. Biofilters that use urban woody vegetation are less studied. This experiment investigated the use of four street tree species [ Schauer, (R. Br.) Peter G. Wilson & J.T. Waterh., (Sm.) Colvill ex Sweet, and L.] and an unplanted control in model biofilters. All four tree species are used in urban landscapes in southern Australia and were chosen to investigate potential species differences in biofiltration systems. The trees were grown in mesocosms as a randomized block factorial design in soils with three saturated hydraulic conductivity rates (4, 95, and 170 mm h). The trees were regularly flooded with mains water (tap water) or artificial stormwater. Tree growth and nutrient removal performance of the systems were investigated over 13 mo. All four species grew well in all three soils, including one chosen for its low, and potentially growth-limiting, drainage rate. Tree growth increased significantly, except for , when flooded with stormwater. Unplanted controls were a source of nutrients; however, the presence of trees reduced oxidized nitrogen and filterable reactive phosphorus concentrations in leachate. There was little effect of species on the removal of nutrients from stormwater. Trees have the potential to be effective elements in urban biofiltration systems, but further field-level evaluation of these systems is required to fully assess this potential. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

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.

Effects of rapid urbanization on streamflow, erosion, and sedimentation in a desert stream in the American Southwest

USGS Publications Warehouse

Whitney, John W.; Glancy, Patrick A.; Buckingham , Susan E.; Ehrenberg, Arthur C.

2015-01-01

Rapid urbanization has resulted in a series of sequential effects on a desert stream in the American Southwest. Lower Las Vegas Wash was a dry wash characterized by infrequent flood deposition when Las Vegas, Nevada was established in 1905. Wastewater effluent was discharged into the wash in low volumes for over 3 decades. Wastewater volumes increased commensurably with accelerated population growth during the late 20th century and created a sequence of feedback effects on the floodplain. Initially slow saturation of the valley fill created a desert oasis of dense floodplain vegetation and wetlands. Annual streamflow began in 1958 and erosion began a decade later with shallow incision in discontinuous channel segments. Increasing baseflow gradually enlarged channels; headcutting was active during the 1970s to 1984. The incised channels concentrated storm runoff, which accelerated local channel erosion, and in 1984 the headcuts were integrated during a series of monsoon floods. Wetlands were drained and most floodplain vegetation destroyed. Channel erosion continued unabated until engineering interventions began in the 21st century. No natural channel recovery occurred after initial urbanization effects because streamflow never stabilized in the late 20th century. A 6.6 M m3 sediment slug, eroded from the wash in ∼25 years, was deposited in Las Vegas Bay in Lake Mead. Falling reservoir levels during the 21st century are responsible for sediment redistribution and infilling of the bay. Close monitoring of impacts is recommended when urban wastewater and storm runoff are discharged on a desert wash. Channel interventions, when necessary, are advised in order to prevent costly engineering schemes of channel stabilization, flood control, and floodplain restoration.

Modeling pluvial flooding damage in urban environments: spatial relationships between citizens' complaints and overland catchment areas

NASA Astrophysics Data System (ADS)

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

2013-04-01

Extreme weather events such as floods and storms are expected to cause severe economic losses in The Netherlands. Cumulative damage due to pluvial flooding can be considerable, especially in lowland areas where this type of floods occurs relatively frequently. Currently, in The Netherlands, water-related damages to property and contents are covered through private insurance. As pluvial flooding is becoming heavier and more likely to occur, sound modelling of damages is required to ensure that insurance systems are able to stand as an adaptation measure. Current damage models based on rainfall intensity, registries of insurance claims, and classifications of building types are unable to fully explain damage variability. Further developments assessing additional explanatory factors and reducing uncertainties, are required in order to significantly explain damage. In this study, urban topography is used as an explanatory factor for modelling of urban pluvial flooding. Flood damage is evaluated based on complaints data, a valuable resource for assessing vulnerability to urban pluvial flooding. Though previous research has shown coincidences between the localization of high complaint counts and large size catchments areas in Rotterdam, additional research is needed to establish the precise spatial relationship of those two variables. This additional task is the focus of the presented work. To that end a data base of complaints, that was made available by the Municipality Administration of the City, will be analysed. It comprises close to 36800 complaints from 2004 to 2011. The geographical position of the registries is aggregated into 4 to 6-digit Postal Code zones, which represents entire streets or relative positions along a street, respectively. The Municipality also provided the DEM, characterized by a spatial resolution of 0.5 m × 0.5 m, a vertical precision of 5 cm, and an accuracy better than two standard deviations of 15 cm. First the localization of complaints will be tested for spatial randomness: the distribution of Global Moran's I will be used as a measure of spatial aggregation of complaints. We expect high values of spatial aggregation, that would confirm the existence of a spatial structure in the distribution of complaints. Then we will probe how much does the extent of catchment areas influence such distribution of complaints. That will be done through both an ordinary least squares regression and a geographically weighted regression. By contrasting the results from these two regressions, the relationship between complaints and size of catchment area across the urban environment will be evaluated. The results will confirm whether complaints have a spatial distribution pattern. Furthermore, the results will provide insight into the importance of the size of catchment areas as a significant factor for complaints distribution, and for the assessment of urban vulnerability to pluvial flooding in the City of Rotterdam.

Flood of September 22, 1998, in Arecibo and Utuado, Puerto Rico

USGS Publications Warehouse

Torres-Sierra, Heriberto

2002-01-01

Hurricane Georges made landfall on the southeastern part of Puerto Rico during September 21, 1998. Georges, with maximum sustained winds of 185 kilometers per hour and gusts to 240 kilometers per hour, produced 24-hour total rainfall amounts of 770 millimeters on the island's mountainous interior. Severe flooding affected almost half of the island's 78 municipios during September 21-22, 1998. The most affected municipios were Adjuntas, Aguada, Aguadilla, A?asco, Arecibo, Cayey, Ciales, Comerio, Barceloneta, Dorado, Jayuya, Manati, Mayaguez, Morovis, Orocovis, Patillas, Toa Alta, Toa Baja, and Utuado. The combination of strong winds, intense rainfall and severe flooding caused widespread property damages. More than 20,000 houses were destroyed and more than 100,000 houses sustained damage. Floodwaters and landslides destroyed or damaged many bridges and roads throughout the island. Records indicate that Hurricane Georges induced flood discharges in the Rio Grande de Arecibo Basin that were the largest on record. Floodwaters inundated urban and rural areas, affecting urban subdivisions, businesses, vehicles, bridges, roads, and high-tension electric power lines. To define the extent and depth of inundation, more than 280 high-water marks were identified and surveyed in Arecibo and Utuado. In addition estimates of flood magnitude and frequency were made at selected gaging stations, and flood profiles were developed for certain stream reaches. Flooding was most severe in the towns of Arecibo and Utuado. In Arecibo, the most affected communities were the rural area of San Francisco, the urban subdivisions of Martell, Nolla, and Arecibo Gardens, and the low-lying areas of downtown Arecibo. In these areas, the water depths ranged from 0.6 to 1.8 meters. In Utuado, floodwaters from the Rio Vivi and the Rio Grande de Arecibo inundated the downtown area affecting homes, public facilities, and businesses. In the urban subdivision of Jesus Maria Lago, the depth of flooding exceeded 2.5 meters. Frequency analysis indicates that flood-peak discharges equaled or exceeded the 100-year recurrence interval at five streamflow-gaging stations in the Rio Grande de Arecibo Basin.

Uncertainty in urban flood damage assessment due to urban drainage modelling and depth-damage curve estimation.

PubMed

Freni, G; La Loggia, G; Notaro, V

2010-01-01

Due to the increased occurrence of flooding events in urban areas, many procedures for flood damage quantification have been defined in recent decades. The lack of large databases in most cases is overcome by combining the output of urban drainage models and damage curves linking flooding to expected damage. The application of advanced hydraulic models as diagnostic, design and decision-making support tools has become a standard practice in hydraulic research and application. Flooding damage functions are usually evaluated by a priori estimation of potential damage (based on the value of exposed goods) or by interpolating real damage data (recorded during historical flooding events). Hydraulic models have undergone continuous advancements, pushed forward by increasing computer capacity. The details of the flooding propagation process on the surface and the details of the interconnections between underground and surface drainage systems have been studied extensively in recent years, resulting in progressively more reliable models. The same level of was advancement has not been reached with regard to damage curves, for which improvements are highly connected to data availability; this remains the main bottleneck in the expected flooding damage estimation. Such functions are usually affected by significant uncertainty intrinsically related to the collected data and to the simplified structure of the adopted functional relationships. The present paper aimed to evaluate this uncertainty by comparing the intrinsic uncertainty connected to the construction of the damage-depth function to the hydraulic model uncertainty. In this way, the paper sought to evaluate the role of hydraulic model detail level in the wider context of flood damage estimation. This paper demonstrated that the use of detailed hydraulic models might not be justified because of the higher computational cost and the significant uncertainty in damage estimation curves. This uncertainty occurs mainly because a large part of the total uncertainty is dependent on depth-damage curves. Improving the estimation of these curves may provide better results in term of uncertainty reduction than the adoption of detailed hydraulic models.

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.

A Participatory Modeling Application of a Distributed Hydrologic Model in Nuevo Leon, Mexico for the 2010 Hurricane Alex Flood Event

NASA Astrophysics Data System (ADS)

Baish, A. S.; Vivoni, E. R.; Payan, J. G.; Robles-Morua, A.; Basile, G. M.

2011-12-01

A distributed hydrologic model can help bring consensus among diverse stakeholders in regional flood planning by producing quantifiable sets of alternative futures. This value is acute in areas with high uncertainties in hydrologic conditions and sparse observations. In this study, we conduct an application of the Triangulated Irregular Network (TIN)-based Real-time Integrated Basin Simulator (tRIBS) in the Santa Catarina basin of Nuevo Leon, Mexico, where Hurricane Alex in July 2010 led to catastrophic flooding of the capital city of Monterrey. Distributed model simulations utilize best-available information on the regional topography, land cover, and soils obtained from Mexican government agencies or analysis of remotely-sensed imagery from MODIS and ASTER. Furthermore, we developed meteorological forcing for the flood event based on multiple data sources, including three local gauge networks, satellite-based estimates from TRMM and PERSIANN, and the North American Land Data Assimilation System (NLDAS). Remotely-sensed data allowed us to quantify rainfall distributions in the upland, rural portions of the Santa Catarina that are sparsely populated and ungauged. Rural areas had significant contributions to the flood event and as a result were considered by stakeholders for flood control measures, including new reservoirs and upland vegetation management. Participatory modeling workshops with the stakeholders revealed a disconnect between urban and rural populations in regard to understanding the hydrologic conditions of the flood event and the effectiveness of existing and potential flood control measures. Despite these challenges, the use of the distributed flood forecasts developed within this participatory framework facilitated building consensus among diverse stakeholders and exploring alternative futures in the basin.

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.

Efficient Probabilistic Forecasting for High-Resolution Models through Clustered-State Data Assimilation

NASA Astrophysics Data System (ADS)

Hamidi, A.; Grossberg, M.; Khanbilvardi, R.

2016-12-01

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.

Preliminary evaluation of flood frequency relations in the urban areas of Memphis, Tennessee

USGS Publications Warehouse

Boning, Charles W.

1977-01-01

A storm-runoff relation for streams in the urban areas of Memphis was determined by a statistical evaluation of 59 flood discharges from 19 gaging stations. These flood discharges were related to drainage area, percent imperviousness of the drainage basin, and rainfall occuring over 120-minute periods. The defined relation is Q=m3A*777A - .02 tI,,,,P + 1j-227 (1120).539(t120).40 where Q is flood discharge in cfs, A is drainage area in square miles, IMP is percent imperviousness in the basin, and I120 is rainfall in inches, over 120 minute time period. The defined relation was used to synthesize sets of annual flood peaks for drainage basins ranging from .05 square miles to 10 square miles and imperviousness ranging from 0 to 80 percent for the period of rainfall record at Memphis. From these series of flood peaks, frequency relations were defined and presented for 2, 5, 10, 25, 50 and 100 year recurrent intervals.

A GIS-Based Model for the analysis of an urban flash flood and its hydro-geomorphic response. The Valencia event of 1957

NASA Astrophysics Data System (ADS)

Portugués-Mollá, I.; Bonache-Felici, X.; Mateu-Bellés, J. F.; Marco-Segura, J. B.

2016-10-01

Flash floods are recurrent events around the Mediterranean region. Extreme episodes activate hydro-geomorphic high-intensity processes with low frequency. In urban environments, the complexity becomes higher due to the existence of very quick-response runoff. However, immediate recovery works remove the urban marks. After a short time both the significance and magnitude of the hydro-geomorphic event become completely unrecognizable. Nevertheless, these episodes generate extensive documentation which is testimony of the processes in almost real time. It is necessary to exploit this source typology in order to draw flood sketches when events far in time may lack a sufficiently rich database. This is particularly the case for the Valencia flash flood (October 1957), located in the lower Turia River basin (Eastern Spain). It left numerous pieces of hydro-geomorphic evidence, but its tracks were covered a short while after the flood. In any case, it remains part of a non-systematic legacy that has not yet been exploited, consisting of immediate aerial and oblique high resolution photography, pictures at street level, water marks and administrative records. Paradoxically, despite being considered a milestone in metropolitan territorial planning (the river was definitely diverted), an accurate reconstruction of the hydraulic behaviour was required from an integrated point of view. To this aim, the development of a GIS-Based Model enabled the utilisation of the above-mentioned materials. This non-conventional information was treated jointly from a new perspective. It provided database support through a vast amount of organised, structured and georeferenced information about the 1957 event. In a second stage, the GBM made it possible to characterise the Turia urban reach and interpret both the hydro-geomorphic (trenches along barrier beaches, erosion, deposition, etc.) and hydraulic (urban streams along the streets, flow directions, flood extent, levees breaks, overflows and inflows, etc.) processes mainly through photo-interpretation.

Direct local building inundation depth determination in 3-D point clouds generated from user-generated flood images

NASA Astrophysics Data System (ADS)

Griesbaum, Luisa; Marx, Sabrina; Höfle, Bernhard

2017-07-01

In recent years, the number of people affected by flooding caused by extreme weather events has increased considerably. In order to provide support in disaster recovery or to develop mitigation plans, accurate flood information is necessary. Particularly pluvial urban floods, characterized by high temporal and spatial variations, are not well documented. This study proposes a new, low-cost approach to determining local flood elevation and inundation depth of buildings based on user-generated flood images. It first applies close-range digital photogrammetry to generate a geo-referenced 3-D point cloud. Second, based on estimated camera orientation parameters, the flood level captured in a single flood image is mapped to the previously derived point cloud. The local flood elevation and the building inundation depth can then be derived automatically from the point cloud. The proposed method is carried out once for each of 66 different flood images showing the same building façade. An overall accuracy of 0.05 m with an uncertainty of ±0.13 m for the derived flood elevation within the area of interest as well as an accuracy of 0.13 m ± 0.10 m for the determined building inundation depth is achieved. Our results demonstrate that the proposed method can provide reliable flood information on a local scale using user-generated flood images as input. The approach can thus allow inundation depth maps to be derived even in complex urban environments with relatively high accuracies.

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.

Improving techniques to estimate the magnitude and frequency of floods on urban streams in South Carolina, North Carolina, and Georgia, 2011 (ver. 1.1, March 2014) : U.S. Geological Survey scientific investigations report 2014-5030.

DOT National Transportation Integrated Search

2014-03-01

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 dens...

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.

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)

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.

The potential use of natural resources in urban informal settlements as substitutes for financial capital during flooding emergencies

NASA Astrophysics Data System (ADS)

Dalu, Mwazvita T. B.; Shackleton, Charlie M.

2018-04-01

Rapid and widespread land cover change and the subsequent loss of the buffering capacity provided by healthy ecosystems against natural hazards has resulted in increased vulnerability to natural hazards. There is an insufficient understanding of the natural resources contribution to the resilience of poor urban communities living in informal settlements and the financial implications thereof. Thus, household strategies used to recover from the October 2012 flood shock were investigated within the informal settlements of three small South African towns using questionnaires. Within the vulnerability paradigm and the sustainable livelihood framework, the study also quantified and evaluated the relative contribution of natural resources to recovery strategies and the impacts on household financial capital. We found that natural resources contributed up to 70% to recovery of households from the flood shock, most of this being to reconstruct housing structures after the flood. Factors such as household head education level, household income, kinship level, the extent of property damage and the cost associated with property rehabilitation significantly influenced the uptake of natural resources in recovery from floods, and this was variable among settlements and towns. The main findings showed that natural resources reduced household vulnerability of urban informal settlements by providing an emergency-net function that substitutes financial capital. Their inclusion in disaster management plans and responses has the potential to contribute to the sustainable livelihoods of the urban poor in the Eastern Cape, South Africa.

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.

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.

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.

Techniques for estimating magnitude and frequency of peak flows for Pennsylvania streams

USGS Publications Warehouse

Stuckey, Marla H.; Reed, Lloyd A.

2000-01-01

Regression equations for estimating the magnitude and frequency of floods on ungaged streams in Pennsylvania with drainage areas less that 2,000 square miles were developed on the basis of peak-flow data collected at 313 streamflow-gaging stations. All streamflow-gaging stations used in the development of the equations had 10 or more years of record and include active and discontinued continuous-record and crest-stage partial-record streamflow-gaging stations. Regional regression equations were developed for flood flows expected every 10, 25, 50, 100, and 500 years by the use of a weighted multiple linear regression model.The State was divided into two regions. The largest region, Region A, encompasses about 78 percent of Pennsylvania. The smaller region, Region B, includes only the northwestern part of the State. Basin characteristics used in the regression equations for Region A are drainage area, percentage of forest cover, percentage of urban development, percentage of basin underlain by carbonate bedrock, and percentage of basin controlled by lakes, swamps, and reservoirs. Basin characteristics used in the regression equations for Region B are drainage area and percentage of basin controlled by lakes, swamps, and reservoirs. The coefficient of determination (R2) values for the five flood-frequency equations for Region A range from 0.93 to 0.82, and for Region B, the range is from 0.96 to 0.89.While the regression equations can be used to predict the magnitude and frequency of peak flows for most streams in the State, they should not be used for streams with drainage areas greater than 2,000 square miles or less than 1.5 square miles, for streams that drain extensively mined areas, or for stream reaches immediately below flood-control reservoirs. In addition, the equations presented for Region B should not be used if the stream drains a basin with more than 5 percent urban development.

A step towards considering the spatial heterogeneity of urban key features in urban hydrology flood modelling

NASA Astrophysics Data System (ADS)

Leandro, J.; Schumann, A.; Pfister, A.

2016-04-01

Some of the major challenges in modelling rainfall-runoff in urbanised areas are the complex interaction between the sewer system and the overland surface, and the spatial heterogeneity of the urban key features. The former requires the sewer network and the system of surface flow paths to be solved simultaneously. The latter is still an unresolved issue because the heterogeneity of runoff formation requires high detailed information and includes a large variety of feature specific rainfall-runoff dynamics. This paper discloses a methodology for considering the variability of building types and the spatial heterogeneity of land surfaces. The former is achieved by developing a specific conceptual rainfall-runoff model and the latter by defining a fully distributed approach for infiltration processes in urban areas with limited storage capacity dependent on OpenStreetMaps (OSM). The model complexity is increased stepwise by adding components to an existing 2D overland flow model. The different steps are defined as modelling levels. The methodology is applied in a German case study. Results highlight that: (a) spatial heterogeneity of urban features has a medium to high impact on the estimated overland flood-depths, (b) the addition of multiple urban features have a higher cumulative effect due to the dynamic effects simulated by the model, (c) connecting the runoff from buildings to the sewer contributes to the non-linear effects observed on the overland flood-depths, and (d) OSM data is useful in identifying pounding areas (for which infiltration plays a decisive role) and permeable natural surface flow paths (which delay the flood propagation).

Homogenizing an urban habitat mosaic: arthropod diversity declines in New York City parks after Super Storm Sandy.

PubMed

Savage, Amy M; Youngsteadt, Elsa; Ernst, Andrew F; Powers, Shelby A; Dunn, Robert R; Frank, Steven D

2018-01-01

The frequency and intensity of hurricanes are increasing globally, and anthropogenic modifications in cities have created systems that may be particularly vulnerable to their negative effects. Organisms living in cities are exposed to variable levels of chronic environmental stress. However, whether chronic stress ameliorates or exacerbates the negative effects of hurricanes remains an open question. Here, we consider two hypotheses about the simultaneous consequences of acute disturbances from hurricanes and chronic stress from urbanization for the structure of urban arthropod communities. The tipping point hypothesis posits that organisms living in high stress habitats are less resilient than those in low stress habitats because they are living near the limits of their environmental tolerances; while the disturbance tolerance hypothesis posits that high stress habitats host organisms pre-adapted for coping with disturbance, making them more resilient to the effects of storms. We used a before-after-control-impact design in the street medians and city parks of Manhattan (New York City, New York, USA) to compare arthropod communities before and after Super Storm Sandy in sites that were flooded and unflooded during the storm. Our evidence supported the disturbance tolerance hypothesis. Significant compositional differences between street medians and city parks before the storm disappeared after the storm; similarly, unflooded city parks had significantly different arthropod composition while flooded sites were indistinguishable. These differences were driven by reduced occurrences and abundances of arthropods in city parks. Finally, those arthropod groups that were most tolerant to urban stress were also the most tolerant to flooding. Our results suggest that the species that survive in high stress environments are likely to be the ones that thrive in response to acute disturbance. As storms become increasingly common and extreme, this juxtaposition in responses to storm-associated disturbance may lead to diversity loss in cities, potentially leading entire urban landscapes to mirror the reduced diversity of street medians. © 2017 by the Ecological Society of America.

EXPERIMENTAL STUDIES ON DIFFICULTY OF EVACUATION FROM UNDERGROUND SPACES UNDER INUNDATED SITUATIONS USING REAL SCALE MODELS

NASA Astrophysics Data System (ADS)

Baba, Yasuyuki; Ishigaki, Taisuke; Toda, Keiichi; Nakagawa, Hajime

Many urbanized cities in Japan are located in alluvial plains, and the vulnerability of urbanized areas to flood disaster is highlighted by flood attacks due to heavy rain fall or typhoons. Underground spaces located in the urbanized area are flood-prone areas, and the intrusion of flood watar into underground space inflicted severe damages on urban functions and infrastructures. In a similar way, low-lying areas like "bowl-shaped" depression and underpasses under highway and railroad bridges are also prone to floods. The underpasses are common sites of accidents of submerged vehicles, and severe damage including human damage occasionally occurs under flooding conditions. To reduce the damage due to inundation in underground space, needless to say, early evacuation is one of the most important countermeasures. This paper shows some experimental results of evacuation tests from underground spaces under inundated situations. The difficulities of the evacuation from underground space has been investigated by using real scale models (door, staircase and vehicle), and the limit for safety evacuation is discussed. From the results, it is found that water depth of 0.3 - 0.4m would be a critical situation for the evacuation from underground space through staircases and door and that 0.7 - 0.8m deep on the ground would be also a critical situation for safety evacuation though the doors of the vehicle. These criteria have some possibility to vary according to different inundated situations, and they are also influenced by the individual variation like the difference of physical strength. This means that these criteria requires cautious stance to use although they show a sort of an index of the limitation for saftty evacuation from underground space.

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.

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.

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…

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.

Effects of Hydrologic Restoration on Flood Resilience and Sediment Dynamics of Urban Creeks in the UK and USA

NASA Astrophysics Data System (ADS)

Wright, N.

2015-12-01

Hydrologic restoration in urban creeks is increasingly regarded as a more sustainable option than traditional grey infrastructures in many countries including the UK and USA. Hydrologic restoration aims to recreate naturally oriented hydro-morphodynamic processes while adding ecological and amenity value to a river corridor. Nevertheless, the long-term hydraulic performance of river restorations is incompletely understood. The aim of this research was to investigate the long-term effects of river restoration on the water storage, flood attenuation and sediment dynamics of two urban creeks through detailed hydro-morphodynamic modelling. The first case study is based on Johnson Creek located at Portland, Oregon, USA, and the second case based on Ouseburn River in Newcastle upon Tyne, N.E. England. This study focuses on the downstream of the Johnson Creek, where creek is reconnected to a restored East Lents floodplain of 0.28 km2. In order to offset the increased urban runoff in the Ouseburn catchment, a number of attenuation ponds were implemented along the river. In this study, an integrated 1D and 2D flood model (ISIS - TUFLOW) and the recently updated layer-based hydro-morphodynamic model have been used to understand the long-term impacts of these restorations on the flood and sediment dynamics. The event-based simulations (500 year, 100 year, 50 year, 10 year and 5 year), as well as the continuous simulations based on the historical flow datasets were systematically undertaken. Simulation results showed that the flood storage as a result of river restoration attenuate the flood peak by up to 25% at the downstream. Results also indicated that about 30% of the sediments generated from the upstream deposited in the resorted regions. The spatial distribution and amount of short and long-term sediment deposition on the floodplain and pond are demonstrated, and the resulting potential loss of the flood storage capacity are analysed and discussed.

Predicting Coastal Flood Severity using Random Forest Algorithm

NASA Astrophysics Data System (ADS)

Sadler, J. M.; Goodall, J. L.; Morsy, M. M.; Spencer, K.

2017-12-01

Coastal floods have become more common recently and are predicted to further increase in frequency and severity due to sea level rise. Predicting floods in coastal cities can be difficult due to the number of environmental and geographic factors which can influence flooding events. Built stormwater infrastructure and irregular urban landscapes add further complexity. This paper demonstrates the use of machine learning algorithms in predicting street flood occurrence in an urban coastal setting. The model is trained and evaluated using data from Norfolk, Virginia USA from September 2010 - October 2016. Rainfall, tide levels, water table levels, and wind conditions are used as input variables. Street flooding reports made by city workers after named and unnamed storm events, ranging from 1-159 reports per event, are the model output. Results show that Random Forest provides predictive power in estimating the number of flood occurrences given a set of environmental conditions with an out-of-bag root mean squared error of 4.3 flood reports and a mean absolute error of 0.82 flood reports. The Random Forest algorithm performed much better than Poisson regression. From the Random Forest model, total daily rainfall was by far the most important factor in flood occurrence prediction, followed by daily low tide and daily higher high tide. The model demonstrated here could be used to predict flood severity based on forecast rainfall and tide conditions and could be further enhanced using more complete street flooding data for model training.

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.

Urban infrastructure and longitudinal stream profiles

NASA Astrophysics Data System (ADS)

Lindner, G. A.; Miller, A. J.

2009-12-01

Urban streams usually are highly engineered or modified by human activity and are conventionally thought of as being geometrically, and thus hydraulically, simple. The work presented here, a contribution to NSF CNH Project 0709659, is designed to capture the influence of urban infrastructure on the character of longitudinal profiles and flow hydraulics along streams in the Baltimore metropolitan area. Detailed topographic data sets are derived from LiDAR supplemented by total-station surveys of the channel bed and low-flow water surface. These in turn are used to drive 2D depth-averaged hydraulic models comparing flow conditions over a range of urban development patterns and stormwater management regimes. Results from stream surveys of 1-2 km length indicate that channels in older, highly urbanized areas typically have straight planforms and strongly stepped profiles characterized by a series of deep, stagnant pools with short intervening riffles or runs. This pattern is associated with frequent interruption of the channel profile by bridges, culverts, road embankments and other artificial structures. In one survey reach of the Dead Run watershed, 50 percent of cumulative channel length has zero gradient at low flow, and 50 percent of cumulative head loss is accounted for by only 4 percent of channel length. In the suburban Red Run watershed recent development has occurred under strict stormwater management regulations with minimal encroachment on the riparian zone. Although their average gradients are similar, the Red Run survey reach is steeper than the Dead Run reach over most its length but has a smaller fraction of total head loss caused by local slope breaks. Modeling results indicate that these differences in stream morphology are associated with differences in velocity, flow pattern, and residence time at base flow; the stepped nature of the profile in the older urban area becomes less pronounced at intermediate to high flows, but the controlling influence of infrastructure may become dominant again during large floods. Because flashy urban streams have lower and more persistent low flows as well as more extreme flood flows, these hydraulic patterns may have implications for both biogeochemical cycling at base flow and transport and deposition of sediment and other constituents during flood periods. Continuing research will develop a typology of urban streams in terms of the influence of engineering practices on flow patterns and material transport.

Rainfall-Runoff Simulations to Assess the Potential of SuDS for Mitigating Flooding in Highly Urbanized Catchments.

PubMed

Jato-Espino, Daniel; Charlesworth, Susanne M; Bayon, Joseba R; Warwick, Frank

2016-01-21

Sustainable Urban Drainage Systems (SuDS) constitute an alternative to conventional drainage when managing stormwater in cities, reducing the impact of urbanization by decreasing the amount of runoff generated by a rainfall event. This paper shows the potential benefits of installing different types of SuDS in preventing flooding in comparison with the common urban drainage strategies consisting of sewer networks of manholes and pipes. The impact of these systems on urban water was studied using Geographic Information Systems (GIS), which are useful tools when both delineating catchments and parameterizing the elements that define a stormwater drainage system. Taking these GIS-based data as inputs, a series of rainfall-runoff simulations were run in a real catchment located in the city of Donostia (Northern Spain) using stormwater computer models, in order to compare the flow rates and depths produced by a design storm before and after installing SuDS. The proposed methodology overcomes the lack of precision found in former GIS-based stormwater approaches when dealing with the modeling of highly urbanized catchments, while the results demonstrated the usefulness of these systems in reducing the volume of water generated after a rainfall event and their ability to prevent localized flooding and surcharges along the sewer network.

Rainfall–Runoff Simulations to Assess the Potential of SuDS for Mitigating Flooding in Highly Urbanized Catchments

PubMed Central

Jato-Espino, Daniel; Charlesworth, Susanne M.; Bayon, Joseba R.; Warwick, Frank

2016-01-01

Sustainable Urban Drainage Systems (SuDS) constitute an alternative to conventional drainage when managing stormwater in cities, reducing the impact of urbanization by decreasing the amount of runoff generated by a rainfall event. This paper shows the potential benefits of installing different types of SuDS in preventing flooding in comparison with the common urban drainage strategies consisting of sewer networks of manholes and pipes. The impact of these systems on urban water was studied using Geographic Information Systems (GIS), which are useful tools when both delineating catchments and parameterizing the elements that define a stormwater drainage system. Taking these GIS-based data as inputs, a series of rainfall–runoff simulations were run in a real catchment located in the city of Donostia (Northern Spain) using stormwater computer models, in order to compare the flow rates and depths produced by a design storm before and after installing SuDS. The proposed methodology overcomes the lack of precision found in former GIS-based stormwater approaches when dealing with the modeling of highly urbanized catchments, while the results demonstrated the usefulness of these systems in reducing the volume of water generated after a rainfall event and their ability to prevent localized flooding and surcharges along the sewer network. PMID:26805864

Hydrologic data for urban studies in the Houston, Texas, metropolitan area, 1979

USGS Publications Warehouse

Liscum, Fred; Weigel, Jay F.; Bruchmiller, J.P.

1982-01-01

Hydrologic investigations of urban watersheds in Texas were begun by the U.S. Geological Survey in 1954. Studies are now in progress in Austin, Houston, and San Antonio.The U.S. Geological Survey, in cooperation with the city of Houston, began studies in the Houston metropolitan area in 1964. The program was expanded in 1968 to include collection of water-quality data. The objectives of the Houston urban-hydrology study are as follows:To determine, on the basis of historical data and hydro!ogic analyses, the magnitude and frequency of flood peaks and flood volumes.To determine the effect of urban development on flood peaks and volumes.To ascertain the variation in water quality for different flow conditions and different seasons.This report, the sixteenth in a series of reports to be published annually, is primarily applicable to objective 2. The report presents hydro!ogic data collected in the Houston urban area for the 1979 water year (October 1, 1978 to September 30, 1979).A report by Johnson and Sayre (1973) utilized records collected from 1965 to 1969 to make a study of the effects of urbanization on floods in the Houston area. The report also summarizes various basin parameters. A report by Waddell, Massey, and Jennings (1979) presents data on computed runoff from the Houston area and computed concentrations and loads of selected waterquality constituents combined in the inflow to Galveston Bay. The study utilized a variation of the "STORM" model developed by the Hydro!ogic Engineering Center of the U.S. Army Corps of Engineers. A report prepared by Li scum and Massey (1980) presents a technique for estimating the magnitude and frequency of floods in the Houston area from drainage areas, bank-full conveyance, and percentage of urban development.A definition of terms related to streamflow, water quality, and other hydrologic data, as used in this report, are defined in "U.S. Geological Survey, Water-resources data for Texas, volume 2, 1979."To facilitate the publication and distribution of this report at the earliest feasible time, some material has been included that does not conform to the formal publications standards of the U.S. Geological Survey. 

Urban ecosystem services for resilience planning and management in New York City.

PubMed

McPhearson, Timon; Hamstead, Zoé A; Kremer, Peleg

2014-05-01

We review the current state of knowledge about urban ecosystem services in New York City (NYC) and how these services are regulated, planned for, and managed. Focusing on ecosystem services that have presented challenges in NYC-including stormwater quality enhancement and flood control, drinking water quality, food provisioning and recreation-we find that mismatches between the scale of production and scale of management occur where service provision is insufficient. Adequate production of locally produced services and services which are more accessible when produced locally is challenging in the context of dense urban development that is characteristic of NYC. Management approaches are needed to address scale mismatches in the production and consumption of ecosystem services. By coordinating along multiple scales of management and promoting best management practices, urban leaders have an opportunity to ensure that nature and ecosystem processes are protected in cities to support the delivery of fundamental urban ecosystem services.

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/

Evaluating relationships between natural resource management, land use changes, and flooding in the Appalachian region

Treesearch

Nicolas P. Zegre; Samuel J. Lamont

2013-01-01

Th e Appalachian Region has a long history of natural resource management and recurrent history of frequent and large-scale floods. Land use activities such as urbanization, mining, forest harvesting, and agriculture can have a noticeable effect on the volume, magnitude, timing, and frequency of floods. Determining the effects of land use on flooding is difficult for...

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.

Comparison of the 2-, 25-, and 100-year recurrence interval floods computed from observed data with the 1995 urban flood-frequency estimating equations for Georgia

USGS Publications Warehouse

Inman, Ernest J.

1997-01-01

Flood-frequency relations were computed for 28 urban stations, for 2-, 25-, and 100-year recurrence interval floods and the computations were compared to corresponding recurrence interval floods computed from the estimating equations from a 1995 investigation. Two stations were excluded from further comparisons or analyses because neither station had a significant flood during the period of observed record. The comparisons, based on the student's t-test statistics at the 0.05 level of significance, indicate that the mean residuals of the 25- and 100-year floods were negatively biased by 26.2 percent and 31.6 percent, respectively, at the 26 stations. However, the mean residuals of the 2-year floods were 2.5 percent lower than the mean of the 2-year floods computed from the equations, and were not significantly biased. The reason for this negative bias is that the period of observed record at the 26 stations was a relatively dry period. At 25 of the 26 stations, the two highest simulated peaks used to develop the estimating equations occurred many years before the observed record began. However, no attempt was made to adjust the estimating equations because higher peaks could occur after the period of observed record and an adjustment to the equations would cause an underestimation of design floods.

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.

Optimization of storage tank locations in an urban stormwater drainage system using a two-stage approach.

PubMed

Wang, Mingming; Sun, Yuanxiang; Sweetapple, Chris

2017-12-15

Storage is important for flood mitigation and non-point source pollution control. However, to seek a cost-effective design scheme for storage tanks is very complex. This paper presents a two-stage optimization framework to find an optimal scheme for storage tanks using storm water management model (SWMM). The objectives are to minimize flooding, total suspended solids (TSS) load and storage cost. The framework includes two modules: (i) the analytical module, which evaluates and ranks the flooding nodes with the analytic hierarchy process (AHP) using two indicators (flood depth and flood duration), and then obtains the preliminary scheme by calculating two efficiency indicators (flood reduction efficiency and TSS reduction efficiency); (ii) the iteration module, which obtains an optimal scheme using a generalized pattern search (GPS) method based on the preliminary scheme generated by the analytical module. The proposed approach was applied to a catchment in CZ city, China, to test its capability in choosing design alternatives. Different rainfall scenarios are considered to test its robustness. The results demonstrate that the optimal framework is feasible, and the optimization is fast based on the preliminary scheme. The optimized scheme is better than the preliminary scheme for reducing runoff and pollutant loads under a given storage cost. The multi-objective optimization framework presented in this paper may be useful in finding the best scheme of storage tanks or low impact development (LID) controls. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

24 CFR 3285.102 - Installation of manufactured homes in flood hazard areas.

Code of Federal Regulations, 2010 CFR

2010-04-01

... HOUSING COMMISSIONER, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Pre-Installation Considerations § 3285.102 Installation of manufactured homes in flood hazard...

24 CFR 3285.102 - Installation of manufactured homes in flood hazard areas.

Code of Federal Regulations, 2011 CFR

2011-04-01

... HOUSING COMMISSIONER, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Pre-Installation Considerations § 3285.102 Installation of manufactured homes in flood hazard...

24 CFR 3285.102 - Installation of manufactured homes in flood hazard areas.

Code of Federal Regulations, 2012 CFR

2012-04-01

... HOUSING COMMISSIONER, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Pre-Installation Considerations § 3285.102 Installation of manufactured homes in flood hazard...

Water turbidity detection using ERTS-1 imagery

NASA Technical Reports Server (NTRS)

Yarger, H. L.; Mccauley, J. R.; James, G. W.; Magnuson, L. M.; Marzolf, G. R.

1973-01-01

ERTS-1 images of two federal reservoirs in Kansas exhibit good correlation with suspended load. The major reservoirs in Kansas, as well as in other Great Plains states, are playing increasingly important roles in flood control, recreation, agriculture, and urban water supply. Satellite imagery may prove useful for acquiring timely low cost water quality data required for optimum management of these fresh water resources.

Assessing the performances of low impact development alternatives by long-term simulation for a semi-arid area in Tianjin, northern China.

PubMed

Huang, Jinhui Jeanne; Li, Yu; Niu, Shuai; Zhou, Shu H

2014-01-01

For areas that are urbanized rapidly, the practice of low impact development (LID) has gained an important place in stormwater management and urban planning due to its capability and beneficial effects in restoring the original hydrological cycle. The performances of LID alternatives can vary substantially due to different climate conditions. This study investigated the performances of five LID alternatives under a semi-arid climate in northern China on water balance and flood control. A numerical model, Storm Water Management Model version 5 (US Environmental Protection Agency), was employed to run 10 years' rainfall events for these objectives. Two evaluation methods were proposed in this study: the efficiency index for water balance and a performance radar chart. The investigation of the five LID alternatives revealed that these LID alternatives functioned differently in flood control and water balance, and porous pavement performed best in all indices except the lag time. The two evaluation methods, in conjunction with the long-term numerical simulation, can facilitate design and decision making by providing a clear picture of the performance and functions for these LID alternatives.

A hydro-meteorological ensemble prediction system for real-time flood forecasting purposes in the Milano area

NASA Astrophysics Data System (ADS)

Ravazzani, Giovanni; Amengual, Arnau; Ceppi, Alessandro; Romero, Romualdo; Homar, Victor; Mancini, Marco

2015-04-01

Analysis of forecasting strategies that can provide a tangible basis for flood early warning procedures and mitigation measures over the Western Mediterranean region is one of the fundamental motivations of the European HyMeX programme. Here, we examine a set of hydro-meteorological episodes that affected the Milano urban area for which the complex flood protection system of the city did not completely succeed before the occurred flash-floods. Indeed, flood damages have exponentially increased in the area 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. The flood forecasting system tested in this work comprises the Flash-flood Event-based Spatially distributed rainfall-runoff Transformation, including Water Balance (FEST-WB) and the Weather Research and Forecasting (WRF) models, in order to provide a hydrological ensemble prediction system (HEPS). Deterministic and probabilistic quantitative precipitation forecasts (QPFs) have been provided by WRF model in a set of 48-hours experiments. HEPS has been generated by combining different physical parameterizations (i.e. cloud microphysics, moist convection and boundary-layer schemes) of the WRF model in order to better encompass the atmospheric processes leading to high precipitation amounts. We have been able to test the value of a probabilistic versus a deterministic framework when driving Quantitative Discharge Forecasts (QDFs). Results highlight (i) the benefits of using a high-resolution HEPS in conveying uncertainties for this complex orographic area and (ii) a better simulation of the most of extreme precipitation events, potentially enabling valuable probabilistic QDFs. Hence, the HEPS copes with the significant deficiencies found in the deterministic QPFs. These shortcomings would prevent to correctly forecast the location and timing of high precipitation rates and total amounts at the catchment scale, thus impacting heavily the deterministic QDFs. In contrast, early warnings would have been possible within a HEPS context for the Milano area, proving the suitability of such system for civil protection purposes.

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?

National Program for Inspection of Non-Federal Dams. Old Quincy Reservoir Dam (MA 00827), Massachusetts-Rhode Island Coastal Basin, Braintree, Massachusetts. Phase I Inspection Report.

DTIC Science & Technology

1979-11-01

flood protection to the urban - ized area located downstream along Town Brook. The pond has a water surface area of approximately 36 acres and a storage...in a 1970 paper entitled "Effect of Urban Expansion on Hydrologic Investigations". A peak inflow rate of 1760 csm was adopted for the 1.44 sq. mi...etc. C. None. 2. Weir 2. a. Flashboards a. None. b. Weir Elev. Control (Gate) b. None. c. Vegetation c. Light brush and weeds - two trees d. Seepage or

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.

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.

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.

Unstructured meshing and parameter estimation for urban dam-break flood modeling: building treatments and implications for accuracy and efficiency

NASA Astrophysics Data System (ADS)

Schubert, J. E.; Sanders, B. F.

2011-12-01

Urban landscapes are at the forefront of current research efforts in the field of flood inundation modeling for two major reasons. First, urban areas hold relatively large economic and social importance and as such it is imperative to avoid or minimize future damages. Secondly, urban flooding is becoming more frequent as a consequence of continued development of impervious surfaces, population growth in cities, climate change magnifying rainfall intensity, sea level rise threatening coastal communities, and decaying flood defense infrastructure. In reality urban landscapes are particularly challenging to model because they include a multitude of geometrically complex features. Advances in remote sensing technologies and geographical information systems (GIS) have promulgated fine resolution data layers that offer a site characterization suitable for urban inundation modeling including a description of preferential flow paths, drainage networks and surface dependent resistances to overland flow. Recent research has focused on two-dimensional modeling of overland flow including within-curb flows and over-curb flows across developed parcels. Studies have focused on mesh design and parameterization, and sub-grid models that promise improved performance relative to accuracy and/or computational efficiency. This presentation addresses how fine-resolution data, available in Los Angeles County, are used to parameterize, initialize and execute flood inundation models for the 1963 Baldwin Hills dam break. Several commonly used model parameterization strategies including building-resistance, building-block and building hole are compared with a novel sub-grid strategy based on building-porosity. Performance of the models is assessed based on the accuracy of depth and velocity predictions, execution time, and the time and expertise required for model set-up. The objective of this study is to assess field-scale applicability, and to obtain a better understanding of advantages and drawbacks of each method, and to recommend best practices for future studies. The Baldwin Hills dam-break flood is interesting for a couple of reasons. First, the flood caused high velocity, rapidly varied flow through a residential neighborhood and extensive damage to dozens residential structures. These conditions pose a challenge for many numerical models, the test is a rigorous one. Second, previous research has shown that flood extent predictions are sensitive to topographic data and stream flow predictions are sensitive to resistance parameters. Given that the representation of buildings affects the modeling of topography and resistance, a sensitivity to the representation of buildings is expected. Lastly, the site is supported by excellent geospatial data including validation datasets, and is made available through the Los Angeles County Imagery Acquisition Consortium (LAR-IAC), a joint effort of many public agencies in Los Angeles County to provide county-wide data. Hence, a broader aim of this study is to characterize the most useful aspects of the LAR-IAC data from a flood mapping perspective.

Urbanization Impacts on Flooding in the Kansas River Basin and Evaluation of Wetlands as a Mitigation Measure

EPA Science Inventory

This study evaluates the impacts of future land use changes on flooding in the Kansas River Basin. It also studies the impacts of wetlands on flood reduction. The study presents Hydrologic Engineering Centers-Hydrologic Modeling System (HEC-HMS) based runoff modeling and River A...

Climate-Related Hazards: A Method for Global Assessment of Urban and Rural Population Exposure to Cyclones, Droughts, and Floods

PubMed Central

Christenson, Elizabeth; Elliott, Mark; Banerjee, Ovik; Hamrick, Laura; Bartram, Jamie

2014-01-01

Global climate change (GCC) has led to increased focus on the occurrence of, and preparation for, climate-related extremes and hazards. Population exposure, the relative likelihood that a person in a given location was exposed to a given hazard event(s) in a given period of time, was the outcome for this analysis. Our objectives were to develop a method for estimating the population exposure at the country level to the climate-related hazards cyclone, drought, and flood; develop a method that readily allows the addition of better datasets to an automated model; differentiate population exposure of urban and rural populations; and calculate and present the results of exposure scores and ranking of countries based on the country-wide, urban, and rural population exposures to cyclone, drought, and flood. Gridded global datasets on cyclone, drought and flood occurrence as well as population density were combined and analysis was carried out using ArcGIS. Results presented include global maps of ranked country-level population exposure to cyclone, drought, flood and multiple hazards. Analyses by geography and human development index (HDI) are also included. The results and analyses of this exposure assessment have implications for country-level adaptation. It can also be used to help prioritize aid decisions and allocation of adaptation resources between countries and within a country. This model is designed to allow flexibility in applying cyclone, drought and flood exposure to a range of outcomes and adaptation measures. PMID:24566046

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.

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 new survey tool to assess pluvial damage to residential buildings

NASA Astrophysics Data System (ADS)

Rözer, Viktor; Spekkers, Matthieu; ten Veldhuis, Marie-Claire; Kreibich, Heidi

2017-04-01

Pluvial floods have caused severe damage to urban dwellings in Europe and elsewhere in recent years. These type of flood events are caused by storm events with exceptionally high rainfall rates, which lead to inundation of streets and buildings and are commonly associated with a failure of the urban drainage system. Therefore, pluvial floods often happen with little warning and in areas that are not obviously prone to flooding. With a predicted increase in extreme weather events as well as an ongoing urbanization, pluvial flood damage is expected to increase in the future. So far little research was done on the adverse consequences of pluvial floods, as empirical damage data of pluvial flooding is scarce. Therefore, a newly developed survey tool to assess pluvial flood damage as well as the results of a comparison between two international pluvial flood case studies are presented. The questionnaire used in the two study areas was developed with the aim to create a harmonized transnational pluvial flood damage survey that can potentially be extended to other European countries. New indicator variables have been developed to account for different national and regional standards in building structure, early warning, socio-economic data and recovery. The surveys comprise interviews with 510 households in the Münster area (Germany) and 349 households in Amsterdam (the Netherlands), which were affected by the heavy rainfall events on July 28 2014. The respondents were asked more than 80 questions about the damage to their building structure and contents, as well as on topics such as early warning, emergency and precautionary measures, building properties and hazard characteristics. A comparison of the two surveys revealed strong similarities concerning damage reducing effects and the popularity of precautionary measures, besides significant differences between the mean water levels inside the house as well as the median of the building structure and content damage. A comparison between the relative damage contributions for different entry points of water into the house indicates an effect of regional distinctions in building topology on the total damage. The results of this comparison give important insights for the development and transferability of pluvial flood damage models.

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.

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.

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.

A national scale flood hazard mapping methodology: The case of Greece - Protection and adaptation policy approaches.

PubMed

Kourgialas, Nektarios N; Karatzas, George P

2017-12-01

The present work introduces a national scale flood hazard assessment methodology, using multi-criteria analysis and artificial neural networks (ANNs) techniques in a GIS environment. The proposed methodology was applied in Greece, where flash floods are a relatively frequent phenomenon and it has become more intense over the last decades, causing significant damages in rural and urban sectors. In order the most prone flooding areas to be identified, seven factor-maps (that are directly related to flood generation) were combined in a GIS environment. These factor-maps are: a) the Flow accumulation (F), b) the Land use (L), c) the Altitude (A), b) the Slope (S), e) the soil Erodibility (E), f) the Rainfall intensity (R), and g) the available water Capacity (C). The name to the proposed method is "FLASERC". The flood hazard for each one of these factors is classified into five categories: Very low, low, moderate, high, and very high. The above factors are combined and processed using the appropriate ANN algorithm tool. For the ANN training process spatial distribution of historical flooded points in Greece within the five different flood hazard categories of the aforementioned seven factor-maps were combined. In this way, the overall flood hazard map for Greece was determined. The final results are verified using additional historical flood events that have occurred in Greece over the last 100years. In addition, an overview of flood protection measures and adaptation policy approaches were proposed for agricultural and urban areas located at very high flood hazard areas. Copyright © 2017 Elsevier B.V. All rights reserved.

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

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,...

Water in the Balance: A Parking Lot Story

NASA Astrophysics Data System (ADS)

Haas, N. A.; Vitousek, S.

2017-12-01

The greater Chicagoland region has seen a high degree of urbanization since 1970. For example, between 1970-1990 the region experienced 4% population growth, a 35% increase in urban land use, and approximately 454 square miles of agricultural land was mostly converted into urban uses. Transformation of land into urban uses in the Chicagoland region has altered the stream and catchment response to rainfall events, specifically an increase in stream flashiness and increase in urban flooding. Chicago has begun to address these changes through green infrastructure. To understand the impact of green infrastructure at local, city-wide, and watershed scales, individual projects need to be accurately and sufficiently modeled. A traditional parking lot conversion into a porous parking lot at the University of Illinois at Chicago was modeled using SWMM and scrutinized using field data to look at stormwater runoff and water balance prior and post reconstruction. SWMM modeling suggested an 87% reduction in peak flow as well as a 100% reduction in flooding for a 24 hour, 1.72-inch storm. For the same storm, field data suggest an 89% reduction in peak flow as well as a 100% reduction in flooding. Modeling suggested 100% reductions in flooding for longer duration storms (24 hour+) and a smaller reduction in peak flow ( 66%). The highly parameterized SWMM model agrees well with collected data and analysis. Further effort is being made to use data mining to create correlations within the collected datasets that can be integrated into a model that follows a standardized formation process and reduces parameterization.

The Dallas-Fort Worth (DFW) Urban Radar Network: Enhancing Resilience in the Presence of Floods, Tornadoes, Hail and High Winds

NASA Astrophysics Data System (ADS)

Chandra*, Chandrasekar V.; the full DFW Team

2015-04-01

Currently, the National Weather Service (NWS) Next Generation Weather Radar (NEXRAD) provides observations updated every five-six minutes across the United States. However, at the maximum NEXRAD operating range of 230 km, the 0.5 degree radar beam (lowest tilt) height is about 5.4 km above ground level (AGL) because of the effect of Earth curvature. Consequently, much of the lower atmosphere (1-3 km AGL) cannot be observed by the NEXRAD. To overcome the fundamental coverage limitations of today's weather surveillance radars, and improve the spatial and temporal resolution issues, at urban scale, the National Science Foundation Engineering Research Center (NSF-ERC) for Collaborative Adaptive Sensing of the Atmosphere (CASA) has embarked the development of Dallas-Fort worth (DFW) urban remote sensing network to conduct high-resolution sensing in the lower atmosphere for a metropolitan environment, communicate high resolution observations and nowcasting of severe weather including flash floods, hail storms and high wind events. Being one of the largest inland metropolitan areas in the U.S., the DFW Metroplex is home to over 6.5 million people by 2012 according to the North Central Texas Council of Governments (NCTCOG). It experiences a wide range of natural weather hazards, including urban flash flood, high wind, tornado, and hail, etc. Successful monitoring of the rapid changing meteorological conditions in such a region is necessary for emergency management and decision making. Therefore, it is an ideal location to investigate the impacts of hazardous weather phenomena, to enhance resilience in an urban setting and demonstrate the CASA concept in a densely populated urban environment. The DFW radar network consists of 8 dual-polarization X-band weather radars and standard NEXRAD S-band radar, covering the greater DFW metropolitan region. This paper will present high resolution observation of tornado, urban flood, hail storm and damaging wind event all within the city.

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.

Hydrology Analysis and Modelling for Klang River Basin Flood Hazard Map

NASA Astrophysics Data System (ADS)

Sidek, L. M.; Rostam, N. E.; Hidayah, B.; Roseli, ZA; Majid, W. H. A. W. A.; Zahari, N. Z.; Salleh, S. H. M.; Ahmad, R. D. R.; Ahmad, M. N.

2016-03-01

Flooding, a common environmental hazard worldwide has in recent times, increased as a result of climate change and urbanization with the effects felt more in developing countries. As a result, the explosive of flooding to Tenaga Nasional Berhad (TNB) substation is increased rapidly due to existing substations are located in flood prone area. By understanding the impact of flood to their substation, TNB has provided the non-structure mitigation with the integration of Flood Hazard Map with their substation. Hydrology analysis is the important part in providing runoff as the input for the hydraulic part.

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.

Impacts of Urbanization on Flood and Soil Erosion Hazards in Istanbul, Turkey

ERIC Educational Resources Information Center

Ozacar, Biricik Gozde

2013-01-01

Due to the inappropriate planning and explosive population growth in urban areas, especially in developing countries, sustainable and disaster-safe urbanization has become the most important challenge for governments. Urbanization presents benefits in different ways but has led simultaneously to changes in land use/land cover (LULC), impacting…

Torrential floods and town and country planning in Serbia

NASA Astrophysics Data System (ADS)

Ristić, R.; Kostadinov, S.; Abolmasov, B.; Dragićević, S.; Trivan, G.; Radić, B.; Trifunović, M.; Radosavljević, Z.

2012-01-01

Torrential floods are the most frequent natural catastrophic events in Serbia, causing the loss of human lives and huge material damage, both in urban and rural areas. The analysis of the intra-annual distribution of maximal discharges aided in noticing that torrential floods have a seasonal character. The erosion and torrent control works (ETCWs) in Serbia began at the end of the 19th century. Effective protection from torrential floods encompasses biotechnical works on the slopes in the watershed and technical works on the torrent beds, within a precisely defined administrative and spatial framework in order to achieve maximal safety for people and their property. Cooperation to overcome the conflicts between the sectors of the water resources management, forestry, agriculture, energetics, environmental protection and local economic development groups is indispensable at the following levels: policy, spatial planning, practice, investments and education. The lowest and most effective level is through the Plans for Announcement of Erosive Regions (PAERs) and the Plans for Protection from Torrential Floods (PPTFs), with Hazard Zones (HZs) and Threatened Areas (TAs) mapping on the basis of the hydrologic, hydraulic and spatial analysis of the factors that are important for the formation of torrential floods. Solutions defined through PAERs and PPTFs have to be integrated into Spatial Plans at local and regional levels.

Integrated Framework for an Urban Climate Adaptation Tool

NASA Astrophysics Data System (ADS)

Omitaomu, O.; Parish, E. S.; Nugent, P.; Mei, R.; Sylvester, L.; Ernst, K.; Absar, M.

2015-12-01

Cities have an opportunity to become more resilient to future climate change through investments made in urban infrastructure today. However, most cities lack access to credible high-resolution climate change projection information needed to assess and address potential vulnerabilities from future climate variability. Therefore, we present an integrated framework for developing an urban climate adaptation tool (Urban-CAT). Urban-CAT consists of four modules. Firstly, it provides climate projections at different spatial resolutions for quantifying urban landscape. Secondly, this projected data is combined with socio-economic data using leading and lagging indicators for assessing landscape vulnerability to climate extremes (e.g., urban flooding). Thirdly, a neighborhood scale modeling approach is presented for identifying candidate areas for adaptation strategies (e.g., green infrastructure as an adaptation strategy for urban flooding). Finally, all these capabilities are made available as a web-based tool to support decision-making and communication at the neighborhood and city levels. In this paper, we present some of the methods that drive each of the modules and demo some of the capabilities available to-date using the City of Knoxville in Tennessee as a case study.

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.

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.

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.

Magnitude and frequency of flooding on small urban watersheds in the Tampa Bay area, west-central Florida

USGS Publications Warehouse

Lopez, M.A.; Woodham, W.M.

1983-01-01

Hydrologic data collected on nine small urban watersheds in the Tampa Bay area of west-central Florida and a method for estimating peak discharges in the study area are described. The watersheds have mixed land use and range in size from 0.34 to 3.45 square miles. Watershed soils, land use, and storm-drainage system data are described. Urban development ranged from a sparsely populated area with open-ditch storm sewers and 19% impervious area to a completely sewered watershed with 61% impervious cover. The U.S. Geological Survey natural-basin and urban-watershed models were calibrated for the nine watersheds using 5-minute interval rainfall data from the Tampa, Florida, National Weather Service rain gage to simulate annual peak discharge for the period 1906-52. A log-Pearson Type III frequency analysis of the simulated annual maximum discharge was used to determine the 2-, 5-, 10-, 25-, 50-, and 100-year flood discharges for each watershed. Flood discharges were related in a multiple-linear regression to drainage area, channel slope, detention storage area, and an urban-development factor determined by the extent of curb and gutter street drainage and storm-sewer system. The average standard error for the regional relations ranged from + or - 32 to + or - 42%. (USGS)

Management of Urban Stormwater Runoff in the Chesapeake Bay Watershed

USGS Publications Warehouse

Hogan, Dianna M.

2008-01-01

Urban and suburban development is associated with elevated nutrients, sediment, and other pollutants in stormwater runoff, impacting the physical and environmental health of area streams and downstream water bodies such as the Chesapeake Bay. Stormwater management facilities, also known as Best Management Practices (BMPs), are increasingly being used in urban areas to replace functions, such as flood protection and water quality improvement, originally performed by wetlands and riparian areas. Scientists from the U.S. Geological Survey (USGS) have partnered with local, academic, and other Federal agency scientists to better understand the effectiveness of different stormwater management systems with respect to Chesapeake Bay health. Management of stormwater runoff is necessary in urban areas to address flooding and water quality concerns. Improving our understanding of what stormwater management actions may be best suited for different types of developed areas could help protect the environmental health of downstream water bodies that ultimately receive runoff from urban landscapes.

Water in urban planning, Salt Creek Basin, Illinois water management as related to alternative land-use practices

USGS Publications Warehouse

Spieker, Andrew Maute

1970-01-01

Water management can be an integral part of urban comprehensive planning in a large metropolitan area. Water both imposes constraints on land use and offers opportunities for coordinated land and water management. Salt Creek basin in Cook and Du Page Counties of the Chicago metropolitan area is typical of rapidly developing suburban areas and has been selected to illustrate some of these constraints and opportunities and to suggest the effects of alternative solutions. The present study concentrates on the related problems of ground-water recharge, water quality, management of flood plains, and flood-control measures. Salt Creek basin has a drainage area of 150 square miles. It is in flat to. gently rolling terrain, underlain by glacial drift as much as 200 feet thick which covers a dolomite aquifer. In 1964, the population of the basin was about 400,000, and 40 percent of the land was in urban development. The population is expected to number 550,000 to 650,000 by 1990, and most of the land will be taken by urban development. Salt Creek is a sluggish stream, typical of small drainage channels in the headwaters area of northeastern Illinois. Low flows of 15 to 25 cubic feet per second in the lower part of the basin consist largely of sewage effluent. Nearly all the public water supplies in the basin depend on ground water. Of the total pumpage of 27.5 million gallons per day, 17.5 million gallons per day is pumped from the deep (Cambrian-Ordovician) aquifers and 10 million gallons per day is pumped from the shallow (Silurian dolomite and glacial drift) aquifers. The potential yield of the shallow aquifers, particularly glacial drift in the northern part of the basin, far exceeds present use. The largest concentration of pumpage from the shallow ,aquifers is in the Hinsdale-La Grange area. Salt Creek serves as an important source of recharge to these supplies, particularly just east of Hinsdale. The entire reach of Salt Creek south and east of Elmhurst can be regarded as an area of potential recharge to the shallow aquifers. Preservation of the effectiveness of these potential recharge areas should be considered in land-use planning. Salt Creek is polluted in times of both low and high flow. Most communities in the basin in Du Page County discharge their treated sewage into the creek, whereas those in Cook County transfer their sewage to plants of the Metropolitan Sanitary District outside the basin. During periods of high runoff, combined storm runoff and overflow from sanitary sewers enter the creek. Such polluted water detracts from the stream's esthetic and recreational potential and poses a threat to ground-water supplies owing to induced recharge of polluted water to shallow aquifers. Alternative approaches .to the pollution problem include improvement of the degree of sewage treatment, detention and treatment of storm runoff, dilution of sewage through flow augmentation, or transfer of sewage from the basin to a central treatment plant. To result in an enhanced environment, the streambed would have to be cleansed of accumulated sludge deposits. The overbank flooding in Salt Creek basin every 2 to 3 years presents problems because of encroachments and developments on the flood plains. Flood plains in an urban area can be managed by identifying them, by recognizing that either their natural storage capacity or equivalent artificial capacity is needed to accommodate floods, and by planning land use accordingly. Examples of effective floodplain management include (1) preservation of greenbelts or regional parks along stream courses, (2) use of flood plains for recreation, parking lots. or other low-intensity uses, (3) use of flood-proofed commercial buildings, and (4) provision for compensatory storage to replace natural storage capacity. Results of poor flood-plain management include uncontrolled residential development and encroachment by fill into natural storage areas where no compensatory storage has been

Identifying heavy metal levels in historical flood water deposits using sediment cores.

PubMed

Lintern, Anna; Leahy, Paul J; Heijnis, Henk; Zawadzki, Atun; Gadd, Patricia; Jacobsen, Geraldine; Deletic, Ana; Mccarthy, David T

2016-11-15

When designing mitigation and restoration strategies for aquatic systems affected by heavy metal contamination, we must first understand the sources of these pollutants. In this study, we introduce a methodology that identifies the heavy metal levels in floodplain lake sediments deposited by one source; fluvial floods. This is done by comparing sediment core heavy metal profiles (i.e., historical pollution trends) to physical and chemical properties of sediments in these cores (i.e., historical flooding trends). This methodology is applied to Willsmere and Bolin Billabongs, two urban floodplain lakes (billabongs) of the Yarra River (South-East Australia). Both billabongs are periodically inundated by flooding of the Yarra River and one billabong (Willsmere Billabong) is connected to an urban stormwater drainage network. 1-2-m long sediment cores (containing sediment deposits up to 500 years old) were taken from the billabongs and analysed for heavy metal concentrations (arsenic, chromium, copper, lead, nickel, zinc). In cores from both billabongs, arsenic concentrations are high in the flood-borne sediments. In Bolin Billabong, absolute metal levels are similar in flood and non-flood deposits. In Willsmere Billabong, absolute copper, lead and zinc levels were generally lower in fluvial flood-borne sediments in the core compared to non-fluvial sediments. This suggests that heavy metal concentrations in Bolin Billabong sediments are relatively similar regardless of whether or not fluvial flooding is occurring. However for Willsmere Billabong, heavy metal concentrations are high when overland runoff, direct urban stormwater discharges or atmospheric deposition is occurring. As such, reducing the heavy metal concentrations in these transport pathways will be of great importance when trying to reduce heavy metal concentrations in Willsmere Billabong sediments. This study presents a proof-of-concept that can be applied to other polluted aquatic systems, to understand the importance of river floods in the contamination of the bed sediments of aquatic systems. As a cost effective and less time consuming alternative to extensive field monitoring, our proposed method can be used to identify the key sources of pollution and therefore support the development of effective management strategies. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

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.

Genesis of the City Flood Queretaro

NASA Astrophysics Data System (ADS)

Sosa, E. G.; Salinas, N. R.

2013-12-01

In 1446 the emperor Moctezuma Ihuicamina talked about of the Queretaro region, which was northern border of their empire (From Torquemeda, 1975). Septien (1999, page 17, Volume 1). "The news that came the Otomi region, spoken the good soil fertility of the Querétaro valley, being an attractive to this place". The aims research is show how the from foundation of the prehispanic period the city of Santiago Queretaro was marked by the development and growth, and as fascinating Mexico historical events recorded their urban-hydraulic direction shows a clear symbiosis between the model prehispanic and colonial urban was conceived it as a compact core, it is currently set to modern urbanization, fragmenting the natural system of the hydrologic surface runoff , adapting and adopting solutions that break the natural equilibrium of the valley Queretaro. In the period 1970-2003 in Mexico 1744 floods was reported but in Queretaro occurred only 10 floods because in 22nd place ranking by frequency of floods, Matias Ramirez et al (2006). Since the foundation of Santiago de Querétaro (1455) the changes of uses soils and the construction of channels had caused the strangulation of city, without regarding the natural of the ways of water of the river Querétaro, so occupied by collectors or drains that also constriction the system of urban water of city of Queretaro that breakdowns with the architecture and natural ways of water. Similarly, historical tracking flooding is not only an exploration of public actions on the implementation of protection works, but also updates the concept of cultural heritage, as fixed and cultivates social memory of the preservation of knowledge the territory. Every time a flood comes increasing concern of whether it corresponds to situations already lived. The flood occurred last February 2010 that affected five delegations besides Querétaro Historic Center (Alameda), the Arquitos, Quintas del Marques, among other colonies, is testimony to the current reality of a long history that continues altering the cultural heritage Queretaro and Mexico (Diario de Querétaro, February 3, 2010).

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.

Hydrological Modeling of Storm Water Drainage System due to Frequent and Intense Precipitation of Dhaka city using Storm Water Management Model (SWMM)

NASA Astrophysics Data System (ADS)

Hossain, S., Jr.

2015-12-01

Rainfall induced flooding during rainy season is a regular phenomenon in Dhaka City. Almost every year a significant part of the city suffers badly with drainage congestion. There are some highly dense areas with lower ground elevation which submerge under water even with an intense precipitation of few hours. The higher areas also suffer with the drainage problem due to inadequate maintenance of the system and encroachment or illegal filling up of the drainage canals and lakes. Most part of the city suffered from long term urban flooding during historical extreme rainfall events in September 2004, 2007 and July 2009. The situation is likely to worsen in the future due to Climate Change, which may lead to more frequent and intense precipitation. To assess the major and minor drainage systems and elements of the urban basins using the hydrodynamic modelling and, through this, identifying the flooding events and areas, taking into account the current situation and future flood or drainage scenarios. Stormwater modeling has a major role in preventing issues such as flash floods and urban water-quality problems. Stormwater models of a lowered spatial resolution would thus appear valuable if only their ability to provide realistic results could be proved. The present scenario of urban morphology of Dhaka city and existing drainage system is complex for hydrological and hydrodynamic modeling. Furthermore limitations of background data and uncertain future urban scenarios may confine the potential outputs of a model. Although several studies were carried out including modeling for drainage master planning, a detail model for whole DAP (Detaile Area Plan) of Dhaka city area is not available. The model developed under this study is covering the existing drainage system in the study area as well as natural flows in the fringe area. A good number of models are available for hydrological and hydraulic analysis of urban areas. These are MIKE 11, MOUSE, HEC-RAS, HEC HMS and EPA SWMM. EPA-SWMM is used for the study area which is mostly developed and consists pipe networks, open channels and water bodies. This study proposes a methodology for rapid catchment delineation and stormwater management model (SWMM) set-up in a large urban area with model calibration and validation.

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.

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.

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.

An application of the distributed hydrologic model CASC2D to a tropical montane watershed

NASA Astrophysics Data System (ADS)

Marsik, Matt; Waylen, Peter

2006-11-01

SummaryIncreased stormflow in the Quebrada Estero watershed (2.5 km 2), in the northwestern Central Valley tectonic depression of Costa Rica, reportedly has caused flooding of the city of San Ramón in recent decades. Although scientifically untested, urban expansion was deemed the cause and remedial measures were recommended by the Programa de Investigación en Desarrollo Humano Sostenible (ProDUS). CASC2D, a physically-based, spatially explicit hydrologic model, was constructed and calibrated to a June 10th 2002 storm that delivered 110.5 mm of precipitation in 4.5 h visibly exceeded the bankfull stage (0.9 m) of the Quebrada flooding portions of San Ramón. The calibrated hydrograph showed a peak discharge 16.68% (2.5 m 3 s -1) higher, an above flood stage duration 20% shorter, and time to peak discharge 11 min later than the same observed discharge hydrograph characteristics. Simulations of changing land cover conditions from 1979 to 1999 showed an increase also in the peak discharge, above flood stage duration, and time to peak discharge. Analysis using a modified location quotient identified increased urbanization in lower portions of the watershed over the time period studied. These results suggest that increased urbanization in the Quebrada Estero watershed have increased flooding peaks, and durations above threshold, confirming the ProDUS report. These results and the CASC2D model offer an easy-to-use, pragmatic planning tool for policymakers in San Ramón to assess future development scenarios and their potential flooding impacts to San Ramón.

A Study on Estimation on Flood Warning Trigger Rainfall in medium and small Stream Affected by Urban Effects

NASA Astrophysics Data System (ADS)

Youngseok, Song; Moojong, Park; JungHo, Lee; HeeSup, Lee

2013-04-01

As extreme floods occur frequently in recent years due to global climate changes, an in sudden local flooding of great volume and short duration is becoming the significant danger and loss of life and property in the Korean Peninsula as well as most parts of the world. The desire for living without hazardous damages grows these days, the city strategy to make the safer community has become an issue. Previously most of flood prevention efforts have been made for relatively large watersheds near to channel flow. However, as economical development and the expansion of city near medium and small stream, human casualty and property by flood occurs frequently. Therefore, to reduce the damage of human lives and property by flood, we develop an assessment method for flood warning trigger rainfall considering urban effect. Considering complex land use, HEC-HMS is used for rural area and SWMM is adopted for sewer networks runoff. And relationship between runoff and stream water level, HEC-RAS is accompanied with runoff results. Proposed flood warning trigger rainfall assessment method shows good agreement with gauged data and could be used for another case to mitigate damage. 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." Keyword: HEC-HMS, HEC-RAS, critical precipitation, medium and small stream

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.

A bill to amend the National Flood Insurance Act of 1968 to require the Administrator of the Federal Emergency Management Agency to consider reconstruction and improvement of flood protection systems when establishing flood insurance rates.

THOMAS, 112th Congress

Sen. Feinstein, Dianne [D-CA

2011-06-28

Senate - 06/28/2011 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:

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.

Improving LUC estimation accuracy with multiple classification system for studying impact of urbanization on watershed flood

NASA Astrophysics Data System (ADS)

Dou, P.

2017-12-01

Guangzhou has experienced a rapid urbanization period called "small change in three years and big change in five years" since the reform of China, resulting in significant land use/cover changes(LUC). To overcome the disadvantages of single classifier for remote sensing image classification accuracy, a multiple classifier system (MCS) is proposed to improve the quality of remote sensing image classification. The new method combines advantages of different learning algorithms, and achieves higher accuracy (88.12%) than any single classifier did. With the proposed MCS, land use/cover (LUC) on Landsat images from 1987 to 2015 was obtained, and the LUCs were used on three watersheds (Shijing river, Chebei stream, and Shahe stream) to estimate the impact of urbanization on water flood. The results show that with the high accuracy LUC, the uncertainty in flood simulations are reduced effectively (for Shijing river, Chebei stream, and Shahe stream, the uncertainty reduced 15.5%, 17.3% and 19.8% respectively).

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.

Regression equations for estimating flood flows for the 2-, 10-, 25-, 50-, 100-, and 500-Year recurrence intervals in Connecticut

USGS Publications Warehouse

Ahearn, Elizabeth A.

2004-01-01

Multiple linear-regression equations were developed to estimate the magnitudes of floods in Connecticut for recurrence intervals ranging from 2 to 500 years. The equations can be used for nonurban, unregulated stream sites in Connecticut with drainage areas ranging from about 2 to 715 square miles. Flood-frequency data and hydrologic characteristics from 70 streamflow-gaging stations and the upstream drainage basins were used to develop the equations. The hydrologic characteristics?drainage area, mean basin elevation, and 24-hour rainfall?are used in the equations to estimate the magnitude of floods. Average standard errors of prediction for the equations are 31.8, 32.7, 34.4, 35.9, 37.6 and 45.0 percent for the 2-, 10-, 25-, 50-, 100-, and 500-year recurrence intervals, respectively. Simplified equations using only one hydrologic characteristic?drainage area?also were developed. The regression analysis is based on generalized least-squares regression techniques. Observed flows (log-Pearson Type III analysis of the annual maximum flows) from five streamflow-gaging stations in urban basins in Connecticut were compared to flows estimated from national three-parameter and seven-parameter urban regression equations. The comparison shows that the three- and seven- parameter equations used in conjunction with the new statewide equations generally provide reasonable estimates of flood flows for urban sites in Connecticut, although a national urban flood-frequency study indicated that the three-parameter equations significantly underestimated flood flows in many regions of the country. Verification of the accuracy of the three-parameter or seven-parameter national regression equations using new data from Connecticut stations was beyond the scope of this study. A technique for calculating flood flows at streamflow-gaging stations using a weighted average also is described. Two estimates of flood flows?one estimate based on the log-Pearson Type III analyses of the annual maximum flows at the gaging station, and the other estimate from the regression equation?are weighted together based on the years of record at the gaging station and the equivalent years of record value determined from the regression. Weighted averages of flood flows for the 2-, 10-, 25-, 50-, 100-, and 500-year recurrence intervals are tabulated for the 70 streamflow-gaging stations used in the regression analysis. Generally, weighted averages give the most accurate estimate of flood flows at gaging stations. An evaluation of the Connecticut's streamflow-gaging network was performed to determine whether the spatial coverage and range of geographic and hydrologic conditions are adequately represented for transferring flood characteristics from gaged to ungaged sites. Fifty-one of 54 stations in the current (2004) network support one or more flood needs of federal, state, and local agencies. Twenty-five of 54 stations in the current network are considered high-priority stations by the U.S. Geological Survey because of their contribution to the longterm understanding of floods, and their application for regionalflood analysis. Enhancements to the network to improve overall effectiveness for regionalization can be made by increasing the spatial coverage of gaging stations, establishing stations in regions of the state that are not well-represented, and adding stations in basins with drainage area sizes not represented. Additionally, the usefulness of the network for characterizing floods can be maintained and improved by continuing operation at the current stations because flood flows can be more accurately estimated at stations with continuous, long-term record.

Effects of flooding on field populations of Formosan subterranean termites (Isoptera: Rhinotermitidae) in New Orleans, Louisiana.

PubMed

Osbrink, Weste L A; Cornelius, Mary L; Lax, Alan R

2008-08-01

Hurricane Katrina (2005) resulted in extensive flooding in the city of New Orleans, LA. Periodic sampling of monitors before the flood, and of different monitors in the same areas after the flood, was used to evaluate the effects of long-term flooding on populations of Formosan subterranean termites, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae). Monitors were located adjacent to buildings and in urban forests. Significant population reductions occurred in areas that flooded 2-3 wk with brackish water, with termite populations associated with pine (Pinus spp.) trees and buildings slower to recover than populations associated with oak trees. Alate production in flooded areas showed no reduction from previous years.

Urban topography for flood modeling by fusion of OpenStreetMap, SRTM and local knowledge

NASA Astrophysics Data System (ADS)

Winsemius, Hessel; Donchyts, Gennadii; Eilander, Dirk; Chen, Jorik; Leskens, Anne; Coughlan, Erin; Mawanda, Shaban; Ward, Philip; Diaz Loaiza, Andres; Luo, Tianyi; Iceland, Charles

2016-04-01

Topography data is essential for understanding and modeling of urban flood hazard. Within urban areas, much of the topography is defined by highly localized man-made features such as roads, channels, ditches, culverts and buildings. This results in the requirement that urban flood models require high resolution topography, and water conveying connections within the topography are considered. In recent years, more and more topography information is collected through LIDAR surveys however there are still many cities in the world where high resolution topography data is not available. Furthermore, information on connectivity is required for flood modelling, even when LIDAR data are used. In this contribution, we demonstrate how high resolution terrain data can be synthesized using a fusion between features in OpenStreetMap (OSM) data (including roads, culverts, channels and buildings) and existing low resolution and noisy SRTM elevation data using the Google Earth Engine platform. Our method uses typical existing OSM properties to estimate heights and topology associated with the features, and uses these to correct noise and burn features on top of the existing low resolution SRTM elevation data. The method has been setup in the Google Earth Engine platform so that local stakeholders and mapping teams can on-the-fly propose, include and visualize the effect of additional features and properties of features, which are deemed important for topography and water conveyance. These features can be included in a workshop environment. We pilot our tool over Dar Es Salaam.

Integrated assessments of green infrastructure for flood mitigation to support robust decision-making for sponge city construction in an urbanized watershed.

PubMed

Mei, Chao; Liu, Jiahong; Wang, Hao; Yang, Zhiyong; Ding, Xiangyi; Shao, Weiwei

2018-10-15

Green Infrastructure (GI) has become increasingly important in urban stormwater management because of the effects of climate change and urbanization. To mitigate severe urban water-related problems, China is implementing GI at the national scale under its Sponge City Program (SCP). The SCP is currently in a pilot period, however, little attention has been paid to the cost-effectiveness of GI implementation in China. In this study, an evaluation framework based on the Storm Water Management Model (SWMM) and life cycle cost analysis (LCCA) was applied to undertake integrated assessments of the development of GI for flood mitigation, to support robust decision making regarding sponge city construction in urbanized watersheds. A baseline scenario and 15 GI scenarios under six design rainfall events with recurrence intervals ranging from 2-100 years were simulated and assessed. Model simulation results confirmed the effectiveness of GI for flood mitigation. Nevertheless, even under the most beneficial scenario, the results showed the hydrological performance of GI was incapable of eliminating flooding. Analysis indicated the bioretention cell (BC) plus vegetated swale (VS) scenario was the most cost-effective GI option for unit investment under all rainfall events. However, regarding the maximum potential of the implementation areas of all GI scenarios, the porous pavement plus BC + VS strategy was considered most reasonable for the study area. Although the optimal combinations are influenced by uncertainties in both the model and the GI parameters, the main trends and key insights derived remain unaffected; therefore, the conclusions are relevant regarding sponge city construction within the study area. Copyright © 2018 Elsevier B.V. All rights reserved.

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.

Best management practices for nutrient and sediment retention in urban stormwater runoff.

PubMed

Hogan, Dianna M; Walbridge, Mark R

2007-01-01

Stormwater management infrastructure is utilized in urban areas to alleviate flooding caused by decreased landscape permeability from increased impervious surface cover (ISC) construction. In this study, we examined two types of stormwater detention basins, SDB-BMPs (stormwater detention basin-best management practice), and SDB-FCs (stormwater detention basin-flood control). Both are constructed to retain peak stormwater flows for flood mitigation. However, the SDB-BMPs are also designed using basin topography and wetland vegetation to provide water quality improvement (nutrient and sediment removal and retention). The objective of this study was to compare SDB (both SDB-BMP and SDB-FC) surface soil P concentrations, P saturation, and Fe chemistry with natural riparian wetlands (RWs), using sites in Fairfax County, Virginia as a model system. The SDB-BMPs had significantly greater surface soil total P (P(t)) concentrations than the RWs and SDB-FCs (831.9 +/- 32.5 kg ha(-1), 643.3 +/- 19.1 kg ha(-1), and 652.1 +/- 18.8 kg ha(-1), respectively). The soil P sorption capacities of SDB-BMPs were similar to the RWs, and were greater than those of SDB-FCs, appearing to result in greater soil P removal and retention in SDB-BMPs compared with SDB-FCs. Increased Fe concentrations and relatively greater amounts of more crystalline forms of Fe in SDB-BMP soils suggested increased sediment deposition compared with RW and SDB-FC soils. Data suggest that SDB nutrient and sediment retention is facilitated in SDB-BMPs. When stormwater management is necessary, use of SDB-BMPs instead of SDB-FCs could foster more responsible urban development and be an appropriate mitigation action for receiving aquatic ecosystems.

Best management practices for nutrient and sediment retention in urban stormwater runoff

USGS Publications Warehouse

Hogan, D.M.; Walbridge, M.R.

2007-01-01

Stormwater management infrastructure is utilized in urban areas to alleviate flooding caused by decreased landscape permeability from increased impervious surface cover (ISC) construction. In this study, we examined two types of stormwater detention basins, SDB-BMPs (stormwater detention basin-best management practice), and SDB-FCs (stormwater detention basin-flood control). Both are constructed to retain peak stormwater flows for flood mitigation. However, the SDB-BMPs are also designed using basin topography and wetland vegetation to provide water quality improvement (nutrient and sediment removal and retention). The objective of this study was to compare SDB (both SDB-BMP and SDB-FC) surface soil P concentrations, P saturation, and Fe chemistry with natural riparian wetlands (RWs), using sites in Fairfax County, Virginia as a model system. The SDB-BMPs had significantly greater surface soil total P (Pt) concentrations than the RWs and SDB-FCs (831.9 ?? 32.5 kg ha-1, 643.3 ?? 19.1 kg ha-1, and 652.1 ?? 18.8 kg ha-1, respectively). The soil P sorption capacities of SDB-BMPs were similar to the RWs, and were greater than those of SDB-FCs, appearing to result in greater soil P removal and retention in SDB-BMPs compared with SDB-FCs. Increased Fe concentrations and relatively greater amounts of more crystalline forms of Fe in SDB-BMP soils suggested increased sediment deposition compared with RW and SDB-FC soils. Data suggest that SDB nutrient and sediment retention is facilitated in SDB-BMPs. When stormwater management is necessary, use of SDB-BMPs instead of SDB-FCs could foster more responsible urban development and be an appropriate mitigation action for receiving aquatic ecosystems. ?? ASA, CSSA, SSSA.

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.

Automatic Generalizability Method of Urban Drainage Pipe Network Considering Multi-Features

NASA Astrophysics Data System (ADS)

Zhu, S.; Yang, Q.; Shao, J.

2018-05-01

Urban drainage systems are indispensable dataset for storm-flooding simulation. Given data availability and current computing power, the structure and complexity of urban drainage systems require to be simplify. However, till data, the simplify procedure mainly depend on manual operation that always leads to mistakes and lower work efficiency. This work referenced the classification methodology of road system, and proposed a conception of pipeline stroke. Further, length of pipeline, angle between two pipelines, the pipeline belonged road level and diameter of pipeline were chosen as the similarity criterion to generate the pipeline stroke. Finally, designed the automatic method to generalize drainage systems with the concern of multi-features. This technique can improve the efficiency and accuracy of the generalization of drainage systems. In addition, it is beneficial to the study of urban storm-floods.

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.

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.

Estimated flood peak discharges on Twin, Brock, and Lightning creeks, Southwest Oklahoma City, Oklahoma, May 8, 1993

USGS Publications Warehouse

Tortorelli, R.L.

1996-01-01

The flash flood in southwestern Oklahoma City, Oklahoma, May 8, 1993, was the result of an intense 3-hour rainfall on saturated ground or impervious surfaces. The total precipitation of 5.28 inches was close to the 3-hour, 100-year frequency and produced extensive flooding. The most serious flooding was on Twin, Brock, and Lightning Creeks. Four people died in this flood. Over 1,900 structures were damaged along the 3 creeks. There were about $3 million in damages to Oklahoma City public facilities, the majority of which were in the three basins. A study was conducted to determine the magnitude of the May 8, 1993, flood peak discharge in these three creeks in southwestern Oklahoma City and compare these peaks with published flood estimates. Flood peak-discharge estimates for these creeks were determined at 11 study sites using a step-backwater analysis to match the flood water-surface profiles defined by high-water marks. The unit discharges during peak runoff ranged from 881 cubic feet per second per square mile for Lightning Creek at SW 44th Street to 3,570 cubic feet per second per square mile for Brock Creek at SW 59th Street. The ratios of the 1993 flood peak discharges to the Federal Emergency Management Agency 100-year flood peak discharges ranged from 1.25 to 3.29. The water-surface elevations ranged from 0.2 foot to 5.9 feet above the Federal Emergency Management Agency 500-year flood water-surface elevations. The very large flood peaks in these 3 small urban basins were the result of very intense rainfall in a short period of time, close to 100 percent runoff due to ground surfaces being essentially impervious, and the city streets acting as efficient conveyances to the main channels. The unit discharges compare in magnitude to other extraordinary Oklahoma urban floods.

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)

Modeling Rainfall-Runoff Dynamics in Tropical, Urban Socio-Hydrological Systems: Green Infrastructure and Variable Precipitation Interception

NASA Astrophysics Data System (ADS)

Nytch, C. J.; Meléndez-Ackerman, E. J.

2014-12-01

There is a pressing need to generate spatially-explicit models of rainfall-runoff dynamics in the urban humid tropics that can characterize flow pathways and flood magnitudes in response to erratic precipitation events. To effectively simulate stormwater runoff processes at multiple scales, complex spatio-temporal parameters such as rainfall, evapotranspiration, and antecedent soil moisture conditions must be accurately represented, in addition to uniquely urban factors including stormwater conveyance structures and connectivity between green and gray infrastructure elements. In heavily urbanized San Juan, Puerto Rico, stream flashiness and frequent flooding are major issues, yet still lacking is a hydrological analysis that models the generation and movement of fluvial and pluvial stormwater through the watershed. Our research employs a novel and multifaceted approach to dealing with this problem that integrates 1) field-based rainfall interception and infiltration methodologies to quantify the hydrologic functions of natural and built infrastructure in San Juan; 2) remote sensing analysis to produce a fine-scale typology of green and gray cover types in the city and determine patterns of spatial distribution and connectivity; 3) assessment of precipitation and streamflow variability at local and basin-wide scales using satellite and radar precipitation estimates in concert with rainfall and stream gauge point data and participatory flood mapping; 4) simulation of historical, present-day, and future stormwater runoff scenarios with a fully distributed hydrologic model that couples diverse components of urban socio-hydrological systems from formal and informal knowledge sources; and 5) bias and uncertainty analysis of parameters and model structure within a Bayesian hierarchical framework. Preliminary results from the rainfall interception study suggest that canopy structure and leaf area index of different tree species contribute to variable throughfall and stemflow responses. Additional investigations are pending. The findings from this work will help inform urban planning and design, and build adaptive capacity to reduce flood vulnerability in the context of a changing climate.

Modeling stream-groundwater interactions and associated groundwater salinization in an urban floodplain

NASA Astrophysics Data System (ADS)

Ledford, S. H.; Lautz, L.

2014-12-01

The salinization of freshwater in the Northeastern United States from road salt application is well documented by the observed long-term increases in chloride concentrations in groundwater over the last fifty years. However, the processes controlling exchange of chloride between surface water and groundwater have not been fully investigated, particularly in urban streams where stream-groundwater interactions can be reduced due to bank armoring and channelization. Our research builds on previous findings that showed the potential for an urban riparian floodplain to buffer seasonal changes in chloride concentrations in an urban stream, resulting in smaller annual ranges of chloride in areas with intact riparian floodplains. A reach of Meadowbrook Creek, in Syracuse, New York, that is disconnected from the groundwater had large seasonal shifts in chloride concentration, varying from 2173 mg/L Cl- in the winter to 161.2 mg/L Cl- in the summer. This is in contrast to a downstream reach of the stream that receives groundwater discharge from a riparian floodplain, where chloride concentrations ranged from 657.0 mg/L in the winter to 252.0 mg/L in the summer. We originally hypothesized that winter snowmelt events caused overbank flooding of saline surface water, which recharged the floodplain groundwater, causing salinization. This saline water was then slowly discharged as baseflow throughout the year and was replaced with freshwater overbank events in the summer. However, a three dimensional model of the floodplain created using Visual MODFLOW indicates that surface water-groundwater interactions, such as hyporheic exchange, may have a greater control on winter salt input than overbank events, while summer flooding recharges the aquifer with freshwater. The model was compared to riparian aquifer samples collected from May 2013 until June 2014 to qualitatively study the impact of different types of surface water-groundwater interactions (e.g. groundwater recharge and discharge, hyporheic interaction) on salt storage and to identify the mechanisms by which urban riparian floodplains buffer seasonal variability of stream chloride concentrations in urban systems impacted by road salt.

Modelling the catchment-scale environmental impacts of wastewater treatment in an urban sewage system for CO₂ emission assessment.

PubMed

Mouri, Goro; Oki, Taikan

2010-01-01

Water shortages and water pollution are a global problem. Increases in population can have further acute effects on water cycles and on the availability of water resources. Thus, wastewater management plays an important role in mitigating negative impacts on natural ecosystems and human environments and is an important area of research. In this study, we modelled catchment-scale hydrology, including water balances, rainfall, contamination, and urban wastewater treatment. The entire water resource system of a basin, including a forest catchment and an urban city area, was evaluated synthetically from a spatial distribution perspective with respect to water quantity and quality; the Life Cycle Assessment (LCA) technique was applied to optimize wastewater treatment management with the aim of improving water quality and reducing CO₂ emissions. A numerical model was developed to predict the water cycle and contamination in the catchment and city; the effect of a wastewater treatment system on the urban region was evaluated; pollution loads were evaluated quantitatively; and the effects of excluding rainwater from the treatment system during flooding and of urban rainwater control on water quality were examined. Analysis indicated that controlling the amount of rainwater inflow to a wastewater treatment plant (WWTP) in an urban area with a combined sewer system has a large impact on reducing CO₂ emissions because of the load reduction on the urban sewage system.

Rice emissions during field flooding and air pollution feedbacks across South Korea

NASA Astrophysics Data System (ADS)

So, C.; Diskin, G. S.; DiGangi, J. P.; Choi, Y.; Rana, M.; Hughes, S.; Blake, D. R.; Nault, B.; Schroeder, J.; Campuzano Jost, P.; Jimenez, J. L.; Kim, M. J.; Teng, A.; Crounse, J. D.; Wenneberg, P.; Kaser, L.; Mikoviny, T.; Müller, M.; Wisthaler, A.; Pusede, S. E.

2017-12-01

Nitrous oxide (N2O) and methane (CH4) are important long-lived greenhouse gases. Known anthropogenic sources of these gases include rice cultivation, which represents anywhere between 5% and 20% of methane emissions globally. Other volatile molecules are also produced by soil biogeochemistry when rice fields are flooded, including small organic oxygenates. Here, we use recent aircraft measurements from the KORUS-AQ experiment to describe controls over rice emissions of N2O and CH4 at regional-scales across the South Korean Peninsula. We also investigate potential emissions of molecular hydrogen and volatile alcohols and organic acids and consider the effect of aerosol nitrate and sulfate deposition on rice soil biogeochemistry on paddies downwind of polluted urban areas.

Economic impact of climate on water management in Oklahoma

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

Eddy, A.

1981-08-01

Topics and authors are listed below: The Oklahoma Water Plan, Jim Schuelin; The Garber-Wellington Research Project, Odell Morgan; The Tulsa Urban Study, Howard Chalker; Some Civil Defense/Flood Warning Problems, Ron Hill; The Impact of Climate on Rural Water Management, Ellen Cooter; Economic Models for Water Resource and Climate Impact Applications, William S. Cooter; Flood Forecasting, Jack Bowman; Small Basin Rainfall Characteristics via Factor Analysis, John M. Harlin; Radar Clouds Over Oklahoma, Bernard N. Meisner; The Oklahoma Climatological Survey Data Bank, Amos Eddy; Derived Variables: Climatic and Hydrologic Data from Weather Station Records, Jayne M. Salisbury; Precipitation Estimates Using Radar, Kenmore » Wilk and David Zittel; and A Water Control Data System, Joe Z. Durham.« less

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.

Urban Stormwater Management Model and Tools for Designing Stormwater Management of Green Infrastructure Practices

NASA Astrophysics Data System (ADS)

Haris, H.; Chow, M. F.; Usman, F.; Sidek, L. M.; Roseli, Z. A.; Norlida, M. D.

2016-03-01

Urbanization is growing rapidly in Malaysia. Rapid urbanization has known to have several negative impacts towards hydrological cycle due to decreasing of pervious area and deterioration of water quality in stormwater runoff. One of the negative impacts of urbanization is the congestion of the stormwater drainage system and this situation leading to flash flood problem and water quality degradation. There are many urban stormwater management softwares available in the market such as Storm Water Drainage System design and analysis program (DRAINS), Urban Drainage and Sewer Model (MOUSE), InfoWorks River Simulation (InfoWork RS), Hydrological Simulation Program-Fortran (HSPF), Distributed Routing Rainfall-Runoff Model (DR3M), Storm Water Management Model (SWMM), XP Storm Water Management Model (XPSWMM), MIKE-SWMM, Quality-Quantity Simulators (QQS), Storage, Treatment, Overflow, Runoff Model (STORM), and Hydrologic Engineering Centre-Hydrologic Modelling System (HEC-HMS). In this paper, we are going to discuss briefly about several softwares and their functionality, accessibility, characteristics and components in the quantity analysis of the hydrological design software and compare it with MSMA Design Aid and Database. Green Infrastructure (GI) is one of the main topics that has widely been discussed all over the world. Every development in the urban area is related to GI. GI can be defined as green area build in the develop area such as forest, park, wetland or floodway. The role of GI is to improve life standard such as water filtration or flood control. Among the twenty models that have been compared to MSMA SME, ten models were selected to conduct a comprehensive review for this study. These are known to be widely accepted by water resource researchers. These ten tools are further classified into three major categories as models that address the stormwater management ability of GI in terms of quantity and quality, models that have the capability of conducting the economic analysis of GI and models that can address both stormwater management and economic aspects together.

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.

Nationwide summary of US Geological Survey regional regression equations for estimating magnitude and frequency of floods for ungaged sites, 1993

USGS Publications Warehouse

Jennings, M.E.; Thomas, W.O.; Riggs, H.C.

1994-01-01

For many years, the U.S. Geological Survey (USGS) has been involved in the development of regional regression equations for estimating flood magnitude and frequency at ungaged sites. These regression equations are used to transfer flood characteristics from gaged to ungaged sites through the use of watershed and climatic characteristics as explanatory or predictor variables. Generally these equations have been developed on a statewide or metropolitan area basis as part of cooperative study programs with specific State Departments of Transportation or specific cities. The USGS, in cooperation with the Federal Highway Administration and the Federal Emergency Management Agency, has compiled all the current (as of September 1993) statewide and metropolitan area regression equations into a micro-computer program titled the National Flood Frequency Program.This program includes regression equations for estimating flood-peak discharges and techniques for estimating a typical flood hydrograph for a given recurrence interval peak discharge for unregulated rural and urban watersheds. These techniques should be useful to engineers and hydrologists for planning and design applications. This report summarizes the statewide regression equations for rural watersheds in each State, summarizes the applicable metropolitan area or statewide regression equations for urban watersheds, describes the National Flood Frequency Program for making these computations, and provides much of the reference information on the extrapolation variables needed to run the program.

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 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.

How urban system vulnerabilities to flooding could be assessed to improve resilience and adaptation in spatial planning

NASA Astrophysics Data System (ADS)

Pasi, Riccardo; Viavattene, Christophe; La Loggia, Goffredo

2016-04-01

Natural hazards damage assets and infrastructure inducing disruptions to urban functions and key daily services. These disruptions may be short or long with a variable spatial scale of impact. From an urban planning perspective, measuring these disruptions and their consequences at an urban scale is fundamental in order to develop more resilient cities. Whereas the assessment of physical vulnerabilities and direct damages is commonly addressed, new methodologies for assessing the systemic vulnerability at the urban scale are required to reveal these disruptions and their consequences. Physical and systemic vulnerability should be measured in order to reflect the multifaceted fragility of cities in the face of external stress, both in terms of the natural/built environment and socio-economic sphere. Additionally, a systemic approach allows the consideration of vulnerability across different spatial scales, as impacts may vary and be transmitted across local, regional or national levels. Urban systems are spatially distributed and the nature of this can have significant effects on flood impacts. The proposed approach identifies the vulnerabilities of flooding within urban contexts, including both in terms of single elementary units (buildings, infrastructures, people, etc.) and systemic functioning (urban functions and daily life networks). Direct losses are appraised initially using conventional methodologies (e.g. depth-damage functions). This aims to both understand the spatial distribution of physical vulnerability and associated losses and, secondly, to identify the most vulnerable building types and ways to improve the physical adaptation of our cities, proposing changes to building codes, design principles and other municipal regulation tools. The subsequent systemic approach recognises the city as a collection of sub-systems or functional units (such as neighbourhoods and suburbs) providing key daily services for inhabitants (e.g. healthcare facilities, schools, administration offices, food shops, leisure and cultural services etc.) and which are interconnected through transport networks. Moreover, each city is part of broader systems - which may or may not follow administrative boundaries - and, as such, need to be connected to its wider surroundings, in a multi-scalar perspective. The systemic analysis, herein limited to residential households, evaluates the presence, the distribution among functional units and the redundancy of key daily services. As such, systemic interdependences between neighbourhoods/suburbs and municipalities emerge, highlighting how systemic vulnerability spreads beyond the flooded areas. This aims to understand which planning patterns and existing mixed-use developments are more flood resilient (thereby informing future urban development/regeneration) and which infrastructure and assets have a key role within the urban system (and have therefore to be prioritised for protection). The methodology is currently developed through an extensive use of Geographic Information Systems (GIS) and applied to an Italian case study (Noale municipality, Venice). Current developments and on-going issues in its application and in the data collection (including the use of aerial survey data) will be discussed in the presentation.

Microplastic contamination of river beds significantly reduced by catchment-wide flooding

NASA Astrophysics Data System (ADS)

Hurley, Rachel; Woodward, Jamie; Rothwell, James J.

2018-04-01

Microplastic contamination of the oceans is one of the world's most pressing environmental concerns. The terrestrial component of the global microplastic budget is not well understood because sources, stores and fluxes are poorly quantified. We report catchment-wide patterns of microplastic contamination, classified by type, size and density, in channel bed sediments at 40 sites across urban, suburban and rural river catchments in northwest England. Microplastic contamination was pervasive on all river channel beds. We found multiple urban contamination hotspots with a maximum microplastic concentration of approximately 517,000 particles m-2. After a period of severe flooding in winter 2015/16, all sites were resampled. Microplastic concentrations had fallen at 28 sites and 18 saw a decrease of one order of magnitude. The flooding exported approximately 70% of the microplastic load stored on these river beds (equivalent to 0.85 ± 0.27 tonnes or 43 ± 14 billion particles) and eradicated microbead contamination at 7 sites. We conclude that microplastic contamination is efficiently flushed from river catchments during flooding.

A preliminary comparison of hydrodynamic approaches for flood inundation modeling of urban areas in Jakarta Ciliwung river basin

NASA Astrophysics Data System (ADS)

Rojali, Aditia; Budiaji, Abdul Somat; Pribadi, Yudhistira Satya; Fatria, Dita; Hadi, Tri Wahyu

2017-07-01

This paper addresses on the numerical modeling approaches for flood inundation in urban areas. Decisive strategy to choose between 1D, 2D or even a hybrid 1D-2D model is more than important to optimize flood inundation analyses. To find cost effective yet robust and accurate model has been our priority and motivation in the absence of available High Performance Computing facilities. The application of 1D, 1D/2D and full 2D modeling approach to river flood study in Jakarta Ciliwung river basin, and a comparison of approaches benchmarked for the inundation study are presented. This study demonstrate the successful use of 1D/2D and 2D system to model Jakarta Ciliwung river basin in terms of inundation results and computational aspect. The findings of the study provide an interesting comparison between modeling approaches, HEC-RAS 1D, 1D-2D, 2D, and ANUGA when benchmarked to the Manggarai water level measurement.

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

Urban drainage control applying rational method and geographic information technologies

NASA Astrophysics Data System (ADS)

Aldalur, Beatriz; Campo, Alicia; Fernández, Sandra

2013-09-01

The objective of this study is to develop a method of controlling urban drainages in the town of Ingeniero White motivated by the problems arising as a result of floods, water logging and the combination of southeasterly and high tides. A Rational Method was applied to control urban watersheds and used tools of Geographic Information Technology (GIT). A Geographic Information System was developed on the basis of 28 panchromatic aerial photographs of 2005. They were georeferenced with control points measured with Global Positioning Systems (basin: 6 km2). Flow rates of basins and sub-basins were calculated and it was verified that the existing open channels have a low slope with the presence of permanent water and generate stagnation of water favored by the presence of trash. It is proposed for the output of storm drains, the use of an existing channel to evacuate the flow. The solution proposed in this work is complemented by the placement of three pumping stations: one on a channel to drain rain water which will allow the drain of the excess water from the lower area where is located the Ingeniero White city and the two others that will drain the excess liquid from the port area.

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.

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.

Climate Change and Flooding in an Ecologically Fragile Zone of Nigerian Coastal Areas: A Case Study of Ilaje Settlement in Lagos, Nigeria

NASA Astrophysics Data System (ADS)

Oni, A. F.

2017-12-01

Climate change exacerbates the environmental condition directly or indirectly. The frequency of climate-related disasters worldwide has been on the increase with their amplitude growing. The consequences of climate-related disaster are not limited to loss of lives and properties alone, but also serious repercussions on post-disaster reconstruction, as well as the cost implications for resilience of the infrastructure and natural environment. In developing countries, the low-income group whose income is below the world poverty line is the most vulnerable to the dangers of climate change. To worsen the case, the political and economic strength of these countries in terms of economic resources, technological development and urban planning management necessary for adapting to climate change are relatively weak. This study takes an inventory of the study area environment to establish its environmental state in terms of the extent of its vulnerability and economic strength. It was found that the study area is vulnerable being a coastal area and could be described as a slum settlement. Also, information on frequency and extent of flooding in association with change in temperature was collected. The results show that the frequency of flood occurrence within the period has increased and the increase was attributed to rise in sea level alongside a significant increase in temperature within the period of study. The implications of the findings on loss of lives/properties and continuous decline in the area economic strength as it relates to resilience of the area was discussed. The study suggests an effective urban land use management and control, as well as redevelopment of resilient infrastructure in the area. The study concludes that the increase in temperature for the period as an indicator of climate change causes rise in sea level and the subsequent increase in flooding occurrence. Key Words: Ecologically Fragile Zone, Climate Change, Flooding and Vulnerability.

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.

A new service offered by rural environment to the city: stormwater reception.

NASA Astrophysics Data System (ADS)

Chiaradia, Enrico Antonio; Weber, Enrico; Masseroni, Daniele; Battista Bischetti, Gian; Gandolfi, Claudio

2017-04-01

Stormwaters are the main cause of urban floods in many urbanized areas. Historically, stormwater management practices have been focused on building infrastructures that achieve runoff attenuation through the storage of water volumes in large detention basins. However, this approach has proven to be insufficient to resolve the problem as well as it is difficult to implement in areas with a dense urban fabric. Nowadays, around the world, water managers are increasingly embracing "soft path" approaches, that aim to manage the excess of urban runoff through Green Infrastructures, where detention capacities are provided by the retention proprieties of soil and vegetation elements. Along the line of these new sustainable stormwater management practices, the aim of this study is to promote a further paradigm-shift with respect to the traditional practices i.e. to investigate the possibility to use the already existing green infrastructures of the peri-urban rural areas as reception element of the surplus of urban runoff. Many territories in Northern Italy, for example. are characterized by a high density of irrigation canals and agricultural fields that, in some cases, are isolated or pent-up inside urbanized areas. Both these elements may represent storage volumes for accumulating stormwater from urban areas. In this work, we implemented a holistic framework, based on Self Organized Map technique (SOM), with the objective to produce a spatial map of the stormwater reception level that can be provided by the rural environment. We elaborated physiographic characteristics of irrigation canals and agricultural fields through the SOM algorithm obtaining as output a series of cluster groups with the same level of receptivity. This procedure was applied on an area of 1933 km2 around the city of Milan and a map of 250x250m resolution was obtained with three different levels of stormwater reception capacity. About 50% of rural environment has a good level of reception and only 30% and 20% of rural areas have respectively a moderate and scarce level of reception. By the results we can conclude that the rural environment could become a valuable structural alternative to the traditional stormwater control methods, ascribing the rural environment to a new role in urban flood protection from.

Simulating the effect of flow path roughness to examine how green infrastructure restores urban runoff timing and magnitude

Treesearch

Yang Yang; Theodore A. Endreny; David J. Nowak

2015-01-01

Impervious land cover was the choice for many urban development projects in order to accelerate runoff and reduce the depth and duration of local flooding, however this led to increases in downstream runoff characterized by large, flashy peak flows. Urban ecosystem restoration now involves slowing down urban runoff to restore local hydrology with green infrastructure,...

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.

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.

The framework of a UAS-aided flash flood modeling system for coastal regions

NASA Astrophysics Data System (ADS)

Zhang, H.; Xu, H.

2016-02-01

Flash floods cause severe economic damage and are one of the leading causes of fatalities connected with natural disasters in the Gulf Coast region. Current flash flood modeling systems rely on empirical hydrological models driven by precipitation estimates only. Although precipitation is the driving factor for flash floods, soil moisture, urban drainage system and impervious surface have been recognized to have significant impacts on the development of flash floods. We propose a new flash flooding modeling system that integrates 3-D hydrological simulation with satellite and multi-UAS observations. It will have three advantages over existing modeling systems. First, it will incorporate 1-km soil moisture data through integrating satellite images from European SMOS mission and NASA's SMAP mission. The utilization of high-resolution satellite images will provide essential information to determine antecedent soil moisture condition, which is an essential control on flood generation. Second, this system is able to adjust flood forecasting based on real-time inundation information collected by multi-UAS. A group of UAS will be deployed during storm events to capture the changing extent of flooded areas and water depth at multiple critical locations simultaneously. Such information will be transmitted to a hydrological model to validate and improve flood simulation. Third, the backbone of this system is a state-of-the-art 3-D hydrological model that assimilates the hydrological information from satellites and multi-UAS. The model is able to address surface water-groundwater interactions and reflect the effects of various infrastructures. Using Web-GIS technologies, the modeling results will be available online as interactive flood maps accessible to the public. To support the development and verification of this modeling system, surface and subsurface hydrological observations will be conducted in a number of small watersheds in the Coastal Bend region. We envision this system will provide an innovative means to benefit the forecasting, evaluation and mitigation of flash floods in costal regions.

Urban development under extreme hydrologic and weather conditions for El Paso-Juarez: Recommendations resulting from hydrologic modeling, GIS, and remote sensing analyses

NASA Astrophysics Data System (ADS)

Barud-Zubillaga, Alberto

During the 2006 El Paso-Juarez flood there were many concerns regarding the capability of the existing stormwater system to handle 50- and 100-year flood events in El Paso, Texas and Juarez, Mexico area. Moreover in 2008, a considerable wet year from the normal 223 mm of annual precipitation for El Paso demonstrated that the area could very well received large amounts of precipitation at localized areas in short periods of time, representing a great flood threat to residents living in areas prone to flood. Some climate change projections for the area are exactly what had occurred over the last two decades; an increased number of torrential rainstorms over smaller concentrated pieces of land separated by longer years of drought between rainstorms. This study consisted in three projects focused on three critical regions within the El Paso-Juarez area that were greatly affected by the 2006 Flood. The goal was to identify if natural arroyos or the existent built stormwater system, could properly managed the projected precipitation patterns. The three projects described in this dissertation touch on the following points: (a) the importance of a reliable precipitation model that could accurately describes precipitation patterns in the region under extreme drought and wet climates conditions; (b) differences in land use/land cover characteristics as factors promoting or disrupting the possibility for flooding, and (c) limitations and capabilities of existent stormwater systems and natural arroyos as means to control flooding. Conclusions and recommendations are shown below, which apply not only to each particular project, but also to all study areas and similar areas in the El Paso-Juarez region. Urbanization can improve or worsen a pre-existing natural stormwater system if built under its required capacity. Such capacity should be calculated considering extreme weather conditions, based on a denser network of precipitation stations to capture the various microclimates found in the region and taking into account climate change predictions. Development of new areas needs to consider not only the watershed of study but its relation to other watersheds around them. Basin parameters seemed to be of low impact while comparing them with precipitation rates. High resolution DEMs, such as those derived from LiDAR can dramatically improve the accuracy and reliability of a hydrological model. Hardware capabilities and limitations however should be considered. The overall recommendations derived from this dissertation are to direct new studies, policies and regulations at the three levels of government---local, state and federal---to: limit urban development to areas of no or low potential for flooding; implementing some type of ecological, green corridors, or conservation easements to preserve these areas; build semi-natural or hybrid stormwater infrastructure to slowdown, collect, and ultimately, transport runoff to the Rio Grande or any other waterway; consider extreme wet and dry scenarios for designation of flood-prone areas and future construction of stormwater infrastructure; and design stormwater infrastructure to retrofit the existing natural and irrigation drains.

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.

Probabilistic flood extent estimates from social media flood observations

NASA Astrophysics Data System (ADS)

Brouwer, Tom; Eilander, Dirk; van Loenen, Arnejan; Booij, Martijn J.; Wijnberg, Kathelijne M.; Verkade, Jan S.; Wagemaker, Jurjen

2017-05-01

The increasing number and severity of floods, driven by phenomena such as urbanization, deforestation, subsidence and climate change, create a growing need for accurate and timely flood maps. In this paper we present and evaluate a method to create deterministic and probabilistic flood maps from Twitter messages that mention locations of flooding. A deterministic flood map created for the December 2015 flood in the city of York (UK) showed good performance (F(2) = 0.69; a statistic ranging from 0 to 1, with 1 expressing a perfect fit with validation data). The probabilistic flood maps we created showed that, in the York case study, the uncertainty in flood extent was mainly induced by errors in the precise locations of flood observations as derived from Twitter data. Errors in the terrain elevation data or in the parameters of the applied algorithm contributed less to flood extent uncertainty. Although these maps tended to overestimate the actual probability of flooding, they gave a reasonable representation of flood extent uncertainty in the area. This study illustrates that inherently uncertain data from social media can be used to derive information about flooding.

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.

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.

Ecosystem Services and Potential Utilization of of Urban Typha angustifolia Wetlands of across Metropolitan Bangkok, Thailand

NASA Astrophysics Data System (ADS)

Sritrairat, S.

2014-12-01

Over half the world's 7.2 billion population are living in urban habitats. While these cities only occupy 2% of the world's surface, the ecological footprint by these cities combined is far greater than that of the other 98% of the world. Bangkok, Thailand has experienced this rapid urbanization that has resulted in various environmental problems, including pollution, land subsidence, and flooding. Major flooding in 2011 has raised awareness about the importance of restoring ecosystem services in urban space to cope up with the forecasted extreme climatic conditions. Finding localized flooding, carbon and pollution mitigation methods will be important to cities. Upland reforestration has been proposed as a way to decrease these anthropogenic and climate change impacts. However, there is also a large area of wetlands in Bangkok with possibly high ecosystem services that have not been quantified. This study measure above ground and below ground carbon accumulation in wide-spread Typha angustifolia wetlands as an untapped source of ecosystem services that are worth projected. These wetlands are typically viewed as wasteland and are not being protected. We examined carbon and heavy metals (Pb, Zn, Cu) pools in 7 wetlands across Bangkok with various environmental settings--from industrialized zone, to residential area, farms, and protected urban green space. The results indicate recent peat accumulation layer by these wetlands at high rate. Heavy concentration are found near contaminant source such as industries and farms. Combined with their ability to buffer storms and being habitats for wildlife, these wetlands have important values in increasing ecosystem services in urban space and should be considered for protection.

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.

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.

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.

Handbook for Federal Insurance Administration: Flood-insurance studies

USGS Publications Warehouse

Kennedy, E.J.

1973-01-01

A flood insurance study, made for the Federal Insurance Administration (FIA) of the Department of Housing and Urban Development (HUD) is an analysis of flood inundation frequency for all flood plains within the corporate limits of the community being studied. The study is an application of surveying, hydrology, and hydraulics to determine flood insurance premium rates. Much of the surveying needed can be done by private firms, either by ground methods or photogrammetry. Contracts are needed to let large surveys but purchase orders can be used for small ones. Photogrammetric stereo models, digital regression models, and step-backwater models are needed for most studies. Damage survey data are not involved.

Street floods in Metro Manila and possible solutions.

PubMed

Lagmay, Alfredo Mahar; Mendoza, Jerico; Cipriano, Fatima; Delmendo, Patricia Anne; Lacsamana, Micah Nieves; Moises, Marc Anthony; Pellejera, Nicanor; Punay, Kenneth Niño; Sabio, Glenn; Santos, Laurize; Serrano, Jonathan; Taniza, Herbert James; Tingin, Neil Eneri

2017-09-01

Urban floods from thunderstorms cause severe problems in Metro Manila due to road traffic. Using Light Detection and Ranging (LiDAR)-derived topography, flood simulations and anecdotal reports, the root of surface flood problems in Metro Manila is identified. Majority of flood-prone areas are along the intersection of creeks and streets located in topographic lows. When creeks overflow or when rapidly accumulated street flood does not drain fast enough to the nearest stream channel, the intersecting road also gets flooded. Possible solutions include the elevation of roads or construction of well-designed drainage structures leading to the creeks. Proposed solutions to the flood problem of Metro Manila may avoid paralyzing traffic problems due to short-lived rain events, which according to Japan International Cooperation Agency (JICA) cost the Philippine economy 2.4billionpesos/day. Copyright © 2017. Published by Elsevier B.V.

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.

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...

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.

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.

Impact of the 1993 flood on the distribution of organic contaminants in bed sediments of the Upper Mississippi River

USGS Publications Warehouse

Barber, L.B.; Writer, J.H.

1998-01-01

The 1500 km Upper Mississippi River (UMR) consists of 29 navigation pools and can be divided into the upper reach (pools 1-4), the middle reach (pools 5-13), and the lower reach (pools 14-26). Comparison of composite bed sediment samples collected from the downstream third of 24 pools before and after the 1993 UMR flood provides fieldscale data on the effect of the flood on sediment organic compound distributions. The sediments were analyzed for organic carbon, coprostanol, polynuclear aromatic hydrocarbons including pyrene, linear alkylbenzene-sulfonates, polychlorinated biphenyls (PCBs), and organochlorine pesticides. Most of the target compounds were detected in all of the sediment samples, although concentrations were generally <1 mg/kg. The highest concentrations typically occurred in the upper reach, an urbanized area on a relatively small river. Pool 4 (Lake Pepin) is an efficient sediment trap, and concentrations of the compounds below pool 4 were substantially lower than those in pools 2-4. Differences in concentrations before and after the 1993 flood also were greatest in the upper reach. In pools 1-4, concentrations of pyrene and PCBs decreased after the flood whereas coprostanol increased. These results suggest that bed sediments stored in the pools were diluted or buried by sediments with different organic compound compositions washed in from urban and agricultural portions of the watershed.The 1500 km Upper Mississippi River (UMR) consists of 29 navigation pools and can be divided into the upper reach (pools 1-4), the middle reach (pools 5-13), and the lower reach (pools 14-26). Comparison of composite bed sediment samples collected from the downstream third of 24 pools before and after the 1993 UMR flood provides field-scale data on the effect of the flood on sediment organic compound distributions. The sediments were analyzed for organic carbon, coprostanol, polynuclear aromatic hydrocarbons including pyrene, linear alkylbenzene-sulfonates, polychlorinated biphenyls (PCBs), and organochlorine pesticides. Most of the target compounds were detected in all of the sediment samples, although concentrations were generally <1 mg/kg. The highest concentrations typically occurred in the upper reach, an urbanized area on a relatively small river. Pool 4 (Lake Pepin) is an efficient sediment trap, and concentrations of the compounds below pool 4 were substantially lower than those in pools 2-4. Differences in concentrations before and after the 1993 flood also were greatest in the upper reach. In pools 1-4, concentrations of pyrene and PCBs decreased after the flood whereas coprostanol increased. These results suggest that bed sediments stored in the pools were diluted or buried by sediments with different organic compound compositions washed in from urban and agricultural portions of the watershed.

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.

Grand Forks - East Grand Forks Urban Water Resources Study. Summary Report.

DTIC Science & Technology

1981-07-01

as wastewater management), Corps involvement carries only through the planning stage; findings are turned over to local inter - ests for incorporation...NEW DEVELOPMENT PLANS DE 14 9 CONSIDERED REACH 2 FLOOD BARRIER RAISE 19 U. ( ___ S-~----. - FIGURES (CWlT) NIUMR -FAGE 10 CONSIDERED FLOOD BARRIER...residents and flood fighters dubbed their refuge "Isle de Sandbag," reflecting the millions of sandbags used to save the community from being totally

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.

An Overview of Synoptic and Mesoscale Factors Contributing to the Disastrous Atlanta Flood of 2009

EPA Science Inventory

If IPCC (2007) projections are accurate, the frequency and severity of extreme hydroclimate events (e.g., droughts, floods) will likely increase in response to the acceleration in the water cycle. Additionally, a majority of the population lives in urban areas, and by 2030 this ...

A bill to amend the National Flood Insurance Act of 1968 to clarify the effective date of policies covering properties affected by floods in progress.

THOMAS, 112th Congress

Sen. Johanns, Mike [R-NE

2011-07-12

Senate - 07/12/2011 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:

Effect of Flooding on the Survival of Formosan Subterranean Termites (Isoptera: Rhinotermitidae) in Laboratory Tests

USDA-ARS?s Scientific Manuscript database

Underground monitoring stations were active with Formosan subterranean termites, Coptotermes formosanus Shiraki, less than a month after the flood waters receded from an urban park, City Park, New Orleans, Louisiana. This study examines whether the presence of galleries in soil or wood increases su...

Combined sewage overflows (CSO) are major urban breeding sites for Culex quinquefasciatus in Atlanta, Georgia.

PubMed

Calhoun, Lisa M; Avery, Melissa; Jones, Leeann; Gunarto, Karina; King, Raymond; Roberts, Jacquelin; Burkot, Thomas R

2007-09-01

A longitudinal study of mosquito ecology in Tanyard Creek, an urban stream in Atlanta, GA, that receives combined storm and waste water effluent from the Atlanta combined sewage overflow system, was undertaken in 2006. Culex quinquefasciatus was the dominant species found, but Culex restuans was also abundant during the spring with limited numbers of Culex nigripalpis and Anopheles punctipennis also collected. Significant differences in mosquito densities were found with greater densities associated with side pools of water and stagnant water. Mosquito numbers are regulated largely by flooding of the stream by effluent discharges exceeding 15 kgal/min. These floods are associated with significant immediate reductions, but not complete elimination, of mosquitoes from Tanyard Creek. Mosquito numbers rebound within 5-10 days after such floods and rapidly reach high densities.

Urban Cholera and Water Sustainability Challenges under Climatic and Anthropogenic Change

NASA Astrophysics Data System (ADS)

Akanda, A. S.; Jutla, A.; Huq, A.; Faruque, A. G.; Colwell, R. R.

2013-12-01

The last three decades of surveillance data shows a drastic increase of cholera prevalence in the largest cholera-endemic city of the world - Dhaka, Bangladesh. Emerging megacities in the developing world, especially those located in coastal regions of the tropics remain vulnerable to similar. However, there has not been any systematic study on linking the long-term disease trends with changes in related climatic, environmental, or societal variables. Here, we analyze the 30-year dynamics of urban cholera prevalence in Dhaka with changes in climatic or societal factors: regional hydrology, flooding, water usage, changes in distribution systems, population growth and density in urban settlements, as well as shifting climate patterns. An interesting change is observed in the seasonal trends of cholera incidence; while an endemic upward trend is seen in the dry season, the post-monsoon trend seem to be more epidemic in nature. Evidence points to growing urbanization and rising population in unplanned settlements that have negligible to poor water and sanitation systems compounded by increasing frequency of record flood events. Growing water scarcity in the dry season and lack of sustainable water and sanitation infrastructure for urban settlements have increased endemicity of spring outbreaks, while record flood events and prolonged post-monsoon inundation have contributed to increased epidemic outbreaks in fall. We analyze our findings with the World Health Organization recommended guidelines and investigate water sustainability challenges in the context of climatic and anthropogenic changes in the region.

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.

Sustainable Strategies for the Dynamic Equilibrium of the Urban Stream, Cheonggyecheon

NASA Astrophysics Data System (ADS)

Seo, D.; Kwon, Y.

2018-04-01

Cheonggyecheon, which had been transformed into a 14-lane urban highway and a large underground sewer system, was finally converted back to an urban stream again. Its transformation has been praised as a successful example of urban downtown regeneration and beautification. It is, however, obvious that there have not been prudent ecological considerations since the project’s principal goals were to provide public recreational use and achieve maximum flood control capacity via the use of embankments. For a healthier and sustainable stream environment, Cheonggyecheon should be ecologically re-restored again, based on a dynamic equilibrium model. It must primarily establish a corridor of vegetation, an aquatic transitional zone, and install constructed wetlands nearby which support the water source. The upper streams of Cheonggyecheon should be further restored and supply natural waters. Furthermore, there ultimately needs to be de-channelization for hydrological sustainability. This would vary from merely increasing the sinuosity to thoroughly reconstruct a naturalized stream. Complete dynamic equilibrium of Cheonggyecheon can be accomplished through more fundamental sustainable strategies.

Evidence for Near-Road Air Pollution Abatement by Tree Cover

EPA Science Inventory

Urbanized areas represent concentrated demand for ecosystem services to buffer hazards and promote healthful lifestyles. Urban tree cover has been linked to multiple local health benefits including clean air and water, flood and drought protection, heat mitigation, and opportuni...

Research on the effects of urbanization on small stream flow quantity

DOT National Transportation Integrated Search

1978-12-01

This study is a preliminary investigation into the feasibility of using simple techniques to evaluate the effects of urbanization on flood flows in small streams. A number of regression techniques and computer simulation techniques were evaluated, an...

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...

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.

Using Agent-Based Modeling to Enhance System-Level Real-time Control of Urban Stormwater Systems

NASA Astrophysics Data System (ADS)

Rimer, S.; Mullapudi, A. M.; Kerkez, B.

2017-12-01

The ability to reduce combined-sewer overflow (CSO) events is an issue that challenges over 800 U.S. municipalities. When the volume of a combined sewer system or wastewater treatment plant is exceeded, untreated wastewater then overflows (a CSO event) into nearby streams, rivers, or other water bodies causing localized urban flooding and pollution. The likelihood and impact of CSO events has only exacerbated due to urbanization, population growth, climate change, aging infrastructure, and system complexity. Thus, there is an urgent need for urban areas to manage CSO events. Traditionally, mitigating CSO events has been carried out via time-intensive and expensive structural interventions such as retention basins or sewer separation, which are able to reduce CSO events, but are costly, arduous, and only provide a fixed solution to a dynamic problem. Real-time control (RTC) of urban drainage systems using sensor and actuator networks has served as an inexpensive and versatile alternative to traditional CSO intervention. In particular, retrofitting individual stormwater elements for sensing and automated active distributed control has been shown to significantly reduce the volume of discharge during CSO events, with some RTC models demonstrating a reduction upwards of 90% when compared to traditional passive systems. As more stormwater elements become retrofitted for RTC, system-level RTC across complete watersheds is an attainable possibility. However, when considering the diverse set of control needs of each of these individual stormwater elements, such system-level RTC becomes a far more complex problem. To address such diverse control needs, agent-based modeling is employed such that each individual stormwater element is treated as an autonomous agent with a diverse decision making capabilities. We present preliminary results and limitations of utilizing the agent-based modeling computational framework for the system-level control of diverse, interacting stormwater elements.

Lessons learned from combined experimental and numerical modelling of urban floods

NASA Astrophysics Data System (ADS)

Archambeau, Pierre; Bruwier, Martin; Finaud-Guyot, Pascal; Erpicum, Sébastien; Pirotton, Michel; Dewals, Benjamin

2017-04-01

Field data for validating hydraulic models remain scarce. They are often limited to inundation extents and water marks, which provide little insights into the dynamic features of the flow in urbanized floodplains, such as the discharge partition in-between the streets and the velocity fields. To address this issue, a unique experimental setup representing a whole urban district was built in the laboratory ICube in Strasbourg and the state-of-the-art shallow-water model Wolf 2D was tested against the experimental measurements (Arrault et al. 2016). The numerical model was also used to extend and refine the analysis of the laboratory observations. The experimental model (5 m × 5 m) represents a square urban district with a total of 14 streets of different widths and 49 intersections (crossroads). The inflow discharge can be controlled in each street individually and the outflow discharges were measured downstream of each street. The numerical model Wolf was developed at the University of Liege and has been extensively used in flood risk research (Beckers et al. 2013, Bruwier et al. 2015, Detrembleur et al. 2015). Several lessons could be learned from this combined experimental and numerical analysis. First, we found that the discharge partition in-between the streets is primarily controlled by the street widths. Second, although the standard shallow-water equations reproduce satisfactorily most of the flow characteristics, adding a turbulence model improves the prediction of the shape and length of the flow recirculations in the streets. Yet, this has little influence on the discharge partition because the computed recirculation widths are hardly affected by the turbulence model. The experiments and the numerical model also show that the water depths in the streets remain fairly constant in-between two intersections, while they drop suddenly downstream of each intersection as a result of complex flow interactions at the intersections. This hints that friction has little influence on the water depths obtained in the experiments. However, tailored numerical tests demonstrate that this is a direct consequence of the distorted nature of the experimental setup. Indeed, the ratio between the water depth and the street width is close to 1 in the experiments, while it would be at least one order of magnitude lower in real-world conditions, even for extreme floods. Finally, remote sensing data, such as digital elevation models, are generally available on a regular grid, which makes it convenient to use also a Cartesian grid for hydraulic modelling. We show here that the discretization of the geometry of the buildings on such a Cartesian grid has a major influence on the modelling accuracy (overestimation of the overall flow resistance). An extended shallow-water model based on non-isotropic porosity parameters is shown to improve substantially the prediction of the discharge partition in-between the streets. It is therefore considered as a valuable tool to advance urban flood modelling in practice. From the lessons learned here, we recommend that future research focuses on the design and exploitation of a less distorted experimental model, as well as on the analysis of extra flow processes such as transient conditions and interactions between overland flow and pressurized flow in underground passages. References Arrault, A., Finaud-Guyot, P., Archambeau, P., Bruwier, M., Erpicum, S., Pirotton, M., & Dewals, B. (2016). Hydrodynamics of long-duration urban ?oods: experiments and numerical modelling. Natural Hazards & Earth System Sciences, 16, 1413-1429. Beckers, A., Dewals, B., Erpicum, S., Dujardin, S., Detrembleur, S., Teller, J., Pirotton, M., & Archambeau, P. (2013). Contribution of land use changes to future flood damage along the river Meuse in the Walloon region. Natural Hazards & Earth System Sciences, 13, 2301-2318. Bruwier, M., Erpicum, S., Pirotton, M., Archambeau, P., & Dewals, B. (2015). Assessing the operation rules of a reservoir system based on a detailed modelling chain. Natural Hazards & Earth System Sciences, 15, 365-379. 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.

State and local response to damaging land subsidence in United States urban areas

USGS Publications Warehouse

Holzer, T.L.

1989-01-01

Land subsidence caused by man-induced depressuring of underground reservoirs has occurred in at least nine urban areas in the United States. Significant efforts to control it have been made in three areas: Long Beach, California; Houston-Galveston, Texas; and Santa Clara Valley, California. In these areas coastal flooding and its control cost more than $300 million. Institutional changes were required in each area to ameliorate its subsidence problem. In Long Beach and Houston Galveston, efforts were made to mitigate subsidence only after significant flood damage had occurred. To arrest subsidence at Long Beach, the city lobbied for a special state law, the California Subsidence Act, that required unitization and repressuring of the Wilmington oil field. In the Houston-Galveston region, the Texas State Legislature authorized formation of the Harris-Galveston Coastal Subsidence District with authority to regulate groundwater pumping by permit. This solution, which was achieved through efforts of entities affected by subsidence, was the product of a series of compromises necessitated by political fragmentation and disjointed water planning in the region. Amelioration of subsidence in the Santa Clara Valley was a collateral benefit from the effort by water users to curtail ground-water overdraft in the valley. Importation of surface water and a tax on ground-water pumpage reduced ground-water use, thereby allowing the recovery of water level and the arresting of subsidence.

Supply and dispersal of flood sediment from a steep, tropical watershed: Hanalei Bay, Kaua'i, Hawai'i, USA

USGS Publications Warehouse

Draut, A.E.; Bothner, Michael H.; Field, M.E.; Reynolds, R.L.; Cochran, S.A.; Logan, J.B.; Storlazzi, C.D.; Berg, C.J.

2009-01-01

In contrast to many small, mountainous watersheds in temperate coastal regions, where fluvial discharge and wave energy commonly coincide, deposition and reworking of tropical flood sediment can be seasonally decoupled, and this has important implications for coral-reef ecosystems. An understanding of the interaction between tropical flood sedimentation and wave climate is essential to identifying and mitigating effects of watershed changes on coral reefs as urbanization and climate change proceed. Sedimentary facies and isotopic properties of sediment in Hanalei Bay, on the island of Kaua'i, Hawai'i, USA, were used to assess deposition and reworking of flood deposits from the Hanalei River in a case study demonstrating the potential ecosystem effects of runoff from a steep, tropical watershed. In Hanalei Bay, the youngest and thickest terrigenous sediment was consistently present near the river mouth and in a bathymetric depression that acted as at least a temporary sediment sink. During this 2 yr study, the largest flood events occurred in late winter and spring 2006; substantial terrestrial sediment delivered by those floods still remained in the bay as of June 2006 because oceanic conditions were not sufficiently energetic to transport all of the sediment offshore. Additional sediment was deposited in the bay by a summer 2006 flood that coincided with seasonal low wave energy. In most years, flood sediment accumulating in the bay and on its fringing reefs would be remobilized and advected out of the bay during winter, when the wave climate is energetic. Turbidity and sedimentation on corals resulting from late spring and summer floods during low wave energy could have a greater impact on coral-reef ecosystems than floods in other seasons, an effect that could be exacerbated if the incidence and sediment load of tropical summer floods increase due to urbanization and climate change. ?? 2008 Geological Society of America.

Waterbird habitat in California's Central Valley basins under climate, urbanization, and water management scenarios

USGS Publications Warehouse

Matchett, Elliott L.; Fleskes, Joseph

2018-01-01

California's Central Valley provides critical, but threatened habitat and food resources for migrating and wintering waterfowl, shorebirds, and other waterbirds. The Central Valley is comprised of nine basins that were defined by the Central Valley Joint Venture (CVJV) to assist in conservation planning. Basins vary in composition and extent of habitats, which primarily include croplands and wetlands that rely on water supplies shared with other competing human and environmental uses. Changes in climate, urban development, and water supply management are uncertain and could reduce future availability of water supplies supporting waterbird habitats and limit effectiveness of wetland restoration planned by the CVJV to support wintering waterbirds. We modeled 17 plausible scenarios including combinations of three climate projections, three urbanization rates, and five water supply management options to promote agricultural and urban water uses, with and without wetland restoration. Our research examines the reduction in quantity and quality of habitats during the fall migration-wintering period by basin under each scenario, and the efficacy of planned wetland restoration to compensate reductions in flooded areas of wetland habitats. Scenario combinations of projected climate, urbanization, and water supply management options reduced availability of flooded cropland and wetland habitats during fall-winter and degraded the quality of seasonal wetlands (i.e., summer-irrigation for improved forage production), though the extent and frequency of impacts varied by basin. Planned wetland restoration may substantially compensate for scenario-related effects on wetland habitats in each basin. However, results indicate that Colusa, Butte, Sutter, San Joaquin, and Tulare Basins may require additional conservation to support summer-irrigation of seasonal wetlands and winter-flooding of cropland habitats. Still further conservation may be required to provide sufficient areas of flooded seasonal and semi-permanent wetlands in San Joaquin and Tulare Basins during fall-winter. The main objective of this research is to provide decision-support for achieving waterbird conservation goals in the valley and to inform CVJV's regional conservation planning.

Adjusting measured peak discharges from an urbanizing watershed to reflect a stationary land use signal

NASA Astrophysics Data System (ADS)

Beighley, R. Edward; Moglen, Glenn E.

2003-04-01

A procedure to adjust gauged streamflow data from watersheds urbanized during or after their gauging period is presented. The procedure adjusts streamflow to be representative of a fixed land use condition, which may reflect current or future development conditions. Our intent is to determine what an event resulting in a peak discharge in, for example, 1950 (i.e., before urbanization) would produce on the current urban watershed. While past approaches assumed uniform spatial and temporal changes in urbanization, this study focuses on the use of geographic information systems (GIS) based methodologies for precisely locating in space and time where land use change has occurred. This information is incorporated into a hydrologic model to simulate the change in discharge as a result of changing land use conditions. In this paper, we use historical aerial photographs, GIS linked tax-map data, and recent land use/land cover data to recreate the spatial development history of eight gauged watersheds in the Baltimore-Washington, D. C., metropolitan area. Using our procedure to determine discharge series representative of the current urban watersheds, we found that the increase of the adjusted 2-year discharge ranged from 16 to 70 percent compared with the measured annual maximum discharge series. For the 100-year discharge the adjusted values ranged from 0 to 47 percent greater than the measured values. Additionally, relationships between the increase in flood flows and four measures of urbanization (increase in urban land, decrease in forested land, increase in high-density development, and the spatial development pattern) are investigated for predicting the increase in flood flows for ungauged watersheds. Watersheds with the largest increases in flood flows typically had more extensive development in the areas far removed from the outlet. In contrast, watersheds with development located nearer to the outlet typically had the smallest increases in peak discharge.

On mechanisms triggering the levees failure along the Foenna stream on 1st January 2006 and which caused the flooding in the urban area of Sinalunga, Tuscany Region (Italy). A case study

NASA Astrophysics Data System (ADS)

Camici, Stefania; Moramarco, Tommaso; Brocca, Luca; Melone, Florisa; Lapenna, Vincenzo; Perrone, Angela; Loperte, Antonio

2010-05-01

On 1st January 2006, during an ordinary flood event, a levee failure along the Foenna stream caused the flooding in the urban area of Sinalunga, a small town located in Tuscany region (Italy). The event was monitored by a public agency with the responsibility for the control and maintenance of the natural channel networks. Long time before of flooding, people living in the surrounding area of the stream blamed the presence of wild animals and of numerous burrows along the levees. Although the numerous actions of maintenance along the levees mainly for removing the burrows, a levee seepage occurred during that flood. The presence of an outflow located on the downstream face, almost 2 m below the levee top, caused the spurt of brown water denoting the presence of sediment erosion. On the upstream face of levee, a little hole of about 30 cm at the same height of the outflow was discovered. Although the agency workers tried to close the hole by using appropriate blankets, in short time the top of the levee subsided and the overtopping flow caused a trapezoidal breach typical for an earth-fill embankment. The formation of breach was so fast that in a little more of one hour the urban area near to the Foenna stream was flooded causing high economic damages. Mechanisms triggered the levees failure are the object of this work. The analysis of the event has been first addressed to assess the state of-fact of levees conditions along the Foenna stream, thus to understand how much the activity of wild animals, in particular that of porcupine, may have affected the hydraulic safety of the embankment. At the purpose, after the event, topographical surveys of cross sections have been done along with tomographic surveys by geoelectric technique for investigating the possible presence, besides of burrows, also of tunnels dug into the levees by animals. Then, the analysis of hydrometeorological conditions of the event has allowed to better understand the evolution of the flood and if its magnitude was able to affect the hydraulic holding of levees. Finally, the seepage vulnerability of these levees has been also assessed to address their hydraulic safety applying two models based on a steady and unsteady infiltration, respectively. Based on the obtained results, the following findings can be drawn. 1) The levees failure near the Sinalunga urban area is certainly due to the presence of the porcupine burrow at middle height of upstream face of levee that has addressed the flow into the embankment and then triggered the seepage phenomenon. 2) The works of the maintenance finalized to the closure of the burrows carried out before of the flood event were necessary but not sufficient to prevent the failure of levees. 3) To prevent the failure due to burrows presence, the levees maintenance should have been addressed through both the closure of burrows and the capture of wild animals; if this action had been done for the Foenna stream then the probability of failure would have been truly low. This last aspect has been also inferred through geoelectrical tomography surveys that showed the possible presence of at least two tunnels along both faces of levees, so emphasizing as the various closure of burrows made in the past by maintenance agency were totally useless. 4) The seepage vulnerability analysis has shown that levees might be to risk of failure for floods whose durations are consistent with the ones might occur in the Foenna basin. However, for this particular event the levees failure can be only ascribed to wild animals activity, seeing that the seepage was caused by a burrow hole.

Somerset County Flood Information System

USGS Publications Warehouse

Hoppe, Heidi L.

2007-01-01

The timely warning of a flood is crucial to the protection of lives and property. One has only to recall the floods of August 2, 1973, September 16 and 17, 1999, and April 16, 2007, in Somerset County, New Jersey, in which lives were lost and major property damage occurred, to realize how costly, especially in terms of human life, an unexpected flood can be. Accurate forecasts and warnings cannot be made, however, without detailed information about precipitation and streamflow in the drainage basin. Since the mid 1960's, the National Weather Service (NWS) has been able to forecast flooding on larger streams in Somerset County, such as the Raritan and Millstone Rivers. Flooding on smaller streams in urban areas was more difficult to predict. In response to this problem the NWS, in cooperation with the Green Brook Flood Control Commission, installed a precipitation gage in North Plainfield, and two flash-flood alarms, one on Green Brook at Seeley Mills and one on Stony Brook at Watchung, in the early 1970's. In 1978, New Jersey's first countywide flood-warning system was installed by the U.S. Geological Survey (USGS) in Somerset County. This system consisted of a network of eight stage and discharge gages equipped with precipitation gages linked by telephone telemetry and eight auxiliary precipitation gages. The gages were installed throughout the county to collect precipitation and runoff data that could be used to improve flood-monitoring capabilities and flood-frequency estimates. Recognizing the need for more detailed hydrologic information for Somerset County, the USGS, in cooperation with Somerset County, designed and installed the Somerset County Flood Information System (SCFIS) in 1990. This system is part of a statewide network of stream gages, precipitation gages, weather stations, and tide gages that collect data in real time. The data provided by the SCFIS improve the flood forecasting ability of the NWS and aid Somerset County and municipal agencies in the planning and execution of flood-preparation and emergency-evacuation procedures in the county. This fact sheet describes the SCFIS and identifies its benefits.

Hysteretic behavior of stage-discharge relationships in urban streams

NASA Astrophysics Data System (ADS)

Miller, A. J.; Lindner, G. A.

2009-12-01

Reliable stage-discharge relationships or rating curves are of critical importance for accurate calculation of streamflow and maintenance of long-term flow records. Urban streams offer particular challenges for the maintenance of accurate rating curves. It is often difficult or impossible to collect direct discharge measurements at high flows, many of which are generated by short-duration high-intensity summer thunderstorms, both because of dangerous conditions in the channel and also because the stream rises and falls so rapidly that field crews cannot reach sites in time and sometimes cannot make measurements rapidly enough to keep pace with changing water levels even when they are on site during a storm. Work in urban streams in the Baltimore metropolitan area has shown that projection of rating curves beyond the range of measured flows can lead to overestimation of flood peaks by as much as 100%, and these can only be corrected when adequate field data are available to support modeling efforts. Even moderate flows that are above safe wading depth and velocity may best be estimated using hydraulic models. Current research for NSF CNH project 0709659 includes the application of 2-d depth-averaged hydraulic models to match existing rating curves over a range of low to moderate flows and to extend rating curves for higher flows, based on field collection of high-water marks. Although it is generally assumed that stage-discharge relationships are single-valued, we find that modeling results in small urban streams often generate hysteretic relationships, with higher discharges on the rising limb of the hydrograph than on the falling limb. The difference between discharges for the same stage on the rising and falling limb can be on the order of 20-30% even for in-channel flows that are less than 1 m deep. As safety considerations dictate that it is preferable to make direct discharge measurements on the falling limb of the hydrograph, the higher direct measurements used in many rating curves probably have been collected on the falling limb and therefore may not capture the correct stage-discharge relationship for the rising limb. In some cases model results selected only from the falling limb are able to match the existing rating curve very closely. Although hysteresis may be explained with reference to the innate properties of the flood wave, other factors also lead to hysteretic behavior. Downstream constrictions and obstructions associated with urban infrastructure may cause substantial backwater effects, particularly during flood flows. Flood conditions at tributary confluences also can exert a controlling influence upstream. Based on our results we recommend that at some sites it is advisable to develop separate rating curves for the rising and falling limbs, and to develop a range of modeling scenarios for predicting the range of potential uncertainty.

Retention of contaminants in constructed and semi-natural wetland soils in urban river systems

NASA Astrophysics Data System (ADS)

Kalinski, Kira; Gröngröft, Alexander; Eschenbach, Annette

2017-04-01

The retention of floods is one of the most relevant ecosystem function of urban floodplains, which is often improved by the construction of retention ponds and other water management measures. Retention ponds are connected to the river in a direct or a parallel arrangement and can be constructed as dry or wet retention pond under normal run-off conditions. Further important ecosystem functions provided by the floodplains soils are carbon sequestration, nutrient and contaminant regulation and recreation. However, with ongoing urbanization these ecosystem functions are significantly endangered. In our study we analyze the soil-based ecosystem functions of two river catchments in the City of Hamburg. The presentation will focus on the retention of contaminants in soils and sediments of eleven retention ponds within one catchment. The amount and concentrations of contaminants will be analyzed for controlling factors like grain size distribution, land-use within the headwaters and others.

A real-time control framework for urban water reservoirs operation

NASA Astrophysics Data System (ADS)

Galelli, S.; Goedbloed, A.; Schwanenberg, D.

2012-04-01

Drinking water demand in urban areas is growing parallel to the worldwide urban population, and it is acquiring an increasing part of the total water consumption. Since the delivery of sufficient water volumes in urban areas represents a difficult logistic and economical problem, different metropolitan areas are evaluating the opportunity of constructing relatively small reservoirs within urban areas. Singapore, for example, is developing the so-called 'Four National Taps Strategies', which detects the maximization of water yields from local, urban catchments as one of the most important water sources. However, the peculiar location of these reservoirs can provide a certain advantage from the logistical point of view, but it can pose serious difficulties in their daily management. Urban catchments are indeed characterized by large impervious areas: this results in a change of the hydrological cycle, with decreased infiltration and groundwater recharge, and increased patterns of surface and river discharges, with higher peak flows, volumes and concentration time. Moreover, the high concentrations of nutrients and sediments characterizing urban discharges can cause further water quality problems. In this critical hydrological context, the effective operation of urban water reservoirs must rely on real-time control techniques, which can exploit hydro-meteorological information available in real-time from hydrological and nowcasting models. This work proposes a novel framework for the real-time control of combined water quality and quantity objectives in urban reservoirs. The core of this framework is a non-linear Model Predictive Control (MPC) scheme, which employs the current state of the system, the future discharges furnished by a predictive model and a further model describing the internal dynamics of the controlled sub-system to determine an optimal control sequence over a finite prediction horizon. The main advantage of this scheme stands in its reduced computational requests and the capability of exploiting real-time hydro-meteorological information, which are crucial for an effective operation of these fast-varying hydrological systems. The framework is here demonstrated on the operation of Marina Reservoir (Singapore), whose recent construction in late 2008 increased the effective catchment area to about 50% of the total available. Its operation, which accounts for drinking water supply, flash floods control and water quality standards, is here designed by combining the MPC scheme with the process-based hydrological model SOBEK. Extensive simulation experiments show the validity of the proposed framework.

Towards an integrated flood management approach to address trade-offs between ecosystem services: Insights from the Dutch and German Rhine, Hungarian Tisza, and Chinese Yangtze basins

NASA Astrophysics Data System (ADS)

Halbe, Johannes; Knüppe, Kathrin; Knieper, Christian; Pahl-Wostl, Claudia

2018-04-01

The utilization of ecosystem services in flood management is challenged by the complexity of human-nature interactions and practical implementation barriers towards more ecosystem-based solutions, such as riverine urban areas or technical infrastructure. This paper analyses how flood management has dealt with trade-offs between ecosystem services and practical constrains towards more ecosystem-based solutions. To this end, we study the evolution of flood management in four case studies in the Dutch and German Rhine, the Hungarian Tisza, and the Chinese Yangtze basins during the last decades, focusing on the development and implementation of institutions and their link to ecosystem services. The complexity of human-nature interactions is addressed by exploring the impacts on ecosystem services through the lens of three management paradigms: (1) the control paradigm, (2) the ecosystem-based paradigm, and (3) the stakeholder involvement paradigm. Case study data from expert interviews and a literature search were structured using a database approach prior to qualitative interpretation. Results show the growing importance of the ecosystem-based and stakeholder involvement paradigms which has led to the consideration of a range of regulating and cultural ecosystem services that had previously been neglected. We detected a trend in flood management practice towards the combination of the different paradigms under the umbrella of integrated flood management, which aims at finding the most suitable solution depending on the respective regional conditions.

Webinar Announcement - The Clean Water State Revolving Fund: Flexible Funding for the Urban Tree Canopy

EPA Pesticide Factsheets

This webinar, presented by the EPA and USDA, explores how the CWSRF can be used as a funding source for green infrastructure and urban forestry projects—a cost effective way to reduce combined sewage flooding problems.

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.

An initial abstraction and constant loss model, and methods for estimating unit hydrographs, peak streamflows, and flood volumes for urban basins in Missouri

USGS Publications Warehouse

Huizinga, Richard J.

2014-01-01

The rainfall-runoff pairs from the storm-specific GUH analysis were further analyzed against various basin and rainfall characteristics to develop equations to estimate the peak streamflow and flood volume based on a quantity of rainfall on the basin.

Development of Urban Inundation Warning Model at Cyclic Artificial Water Way in Song-do International City, Republic of Korea

NASA Astrophysics Data System (ADS)

Lee, T.; Lee, C.; Kim, H.

2016-12-01

Abstract Song-do international city was constructed by reclaiming land from the coastal waters of Yeonsu-gu, Incheon Metropolitan City, Republic of Korea. The □-shaped cyclic artificial water way has been considered for improving water quality, waterfront and internal drainage in Song-do international city. By improving water quality, various marine facilities, such as marina, artificial beach, marine terminal, and so on, will be set up around the artificial water way for the waterfront. Since the water stage of the artificial water way changes depending on water gates operations, it is necessary to develop an urban inundation warning model to evaluate safeties of the waterfront facilities and its passengers. By considering characteristics of urban watershed, we calculate discharge flowing into the water way using XP-SWMM model. As a result of estimating 100-year flood frequency, although there are slight differences in drainage sections, the maximum flood discharge occurs in 90-min rainfall duration. In order to consider impacts of tide and hydraulic structure, we establish Inland drainage plans through the analysis of unsteady flow using HEC-RAS. The urban inundation warning model is configured to issue a warning when the water plain elevation exceeds EL. 1.5m which is usually managed at EL. 1.0m. In this study, the design flood stage of artificial water way and urban inundation warning model are developed for Song-do international city, and therefore it is expected that a reliability of management and operation of the waterfront facilities is improved. Keywords : Artificial Water Way; Waterfront; Urban Inundation Warning Model. Acknowlegement This research was supported by a grant [MPSS-NH-2015-79] through the Disaster and Safety Management Institute funded by Ministry of Public Safety and Security of Korean government.

The urban poor in Dhaka City: their struggles and coping strategies during the floods of 1998.

PubMed

Rashid, S F

2000-09-01

Bangladesh experienced one of the worst floods in recorded history in 1998. This paper focuses on the needs and coping strategies of the urban poor in Dhaka City, which had been very badly affected. The city's roads were completely under water, and most areas were water-logged with drainage and sewage systems blocked. Rising water levels compelled many slum dwellers to move to temporary shelters and relief camps. Women and children were the worst affected. The lack of sanitation facilities and privacy forced women and children to defecate in their own homes. There was an acute scarcity of safe drinking-water, and food prices rose dramatically. Diarrhoea, fever and colds were the most common illnesses affecting the poor. The floods left many of them unemployed, and in some families, the result was increased tension and incidents of domestic violence. In some areas, members felt pressured to repay micro-credit loans. Most NGOs, however, suspended loan repayments. During this period, a committee was set up to co-ordinate and work towards addressing some of the main post-flood problems.

iFLOOD: A Real Time Flood Forecast System for Total Water Modeling in the National Capital Region

NASA Astrophysics Data System (ADS)

Sumi, S. J.; Ferreira, C.

2017-12-01

Extreme flood events are the costliest natural hazards impacting the US and frequently cause extensive damages to infrastructure, disruption to economy and loss of lives. In 2016, Hurricane Matthew brought severe damage to South Carolina and demonstrated the importance of accurate flood hazard predictions that requires the integration of riverine and coastal model forecasts for total water prediction in coastal and tidal areas. The National Weather Service (NWS) and the National Ocean Service (NOS) provide flood forecasts for almost the entire US, still there are service-gap areas in tidal regions where no official flood forecast is available. The National capital region is vulnerable to multi-flood hazards including high flows from annual inland precipitation events and surge driven coastal inundation along the tidal Potomac River. Predicting flood levels on such tidal areas in river-estuarine zone is extremely challenging. The main objective of this study is to develop the next generation of flood forecast systems capable of providing accurate and timely information to support emergency management and response in areas impacted by multi-flood hazards. This forecast system is capable of simulating flood levels in the Potomac and Anacostia River incorporating the effects of riverine flooding from the upstream basins, urban storm water and tidal oscillations from the Chesapeake Bay. Flood forecast models developed so far have been using riverine data to simulate water levels for Potomac River. Therefore, the idea is to use forecasted storm surge data from a coastal model as boundary condition of this system. Final output of this validated model will capture the water behavior in river-estuary transition zone far better than the one with riverine data only. The challenge for this iFLOOD forecast system is to understand the complex dynamics of multi-flood hazards caused by storm surges, riverine flow, tidal oscillation and urban storm water. Automated system simulations will help to develop a seamless integration with the boundary systems in the service-gap area with new insights into our scientific understanding of such complex systems. A visualization system is being developed to allow stake holders and the community to have access to the flood forecasting for their region with sufficient lead time.

Annual compilation and analysis of hydrologic data for urban studies in the Bryan, Texas, metropolitan area, 1969

USGS Publications Warehouse

Robbins, W.D.

1972-01-01

Hydrologic investigations of urban areas in Texas were begun by the U.S. Geological Survey in 1954. These studies are now in progress in Austin, Houston, Dallas, Dallas County, Fort Worth, San Antonio, and Bryan. Hydrologic investigations of urban areas in Texas were begun by the U.S. Geological Survey in 1954. These studies are now in progress in Austin, Houston, Dallas, Dallas County, Fort Worth, San Antonio, and Bryan. 1. To determine, on the basis of historical data and hydrologic analyses, the magnitude and frequency of floods. 2. To document and define the areal extent of floods of greater than ordinary magnitude. 3. To determine the effect of urban development on flood peaks and volume. 4. To provide applied research facilities for studies at Texas A & M University at College Stations. This report, the first in a series of reports to be published annually, is primarily applicable to objectives 2, 3, and 4. The report presents the basic hydrologic data collected in two study areas during the 1969 water year (October 1, 1968, to September 30, 1969) and basic hydrologic data collected during part of the 1968 water year (April 5, 1968, to September 30, 1968). The locations of the two basins within the study area, Burton Creek and Hudson Creek, are shown on figure 1.

Identifying the driving forces of urban expansion and its environmental impact in Jakarta-Bandung mega urban region

NASA Astrophysics Data System (ADS)

Pravitasari, A. E.; Rustiadi, E.; Mulya, S. P.; Setiawan, Y.; Fuadina, L. N.; Murtadho, A.

2018-05-01

The socio-economic development in Jakarta-Bandung Mega Urban Region (JBMUR) caused the increasing of urban expansion and led to a variety of environmental damage such as uncontrolled land use conversion and raising anthropogenic disaster. The objectives of this study are: (1) to identify the driving forces of urban expansion that occurs on JBMUR and (2) to analyze the environmental quality decline on JBMUR by producing time series spatial distribution map and spatial autocorrelation of floods and landslide as the proxy of anthropogenic disaster. The driving forces of urban expansion in this study were identified by employing Geographically Weighted Regression (GWR) model using 6 (six) independent variables, namely: population density, percentage of agricultural land, distance to the center of capital city/municipality, percentage of household who works in agricultural sector, distance to the provincial road, and distance to the local road. The GWR results showed that local demographic, social and economic factors including distance to the road spatially affect urban expansion in JBMUR. The time series spatial distribution map of floods and landslide event showed the spatial cluster of anthropogenic disaster in some areas. Through Local Moran Index, we found that environmental damage in one location has a significant impact on the condition of its surrounding area.

The impact of projected increases in urbanization on ecosystem services.

PubMed

Eigenbrod, F; Bell, V A; Davies, H N; Heinemeyer, A; Armsworth, P R; Gaston, K J

2011-11-07

Alteration in land use is likely to be a major driver of changes in the distribution of ecosystem services before 2050. In Europe, urbanization will probably be the main cause of land-use change. This increase in urbanization will result in spatial shifts in both supplies of ecosystem services and the beneficiaries of those services; the net outcome of such shifts remains to be determined. Here, we model changes in urban land cover in Britain based on large (16%) projected increases in the human population by 2031, and the consequences for three different services--flood mitigation, agricultural production and carbon storage. We show that under a scenario of densification of urban areas, the combined effect of increasing population and loss of permeable surfaces is likely to result in 1.7 million people living within 1 km of rivers with at least 10 per cent increases in projected peak flows, but that increasing suburban 'sprawl' will have little effect on flood mitigation services. Conversely, losses of stored carbon and agricultural production are over three times as high under the sprawl as under the 'densification' urban growth scenarios. Our results illustrate the challenges of meeting, but also of predicting, future demands and patterns of ecosystem services in the face of increasing urbanization.

The impact of projected increases in urbanization on ecosystem services

PubMed Central

Eigenbrod, F.; Bell, V. A.; Davies, H. N.; Heinemeyer, A.; Armsworth, P. R.; Gaston, K. J.

2011-01-01

Alteration in land use is likely to be a major driver of changes in the distribution of ecosystem services before 2050. In Europe, urbanization will probably be the main cause of land-use change. This increase in urbanization will result in spatial shifts in both supplies of ecosystem services and the beneficiaries of those services; the net outcome of such shifts remains to be determined. Here, we model changes in urban land cover in Britain based on large (16%) projected increases in the human population by 2031, and the consequences for three different services—flood mitigation, agricultural production and carbon storage. We show that under a scenario of densification of urban areas, the combined effect of increasing population and loss of permeable surfaces is likely to result in 1.7 million people living within 1 km of rivers with at least 10 per cent increases in projected peak flows, but that increasing suburban ‘sprawl’ will have little effect on flood mitigation services. Conversely, losses of stored carbon and agricultural production are over three times as high under the sprawl as under the ‘densification’ urban growth scenarios. Our results illustrate the challenges of meeting, but also of predicting, future demands and patterns of ecosystem services in the face of increasing urbanization. PMID:21389035

Stream hydrologic response to increased urbanization in Mid-Atlantic watersheds

EPA Science Inventory

Urban development alters stream hydrology; resulting in increases in the Richard-Baker Flashiness index, peak flow, and the number of flood events for many watersheds throughout the U.S. To better understand and predict the relationship between stream flow patterns and watershed ...

High-resolution maps of forest-urban watersheds present an opportunity for ecologists and managers

EPA Science Inventory

Dense populations of people and abundant impervious surfaces contribute to poor water quality and increased flooding in forest-urban watersheds. Green infrastructure mitigates these effects, but precisely quantifying benefits is difficult because most land cover maps rely on coar...

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.

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/

Floods of February-March 1961 in the southeastern States

USGS Publications Warehouse

Barnes, Harry Hawthorne; Somers, William Philip

1961-01-01

Widespread, prolonged, disastrous floods struck parts of Louisiana, Mississippi, Alabama, Georgia, and Florida following heavy rains Feb. 17-26, 1961. Three distinct low-pressure systems recurred in essentially the same area. Precipitation totaled more than 18 inches in some areas. Multiple floods of small streams became superimposed in the large rivers to produce rare, record-breaking peaks and prolonged inundation. Four lives were lost; one in Louisiana and three in Mississippi. Highways, railroads, urban areas, and farms were heavily damaged.

National Economic Development Procedures Manual - Urban Flood Damage. Volume 2: Primer for Surveying Flood Damage for Residential Structures and Contents

DTIC Science & Technology

1991-10-01

procedures and techniques to measure flood damage and to further implement the Principles and Guidelines of the U.S. Water Resources Council. This manual... guidelines for using the OMB approved questionnaires are provided in Engineer Regulation 1105-2-100. The compendium provides the analyst with a helpful...question content, the analyst must also comply with OMB guidelines concerning implementation of the Privacy Act of 1974 (P.L. 93-579). This Act requires

On correlation between urban development, land subsidence and flooding phenomena in Jakarta

NASA Astrophysics Data System (ADS)

Abidin, H. Z.; Andreas, H.; Gumilar, I.; Wibowo, I. R. R.

2015-06-01

Jakarta is the capital city of Indonesia with a population of about 10.2 million people, inhabiting an area of about 660 square-km. It is located within a deltaic plain and passes by 13 natural and artificial rivers. In the last three decades, urban development of Jakarta has grown very rapidly in the sectors of industry, trade, transportation, real estate and many others, which has caused several negative environmental impacts. In turns Jakarta is then prone toward a few natural hazards mainly land subsidence and flooding. In general, based on geodetic measurement methods (e.g. Leveling, GPS surveys, and InSAR), conducted since 1982 up to 2014, it is obtained that land subsidence in Jakarta exhibits spatial and temporal variations, with the typical rates of about 3 to 10 cm year-1. In general, the impacts of land subsidence in Jakarta can be seen in the forms of cracking of permanent constructions and roads, changes in river canal and drain flow systems, wider expansion of coastal and/or inland flooding areas, and malfunction of drainage system. Several areas along the coast of Jakarta already have experienced tidal flooding during high tide periods. These coastal flooding usually occurs in the areas with relatively large subsidence rates. Subsidence in the areas along the rivers which are flowing throughout Jakarta will also worsen the impacts of riverine flooding. The changes in river canal and drain flow systems and malfunction of drainage system due to land subsidence will also aggravate the flooding. Land subsidence will have direct and indirect affects with the flooding in Jakarta, both in coastal or inland areas.

Current and Future Urban Stormwater Flooding Scenarios in the Southeast Florida Coasts

NASA Astrophysics Data System (ADS)

Huq, E.; Abdul-Aziz, O. I.

2016-12-01

This study computed rainfall-fed stormwater flooding under the historical and future reference scenarios for the Southeast Coasts Basin of Florida. A large-scale, mechanistic rainfall-runoff model was developed using the U.S. E.P.A. Storm Water Management Model (SWMM 5.1). The model parameterized important processes of urban hydrology, groundwater, and sea level, while including hydroclimatological variables and land use features. The model was calibrated and validated with historical streamflow data. It was then used to estimate the sensitivity of stormwater runoff to the reference changes in hydroclimatological variables (rainfall and evapotranspiration) and different land use/land cover features (imperviousness, roughness). Furthermore, historical (1970-2000) and potential 2050s stormwater budgets were also estimated for the Florida Southeast Coasts Basin by incorporating climatic projections from different GCMs and RCMs, as well as by using relevant projections of sea level and land use/cover. Comparative synthesis of the historical and future scenarios along with the results of sensitivity analysis can aid in efficient management of stormwater flooding for the southeast Florida coasts and similar urban centers under a changing regime of climate, sea level, land use/cover and hydrology.

On Assessment and Estimation of Potential Losses due to Land Subsidence in Urban Areas of Indonesia

NASA Astrophysics Data System (ADS)

Abidin, Hasanuddin Z.; Andreas, Heri; Gumilar, Irwan; Sidiq, Teguh P.

2016-04-01

Land subsidence is natural-anthropogenic hazard affecting several large urban areas in Indonesia, i.e. Jakarta, Bandung and Semarang. Geodetic based results from various techniques (e.g. Leveling, GPS and InSAR) show that land subsidence rates in all three cities generally have spatial and temporal variations, and their magnitude is in average about 5-10 cm/year. The impacts of subsidence in those cities can be seen in the field in various forms such as cracking of permanent constructions and roads, tilting of houses and buildings, 'sinking' of houses and buildings, changes in river canal and drain flow systems, wider expansion of coastal and/or inland flooding areas, and increased inland sea water intrusion. These impacts can be categorized into infrastructure, environmental, economic, and social impacts. The potential losses due to land subsidence in urban areas are actually quite significant. Related infrastructural, social and environmental costs due to direct and indirect impacts of land subsidence are economically quite significant, and can not be underestimated in sustainable urban development. The planning, development and maintenance costs of building and infrastructures in the affected areas are usually much higher than the normal situation. The collateral impact of coastal subsidence in Jakarta and Semarang, in the form of coastal flooding during high tides is also quite damaging. This repeated coastal flooding in several areas along the coast will deteriorate the structure and function of building and infrastructures, badly influences the quality of the living environment and life (e.g. health and sanitation condition), and also disrupts economic and social activities in the affected areas. As in the case of Bandung, inland subsidence also has a quite significant impact on inland flooding phenomena, since it will theoretically lead to expanded coverage and deeper water depth of flooded (inundated) areas. Since the direct and indirect impacts of subsidence have also relation among each other, the accurate quantification of the potential losses caused by land subsidence in urban areas is not an easy task to accomplish. The direct losses can be easier to estimate than the indirect losses. For example, the direct losses due to land subsidence in Bandung was estimated to be at least 180 Million USD; but the indirect losses is still unknown.

Methods for determining magnitude and frequency of floods in California, based on data through water year 2006

USGS Publications Warehouse

Gotvald, Anthony J.; Barth, Nancy A.; Veilleux, Andrea G.; Parrett, Charles

2012-01-01

Methods for estimating the magnitude and frequency of floods in California that are not substantially affected by regulation or diversions have been updated. Annual peak-flow data through water year 2006 were analyzed for 771 streamflow-gaging stations (streamgages) in California having 10 or more years of data. Flood-frequency estimates were computed for the streamgages by using the expected moments algorithm to fit a Pearson Type III distribution to logarithms of annual peak flows for each streamgage. Low-outlier and historic information were incorporated into the flood-frequency analysis, and a generalized Grubbs-Beck test was used to detect multiple potentially influential low outliers. Special methods for fitting the distribution were developed for streamgages in the desert region in southeastern California. Additionally, basin characteristics for the streamgages were computed by using a geographical information system. 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 basins in California that are outside of the southeastern desert region. Flood-frequency estimates and basin characteristics for 630 streamgages were combined to form the final database used in the regional regression analysis. Five hydrologic regions were developed for the area of California outside of the desert region. The final regional regression equations are functions of drainage area and mean annual precipitation for four of the five regions. In one region, the Sierra Nevada region, the final equations are functions of drainage area, mean basin elevation, and mean annual precipitation. Average standard errors of prediction for the regression equations in all five regions range from 42.7 to 161.9 percent. For the desert region of California, an analysis of 33 streamgages was used to develop regional estimates of all three parameters (mean, standard deviation, and skew) of the log-Pearson Type III distribution. The regional estimates were then 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 basins. The final regional regression equations are functions of drainage area. Average standard errors of prediction for these regression equations range from 214.2 to 856.2 percent. Annual peak-flow data through water year 2006 were analyzed for eight streamgages in California having 10 or more years of data considered to be affected by urbanization. Flood-frequency estimates were computed for the urban streamgages by fitting a Pearson Type III distribution to logarithms of annual peak flows for each streamgage. Regression analysis could not be used to develop flood-frequency estimation equations for urban streams because of the limited number of sites. Flood-frequency estimates for the eight urban sites were graphically compared to flood-frequency estimates for 630 non-urban sites. The regression equations developed from this study will be incorporated into the U.S. Geological Survey (USGS) StreamStats program. The StreamStats program is a Web-based application that provides streamflow statistics and basin characteristics for USGS streamgages and ungaged sites of interest. StreamStats can also compute basin characteristics and provide estimates of streamflow statistics for ungaged sites when users select the location of a site along any stream in California.