Contribution of an exposure indicator to better anticipate damages with the AIGA flood warning method: a case study in the South of France

NASA Astrophysics Data System (ADS)

Saint-Martin, Clotilde; Fouchier, Catherine; Douvinet, Johnny; Javelle, Pierre; Vinet, Freddy

2016-04-01

On the 3rd October 2015, heavy localized precipitations have occurred in South Eastern France leading to major flash floods on the Mediterranean coast. The severity of those floods has caused 20 fatalities and important damage in almost 50 municipalities in the French administrative area of Alpes-Maritimes. The local recording rain gauges have shown how fast the event has happened: 156 mm of rain were recorded in Mandelieu-la-Napoule and 145 mm in Cannes within 2 hours. As the affected rivers are not monitored, no anticipation was possible from the authorities in charge of risk management. In this case, forecasting floods is indeed complex because of the small size of the watersheds which implies a reduced catchment response time. In order to cope with the need of issuing flood warnings on un-monitored small catchments, Irstea and Météo-France have developed an alternative warning system for ungauged basins called the AIGA method. AIGA is a flood warning system based on a simple distributed hydrological model run at a 1 km² resolution using real time radar rainfall information (Javelle, Demargne, Defrance, Pansu, & Arnaud, 2014). The flood warnings, produced every 15 minutes, result of the comparison of the real time runoff data produced by the model with statistical runoff values. AIGA is running in real time in the South of France, within the RHYTMME project (https://rhytmme.irstea.fr/). Work is on-going in order to offer a similar service for the whole French territory. More than 200 impacts of the 3rd October floods have been located using media, social networks and fieldwork. The first comparisons between these impacts and the AIGA warning levels computed for this event show several discrepancies. However, these latter discrepancies appear to be explained by the land-use. An indicator of the exposure of territories to flooding has thus been created to weight the levels of the AIGA hydrological warnings with the land-use of the area surrounding the streams for which the warnings are issued. This paper aims to explain how this indicator has been created and to assess its relevance with the example of the 3rd October 2015 flood. By completing this approach, the AIGA warnings may characterize not only the flood hazard but more inclusively the risk of flooding, allowing to forecast this type of event. Javelle, P., Demargne, J., Defrance, D., Pansu, J., & Arnaud, P. (2014). Evaluating flash-flood warnings at ungauged locations using post-event surveys: a case study with the AIGA warning system. Hydrological Sciences Journal-Journal Des Sciences Hydrologiques, 59(7), 1390-1402. doi: 10.1080/02626667.2014.923970

Flash flood warnings for ungauged basins based on high-resolution precipitation forecasts

NASA Astrophysics Data System (ADS)

Demargne, Julie; Javelle, Pierre; Organde, Didier; de Saint Aubin, Céline; Janet, Bruno

2016-04-01

Early detection of flash floods, which are typically triggered by severe rainfall events, is still challenging due to large meteorological and hydrologic uncertainties at the spatial and temporal scales of interest. Also the rapid rising of waters necessarily limits the lead time of warnings to alert communities and activate effective emergency procedures. To better anticipate such events and mitigate their impacts, the French national service in charge of flood forecasting (SCHAPI) is implementing a national flash flood warning system for small-to-medium (up to 1000 km²) ungauged basins based on a discharge-threshold flood warning method called AIGA (Javelle et al. 2014). The current deterministic AIGA system has been run in real-time in the South of France since 2005 and has been tested in the RHYTMME project (rhytmme.irstea.fr/). It ingests the operational radar-gauge QPE grids from Météo-France to run a simplified hourly distributed hydrologic model at a 1-km² resolution every 15 minutes. This produces real-time peak discharge estimates along the river network, which are subsequently compared to regionalized flood frequency estimates to provide warnings according to the AIGA-estimated return period of the ongoing event. The calibration and regionalization of the hydrologic model has been recently enhanced for implementing the national flash flood warning system for the entire French territory by 2016. To further extend the effective warning lead time, the flash flood warning system is being enhanced to ingest Météo-France's AROME-NWC high-resolution precipitation nowcasts. The AROME-NWC system combines the most recent available observations with forecasts from the nowcasting version of the AROME convection-permitting model (Auger et al. 2015). AROME-NWC pre-operational deterministic precipitation forecasts, produced every hour at a 2.5-km resolution for a 6-hr forecast horizon, were provided for 3 significant rain events in September and November 2014 and ingested as time-lagged ensembles. The time-lagged approach is a practical choice of accounting for the atmospheric forecast uncertainty when no extensive forecast archive is available for statistical modelling. The evaluation on 185 basins in the South of France showed significant improvements in terms of flash flood event detection and effective warning lead-time, compared to warnings from the current AIGA setup (without any future precipitation). Various verification metrics (e.g., Relative Mean Error, Brier Skill Score) show the skill of ensemble precipitation and flow forecasts compared to single-valued persistency benchmarks. Planned enhancements include integrating additional probabilistic NWP products (e.g., AROME precipitation ensembles on longer forecast horizon), accounting for and reducing hydrologic uncertainties from the model parameters and initial conditions via data assimilation, and developing a comprehensive observational and post-event damage database to determine decision-relevant warning thresholds for flood magnitude and probability. Javelle, P., Demargne, J., Defrance, D., Arnaud, P., 2014. Evaluating flash flood warnings at ungauged locations using post-event surveys: a case study with the AIGA warning system. Hydrological Sciences Journal, doi: 10.1080/02626667.2014.923970 Auger, L., Dupont, O., Hagelin, S., Brousseau, P., Brovelli, P., 2015. AROME-NWC: a new nowcasting tool based on an operational mesoscale forecasting system. Quarterly Journal of the Royal Meteorological Society, 141: 1603-1611, doi: 10.1002/qj.2463

Public responses to flood warning messages: the Floodline service in Scotland

NASA Astrophysics Data System (ADS)

Cranston, Michael; Geddes, Alistair; Black, Andrew; Ambler, Alice; Menmuir, Cordelia

2017-04-01

Over the past decade, efforts have been made to improve the national flood warning system in Scotland, with new capabilities in the underlying flood forecasting tools, as well as development of an active flood warning dissemination service. This paper focusses on the latter service, for which there are around 26,000 customers registered at present, and which saw over 300,000 individual messages being issued during recent floods in winter 2015/16. However, notwithstanding such promising signs of change, evidence of how (if at all) the flood warning messages disseminated by the service actually impacts on recipient behaviour remains more limited. For example, this includes knowledge of the extent to which the messages influence actions on flood preparedness and mitigation. In consequence, there are also ongoing questions over the cost-effectiveness of the service in its current format, and of its scalability to even larger numbers of recipients. This paper will present initial findings from the first detailed study of customer perceptions of the messages distributed via the Scottish flood warning system, officially known as Floodline. In particular, the primary focus will be on results generated from a web-based questionnaire survey of registered Floodline customers. The survey was designed to assess associations between multiple customer characteristics, including location and risk level, type of warning message received, prior experience of flooding, risk awareness, and demographics. The study was conducted for the Scottish Environment Protection Agency, which is responsible for running the Floodline service. More broadly it resonates with current emphases on exploring effective means of hazard communication and encouraging public engagement in flood risk management.

A global flash flood forecasting system

NASA Astrophysics Data System (ADS)

Baugh, Calum; Pappenberger, Florian; Wetterhall, Fredrik; Hewson, Tim; Zsoter, Ervin

2016-04-01

The sudden and devastating nature of flash flood events means it is imperative to provide early warnings such as those derived from Numerical Weather Prediction (NWP) forecasts. Currently such systems exist on basin, national and continental scales in Europe, North America and Australia but rely on high resolution NWP forecasts or rainfall-radar nowcasting, neither of which have global coverage. To produce global flash flood forecasts this work investigates the possibility of using forecasts from a global NWP system. In particular we: (i) discuss how global NWP can be used for flash flood forecasting and discuss strengths and weaknesses; (ii) demonstrate how a robust evaluation can be performed given the rarity of the event; (iii) highlight the challenges and opportunities in communicating flash flood uncertainty to decision makers; and (iv) explore future developments which would significantly improve global flash flood forecasting. The proposed forecast system uses ensemble surface runoff forecasts from the ECMWF H-TESSEL land surface scheme. A flash flood index is generated using the ERIC (Enhanced Runoff Index based on Climatology) methodology [Raynaud et al., 2014]. This global methodology is applied to a series of flash floods across southern Europe. Results from the system are compared against warnings produced using the higher resolution COSMO-LEPS limited area model. The global system is evaluated by comparing forecasted warning locations against a flash flood database of media reports created in partnership with floodlist.com. To deal with the lack of objectivity in media reports we carefully assess the suitability of different skill scores and apply spatial uncertainty thresholds to the observations. To communicate the uncertainties of the flash flood system output we experiment with a dynamic region-growing algorithm. This automatically clusters regions of similar return period exceedence probabilities, thus presenting the at-risk areas at a spatial resolution appropriate to the NWP system. We then demonstrate how these warning areas could eventually complement existing global systems such as the Global Flood Awareness System (GloFAS), to give warnings of flash floods. This work demonstrates the possibility of creating a global flash flood forecasting system based on forecasts from existing global NWP systems. Future developments, in post-processing for example, will need to address an under-prediction bias, for extreme point rainfall, that is innate to current-generation global models.

Early Flood Warning in Africa: Results of a Feasibility study in the JUBA, SHABELLE and ZAMBEZI

NASA Astrophysics Data System (ADS)

Pappenberger, F. P.; de Roo, A. D.; Buizza, Roberto; Bodis, Katalin; Thiemig, Vera

2009-04-01

Building on the experiences gained with the European Flood Alert System (EFAS), pilot studies are carried out in three river basins in Africa. The European Flood Alert System, pre-operational since 2003, provides early flood alerts for European rivers. At present, the experiences with the European EFAS system are used to evaluate the feasibility of flood early warning for Africa. Three case studies are carried in the Juba and Shabelle rivers (Somalia and Ethiopia), and in the Zambesi river (Southern Africa). Predictions in these data scarce regions are extremely difficult to make as records of observations are scarce and often unreliable. Meteorological and Discharge observations are used to calibrate and test the model, as well as soils, landuse and topographic data available within the JRC African Observatory. ECMWF ERA-40, ERA-Interim data and re-forecasts of flood events from January to March 1978, and in March 2001 are evaluated to examine the feasibility for early flood warning. First results will be presented.

Design and field test equipment of river water level detection based on ultrasonic sensor and SMS gateway as flood early warning

NASA Astrophysics Data System (ADS)

Sulistyowati, Riny; Sujono, Hari Agus; Musthofa, Ahmad Khamdi

2017-06-01

Due to the high rainfall, flood often occurs in some regions, especially in the area adjacent to the river banks that led to the idea to make the river water level detection system as a flood early warning. Several researches have produced flood detection equipment based on ultrasonic sensors and android as flood early warning system. This paper reported the results of a field test detection equipment to measure the river water level of the Bengawansolo River that was conducted in three villages in the district of Bungah, Dukun, and Manyar in Gresik regency. Tests were conducted simultaneously for 21 hours during heavy rainfall. The test results demonstrated the accuracy of the equipment of 97.28% for all categories of observation. The application of AFD (Android Flood Detection) via android smartphone demonstrated its precision in conveying the information of water level as represented by the status of SAFE, STAND, WARNING, and DANGER. Some charts presented from the analysis of data was derived from the data acquisition time of testing that can be used as an evaluation of flooding at some points prone to flood.

Flood Monitoring and Early Warning System Using Ultrasonic Sensor

NASA Astrophysics Data System (ADS)

Natividad, J. G.; Mendez, J. M.

2018-03-01

The purpose of this study is to develop a real-time flood monitoring and early warning system in the northern portion of the province of Isabela, particularly the municipalities near Cagayan River. Ultrasonic sensing techniques have become mature and are widely used in the various fields of engineering and basic science. One of advantage of ultrasonic sensing is its outstanding capability to probe inside objective non-destructively because ultrasound can propagate through any kinds of media including solids, liquids and gases. This study focuses only on the water level detection and early warning system (via website and/or SMS) that alerts concern agencies and individuals for a potential flood event. Furthermore, inquiry system is also included in this study to become more interactive wherein individuals in the community could inquire the actual water level and status of the desired area or location affected by flood thru SMS keyword. The study aims in helping citizens to be prepared and knowledgeable whenever there is a flood. The novelty of this work falls under the utilization of the Arduino, ultrasonic sensors, GSM module, web-monitoring and SMS early warning system in helping stakeholders to mitigate casualties related to flood. The paper envisions helping flood-prone areas which are common in the Philippines particularly to the local communities in the province. Indeed, it is relevant and important as per needs for safety and welfare of the community.

Flood Warning and Forecasting System in Slovakia

NASA Astrophysics Data System (ADS)

Leskova, Danica

2016-04-01

In 2015, it finished project Flood Warning and Forecasting System (POVAPSYS) as part of the flood protection in Slovakia till 2010. The aim was to build POVAPSYS integrated computerized flood forecasting and warning system. It took a qualitatively higher level of output meteorological and hydrological services in case of floods affecting large territorial units, as well as local flood events. It is further unfolding demands on performance and coordination of meteorological and hydrological services, troubleshooting observation, evaluation of data, fast communication, modeling and forecasting of meteorological and hydrological processes. Integration of all information entering and exiting to and from the project POVAPSYS provides Hydrological Flood Forecasting System (HYPOS). The system provides information on the current hydrometeorological situation and its evolution with the generation of alerts and notifications in case of exceeding predefined thresholds. HYPOS's functioning of the system requires flawless operability in critical situations while minimizing the loss of its key parts. HYPOS is a core part of the project POVAPSYS, it is a comprehensive software solutions based on a modular principle, providing data and processed information including alarms, in real time. In order to achieve full functionality of the system, in proposal, we have put emphasis on reliability, robustness, availability and security.

Consensus Seasonal Flood Forecasts and Warning Response System (FFWRS): an alternate for nonstructural flood management in Bangladesh.

PubMed

Chowdhury, Rashed

2005-06-01

Despite advances in short-range flood forecasting and information dissemination systems in Bangladesh, the present system is less than satisfactory. This is because of short lead-time products, outdated dissemination networks, and lack of direct feedback from the end-user. One viable solution is to produce long-lead seasonal forecasts--the demand for which is significantly increasing in Bangladesh--and disseminate these products through the appropriate channels. As observed in other regions, the success of seasonal forecasts, in contrast to short-term forecast, depends on consensus among the participating institutions. The Flood Forecasting and Warning Response System (henceforth, FFWRS) has been found to be an important component in a comprehensive and participatory approach to seasonal flood management. A general consensus in producing seasonal forecasts can thus be achieved by enhancing the existing FFWRS. Therefore, the primary objective of this paper is to revisit and modify the framework of an ideal warning response system for issuance of consensus seasonal flood forecasts in Bangladesh. The five-stage FFWRS-i) Flood forecasting, ii) Forecast interpretation and message formulation, iii) Warning preparation and dissemination, iv) Responses, and v) Review and analysis-has been modified. To apply the concept of consensus forecast, a framework similar to that of the Southern African Regional Climate Outlook Forum (SARCOF) has been discussed. Finally, the need for a climate Outlook Fora has been emphasized for a comprehensive and participatory approach to seasonal flood hazard management in Bangladesh.

Coupling Radar Rainfall Estimation and Hydrological Modelling For Flash-flood Hazard Mitigation

NASA Astrophysics Data System (ADS)

Borga, M.; Creutin, J. D.

Flood risk mitigation is accomplished through managing either or both the hazard and vulnerability. Flood hazard may be reduced through structural measures which alter the frequency of flood levels in the area. The vulnerability of a community to flood loss can be mitigated through changing or regulating land use and through flood warning and effective emergency response. When dealing with flash-flood hazard, it is gener- ally accepted that the most effective way (and in many instances the only affordable in a sustainable perspective) to mitigate the risk is by reducing the vulnerability of the involved communities, in particular by implementing flood warning systems and community self-help programs. However, both the inherent characteristics of the at- mospheric and hydrologic processes involved in flash-flooding and the changing soci- etal needs provide a tremendous challenge to traditional flood forecasting and warning concepts. In fact, the targets of these systems are traditionally localised like urbanised sectors or hydraulic structures. Given the small spatial scale that characterises flash floods and the development of dispersed urbanisation, transportation, green tourism and water sports, human lives and property are exposed to flash flood risk in a scat- tered manner. This must be taken into consideration in flash flood warning strategies and the investigated region should be considered as a whole and every section of the drainage network as a potential target for hydrological warnings. Radar technology offers the potential to provide information describing rain intensities almost contin- uously in time and space. Recent research results indicate that coupling radar infor- mation to distributed hydrologic modelling can provide hydrologic forecasts at all potentially flooded points of a region. Nevertheless, very few flood warning services use radar data more than on a qualitative basis. After a short review of current under- standing in this area, two issues are examined: advantages and caveats of using radar rainfall estimates in operational flash flood forecasting, methodological problems as- sociated to the use of hydrological models for distributed flash flood forecasting with rainfall input estimated from radar.

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

NASA Astrophysics Data System (ADS)

Moon, Young-Il; Kim, Jong-Suk

2015-04-01

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

Development of a flood-induced health risk prediction model for Africa

NASA Astrophysics Data System (ADS)

Lee, D.; Block, P. J.

2017-12-01

Globally, many floods occur in developing or tropical regions where the impact on public health is substantial, including death and injury, drinking water, endemic disease, and so on. Although these flood impacts on public health have been investigated, integrated management of floods and flood-induced health risks is technically and institutionally limited. Specifically, while the use of climatic and hydrologic forecasts for disaster management has been highlighted, analogous predictions for forecasting the magnitude and impact of health risks are lacking, as is the infrastructure for health early warning systems, particularly in developing countries. In this study, we develop flood-induced health risk prediction model for African regions using season-ahead flood predictions with climate drivers and a variety of physical and socio-economic information, such as local hazard, exposure, resilience, and health vulnerability indicators. Skillful prediction of flood and flood-induced health risks can contribute to practical pre- and post-disaster responses in both local- and global-scales, and may eventually be integrated into multi-hazard early warning systems for informed advanced planning and management. This is especially attractive for areas with limited observations and/or little capacity to develop flood-induced health risk warning systems.

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.

Community-based early warning systems for flood risk mitigation in Nepal

NASA Astrophysics Data System (ADS)

Smith, Paul J.; Brown, Sarah; Dugar, Sumit

2017-03-01

This paper focuses on the use of community-based early warning systems for flood resilience in Nepal. The first part of the work outlines the evolution and current status of these community-based systems, highlighting the limited lead times currently available for early warning. The second part of the paper focuses on the development of a robust operational flood forecasting methodology for use by the Nepal Department of Hydrology and Meteorology (DHM) to enhance early warning lead times. The methodology uses data-based physically interpretable time series models and data assimilation to generate probabilistic forecasts, which are presented in a simple visual tool. The approach is designed to work in situations of limited data availability with an emphasis on sustainability and appropriate technology. The successful application of the forecast methodology to the flood-prone Karnali River basin in western Nepal is outlined, increasing lead times from 2-3 to 7-8 h. The challenges faced in communicating probabilistic forecasts to the last mile of the existing community-based early warning systems across Nepal is discussed. The paper concludes with an assessment of the applicability of this approach in basins and countries beyond Karnali and Nepal and an overview of key lessons learnt from this initiative.

Building regional early flood warning systems by AI techniques

NASA Astrophysics Data System (ADS)

Chang, F. J.; Chang, L. C.; Amin, M. Z. B. M.

2017-12-01

Building early flood warning system is essential for the protection of the residents against flood hazards and make actions to mitigate the losses. This study implements AI technology for forecasting multi-step-ahead regional flood inundation maps during storm events. The methodology includes three major schemes: (1) configuring the self-organizing map (SOM) to categorize a large number of regional inundation maps into a meaningful topology; (2) building dynamic neural networks to forecast multi-step-ahead average inundated depths (AID); and (3) adjusting the weights of the selected neuron in the constructed SOM based on the forecasted AID to obtain real-time regional inundation maps. The proposed models are trained, and tested based on a large number of inundation data sets collected in regions with the most frequent and serious flooding in the river basin. The results appear that the SOM topological relationships between individual neurons and their neighbouring neurons are visible and clearly distinguishable, and the hybrid model can continuously provide multistep-ahead visible regional inundation maps with high resolution during storm events, which have relatively small RMSE values and high R2 as compared with numerical simulation data sets. The computing time is only few seconds, and thereby leads to real-time regional flood inundation forecasting and make early flood inundation warning system. We demonstrate that the proposed hybrid ANN-based model has a robust and reliable predictive ability and can be used for early warning to mitigate flood disasters.

Establishment and Practical Application of Flood Warning Stage in Taiwan's River

NASA Astrophysics Data System (ADS)

Yang, Sheng-Hsueh; Chia Yeh, Keh-

2017-04-01

In the face of extreme flood events or the possible impact of climate change, non-engineering disaster prevention and early warning work is particularly important. Taiwan is an island topography with more than 3,900 meters of high mountains. The length of the river is less than 100 kilometers. Most of the watershed catchment time is less than 24 hours, which belongs to the river with steep slope and rapid flood. Every year in summer and autumn, several typhoon events invade Taiwan. Typhoons often result in rainfall events in excess of 100 mm/hr or 250 mm/3hr. In the face of Taiwan's terrain and extreme rainfall events, flooding is difficult to avoid. Therefore, most of the river has embankment protection, so that people do not have to face every year flooding caused by economic and life and property losses. However, the river embankment protection is limited. With the increase of the hydrological data, the design criteria for the embankment protection standards in the past was 100 year of flood return period and is now gradually reduced to 25 or 50 year of flood return period. The river authorities are not easy to rise the existing embankment height. The safety of the river embankment in Taiwan is determined by the establishment of the flood warning stage to cope with the possible increase in annual floods and the impact of extreme hydrological events. The flood warning stage is equal to the flood control elevation minus the flood rise rate multiply by the flood early warning time. The control elevation can be the top of the embankment, the design flood level of the river, the embankment gap of the river section, the height of the bridge beam bottom, etc. The flood rise rate is consider the factors such as hydrological stochastic and uncertain rainfall and the effect of flood discharge operation on the flood in the watershed catchment area. The maximum value of the water level difference between the two hours or five hours before the peak value of the analysis result is decided by this rate. The flood early warning time is divided into two levels, the first level is 2 hours, evacuation time for the public, the second level is 5 hours for the implementation of unit preparation time. Finally, The flood warning stages are practical application in 20 water level stations have been incorporated into the flood early warning system of the Danshuei river basin in Taiwan.

Flood warnings in coastal areas: how do social and behavioural patterns influence alert services?

NASA Astrophysics Data System (ADS)

Pescaroli, G.; Magni, M.

2015-01-01

Many studies discuss the economic and technical aspects of flood warnings. Less attention has been given to the social and psychological patterns that affect alert services. In particular, the literature focuses on warnings activated in river basins or marine environments without providing clear evidence of relevance to Mediterranean coastal areas, even though these are subjected to growing flood risk related to climate change. This paper is a first attempt to bridge this gap. Our research develops an in- depth analysis of the village of Cesenatico on the Adriatic Sea coast. Here the municipality adopted two complementary warning systems: a siren and an alert via Short Message Service (SMS). The analysis focuses on a survey conducted in 2011 and 2012 with 228 participants. The relationships between social and behavioural variables and warning services are investigated, and so are flood preparedness and information dissemination. Qualitative evidence from informal interviews is used to support the understanding of key responses. The conclusions show how different social and behavioural patterns can influence the effectiveness and use of warning systems, regardless of the technology adopted and the structural mitigation measures implemented. Education, training and accountability are seen to be critical elements for improvement. Finally, the statistical output is used to suggest new questions and new directions for research.

Flood warnings in coastal areas: how do experience and information influence responses to alert services?

NASA Astrophysics Data System (ADS)

Pescaroli, G.; Magni, M.

2015-04-01

Many studies discuss the economic and technical aspects of flood warnings. Less attention has been given to the social and behavioural patterns that affect alert services. In particular, the literature focuses on warnings activated in river basins or marine environments without providing clear evidence on Mediterranean coastal areas, even though these are subjected to growing flood risk related to climate change. This paper is a first attempt to bridge this gap. Our research develops an in-depth analysis of the village of Cesenatico on the Adriatic Sea coast. Here the municipality adopted two complementary warning systems: a siren and an alert via short message service (SMS). The analysis focuses on a survey conducted in 2011 and 2012 with 228 participants. The relationships between social and behavioural variables and warning services are investigated as well as flood preparedness and information dissemination. Qualitative evidence from informal interviews is used to support the understanding of key responses. The conclusions show how different social and behavioural patterns can influence the effectiveness and use of warning systems, regardless of the technology adopted and the structural mitigation measures implemented. Education, training and accountability are seen to be critical elements for implementation. Finally, the statistical output is used to suggest new questions and new directions for research.

Synergy of Earth Observation and In-Situ Monitoring Data for Flood Hazard Early Warning System

NASA Astrophysics Data System (ADS)

Brodsky, Lukas; Kodesova, Radka; Spazierova, Katerina

2010-12-01

In this study, we demonstrate synergy of EO and in-situ monitoring data for early warning flood hazard system in the Czech Republic developed within ESA PECS project FLOREO. The development of the demonstration system is oriented to support existing monitoring activities, especially snow melt and surface water runoff contributing to flooding events. The system consists of two main parts accordingly, the first is snow cover and snow melt monitoring driven mainly by EO data and the other is surface water runoff modeling and monitoring driven by synergy of in-situ and EO data.

A Collaborative Approach to Flood Early Warning Systems In South East Westmoreland, Jamaica

NASA Astrophysics Data System (ADS)

Hyman, T. A.

2015-12-01

Jamaica is prone to climatic, tectonic and technological hazards, with climatic hazards being the most prevalent. Specifically, flood events from cyclonic activity are the most common and widespread. Jamaica also experiences frequent flash floods, usually with insufficient lead time to enact efficient and targeted responses. On average, there is at least one disastrous flood every four years in Jamaica, and from 1800 to 2003 fifty-four major floods took place, causing 273 fatalities and economic losses of over US2 billion. Notably, the 1979 flood event in Western Jamaica caused 41 deaths and economic losses of US 27 Million, and which also has a 50 year return period. To date, no Flood Warning System exists in Western Jamaica and there are limited rain and river gauges. Additionally, responses to climatic events within South-East Westmoreland communities are ad hoc, with little coordination. Many of the hazard responses have been reactive and some stakeholders have delayed to their detriment.[1] The use of Flood Early Warning Systems (FEWS) to address such challenges is thus an option being considered by the community associations. The Rio Cobre FEWS in the parish of St. Catherine serves as a best practice example of community driven flood warning systems in Jamaica. This is because of the collaborative approach to flood risk, strengthened by institutional arrangements between the Meteorological Service, Water Resources Authority, Office of Disaster Management, Scientists and residents of the surrounding communities. The Community Associations in South-East Westmoreland are thus desirous of implementing a FEWS similar to the Rio Cobre FEWS. This paper thus aims to analyse the implementation process in terms of key stakeholders involved, governance approach and the socio-economic impact of a collaborative approach on infrastructure and livelihoods, in the case of future flooding events. [1] (especially in the case of Hurricane Ivan 2004)

Probabilistic flood warning using grand ensemble weather forecasts

NASA Astrophysics Data System (ADS)

He, Y.; Wetterhall, F.; Cloke, H.; Pappenberger, F.; Wilson, M.; Freer, J.; McGregor, G.

2009-04-01

As the severity of floods increases, possibly due to climate and landuse change, there is urgent need for more effective and reliable warning systems. The incorporation of numerical weather predictions (NWP) into a flood warning system can increase forecast lead times from a few hours to a few days. A single NWP forecast from a single forecast centre, however, is insufficient as it involves considerable non-predictable uncertainties and can lead to a high number of false or missed warnings. An ensemble of weather forecasts from one Ensemble Prediction System (EPS), when used on catchment hydrology, can provide improved early flood warning as some of the uncertainties can be quantified. EPS forecasts from a single weather centre only account for part of the uncertainties originating from initial conditions and stochastic physics. Other sources of uncertainties, including numerical implementations and/or data assimilation, can only be assessed if a grand ensemble of EPSs from different weather centres is used. When various models that produce EPS from different weather centres are aggregated, the probabilistic nature of the ensemble precipitation forecasts can be better retained and accounted for. The availability of twelve global EPSs through the 'THORPEX Interactive Grand Global Ensemble' (TIGGE) offers a new opportunity for the design of an improved probabilistic flood forecasting framework. This work presents a case study using the TIGGE database for flood warning on a meso-scale catchment. The upper reach of the River Severn catchment located in the Midlands Region of England is selected due to its abundant data for investigation and its relatively small size (4062 km2) (compared to the resolution of the NWPs). This choice was deliberate as we hypothesize that the uncertainty in the forcing of smaller catchments cannot be represented by a single EPS with a very limited number of ensemble members, but only through the variance given by a large number ensembles and ensemble system. A coupled atmospheric-hydrologic-hydraulic cascade system driven by the TIGGE ensemble forecasts is set up to study the potential benefits of using the TIGGE database in early flood warning. Physically based and fully distributed LISFLOOD suite of models is selected to simulate discharge and flood inundation consecutively. The results show the TIGGE database is a promising tool to produce forecasts of discharge and flood inundation comparable with the observed discharge and simulated inundation driven by the observed discharge. The spread of discharge forecasts varies from centre to centre, but it is generally large, implying a significant level of uncertainties. Precipitation input uncertainties dominate and propagate through the cascade chain. The current NWPs fall short of representing the spatial variability of precipitation on a comparatively small catchment. This perhaps indicates the need to improve NWPs resolution and/or disaggregation techniques to narrow down the spatial gap between meteorology and hydrology. It is not necessarily true that early flood warning becomes more reliable when more ensemble forecasts are employed. It is difficult to identify the best forecast centre(s), but in general the chance of detecting floods is increased by using the TIGGE database. Only one flood event was studied because most of the TIGGE data became available after October 2007. It is necessary to test the TIGGE ensemble forecasts with other flood events in other catchments with different hydrological and climatic regimes before general conclusions can be made on its robustness and applicability.

Prediction of Flood Warning in Taiwan Using Nonlinear SVM with Simulated Annealing Algorithm

NASA Astrophysics Data System (ADS)

Lee, C.

2013-12-01

The issue of the floods is important in Taiwan. It is because the narrow and high topography of the island make lots of rivers steep in Taiwan. The tropical depression likes typhoon always causes rivers to flood. Prediction of river flow under the extreme rainfall circumstances is important for government to announce the warning of flood. Every time typhoon passed through Taiwan, there were always floods along some rivers. The warning is classified to three levels according to the warning water levels in Taiwan. The propose of this study is to predict the level of floods warning from the information of precipitation, rainfall duration and slope of riverbed. To classify the level of floods warning by the above-mentioned information and modeling the problems, a machine learning model, nonlinear Support vector machine (SVM), is formulated to classify the level of floods warning. In addition, simulated annealing (SA), a probabilistic heuristic algorithm, is used to determine the optimal parameter of the SVM model. A case study of flooding-trend rivers of different gradients in Taiwan is conducted. The contribution of this SVM model with simulated annealing is capable of making efficient announcement for flood warning and keeping the danger of flood from residents along the rivers.

Implementing the national AIGA flash flood warning system in France

NASA Astrophysics Data System (ADS)

Organde, Didier; Javelle, Pierre; Demargne, Julie; Arnaud, Patrick; Caseri, Angelica; Fine, Jean-Alain; de Saint Aubin, Céline

2015-04-01

The French national hydro-meteorological and flood forecasting centre (SCHAPI) aims to implement a national flash flood warning system to improve flood alerts for small-to-medium (up to 1000 km2) ungauged basins. This system is based on the AIGA method, co-developed by IRSTEA these last 10 years. The method, initially set up for the Mediterranean area, is based on a simple event-based hourly hydrologic distributed model run every 15 minutes (Javelle et al. 2014). The hydrologic model ingests operational radar-gauge rainfall grids from Météo-France at a 1-km² resolution to produce discharges for successive outlets along the river network. Discharges are then compared to regionalized flood quantiles of given return periods and warnings (expressed as the range of the return period estimated in real-time) are provided on a river network map. The main interest of the method is to provide forecasters and emergency services with a synthetic view in real time of the ongoing flood situation, information that is especially critical in ungauged flood prone areas. In its enhanced national version, the hourly event-based distributed model is coupled to a continuous daily rainfall-runoff model which provides baseflow and a soil moisture index (for each 1-km² pixel) at the beginning of the hourly simulation. The rainfall-runoff models were calibrated on a selection of 700 French hydrometric stations with Météo-France radar-gauge reanalysis dataset for the 2002-2006 period. To estimate model parameters for ungauged basins, the 2 hydrologic models were regionalised by testing both regressions (using different catchment attributes, such as catchment area, soil type, and climate characteristic) and spatial proximity techniques (transposing parameters from neighbouring donor catchments), as well as different homogeneous hydrological areas. The most valuable regionalisation method was determined for each model through jack-knife cross-validation. The system performance was then evaluated with contingency criteria (e.g., Critical Success Index, Probability Of Detection, Success Ratio) using operational rainfall radar-gauge products from Météo-France for the 2009-2012 period. The regionalised parameters of the distributed model were finally adjusted for each homogeneous hydrological area to optimize the Heidke skill score (HSS) calculated with three levels of warnings (2-, 10- and 50-year flood quantiles). This work is currently being implemented by the SCHAPI to set up an automated national flash flood warning system by 2016. Planned improvements include developing a unique continuous model to be run at a sub-hourly timestep, discharge assimilation, as well as integrating precipitation forecasts while accounting for the main sources of forecast uncertainty. Javelle, P., Demargne, J., Defrance, D., and Arnaud, P. 2014. Evaluating flash flood warnings at ungauged locations using post-event surveys: a case study with the AIGA warning system. Hydrological Sciences Journal, DOI: 10.1080/02626667.2014.923970

NWS - Watch, Warning, Advisory Display

Science.gov Websites

Coastal Waters from Schoodic Point ME to Stonington ME Coastal Waters from Schoodic Point ME to Stonington Watch Flash Flood Warning* Coastal/Flood Watch Coastal/Flood Warning Small Stream Flood Advisory

How do people perceive, understand, and anticipate responding to flash flood risks and warnings? Results from a public survey in Boulder, Colorado, USA

NASA Astrophysics Data System (ADS)

Morss, Rebecca E.; Mulder, Kelsey J.; Lazo, Jeffrey K.; Demuth, Julie L.

2016-10-01

This study investigates flash flood forecast and warning communication, interpretation, and decision making, using data from a survey of 418 members of the public in Boulder, Colorado, USA. Respondents to the public survey varied in their perceptions and understandings of flash flood risks in Boulder, and some had misconceptions about flash flood risks, such as the safety of crossing fast-flowing water. About 6% of respondents indicated consistent reversals of US watch-warning alert terminology. However, more in-depth analysis illustrates the multi-dimensional, situationally dependent meanings of flash flood alerts, as well as the importance of evaluating interpretation and use of warning information along with alert terminology. Some public respondents estimated low likelihoods of flash flooding given a flash flood warning; these were associated with lower anticipated likelihood of taking protective action given a warning. Protective action intentions were also lower among respondents who had less trust in flash flood warnings, those who had not made prior preparations for flash flooding, and those who believed themselves to be safer from flash flooding. Additional analysis, using open-ended survey questions about responses to warnings, elucidates the complex, contextual nature of protective decision making during flash flood threats. These findings suggest that warnings can play an important role not only by notifying people that there is a threat and helping motivate people to take protective action, but also by helping people evaluate what actions to take given their situation.

Early Warning System of Flood Disaster Based on Ultrasonic Sensors and Wireless Technology

NASA Astrophysics Data System (ADS)

Indrasari, W.; Iswanto, B. H.; Andayani, M.

2018-04-01

A flood disaster provides considerable losses to the people who live around the river. To mitigate losses of material due to flood disaster required an early warning system of flood disaster. For that reason, it necessary to design a system that provide alert to the people prior the flood disaster. And this paper describes development of a device for early detection system of flood disasters. This device consists of two ultrasonic sensors as a water level detector, and a water flow sensor as a water flow velocity sensor. The wireless technology and GSM is used as an information medium. The system is designed based on water level conditions in the Katulampa Dam, Bogor. Characterization of water level detector showed that the device effectively works in a range of water level of 14-250 cm, with a maximum relative error of 4.3%. Meanwhile the wireless works properly as far as 75 m, and the SMS transmission time is 8.20 second.

Experiences from coordinated national-level landslide and flood forecasting in Norway

NASA Astrophysics Data System (ADS)

Krøgli, Ingeborg; Fleig, Anne; Glad, Per; Dahl, Mads-Peter; Devoli, Graziella; Colleuille, Hervé

2015-04-01

While flood forecasting at national level is quite well established and operational in many countries worldwide, landslide forecasting at national level is still seldom. Examples of coordinated flood and landslide forecasting are even rarer. Most of the time flood and landslide forecasters work separately (investigating, defining thresholds, and developing models) and most of the time without communication with each other. One example of coordinated operational early warning systems (EWS) for flooding and shallow landslides is found at the Norwegian Water Resources and Energy Directorate (NVE) in Norway. In this presentation we give an introduction to the two separate but tightly collaborative EWSs and to the coordination of these. The two EWSs are being operated from the same office, every day using similar hydro-meteorological prognosis and hydrological models. Prognosis and model outputs on e.g. discharge, snow melt, soil water content and exceeded landslide thresholds are evaluated in a web based decision-making tool (xgeo.no). The experts performing forecasts are hydrologists, geologists and physical geographers. A similar warning scale, based on colors (green, yellow, orange and red) is used for both EWSs, however thresholds for flood and landslide warning levels are defined differently. Also warning areas may not necessary be the same for both hazards and depending on the specific meteorological event, duration of the warning periods can differ. We present how knowledge, models and tools, but also human and economic resources are being shared between the two EWSs. Moreover, we discuss challenges faced in the communication of warning messages using recent flood and landslide events as examples.

Progress and challenges with Warn-on-Forecast

NASA Astrophysics Data System (ADS)

Stensrud, David J.; Wicker, Louis J.; Xue, Ming; Dawson, Daniel T.; Yussouf, Nusrat; Wheatley, Dustan M.; Thompson, Therese E.; Snook, Nathan A.; Smith, Travis M.; Schenkman, Alexander D.; Potvin, Corey K.; Mansell, Edward R.; Lei, Ting; Kuhlman, Kristin M.; Jung, Youngsun; Jones, Thomas A.; Gao, Jidong; Coniglio, Michael C.; Brooks, Harold E.; Brewster, Keith A.

2013-04-01

The current status and challenges associated with two aspects of Warn-on-Forecast-a National Oceanic and Atmospheric Administration research project exploring the use of a convective-scale ensemble analysis and forecast system to support hazardous weather warning operations-are outlined. These two project aspects are the production of a rapidly-updating assimilation system to incorporate data from multiple radars into a single analysis, and the ability of short-range ensemble forecasts of hazardous convective weather events to provide guidance that could be used to extend warning lead times for tornadoes, hailstorms, damaging windstorms and flash floods. Results indicate that a three-dimensional variational assimilation system, that blends observations from multiple radars into a single analysis, shows utility when evaluated by forecasters in the Hazardous Weather Testbed and may help increase confidence in a warning decision. The ability of short-range convective-scale ensemble forecasts to provide guidance that could be used in warning operations is explored for five events: two tornadic supercell thunderstorms, a macroburst, a damaging windstorm and a flash flood. Results show that the ensemble forecasts of the three individual severe thunderstorm events are very good, while the forecasts from the damaging windstorm and flash flood events, associated with mesoscale convective systems, are mixed. Important interactions between mesoscale and convective-scale features occur for the mesoscale convective system events that strongly influence the quality of the convective-scale forecasts. The development of a successful Warn-on-Forecast system will take many years and require the collaborative efforts of researchers and operational forecasters to succeed.

A Prototype Flood Early Warning SensorWeb System for Namibia

NASA Astrophysics Data System (ADS)

Sohlberg, R. A.; Mandl, D.; Frye, S. W.; Cappelaere, P. G.; Szarzynski, J.; Policelli, F.; van Langenhove, G.

2010-12-01

During the past two years, there have been extensive floods in the country of Namibia, Africa which have affected up to a quarter of the population. Via a collaboration between a group funded by the Earth Science Technology Office (ESTO) at NASA that has been performing various SensorWeb prototyping activities for disasters, the Department of Hydrology in Namibia and the United Nations Space-based Information for Disaster and Emergency Response (UN-SPIDER) , experiments were conducted on how to apply various satellite resources integrated into a SensorWeb architecture along with in-situ sensors such as river gauges and rain gauges into a flood early warning system. The SensorWeb includes a global flood model and a higher resolution basin specific flood model. Furthermore, flood extent and status is monitored by optical and radar types of satellites and integrated via some automation. We have taken a practical approach to find out how to create a working system by selectively using the components that provide good results. The vision for the future is to combine this with the country side dwelling unit data base to create risk maps that provide specific warnings to houses within high risk areas based on near term predictions. This presentation will show some of the highlights of the effort thus far plus our future plans.

Regional early flood warning system: design and implementation

NASA Astrophysics Data System (ADS)

Chang, L. C.; Yang, S. N.; Kuo, C. L.; Wang, Y. F.

2017-12-01

This study proposes a prototype of the regional early flood inundation warning system in Tainan City, Taiwan. The AI technology is used to forecast multi-step-ahead regional flood inundation maps during storm events. The computing time is only few seconds that leads to real-time regional flood inundation forecasting. A database is built to organize data and information for building real-time forecasting models, maintaining the relations of forecasted points, and displaying forecasted results, while real-time data acquisition is another key task where the model requires immediately accessing rain gauge information to provide forecast services. All programs related database are constructed in Microsoft SQL Server by using Visual C# to extracting real-time hydrological data, managing data, storing the forecasted data and providing the information to the visual map-based display. The regional early flood inundation warning system use the up-to-date Web technologies driven by the database and real-time data acquisition to display the on-line forecasting flood inundation depths in the study area. The friendly interface includes on-line sequentially showing inundation area by Google Map, maximum inundation depth and its location, and providing KMZ file download of the results which can be watched on Google Earth. The developed system can provide all the relevant information and on-line forecast results that helps city authorities to make decisions during typhoon events and make actions to mitigate the losses.

Enhancing Community Based Early Warning Systems in Nepal with Flood Forecasting Using Local and Global Models

NASA Astrophysics Data System (ADS)

Dugar, Sumit; Smith, Paul; Parajuli, Binod; Khanal, Sonu; Brown, Sarah; Gautam, Dilip; Bhandari, Dinanath; Gurung, Gehendra; Shakya, Puja; Kharbuja, RamGopal; Uprety, Madhab

2017-04-01

Operationalising effective Flood Early Warning Systems (EWS) in developing countries like Nepal poses numerous challenges, with complex topography and geology, sparse network of river and rainfall gauging stations and diverse socio-economic conditions. Despite these challenges, simple real-time monitoring based EWSs have been in place for the past decade. A key constraint of these simple systems is the very limited lead time for response - as little as 2-3 hours, especially for rivers originating from steep mountainous catchments. Efforts to increase lead time for early warning are focusing on imbedding forecasts into the existing early warning systems. In 2016, the Nepal Department of Hydrology and Meteorology (DHM) piloted an operational Probabilistic Flood Forecasting Model in major river basins across Nepal. This comprised a low data approach to forecast water levels, developed jointly through a research/practitioner partnership with Lancaster University and WaterNumbers (UK) and the International NGO Practical Action. Using Data-Based Mechanistic Modelling (DBM) techniques, the model assimilated rainfall and water levels to generate localised hourly flood predictions, which are presented as probabilistic forecasts, increasing lead times from 2-3 hours to 7-8 hours. The Nepal DHM has simultaneously started utilizing forecasts from the Global Flood Awareness System (GLoFAS) that provides streamflow predictions at the global scale based upon distributed hydrological simulations using numerical ensemble weather forecasts from the ECMWF (European Centre for Medium-Range Weather Forecasts). The aforementioned global and local models have already affected the approach to early warning in Nepal, being operational during the 2016 monsoon in the West Rapti basin in Western Nepal. On 24 July 2016, GLoFAS hydrological forecasts for the West Rapti indicated a sharp rise in river discharge above 1500 m3/sec (equivalent to the river warning level at 5 meters) with 53% probability of exceeding the Medium Level Alert in two days. Rainfall stations upstream of the West Rapti catchment recorded heavy rainfall on 26 July, and localized forecasts from the probabilistic model at 8 am suggested that the water level would cross a pre-determined warning level in the next 3 hours. The Flood Forecasting Section at DHM issued a flood advisory, and disseminated SMS flood alerts to more than 13,000 at-risk people residing along the floodplains. Water levels crossed the danger threshold (5.4 meters) at 11 am, peaking at 8.15 meters at 10 pm. Extension of the warning lead time from probabilistic forecasts was significant in minimising the risk to lives and livelihoods as communities gained extra time to prepare, evacuate and respond. Likewise, longer timescale forecasts from GLoFAS could be potentially linked with no-regret early actions leading to improved preparedness and emergency response. These forecasting tools have contributed to enhance the effectiveness and efficiency of existing community based systems, increasing the lead time for response. Nevertheless, extensive work is required on appropriate ways to interpret and disseminate probabilistic forecasts having longer (2-14 days) and shorter (3-5 hours) time horizon for operational deployment as there are numerous uncertainties associated with predictions.

A real-time measurement system for long-life flood monitoring and warning applications.

PubMed

Marin-Perez, Rafael; García-Pintado, Javier; Gómez, Antonio Skarmeta

2012-01-01

A flood warning system incorporates telemetered rainfall and flow/water level data measured at various locations in the catchment area. Real-time accurate data collection is required for this use, and sensor networks improve the system capabilities. However, existing sensor nodes struggle to satisfy the hydrological requirements in terms of autonomy, sensor hardware compatibility, reliability and long-range communication. We describe the design and development of a real-time measurement system for flood monitoring, and its deployment in a flash-flood prone 650 km(2) semiarid watershed in Southern Spain. A developed low-power and long-range communication device, so-called DatalogV1, provides automatic data gathering and reliable transmission. DatalogV1 incorporates self-monitoring for adapting measurement schedules for consumption management and to capture events of interest. Two tests are used to assess the success of the development. The results show an autonomous and robust monitoring system for long-term collection of water level data in many sparse locations during flood events.

A Real-Time Measurement System for Long-Life Flood Monitoring and Warning Applications

PubMed Central

Marin-Perez, Rafael; García-Pintado, Javier; Gómez, Antonio Skarmeta

2012-01-01

A flood warning system incorporates telemetered rainfall and flow/water level data measured at various locations in the catchment area. Real-time accurate data collection is required for this use, and sensor networks improve the system capabilities. However, existing sensor nodes struggle to satisfy the hydrological requirements in terms of autonomy, sensor hardware compatibility, reliability and long-range communication. We describe the design and development of a real-time measurement system for flood monitoring, and its deployment in a flash-flood prone 650 km2 semiarid watershed in Southern Spain. A developed low-power and long-range communication device, so-called DatalogV1, provides automatic data gathering and reliable transmission. DatalogV1 incorporates self-monitoring for adapting measurement schedules for consumption management and to capture events of interest. Two tests are used to assess the success of the development. The results show an autonomous and robust monitoring system for long-term collection of water level data in many sparse locations during flood events. PMID:22666028

Flood and landslide warning based on rainfall thresholds and soil moisture indexes: the HEWS (Hydrohazards Early Warning System) for Sicily

NASA Astrophysics Data System (ADS)

Brigandì, Giuseppina; Tito Aronica, Giuseppe; Bonaccorso, Brunella; Gueli, Roberto; Basile, Giuseppe

2017-09-01

The main focus of the paper is to present a flood and landslide early warning system, named HEWS (Hydrohazards Early Warning System), specifically developed for the Civil Protection Department of Sicily, based on the combined use of rainfall thresholds, soil moisture modelling and quantitative precipitation forecast (QPF). The warning system is referred to 9 different Alert Zones in which Sicily has been divided into and based on a threshold system of three different increasing critical levels: ordinary, moderate and high. In this system, for early flood warning, a Soil Moisture Accounting (SMA) model provides daily soil moisture conditions, which allow to select a specific set of three rainfall thresholds, one for each critical level considered, to be used for issue the alert bulletin. Wetness indexes, representative of the soil moisture conditions of a catchment, are calculated using a simple, spatially-lumped rainfall-streamflow model, based on the SCS-CN method, and on the unit hydrograph approach, that require daily observed and/or predicted rainfall, and temperature data as input. For the calibration of this model daily continuous time series of rainfall, streamflow and air temperature data are used. An event based lumped rainfall-runoff model has been, instead, used for the derivation of the rainfall thresholds for each catchment in Sicily characterised by an area larger than 50 km2. In particular, a Kinematic Instantaneous Unit Hydrograph based lumped rainfall-runoff model with the SCS-CN routine for net rainfall was developed for this purpose. For rainfall-induced shallow landslide warning, empirical rainfall thresholds provided by Gariano et al. (2015) have been included in the system. They were derived on an empirical basis starting from a catalogue of 265 shallow landslides in Sicily in the period 2002-2012. Finally, Delft-FEWS operational forecasting platform has been applied to link input data, SMA model and rainfall threshold models to produce warning on a daily basis for the entire region.

Developments of the European Flood Awareness System (EFAS)

NASA Astrophysics Data System (ADS)

Thiemig, Vera; Olav Skøien, Jon; Salamon, Peter; Pappenberger, Florian; Wetterhall, Fredrik; Holst, Bo; Asp, Sara-Sophia; Garcia Padilla, Mercedes; Garcia, Rafael J.; Schweim, Christoph; Ziese, Markus

2017-04-01

EFAS (http://www.efas.eu) is an operational system for flood forecasting and early warning for the entire Europe, which is fully operational as part of the Copernicus Emergency Management Service since 2012. The prime aim of EFAS is to gain time for preparedness measures before major flood events - particularly in trans-national river basins - strike. This is achieved by providing complementary, added value information to the national and regional services holding the mandate for flood warning as well as to the ERCC (European Response and Coordination Centre). Using a coherent model for all of Europe forced with a range of deterministic and ensemble weather forecasts, the system can give a probabilistic flood forecast for a medium range lead time (up to 10 days) independent of country borders. The system is under continuous development, and we will present the basic set up, some prominent examples of recent and ongoing developments (such as the rapid impact assessment, seasonal outlook and the extended domain) and the future challenges.

Development of a Flood-Warning System and Flood-Inundation Mapping in Licking County, Ohio : Executive Summary Report

DOT National Transportation Integrated Search

2012-04-01

Licking County, Ohio, has experienced numerous floods with the majority of flood damages occurring in the central and south-central areas of the county along four streams: the Licking River, North Fork Licking River, South Fork Licking River, and Rac...

Range Atmospheric and Oceanic Environmental Support Capabilities

DTIC Science & Technology

2011-12-01

Precipitation location/intensity, thunderstorm location/intensity, rainfall/flash flood warning, hydrometer characterization, wind warnings, and...intensity, lightning monitoring, rainfall and flash flood warning, hydrometer characterization, and wind warnings. b. Satellite: MTSAT, GOES-10

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

NASA Astrophysics Data System (ADS)

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

2015-04-01

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

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.

Forecast-based Integrated Flood Detection System for Emergency Response and Disaster Risk Reduction (Flood-FINDER)

NASA Astrophysics Data System (ADS)

Arcorace, Mauro; Silvestro, Francesco; Rudari, Roberto; Boni, Giorgio; Dell'Oro, Luca; Bjorgo, Einar

2016-04-01

Most flood prone areas in the globe are mainly located in developing countries where making communities more flood resilient is a priority. Despite different flood forecasting initiatives are now available from academia and research centers, what is often missing is the connection between the timely hazard detection and the community response to warnings. In order to bridge the gap between science and decision makers, UN agencies play a key role on the dissemination of information in the field and on capacity-building to local governments. In this context, having a reliable global early warning system in the UN would concretely improve existing in house capacities for Humanitarian Response and the Disaster Risk Reduction. For those reasons, UNITAR-UNOSAT has developed together with USGS and CIMA Foundation a Global Flood EWS called "Flood-FINDER". The Flood-FINDER system is a modelling chain which includes meteorological, hydrological and hydraulic models that are accurately linked to enable the production of warnings and forecast inundation scenarios up to three weeks in advance. The system is forced with global satellite derived precipitation products and Numerical Weather Prediction outputs. The modelling chain is based on the "Continuum" hydrological model and risk assessments produced for GAR2015. In combination with existing hydraulically reconditioned SRTM data and 1D hydraulic models, flood scenarios are derived at multiple scales and resolutions. Climate and flood data are shared through a Web GIS integrated platform. First validation of the modelling chain has been conducted through a flood hindcasting test case, over the Chao Phraya river basin in Thailand, using multi temporal satellite-based analysis derived for the exceptional flood event of 2011. In terms of humanitarian relief operations, the EO-based services of flood mapping in rush mode generally suffer from delays caused by the time required for their activation, programming, acquisitions and image processing. Flood-FINDER aims to pre-empt this process and to provide preliminary analyses where no field data is available. In the early 2015, the Flood-FINDER's forecast along the Shire River has been used to guide the rapid mapping activities in Southern Malawi and Northern Mozambique. It proved efficient support providing timely information about the evolution of the flood event over an area lacking of field data. Regarding in-country capacity building, Flood-FINDER allowed UNOSAT to set up in middle 2015 a flood early warning system in Chad along the Chari River basin with the collaboration of Chadian Ministry of hydraulics and livestock. Weekly flood bulletins have been shared with local authorities and UN agencies over the entire rainy season. Finally, an experimental version of the global web alerting platform has been recently developed for supporting the El Nino flood preparedness in the Horn of Africa. Flood-FINDEŔs mission is to support decision makers throughout all the disaster management cycle with flood alerts, modelled scenarios, EO-based impact assessments and with direct support at country level to implement disaster mitigation strategies. The aim for the future is to seek funding for having the global system fully operational using CERN's supercomputing facilities and to establish new in-country projects with local authorities.

Managing Risks? Early Warning Systems for Climate Change

NASA Astrophysics Data System (ADS)

Sitati, A. M.; Zommers, Z. A.; Habilov, M.

2014-12-01

Early warning systems are a tool with which to minimize risks posed by climate related hazards. Although great strides have been made in developing early warning systems most deal with one hazard, only provide short-term warnings and do not reach the most vulnerable. This presentation will review research results of the United Nations Environment Programme's CLIM-WARN project. The project seeks to identify how governments can better communicate risks by designing multi-hazard early warning systems that deliver actionable warnings across timescales. Household surveys and focus group discussions were conducted in 36 communities in Kenya, Ghana and Burkina Faso in order to identify relevant climate related hazards, current response strategies and early warning needs. Preliminary results show significant variability in both risks and needs within and between countries. For instance, floods are more frequent in rural western parts of Kenya. Droughts are frequent in the north while populations in urban areas face a range of hazards - floods, droughts, disease outbreaks - that sometimes occur simultaneously. The majority of the rural population, especially women, the disabled and the elderly, do not have access to modern media such as radio, television, or internet. While 55% of rural populace never watches television, 64% of urban respondents watch television on a daily basis. Communities have different concepts of how to design warning systems. It will be a challenge for national governments to create systems that accommodate such diversity yet provide standard quality of service to all. There is a need for flexible and forward-looking early warning systems that deliver broader information about risks. Information disseminated through the system could not only include details of hazards, but also long-term adaptation options, general education, and health information, thus increasingly both capabilities and response options.

Use of radar rainfall estimates and forecasts to prevent flash flood in real time by using a road inundation warning system

NASA Astrophysics Data System (ADS)

Versini, Pierre-Antoine

2012-01-01

SummaryImportant damages occur in small headwater catchments when they are hit by severe storms with complex spatio-temporal structure, sometimes resulting in flash floods. As these catchments are mostly not covered by sensor networks, it is difficult to forecast these floods. This is particularly true for road submersions, representing major concerns for flood event managers. The use of Quantitative Precipitation Estimates and Forecasts (QPE/QPF) especially based on radar measurements could particularly be adequate to evaluate rainfall-induced risks. Although their characteristic time and space scales would make them suitable for flash flood modelling, the impact of their uncertainties remain uncertain and have to be evaluated. The Gard region (France) has been chosen as case study. This area is frequently affected by severe flash floods, and an application devoted to the road network has also been recently developed for the North part of this region. This warning system combines distributed hydro-meteorological modelling and susceptibility analysis to provide warnings of road inundations. The warning system has been tested on the specific storm of the 29-30 September 2007. During this event, around 200 mm dropped on the South part of the Gard and many roads were submerged. Radar-based QPE and QPF have been used to forecast the exact location of road submersions and the results have been compared to the effective road submersions actually occurred during the event as listed by the emergency services. Used on an area it has not been calibrated, the results confirm that the road submersion warning system represents a promising tool for anticipating and quantifying the consequences of storm events at ground. It rates the submersion risk with an acceptable level of accuracy and demonstrates also the quality of high spatial and temporal resolution radar rainfall data in real time, and the possibility to use them despite their uncertainties. However because of the quality of rainfall forecasts falls drastically with time, it is not often sufficient to provide valuable information for lead times exceeding 1 h.

An operational procedure for rapid flood risk assessment in Europe

NASA Astrophysics Data System (ADS)

Dottori, Francesco; Kalas, Milan; Salamon, Peter; Bianchi, Alessandra; Alfieri, Lorenzo; Feyen, Luc

2017-07-01

The development of methods for rapid flood mapping and risk assessment is a key step to increase the usefulness of flood early warning systems and is crucial for effective emergency response and flood impact mitigation. Currently, flood early warning systems rarely include real-time components to assess potential impacts generated by forecasted flood events. To overcome this limitation, this study describes the benchmarking of an operational procedure for rapid flood risk assessment based on predictions issued by the European Flood Awareness System (EFAS). Daily streamflow forecasts produced for major European river networks are translated into event-based flood hazard maps using a large map catalogue derived from high-resolution hydrodynamic simulations. Flood hazard maps are then combined with exposure and vulnerability information, and the impacts of the forecasted flood events are evaluated in terms of flood-prone areas, economic damage and affected population, infrastructures and cities.An extensive testing of the operational procedure has been carried out by analysing the catastrophic floods of May 2014 in Bosnia-Herzegovina, Croatia and Serbia. The reliability of the flood mapping methodology is tested against satellite-based and report-based flood extent data, while modelled estimates of economic damage and affected population are compared against ground-based estimations. Finally, we evaluate the skill of risk estimates derived from EFAS flood forecasts with different lead times and combinations of probabilistic forecasts. Results highlight the potential of the real-time operational procedure in helping emergency response and management.

Development of a Flood-Warning System and Flood-Inundation Mapping in Licking County, Ohio

DOT National Transportation Integrated Search

2012-08-01

Digital flood-inundation maps for selected reaches of South Fork Licking River, Raccoon Creek, North Fork Licking River, and the Licking River in Licking County, Ohio, were created by the U.S. Geological Survey (USGS), in cooperation with the Ohio De...

Majalaya Flood Early Warning System: A Community Based Approach

NASA Astrophysics Data System (ADS)

Junnaedhi, I. Dewa Gede A.; Riawan, Edi; Suwarman, Rusmawan; Wahyu Hadi, Tri; Lubis, Atika; Joko Trilaksono, Nurjanna; Rahayu, Rahmawati; Kombara, PrawiraYudha; Waskito, Riki; Ekalaya Oktora, Hendra; Supriatna, Rahmat; Anugrah, Aan; Haq Mudzakkir, Abdul; Setiawan, Wawar

2017-06-01

Majalaya, a small city to the south-east of Bandung, was hit by flood almost every year. From January to June 2016, up to 5 severe floods and 4 moderate floods have hit this city. Although it usually not last for long, but the flood stream could be very rapid, thus have a high potential to bring damage to the city. Starting from 2012, ITB through Weather and Climate Prediction Laboratory (WCPL) has support Garda Caah (flood watcher society in Majalaya) with weather prediction system. In the late 2015, ITB also enhancing Garda Caah observation system by installing several Automatic Weather Station (AWS) and Automatic Water Level Recorder (AWLR) throughout Majalaya upstream area. The instruments itself was supported by a re-insurance company MAIPARK and some was built in house by WCPL. The collaboration between ITB, Garda Caah, and Majalaya citizens has been proved to be mutually beneficial. Garda Caah could get more accurate and faster observation and enhanced knowledge, thus could provide a better flood warning for Majalaya citizens. On the other hand, ITB could get data from observation network, with more efficient way to maintain observation instruments as it done by Garda Caah and other Majalaya citizens.

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

NASA Astrophysics Data System (ADS)

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

2016-06-01

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

Application of satellite products and hydrological modelling for flood early warning

NASA Astrophysics Data System (ADS)

Koriche, Sifan A.; Rientjes, Tom H. M.

2016-06-01

Floods have caused devastating impacts to the environment and society in Awash River Basin, Ethiopia. Since flooding events are frequent, this marks the need to develop tools for flood early warning. In this study, we propose a satellite based flood index to identify the runoff source areas that largely contribute to extreme runoff production and floods in the basin. Satellite based products used for development of the flood index are CMORPH (Climate Prediction Center MORPHing technique: 0.25° by 0.25°, daily) product for calculation of the Standard Precipitation Index (SPI) and a Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) for calculation of the Topographic Wetness Index (TWI). Other satellite products used in this study are for rainfall-runoff modelling to represent rainfall, potential evapotranspiration, vegetation cover and topography. Results of the study show that assessment of spatial and temporal rainfall variability by satellite products may well serve in flood early warning. Preliminary findings on effectiveness of the flood index developed in this study indicate that the index is well suited for flood early warning. The index combines SPI and TWI, and preliminary results illustrate the spatial distribution of likely runoff source areas that cause floods in flood prone areas.

Geoethical considerations in early warning of flooding and landslides: Case study from Norway

NASA Astrophysics Data System (ADS)

Devoli, Graziella; Kleivane Krøgli, Ingeborg; Dahl, Mads Peter; Colleuille, Hervé; Nykjær Boje, Søren; Sund, Monica

2015-04-01

The Norwegian Water Resources and Energy Directorate (NVE) runs the national early warning systems (EWS) for flooding and shallow landslides in Norway. The two EWSs have been operational since the late 1980s and 2013 respectively, and are based on weather forecasts, various hydro-meteorological prognosis and expert evaluation. Daily warning levels and related information to the public is prepared and presented through custom build internet platforms. In natural hazards sciences, the risk of a specific threat is defined as the product of hazard and consequence. In this context an EWS is intended to work as a mitigation measure in lowering the consequence and thus the risk of the threat. One of several factors determining the quality of such an EWS, is how warnings are communicated to the public. In contrary to what is common practice in some other countries, experts working with EWS in Norway cannot be held personally responsible for consequences of warnings being issued or not. However, the communication of warnings for flooding and landslides at NVE still implies many considerations of geoethical kind. Which are the consequences today for the forecasters when erroneous warning messages are sent because based on a poorly documented analysis? What is for example the most responsible way to describe uncertainties in warnings issued? What is the optimal compromise between avoiding false alarms and not sending out a specific warning? Is it responsible to rely on a "gut feeling"? Some authorities complain in receiving warning messages too often. Is it responsible to begin notifying these, only in cases of "high hazard level" and no longer in cases of "moderate hazard level"? Is it acceptable to issue general warnings for large geographical areas without being able to pinpoint the treat on local scale? What responsibility lies within the EWS in recommending evacuation or other practical measures to local authorities? By presenting how early warnings of flooding and landslides are communicated in Norway and discussing the questions above, we intend to add to the discussion on what is the ethical responsibility for scientists performing forecasting and communication of natural hazards.

Early warning, warning or alarm systems for natural hazards? A generic classification.

NASA Astrophysics Data System (ADS)

Sättele, Martina; Bründl, Michael; Straub, Daniel

2013-04-01

Early warning, warning and alarm systems have gained popularity in recent years as cost-efficient measures for dangerous natural hazard processes such as floods, storms, rock and snow avalanches, debris flows, rock and ice falls, landslides, flash floods, glacier lake outburst floods, forest fires and even earthquakes. These systems can generate information before an event causes loss of property and life. In this way, they mainly mitigate the overall risk by reducing the presence probability of endangered objects. These systems are typically prototypes tailored to specific project needs. Despite their importance there is no recognised system classification. This contribution classifies warning and alarm systems into three classes: i) threshold systems, ii) expert systems and iii) model-based expert systems. The result is a generic classification, which takes the characteristics of the natural hazard process itself and the related monitoring possibilities into account. The choice of the monitoring parameters directly determines the system's lead time. The classification of 52 active systems moreover revealed typical system characteristics for each system class. i) Threshold systems monitor dynamic process parameters of ongoing events (e.g. water level of a debris flow) and incorporate minor lead times. They have a local geographical coverage and a predefined threshold determines if an alarm is automatically activated to warn endangered objects, authorities and system operators. ii) Expert systems monitor direct changes in the variable disposition (e.g crack opening before a rock avalanche) or trigger events (e.g. heavy rain) at a local scale before the main event starts and thus offer extended lead times. The final alarm decision incorporates human, model and organisational related factors. iii) Model-based expert systems monitor indirect changes in the variable disposition (e.g. snow temperature, height or solar radiation that influence the occurrence probability of snow avalanches) or trigger events (e.g. heavy snow fall) to predict spontaneous hazard events in advance. They encompass regional or national measuring networks and satisfy additional demands such as the standardisation of the measuring stations. The developed classification and the characteristics, which were revealed for each class, yield a valuable input to quantifying the reliability of warning and alarm systems. Importantly, this will facilitate to compare them with well-established standard mitigation measures such as dams, nets and galleries within an integrated risk management approach.

Developing a bridge scour warning system : technical summary.

DOT National Transportation Integrated Search

2016-09-01

Flooding and scour can be major threats to the integrity of bridges. During flood events, : scour at bridge piers and abutments can undermine the foundations of the bridge, causing : significant damage or even total structure loss. Because scour occu...

Developing a bridge scour warning system : final report.

DOT National Transportation Integrated Search

2016-09-01

Flooding and scour can be major threats to the integrity of bridges. During flood events, scour at bridge piers : and abutments can undermine the foundations of the bridge, causing significant damage or even total structure loss. : Because scour occu...

An Assessment of Capacity, Gaps and Opportunities toward Building a Global Early Warning System for Flood Disasters

NASA Astrophysics Data System (ADS)

Hong, Y.; Adler, R.; Huffman, G.

2007-12-01

Many governmental emergency management agencies or non-governmental organizations need real-time information on emerging disasters for preparedness and response. However, progress in warnings for hydrologic disasters has been constrained by the difficulty of measuring spatiotemporal variability of rainfall fluxes continuously over space and time, due largely to insufficient ground monitoring networks, long delay in data transmission and absence of data sharing protocols among many geopolitically trans-boundary basins. In addition, in-situ gauging stations are often washed away by the very floods they are designed to monitor, making reconstruction of gauges a common post-flood activity around the world. In reality, remote sensing precipitation estimates may be the only source of rainfall information available over much of the globe, particularly for vulnerable countries in the tropics where abundant extreme rain storms and severe flooding events repeat every year. Building on progress in remote sensing technology, researchers have improved the accuracy, coverage, and resolution of rainfall estimates by combining imagery from infrared, passive microwave, and weather radar sensors. Today, remote sensing imagery acquired and processed in real time can provide near-real-time rainfall fluxes at relatively fine spatiotemporal scales (kilometers to tens of kilometers and 30-minute to 3-hour). These new suites of rainfall products have the potential to support daily decision-making in analysis of hydrologic hazards. This talk will address several key issues, including remote sensing rainfall retrieval and data assimilation, for hydrologists to develop alternative satellite-based flood warning systems that may supplement in-situ infrastructure when conventional data sources are denied due to natural or administrative causes. This talk will also assess a module-structure global flood prediction system that has been running at real-time by integrating remote sensing forcing data with simplified hydrological models, in an effort to offer a practical solution to the challenge of building cost-effective flood warning systems for the data-spares regions of the world. The real-time outlook of hazardous floods will quickly disseminate through an open-access web-interface to many agencies and organizations for their daily decision-making, with the potential to save human life and reduce economic impacts. The interactive Web interface will also show close-up maps of the disaster risks overlaid on population or integrated with the Google-Earth visualization tool.

The development of flood map in Malaysia

NASA Astrophysics Data System (ADS)

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

2017-11-01

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

Flood warnings, flood disaster assessments, and flood hazard reduction: the roles of orbital remote sensing

NASA Technical Reports Server (NTRS)

Brakenridge, G. R.; Anderson, E.; Nghiem, S. V.; Caquard, S.; Shabaneh, T. B.

2003-01-01

Orbital remote sensing of the Earth is now poised to make three fundamental contributions towards reducing the detrimental effects of extreme floods. Effective Flood warning requires frequent radar observation of the Earth's surface through cloud cover. In contrast, both optical and radar wavelengths will increasingly be used for disaster assessment and hazard reduction.

A probabilistic approach of the Flash Flood Early Warning System (FF-EWS) in Catalonia based on radar ensemble generation

NASA Astrophysics Data System (ADS)

Velasco, David; Sempere-Torres, Daniel; Corral, Carles; Llort, Xavier; Velasco, Enrique

2010-05-01

Early Warning Systems (EWS) are commonly identified as the most efficient tools in order to improve the preparedness and risk management against heavy rains and Flash Floods (FF) with the objective of reducing economical losses and human casualties. In particular, flash floods affecting torrential Mediterranean catchments are a key element to be incorporated within operational EWSs. The characteristic high spatial and temporal variability of the storms requires high-resolution data and methods to monitor/forecast the evolution of rainfall and its hydrological impact in small and medium torrential basins. A first version of an operational FF-EWS has been implemented in Catalonia (NE Spain) under the name of EHIMI system (Integrated Tool for Hydrometeorological Forecasting) with the support of the Catalan Water Agency (ACA) and the Meteorological Service of Catalonia (SMC). Flash flood warnings are issued based on radar-rainfall estimates. Rainfall estimation is performed on radar observations with high spatial and temporal resolution (1km2 and 10 minutes) in order to adapt the warning scale to the 1-km grid of the EWS. The method is based on comparing observed accumulated rainfall against rainfall thresholds provided by the regional Intensity-Duration-Frequency (IDF) curves. The so-called "aggregated rainfall warning" at every river cell is obtained as the spatially averaged rainfall over its associated upstream draining area. Regarding the time aggregation of rainfall, the critical duration is thought to be an accumulation period similar to the concentration time of each cachtment. The warning is issued once the forecasted rainfall accumulation exceeds the rainfall thresholds mentioned above, which are associated to certain probability of occurrence. Finally, the hazard warning is provided and shown to the decision-maker in terms of exceeded return periods at every river cell covering the whole area of Catalonia. The objective of the present work includes the probabilistic component to the FF-EWS. As a first step, we have incorporated the uncertainty in rainfall estimates and forecasts based on an ensemble of equiprobable rainfall scenarios. The presented study has focused on a number of rainfall events and the performance of the FF-EWS evaluated in terms of its ability to produce probabilistic hazard warnings for decision-making support.

An early warning system for flash floods in Egypt

NASA Astrophysics Data System (ADS)

Cools, J.; Abdelkhalek, A.; El Sammany, M.; Fahmi, A. H.; Bauwens, W.; Huygens, M.

2009-09-01

This paper describes the development of the Flash Flood Manager, abbreviated as FlaFloM. The Flash Flood Manager is an early warning system for flash floods which is developed under the EU LIFE project FlaFloM. It is applied to Wadi Watier located in the Sinai peninsula (Egypt) and discharges in the Red Sea at the local economic and tourist hub of Nuweiba city. FlaFloM consists of a chain of four modules: 1) Data gathering module, 2) Forecasting module, 3) Decision support module or DSS and 4) Warning module. Each module processes input data and consequently send the output to the following module. In case of a flash flood emergency, the final outcome of FlaFloM is a flood warning which is sent out to decision-makers. The ‘data gathering module’ collects input data from different sources, validates the input, visualise data and exports it to other modules. Input data is provided ideally as water stage (h), discharge (Q) and rainfall (R) through real-time field measurements and external forecasts. This project, however, as occurs in many arid flash flood prone areas, was confronted with a scarcity of data, and insufficient insight in the characteristics that release a flash flood. Hence, discharge and water stage data were not available. Although rainfall measurements are available through classical off line rain gauges, the sparse rain gauges network couldn’t catch the spatial and temporal characteristics of rainfall events. To overcome this bottleneck, we developed rainfall intensity raster maps (mm/hr) with an hourly time step and raster cell of 1*1km. These maps are derived through downscaling from two sources of global instruments: the weather research and forecasting model (WRF) and satellite estimates from the Tropical Rainfall Measuring Mission (TRMM). The ‘forecast module’ comprises three numerical models that, using data from the gathering module performs simulations on command: a rainfall-runoff model, a river flow model, and a flood model. A rainfall-runoff model transforms the (forecasted) rainfall into a runoff volume (m³) and consequently a time-dependent discharge (m³/s) for each of the subwadis which is then routed through the main channel. The flood model then converts the discharges into water stages and generates a spatially-distributed flood map. The rainfall-runoff model is developed in Matlab-Simulink. The latter two models are implemented in Infoworks and Floodworks (both Wallingford Software), which allows an automatic feed into the warning module. The ‘warning module’ has two tasks: 1) to generate specific flags when modelling results exceed pre-established thresholds for rainfall, discharge, water stage, volumes, etc… 2) to communicate the given flags as warning signals to operators and/or stakeholders. The ‘decision support module’ or DSS finally gives to the user the capability of performing alternative analysis in order to have a better idea of the reliability of the forecasts by means of the comparison of already made forecasts with new data and a sensitivity analysis. Although FlaFloM is now able to send out warnings, the forecasts of this first version are expected to be insufficiently accurate which may lead to false warnings and loss of trust with decision-makers if not communicated well. When new insights and data are available, the model will be updated which improves the forecast accuracy. At this moment, we see two major fields of improvement: 1) better rainfall forecasts and 2) better insights of the response of an arid area to storm events. Firstly, the rainfall maps provided better insights in the spatial and temporal extent of a rainfall event, though absolute rainfall values are not considered accurate. The major reason behind is the fact that both global systems are insufficiently parameterized for arid areas. New data from an improved rain gauge network is expected to add value. Secondly, better insights need to be gained on the response of the Wadi to rainfall. The calibration of the hydrological models is currently based on literature and a geological surface map from which we derived infiltration rates. Modelled discharges or flood volumes can only be assessed qualitatively based on the field knowledge of local Bedouins inhabitants. To reduce uncertainty on forecasts and to guide on new data to be collected, a sensitivity analysis with rainfall scenarios is performed.

Development of a flood-warning network and flood-inundation mapping for the Blanchard River in Ottawa, Ohio

USGS Publications Warehouse

Whitehead, Matthew T.

2011-01-01

Digital flood-inundation maps of the Blanchard River in Ottawa, Ohio, were created by the U.S. Geological Survey (USGS) in cooperation with the U.S. Department of Agriculture, Natural Resources Conservation Service and the Village of Ottawa, Ohio. The maps, which correspond to water levels (stages) at the USGS streamgage at Ottawa (USGS streamgage site number 04189260), were provided to the National Weather Service (NWS) for incorporation into a Web-based flood-warning Network that can be used in conjunction with NWS flood-forecast data to show areas of predicted flood inundation associated with forecasted flood-peak stages. Flood profiles were computed by means of a step-backwater model calibrated to recent field measurements of streamflow. The step-backwater model was then used to determine water-surface-elevation profiles for 12 flood stages with corresponding streamflows ranging from less than the 2-year and up to nearly the 500-year recurrence-interval flood. The computed flood profiles were used in combination with digital elevation data to delineate flood-inundation areas. Maps of the Village of Ottawa showing flood-inundation areas overlain on digital orthophotographs are presented for the selected floods. As part of this flood-warning network, the USGS upgraded one streamgage and added two new streamgages, one on the Blanchard River and one on Riley Creek, which is tributary to the Blanchard River. The streamgage sites were equipped with both satellite and telephone telemetry. The telephone telemetry provides dual functionality, allowing village officials and the public to monitor current stage conditions and enabling the streamgage to call village officials with automated warnings regarding flood stage and/or predetermined rates of stage increase. Data from the streamgages serve as a flood warning that emergency management personnel can use in conjunction with the flood-inundation maps by to determine a course of action when flooding is imminent.

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

NASA Astrophysics Data System (ADS)

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

2015-10-01

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

Citizen Science into Action - Robust Data with Affordable Technologies for Flood Risks Management in the Himalayas

NASA Astrophysics Data System (ADS)

Pandeya, B.; Uprety, M.; Paul, J. D.; Dugar, S.; Buytaert, W.

2017-12-01

With a robust and affordable monitoring system, a wealth of hydrological data can be generated which is fundamental to predict flood risks more accurately. Since the Himalayan region is characterized by data deficiency and unpredictable hydrological behaviour, a locally based participatory monitoring system is a necessity to deal with frequently occurring flooding incidents. A gap in hydrological data is the main bottleneck for establishing any effective flood early warning system. Therefore, an alternative and affordable technical solution can only overcome the situation and support flood risks management activities in the region. In coordination with local people, government authorities and NGOs, we have established a citizen science monitoring system, in which we tested two types of low-cost sensors, ultrasound and LiDAR, in the Karnali river basin of Nepal. The results confirm the robustness of sensor data when compared to conventional radar system based monitoring data. Additionally, our findings also confirmed that the ultrasound sensors are only useful to small rivers whereas the LiDAR sensors are suitable to large river basins with highly variable local climatic conditions. Since the collected sensor data can be directly used in operational flood early warning system in the basin, an opportunity has been created for integrating both affordable technology and citizen science into existing hydrological monitoring practice. Finally, a successful integration could become a testament for upscaling the practice and building flood risk resilient communities in the region.

The 2014 Karnali River Floods in Western Nepal: Making Community Based Early Warning Systems Work When Data Is Lacking

NASA Astrophysics Data System (ADS)

Dugar, S.; MacClune, K.; Venkateswaran, K.; Yadav, S.; Szoenyi, M.

2015-12-01

Implementing Community Based Flood Early Warning System (EWS) in developing countries like Nepal is challenging. Complex topography and geology combined with a sparse network of river and rainfall gauges and little predictive meteorological capacity both nationally and regionally dramatically constrain EWS options. This paper provides a synopsis of the hydrological and meteorological conditions that led to flooding in the Karnali River, West Nepal during mid-August 2014, and analyses the effectiveness of flood EWS in the region. On August 14-15, 2014, a large, slow moving weather system deposited record breaking rainfall in the foothills of the Karnali River catchment. Precipitation depths of 200 to 500 mm were recorded over a 24-hour period, which led to rapid rise of river heights. At the Chisapani river gauge station used for the existing EWS, where the Karnali River exits the Himalaya onto the Indo-Gangetic Plain, water levels rapidly exceeded the 11 meter danger level. Between 3 to 6 am, water levels rose from 11 to 16. 1 meters, well beyond the design height of 15 meters. Analysis suggests that 2014 floods may have been a one-in-1000 year event. Starting with the onset of intense rainfall, the Chisapani gauge reader was in regular communication with downstream stakeholders and communities providing them with timely information regarding rising water level. This provided people just enough time to move to safe places with their livestock and key assets. Though households still lost substantial assets, without the EWS, floodwaters would have caught communities completely unaware and damage would almost certainly have been much worse. In particular, despite the complications associated with access to the Chisapani gauge and failure of critical communication nodes during the floods, EWS was instrumental in saving lives. This study explores both the details of the flood event and performance of the early warning system, and identifies lessons learned to help strengthen flood response in Nepal other regions facing similar data and technology constraints. This research also underscores the need to move from observation to forecast based EWS, ideally coupled with hydrological and meteorological models that would provide flood estimates well in advance to vulnerable communities.

Synoptic-scale atmospheric conditions associated with flash flooding in watersheds of the Catskill Mountains, New York, USA

NASA Astrophysics Data System (ADS)

Teale, N. G.; Quiring, S. M.

2015-12-01

Understanding flash flooding is important in unfiltered watersheds, such as portions of the New York City water supply system (NYCWSS), as water quality is degraded by turbidity associated with flooding. To further understand flash flooding in watersheds of the NYCWSS, synoptic-scale atmospheric conditions most frequently associated with flash flooding between 1987 and 2013 were examined. Flash floods were identified during this time period using USGS 15-minute discharge data at the Esopus Creek near Allaben, NY and Neversink River at Claryville, NY gauges. Overall, 25 flash floods were detected, occurring over 17 separate flash flood days. These flash flood days were compared to the days on which flash flood warnings encompassing the study area was issued by the National Weather Service. The success rate for which the flash flood warnings for Ulster County coincided with flash flood in the study watershed was 0.09, demonstrating the highly localized nature of flash flooding in the Catskill Mountain region. The synoptic-scale atmospheric patterns influencing the study area were characterized by a principal component analysis and k-means clustering of NCEP/NCAR 500 mb geopotential height reanalysis data. This procedure was executed in Spatial Synoptic Typer Tools 4.0. While 17 unique synoptic patterns were identified, only 3 types were strongly associated with flash flooding events. A strong southwesterly flow suggesting advection of moisture from the Atlantic Ocean and Gulf of Mexico is shown in composites of these 3 types. This multiscalar study thereby links flash flooding in the NYCWSS with synoptic-scale atmospheric circulation.Understanding flash flooding is important in unfiltered watersheds, such as portions of the New York City water supply system (NYCWSS), as water quality is degraded by turbidity associated with flooding. To further understand flash flooding in watersheds of the NYCWSS, synoptic-scale atmospheric conditions most frequently associated with flash flooding between 1987 and 2013 were examined. Flash floods were identified during this time period using USGS 15-minute discharge data at the Esopus Creek near Allaben, NY and Neversink River at Claryville, NY gauges. Overall, 25 flash floods were detected, occurring over 17 separate flash flood days. These flash flood days were compared to the days on which flash flood warnings encompassing the study area was issued by the National Weather Service. The success rate for which the flash flood warnings for Ulster County coincided with flash flood in the study watershed was 0.09, demonstrating the highly localized nature of flash flooding in the Catskill Mountain region. The synoptic-scale atmospheric patterns influencing the study area were characterized by a principal component analysis and k-means clustering of NCEP/NCAR 500 mb geopotential height reanalysis data. This procedure was executed in Spatial Synoptic Typer Tools 4.0. While 17 unique synoptic patterns were identified, only 3 types were strongly associated with flash flooding events. A strong southwesterly flow suggesting advection of moisture from the Atlantic Ocean and Gulf of Mexico is shown in composites of these 3 types. This multiscalar study thereby links flash flooding in the NYCWSS with synoptic-scale atmospheric circulation.

Streamflow forecasts from WRF precipitation for flood early warning in mountain tropical areas

NASA Astrophysics Data System (ADS)

Rogelis, María Carolina; Werner, Micha

2018-02-01

Numerical weather prediction (NWP) models are fundamental to extend forecast lead times beyond the concentration time of a watershed. Particularly for flash flood forecasting in tropical mountainous watersheds, forecast precipitation is required to provide timely warnings. This paper aims to assess the potential of NWP for flood early warning purposes, and the possible improvement that bias correction can provide, in a tropical mountainous area. The paper focuses on the comparison of streamflows obtained from the post-processed precipitation forecasts, particularly the comparison of ensemble forecasts and their potential in providing skilful flood forecasts. The Weather Research and Forecasting (WRF) model is used to produce precipitation forecasts that are post-processed and used to drive a hydrologic model. Discharge forecasts obtained from the hydrological model are used to assess the skill of the WRF model. The results show that post-processed WRF precipitation adds value to the flood early warning system when compared to zero-precipitation forecasts, although the precipitation forecast used in this analysis showed little added value when compared to climatology. However, the reduction of biases obtained from the post-processed ensembles show the potential of this method and model to provide usable precipitation forecasts in tropical mountainous watersheds. The need for more detailed evaluation of the WRF model in the study area is highlighted, particularly the identification of the most suitable parameterisation, due to the inability of the model to adequately represent the convective precipitation found in the study area.

Development of a flood-warning system and flood-inundation mapping in Licking County, Ohio

USGS Publications Warehouse

Ostheimer, Chad J.

2012-01-01

Digital flood-inundation maps for selected reaches of South Fork Licking River, Raccoon Creek, North Fork Licking River, and the Licking River in Licking County, Ohio, were created by the U.S. Geological Survey (USGS), in cooperation with the Ohio Department of Transportation; U.S. Department of Transportation, Federal Highway Administration; Muskingum Watershed Conservancy District; U.S. Department of Agriculture, Natural Resources Conservation Service; and the City of Newark and Village of Granville, Ohio. The inundation maps depict estimates of the areal extent of flooding corresponding to water levels (stages) at the following USGS streamgages: South Fork Licking River at Heath, Ohio (03145173); Raccoon Creek below Wilson Street at Newark, Ohio (03145534); North Fork Licking River at East Main Street at Newark, Ohio (03146402); and Licking River near Newark, Ohio (03146500). The maps were provided to the National Weather Service (NWS) for incorporation into a Web-based flood-warning system that can be used in conjunction with NWS flood-forecast data to show areas of predicted flood inundation associated with forecasted flood-peak stages. As part of the flood-warning streamflow network, the USGS re-installed one streamgage on North Fork Licking River, and added three new streamgages, one each on North Fork Licking River, South Fork Licking River, and Raccoon Creek. Additionally, the USGS upgraded a lake-level gage on Buckeye Lake. Data from the streamgages and lake-level gage can be used by emergency-management personnel, in conjunction with the flood-inundation maps, to help determine a course of action when flooding is imminent. Flood profiles for selected reaches were prepared by calibrating steady-state step-backwater models to selected, established streamgage rating curves. The step-backwater models then were used to determine water-surface-elevation profiles for up to 10 flood stages at a streamgage with corresponding streamflows ranging from approximately the 50 to 0.2-percent chance annual-exceedance probabilities for each of the 4 streamgages that correspond to the flood-inundation maps. The computed flood profiles were used in combination with digital elevation data to delineate flood-inundation areas. Maps of Licking County showing flood-inundation areas overlain on digital orthophotographs are presented for the selected floods. The USGS also developed an unsteady-flow model for a reach of South Fork Licking River for use by the NWS to enhance their ability to provide advanced flood warning in the region north of Buckeye Lake, Ohio. The unsteady-flow model was calibrated based on data from four flooding events that occurred from June 2008 to December 2011. Model calibration was approximate due to the fact that there were unmeasured inflows to the river that were not able to be considered during the calibration. Information on unmeasured inflow derived from NWS hydrologic models and additional flood-event data could enable the NWS to further refine the unsteady-flow model.

An entropy decision approach in flash flood warning: rainfall thresholds definition

NASA Astrophysics Data System (ADS)

Montesarchio, V.; Napolitano, F.; Ridolfi, E.

2009-09-01

Flash floods events are floods characterised by very rapid response of the basins to the storms, and often they involve loss of life and damage to common and private properties. Due to the specific space-time scale of this kind of flood, generally only a short lead time is available for triggering civil protection measures. Thresholds values specify the precipitation amount for a given duration that generates a critical discharge in a given cross section. The overcoming of these values could produce a critical situation in river sites exposed to alluvial risk, so it is possible to compare directly the observed or forecasted precipitation with critical reference values, without running on line real time forecasting systems. This study is focused on the Mignone River basin, located in Central Italy. The critical rainfall threshold values are evaluated minimising an utility function based on the informative entropy concept. The study concludes with a system performance analysis, in terms of correctly issued warning, false alarms and missed alarms.

Study of flash floods over some parts of Brazil using precipitation index

NASA Astrophysics Data System (ADS)

Souza, D.; de Souza, R. L. M.; Araujo, R.

2016-12-01

In Brazil, the main phenomena related to natural disasters are derived from the Earth's external dynamics such as floods and flash floods, landslides and storms, where the flash flood phenomenon causes the second highest number of victims, totaling more than 32% of deaths. Floods and flash floods are natural events often triggered by storms or long period of rains, usually associated with rising volume of rainfall on the watershed, leading the river to exceed its maximum. Whereas the occurrence of natural disasters in Brazil is increasing in recent years, the use of more accurate tools to aid in the monitoring of extreme hydrological events it becomes necessary, aiming to decrease the number of human and material losses. In this context, this paper aims to implement an early warning and monitoring system related to extreme precipitation values and hydrological processes. So, initially was studied flood events in the states of São Paulo and Paraná, aimed de determination of the characteristics of rainfall and atmosphere. Later it was used an indicator of precipitation based on the climatology, which indicates warning points on the drainage network related to extreme precipitation, which are obtained by remote sensing sources, for example, radar and satellite, and numerical weather prediction data of short and very short term. The results indicated that most of the flood events over the study area was related to rainfall of deep convection. The use of precipitation indicators also helped the monitoring and the early warning, showing this to be an excellent tool for applications related to flash floods.

Developing a flood monitoring system from remotely sensed data for the Limpopo basin

USGS Publications Warehouse

Asante, K.O.; Macuacua, R.D.; Artan, G.A.; Lietzow, R.W.; Verdin, J.P.

2007-01-01

This paper describes the application of remotely sensed precipitation to the monitoring of floods in a region that regularly experiences extreme precipitation and flood events, often associated with cyclonic systems. Precipitation data, which are derived from spaceborne radar aboard the National Aeronautics and Space Administration's Tropical Rainfall Measuring Mission and from National Oceanic and Atmospheric Administration's infrared-based products, are used to monitor areas experiencing extreme precipitation events that are defined as exceedance of a daily mean areal average value of 50 mm over a catchment. The remotely sensed precipitation data are also ingested into a hydrologic model that is parameterized using spatially distributed elevation, soil, and land cover data sets that are available globally from remote sensing and in situ sources. The resulting stream-flow is classified as an extreme flood event when flow anomalies exceed 1.5 standard deviations above the short-term mean. In an application in the Limpopo basin, it is demonstrated that the use of satellite-derived precipitation allows for the identification of extreme precipitation and flood events, both in terms of relative intensity and spatial extent. The system is used by water authorities in Mozambique to proactively initiate independent flood hazard verification before generating flood warnings. The system also serves as a supplementary information source when in situ gauging systems are disrupted. This paper concludes that remotely sensed precipitation and derived products greatly enhance the ability of water managers in the Limpopo basin to monitor extreme flood events and provide at-risk communities with early warning information. ?? 2007 IEEE.

Small-scale (flash) flood early warning in the light of operational requirements: opportunities and limits with regard to user demands, driving data, and hydrologic modeling techniques

NASA Astrophysics Data System (ADS)

Philipp, Andy; Kerl, Florian; Büttner, Uwe; Metzkes, Christine; Singer, Thomas; Wagner, Michael; Schütze, Niels

2016-05-01

In recent years, the Free State of Saxony (Eastern Germany) was repeatedly hit by both extensive riverine flooding, as well as flash flood events, emerging foremost from convective heavy rainfall. Especially after a couple of small-scale, yet disastrous events in 2010, preconditions, drivers, and methods for deriving flash flood related early warning products are investigated. This is to clarify the feasibility and the limits of envisaged early warning procedures for small catchments, hit by flashy heavy rain events. Early warning about potentially flash flood prone situations (i.e., with a suitable lead time with regard to required reaction-time needs of the stakeholders involved in flood risk management) needs to take into account not only hydrological, but also meteorological, as well as communication issues. Therefore, we propose a threefold methodology to identify potential benefits and limitations in a real-world warning/reaction context. First, the user demands (with respect to desired/required warning products, preparation times, etc.) are investigated. Second, focusing on small catchments of some hundred square kilometers, two quantitative precipitation forecasts are verified. Third, considering the user needs, as well as the input parameter uncertainty (i.e., foremost emerging from an uncertain QPF), a feasible, yet robust hydrological modeling approach is proposed on the basis of pilot studies, employing deterministic, data-driven, and simple scoring methods.

The influence of antecedent conditions on flood risk in sub-Saharan Africa

NASA Astrophysics Data System (ADS)

Bischiniotis, Konstantinos; van den Hurk, Bart; Coughlan de Perez, Erin; Jongman, Brenden; Veldkamp, Ted; Aerts, Jeroen

2017-04-01

Traditionally, flood risk management has focused on long-term flood protection measures. However, many countries are often not able to afford hard infrastructure that provides sufficient safety levels due to the high investment costs. As a consequence, they rely more on post disaster response and timely warning systems. Most early warning systems have predominantly focused on precipitation as the main predictive factor, having usually lead times of hours or days. However, other variables could also play a role. For instance, anomalous positive water storage, soil saturation and evapotranspiration are physical factors that may influence the length of the flood build-up period. This period can vary from some days to several months before the event and it is particularly important in flood risk management since longer flood warning lead times during this period could result in better flood preparation actions. This study addresses how the antecedent conditions of historical reported flood events over the period 1980 to 2010 in sub-Saharan Africa relate to flood generation. The seasonal-scale conditions are reflected in the Standardized Precipitation Evapotranspiration Index (SPEI), which is calculated using monthly precipitation and temperature data and accounts for the wetness/dryness of an area. Antecedent conditions are separated into a) a short term 'weather-scale' period (0-7 days) and b) a 'seasonal-scale' period (up to 6 months) before the flood event in such a way that they do not overlap. Total 7-day precipitation, which is based on daily meteorological data, was used to evaluate the short-term weather-scale conditions. Using a pair of coordinates, derived from the NatCatSERVICE database on global flood losses, each flood event is positioned on a 0.5°x 0.5° grid cell. The antecedent SPEI conditions of the two periods and their joint influence in flood generation are compared to the same period conditions of the other years of the dataset. First results revealed that many floods were preceded by high SPEI for several months before the flooding event, showing that the area was saturated with a long lead-time. Those that were not preceded by high SPEI had very extreme short-term precipitation that caused the flood event. Furthermore, the importance of seasonal-scale conditions is quantified, which in turn might help humanitarian organizations and decision-makers extend the period of the preventive flood risk management planning.

Evaluation of radar rainfall estimates and nowcasts to prevent flash flood in real time by using a road submersion warning tool

NASA Astrophysics Data System (ADS)

Versini, Pierre-Antoine; Sempere-Torres, Daniel

2010-05-01

Important damages occur in small headwater catchments when they are hit by severe storms with complex spatio-temporal structure, sometimes resulting in flash floods. As these catchments are mostly not covered by sensor networks, it is difficult to forecast these floods. This is particularly true for road submersions. These are major concerns for flood event managers. The use of Quantitative Precipitation Estimates and Forecasts (QPE/QPF) especially based on radar measurements could particularly be adequate to evaluate rainfall-induced risks. Although their characteristic time and space scales would make them suitable for flash flood modelling, the impact of their uncertainties remain uncertain and have to be evaluated. The Gard region (France) has been chosen as case study. This area is frequently affected by severe flash floods and different kinds of rainfall observations are available in real time: radar rainfall estimates and nowcasts from METEO FRANCE and the CALAMAR system from SPC (state authority in charge of flood forecasting). An application devoted to the road network, has also been recently developed for this region. It combines distributed hydro-meteorological very short range forecasts and vulnerability analysis to provide warnings of road submersions. The first results demonstrate that it is technically possible to provide distributed short-term forecasts for a large number of sites. The study also demonstrates that a reliable estimation of the spatial distribution of rainfall is essential. For this reason, the road submersion warning system can be used to evaluate the quality of rainfall estimates and nowcasts. The warning system has been tested on the specific storm of the 29-30 September 2007. During this event, more than 300mm dropped on the South part of the Gard and many roads were submerged. Each of the mentioned rainfall datasets (i.e. estimates and nowcasts) was available in real time. They have been used to forecast the exact location of road submersions and the results have been compared to the effective road submersions actually occurred during the event as listed by the emergency services. The results confirm that the road submersion warning system represents a promising tool for anticipating and quantifying the consequences of storm events at ground. It rates the submersion risk with an acceptable level of accuracy and a reasonable false alarm ratio. It demonstrates also the quality of high spatial and temporal resolution radar rainfall data in real time, and the possibility to use them despite their uncertainties. However because of the quality of rainfall nowcasts falls drastically with time, it is not often sufficient to provide valuable information for lead times exceeding one hour.

On the reliable use of satellite-derived surface water products for global flood monitoring

NASA Astrophysics Data System (ADS)

Hirpa, F. A.; Revilla-Romero, B.; Thielen, J.; Salamon, P.; Brakenridge, R.; Pappenberger, F.; de Groeve, T.

2015-12-01

Early flood warning and real-time monitoring systems play a key role in flood risk reduction and disaster response management. To this end, real-time flood forecasting and satellite-based detection systems have been developed at global scale. However, due to the limited availability of up-to-date ground observations, the reliability of these systems for real-time applications have not been assessed in large parts of the globe. In this study, we performed comparative evaluations of the commonly used satellite-based global flood detections and operational flood forecasting system using 10 major flood cases reported over three years (2012-2014). Specially, we assessed the flood detection capabilities of the near real-time global flood maps from the Global Flood Detection System (GFDS), and from the Moderate Resolution Imaging Spectroradiometer (MODIS), and the operational forecasts from the Global Flood Awareness System (GloFAS) for the major flood events recorded in global flood databases. We present the evaluation results of the global flood detection and forecasting systems in terms of correctly indicating the reported flood events and highlight the exiting limitations of each system. Finally, we propose possible ways forward to improve the reliability of large scale flood monitoring tools.

The Hurricane-Flood-Landslide Continuum: Forecasting Hurricane Effects at Landfall

NASA Technical Reports Server (NTRS)

Negri, A.; Golden, J. H.; Updike, R.

2004-01-01

Hurricanes, typhoons, and cyclones strike Central American, Caribbean, Southeast Asian and Pacific Island nations even more frequently than the U.S. The global losses of life and property from the floods, landslides and debris flows caused by cyclonic storms are staggering. One of the keys to reducing these losses, both in the U.S. and internationally, is to have better forecasts of what is about to happen from several hours to days before the event. Particularly in developing nations where science, technology and communication are limited, advance-warning systems can have great impact. In developing countries, warnings of even a few hours or days can mitigate or reduce catastrophic losses of life. With the foregoing needs in mind, we propose an initial project of three years total duration that will aim to develop and transfer a warning system for a prototype region in the Central Caribbean, specifically the islands of Puerto Rico and Hispanola. The Hurricane-Flood-Landslide Continuum will include satellite observations to track and nowcast dangerous levels of precipitation, atmospheric and hydrological models to predict near-future runoff, and streamflow changes in affected regions, and landslide models to warn when and where landslides and debris flows are imminent. Since surface communications are likely to be interrupted during these crises, the project also includes the capability to communicate disaster information via satellite to vital government officials in Puerto Rico, Haiti, and Dominican Republic.

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.

Criteria for evaluating the condition of a tropical cyclone warning system.

PubMed

Parker, D

1999-09-01

This paper evaluates the condition (i.e. health) of a tropical cyclone warning system (TCWS) during a 'quiet period' between infrequent intense cyclones. Capacity to make pre-disaster evaluations is important--disaster warning systems need to be in sound condition before, not after, disaster. The research--part of the UK's International Decade of Natural Disaster Reduction Flagship Programme--focuses upon an evaluatory method first used on flood warning systems. The Criteria-development Matrix comprises social, organisational and institutional criteria by which a TCWS may be assessed using a five-stage development scale. This method is used to evaluate Mauritius's TCWS using in-depth interview data. Ways to enhance the method and apply it to other disaster warning systems are discussed. The TCWS in Mauritius is a relatively sound one from which others can learn. Weaknesses requiring attention for Mauritius's TCWS to progress to an advanced level of development are identified.

Development of a precipitation-area curve for warning criteria of short-duration flash flood

NASA Astrophysics Data System (ADS)

Bae, Deg-Hyo; Lee, Moon-Hwan; Moon, Sung-Keun

2018-01-01

This paper presents quantitative criteria for flash flood warning that can be used to rapidly assess flash flood occurrence based on only rainfall estimates. This study was conducted for 200 small mountainous sub-catchments of the Han River basin in South Korea because South Korea has recently suffered many flash flood events. The quantitative criteria are calculated based on flash flood guidance (FFG), which is defined as the depth of rainfall of a given duration required to cause frequent flooding (1-2-year return period) at the outlet of a small stream basin and is estimated using threshold runoff (TR) and antecedent soil moisture conditions in all sub-basins. The soil moisture conditions were estimated during the flooding season, i.e., July, August and September, over 7 years (2002-2009) using the Sejong University Rainfall Runoff (SURR) model. A ROC (receiver operating characteristic) analysis was used to obtain optimum rainfall values and a generalized precipitation-area (P-A) curve was developed for flash flood warning thresholds. The threshold function was derived as a P-A curve because the precipitation threshold with a short duration is more closely related to basin area than any other variables. For a brief description of the P-A curve, generalized thresholds for flash flood warnings can be suggested for rainfall rates of 42, 32 and 20 mm h-1 in sub-basins with areas of 22-40, 40-100 and > 100 km2, respectively. The proposed P-A curve was validated based on observed flash flood events in different sub-basins. Flash flood occurrences were captured for 9 out of 12 events. This result can be used instead of FFG to identify brief flash flood (less than 1 h), and it can provide warning information to decision-makers or citizens that is relatively simple, clear and immediate.

Effects of forcing uncertainties in the improvement skills of assimilating satellite soil moisture retrievals into flood forecasting models

USDA-ARS?s Scientific Manuscript database

Floods have negative impacts on society, causing damages in infrastructures and industry, and in the worst cases, causing loss of human lives. Thus early and accurate warning is crucial to significantly reduce the impacts on public safety and economy. Reliable flood warning can be generated using ...

Understanding flood risk sensitivity and uncertainty in a subcatchment of the Thames River (United Kingdom)

NASA Astrophysics Data System (ADS)

Theofanidi, Sofia; Cloke, Hannah Louise; Clark, Joanna

2017-04-01

Floods are a global threat to social, economic and environmental development and there is a likelihood, that they could occur more frequently in the future due to climatic change. The severity of their impacts, which can last for years, has led to the urgent need for local communities and national authorities to develop flood warning systems for a better flood preparedness and emergency response. The flood warning systems often rely on hydrological forecasting tools to predict the hydrological response of a watershed before or during a flood event. Hydrological models have been substantially upgraded since the first use of hydrographs and the use of simple conceptual models. Hydrodynamic and hydraulic routing enables the spatial and temporal prediction of flow rates (peak discharges) and water levels. Moreover, the hydrodynamic modeling in 2D permits the estimation of the flood inundation area. This can be particularly useful because the flood zones can provide essential information about the flood risk and the flood damage. In this study, we use a hydrodynamic model which can simulate water levels and river flows in open channel conditions. The model can incorporate the effect of several river structures in the flood modeling process, such as the existence of bridges and weirs. The flood routing method is based on the solution of continuity and energy momentum equations. In addition, the floodplain inundation modeling which is based on the solution of shallow water equations along the channel's banks, will be used for the mapping of flood extent. A GIS interface will serve as a database, including high resolution topography, vector layers of river network, gauging stations, land use and land cover, geology and soil information. The flood frequency analysis, together with historical records on flood warnings, will enable the understanding on the flow regimes and the selection of particular flood events for modeling. One dimensional and two dimensional simulations of the flood events will follow, using simple hydrological boundary conditions. The sensitivity testing of the model, will permit to assess which parameters have the potential to alter significantly the peak discharge during the flood, flood water levels and flood inundation extent. Assessing the model's sensitivity and uncertainty, contributes to the improvement of the flood risk knowledge. The area of study is a subcatchment of the River Thames in the southern part of the United Kingdom. The Thames with its tributaries, support a wide range of social, economic and recreational activities. In addition, the historical and environmental importance of the Thames valley highlights the need for a sustainable flood mitigation planning which includes the better understanding of the flood mechanisms and flood risks.

Citizen Science to Support Community-based Flood Early Warning and Resilience Building

NASA Astrophysics Data System (ADS)

Paul, J. D.; Buytaert, W.; Allen, S.; Ballesteros-Cánovas, J. A.; Bhusal, J.; Cieslik, K.; Clark, J.; Dewulf, A.; Dhital, M. R.; Hannah, D. M.; Liu, W.; Nayaval, J. L.; Schiller, A.; Smith, P. J.; Stoffel, M.; Supper, R.

2017-12-01

In Disaster Risk Management, an emerging shift has been noted from broad-scale, top-down assessments towards more participatory, community-based, bottom-up approaches. Combined with technologies for robust and low-cost sensor networks, a citizen science approach has recently emerged as a promising direction in the provision of extensive, real-time information for flood early warning systems. Here we present the framework and initial results of a major new international project, Landslide EVO, aimed at increasing local resilience against hydrologically induced disasters in western Nepal by exploiting participatory approaches to knowledge generation and risk governance. We identify three major technological developments that strongly support our approach to flood early warning and resilience building in Nepal. First, distributed sensor networks, participatory monitoring, and citizen science hold great promise in complementing official monitoring networks and remote sensing by generating site-specific information with local buy-in, especially in data-scarce regions. Secondly, the emergence of open source, cloud-based risk analysis platforms supports the construction of a modular, distributed, and potentially decentralised data processing workflow. Finally, linking data analysis platforms to social computer networks and ICT (e.g. mobile phones, tablets) allows tailored interfaces and people-centred decision- and policy-support systems to be built. Our proposition is that maximum impact is created if end-users are involved not only in data collection, but also over the entire project life-cycle, including the analysis and provision of results. In this context, citizen science complements more traditional knowledge generation practices, and also enhances multi-directional information provision, risk management, early-warning systems and local resilience building.

Determining the Financial Impact of Flood Hazards in Ungaged Basins

NASA Astrophysics Data System (ADS)

Cotterman, K. A.; Gutenson, J. L.; Pradhan, N. R.; Byrd, A.

2017-12-01

Many portions of the Earth lack adequate authoritative or in situ data that is of great value in determining natural hazard vulnerability from both anthropogenic and physical perspective. Such locations include the majority of developing nations, which do not possess adequate warning systems and protective infrastructure. The lack of warning and protection from natural hazards make these nations vulnerable to the destructive power of events such as floods. The goal of this research is to demonstrate an initial workflow with which to characterize flood financial hazards with global datasets and crowd-sourced, non-authoritative data in ungagged river basins. This workflow includes the hydrologic and hydraulic response of the watershed to precipitation, characterized by the physics-based modeling application Gridded Surface-Subsurface Hydrologic Analysis (GSSHA) model. In addition, data infrastructure and resources are available to approximate the human impact of flooding. Open source, volunteer geographic information (VGI) data can provide global coverage of elements at risk of flooding. Additional valuation mechanisms can then translate flood exposure into percentage and financial damage to each building. The combinations of these tools allow the authors to remotely assess flood hazards with minimal computational, temporal, and financial overhead. This combination of deterministic and stochastic modeling provides the means to quickly characterize watershed flood vulnerability and will allow emergency responders and planners to better understand the implications of flooding, both spatially and financially. In either a planning, real-time, or forecasting scenario, the system will assist the user in understanding basin flood vulnerability and increasing community resiliency and preparedness.

Flood monitoring for ungauged rivers: the power of combining space-based monitoring and global forecasting models

NASA Astrophysics Data System (ADS)

Revilla-Romero, Beatriz; Netgeka, Victor; Raynaud, Damien; Thielen, Jutta

2013-04-01

Flood warning systems typically rely on forecasts from national meteorological services and in-situ observations from hydrological gauging stations. This capacity is not equally developed in flood-prone developing countries. Low-cost satellite monitoring systems and global flood forecasting systems can be an alternative source of information for national flood authorities. The Global Flood Awareness System (GloFAS) has been develop jointly with the European Centre for Medium-Range Weather Forecast (ECMWF) and the Joint Research Centre, and it is running quasi operational now since June 2011. The system couples state-of-the art weather forecasts with a hydrological model driven at a continental scale. The system provides downstream countries with information on upstream river conditions as well as continental and global overviews. In its test phase, this global forecast system provides probabilities for large transnational river flooding at the global scale up to 30 days in advance. It has shown its real-life potential for the first time during the flood in Southeast Asia in 2011, and more recently during the floods in Australia in March 2012, India (Assam, September-October 2012) and Chad Floods (August-October 2012).The Joint Research Centre is working on further research and development, rigorous testing and adaptations of the system to create an operational tool for decision makers, including national and regional water authorities, water resource managers, hydropower companies, civil protection and first line responders, and international humanitarian aid organizations. Currently efforts are being made to link GloFAS to the Global Flood Detection System (GFDS). GFDS is a Space-based river gauging and flood monitoring system using passive microwave remote sensing which was developed by a collaboration between the JRC and Dartmouth Flood Observatory. GFDS provides flood alerts based on daily water surface change measurements from space. Alerts are shown on a world map, with detailed reports for individual gauging sites. A comparison of discharge estimates from the Global Flood Detection System (GFDS) and the Global Flood Awareness System (GloFAS) with observations for representative climatic zones is presented. Both systems have demonstrated strong potential in forecasting and detecting recent catastrophic floods. The usefulness of their combined information on global scale for decision makers at different levels is discussed. Combining space-based monitoring and global forecasting models is an innovative approach and has significant benefits for international river commissions as well as international aid organisations. This is in line with the objectives of the Hyogo and the Post-2015 Framework that aim at the development of systems which involve trans-boundary collaboration, space-based earth observation, flood forecasting and early warning.

Flood-inundation maps and updated components for a flood-warning system or the City of Marietta, Ohio and selected communities along the Lower Muskingum River and Ohio River

USGS Publications Warehouse

Whitehead, Matthew T.; Ostheimer, Chad J.

2014-01-01

Flood profiles for selected reaches were prepared by calibrating steady-state step-backwater models to selected streamgage rating curves. The step-backwater models were used to determine water-surface-elevation profiles for up to 12 flood stages at a streamgage with corresponding stream-flows ranging from approximately the 10- to 0.2-percent chance annual-exceedance probabilities for each of the 3 streamgages that correspond to the flood-inundation maps. Additional hydraulic modeling was used to account for the effects of backwater from the Ohio River on water levels in the Muskingum River. The computed longitudinal profiles of flood levels were used with a Geographic Information System digital elevation model (derived from light detection and ranging) to delineate flood-inundation areas. Digital maps showing flood-inundation areas overlain on digital orthophotographs were prepared for the selected floods.

Assessing various approaches for flash flood forecasting in the Yzeron periurban catchment (150 km2) south-east Lyon, France

NASA Astrophysics Data System (ADS)

Braud, Isabelle; Breil, Pascal; Javelle, Pierre; Pejakovic, Nikola; Guérin, Stéphane

2017-04-01

The Yzeron periurban catchment (150 km2) is prone to flash floods leading to overflow in the downstream part of the catchment. A prevention and management plan has been approved and the set-up of a flood forecasting system is planned. The present study presents a comparison of several solutions for flood forecasting in the catchment. It is based on an extensive data collection (rain gauges, radar/rain gauge reanalyses, discharge and water level data) from this experimental catchment. A set of rainfall-runoff events leading to floods (problematic and non-problematic floods) was extracted and formed the basis for the definition of a first forecasting method. It is based on data analysis and the identification of explaining factors amongst the following: rainfall amount, intensity, antecedent rainfall, initial discharge. Several statistical methods including Factorial Analysis of Mixed Data and Classification and Regression Tree were used for this purpose. They showed that several classes of problematic floods can be identified. The first one is related to wet conditions characterized with high initial discharge and antecedent rainfall. The second class is driven by rainfall amount, initial discharge and rainfall intensity. Thresholds of these variables can be identified to provide a first warning. The second forecasting method assessed in the study is the system that will be operational in France in 2017, based on the AIGA method (Javelle et al., 2016). For this purpose, 18-year discharge simulation using the hydrological model of the AIGA method, forced using radar/rain gauges reanalysis were available at 44 locations within the catchment. The dates for which quantiles of a given return period were overtopped were identified and compared with the list of problematic events. The AIGA method was found relevant in identifying the most problematic events, but the lead time needs further investigation in order to assess the usefulness for population warning. References: Pierre Javelle, Didier Organde, Julie Demargne, Clotilde Saint-Martin, Céline de Saint-Aubin, Léa Garandeau and Bruno Janet (2016). Setting up a French national flash flood warning system for ungauged catchments based on the AIGA method. E3S Web of Conferences 7, 18010 (2016), 3rd European Conference on Flood Risk Management (FLOODrisk 2016), http://dx.doi.org/10.1051/e3sconf/20160718010

The Influence Of Antecedent Conditions On Flood Risk In Sub-Saharan Africa

NASA Astrophysics Data System (ADS)

Bischiniotis, K.

2017-12-01

Flood risk management has traditionally focused on long-term flood protection measures. However, due to high investment costs many lower-income countries are not able to afford hard infrastructure that provides the desired safety levels. Consequently, timely warning of not only extreme events is crucial in risk mitigation at these places. Most flood warning systems have predominantly focused on precipitation as the main predictive factor with lead times of hours or days. Nevertheless, other factors such as anomalous positive water storage, soil saturation and evapotranspiration also affect the flood build-up period. Gaining insights in the processes occurring during this period can increase warning lead times, resulting in more effective preparation. This study follows a pragmatic approach to analyse the hydro-meteorological pre-conditions of 501 damaging floods over the period 1980 to 2010 in sub-Saharan Africa. These are separated into a) weather scale (0-7 days) and b) seasonal scale conditions (up to 6 months) before each event in a way that the two periods do not overlap. The 7-day preceding precipitation (PRE7) and the Standardized Precipitation Evapotranspiration Index (SPEI) reflect the conditions in the two time scale domains, respectively. Using the flood onset date and the location derived from NatCatSERVICE database, the antecedent conditions of each flood are systematically compared to the same conditions during the other years of the dataset, during which no floods were reported. Results indicate that high PRE7 does not always justify the flood generation by itself since there were several cases where similar magnitude precipitation events did not lead to flooding. The SPEI in the end of the flood onset month seems to be a good flood monitoring tool as in most cases it well reflects the wet conditions (80% of the floods). The SPEIs of different averaging times prior to flood events also show that many floods were preceded by wet conditions (70% , 65%, and 57% for averaging time of 1, 3 and 6 months, respectively. Finally, we show that bringing together weather and seasonal-scale conditions can result in an increased flooding likelihood, which in turn might help humanitarian organizations and decision-makers extend the period of the preventive flood risk management planning.

Development of web-based services for an ensemble flood forecasting and risk assessment system

NASA Astrophysics Data System (ADS)

Yaw Manful, Desmond; He, Yi; Cloke, Hannah; Pappenberger, Florian; Li, Zhijia; Wetterhall, Fredrik; Huang, Yingchun; Hu, Yuzhong

2010-05-01

Flooding is a wide spread and devastating natural disaster worldwide. Floods that took place in the last decade in China were ranked the worst amongst recorded floods worldwide in terms of the number of human fatalities and economic losses (Munich Re-Insurance). Rapid economic development and population expansion into low lying flood plains has worsened the situation. Current conventional flood prediction systems in China are neither suited to the perceptible climate variability nor the rapid pace of urbanization sweeping the country. Flood prediction, from short-term (a few hours) to medium-term (a few days), needs to be revisited and adapted to changing socio-economic and hydro-climatic realities. The latest technology requires implementation of multiple numerical weather prediction systems. The availability of twelve global ensemble weather prediction systems through the ‘THORPEX Interactive Grand Global Ensemble' (TIGGE) offers a good opportunity for an effective state-of-the-art early forecasting system. A prototype of a Novel Flood Early Warning System (NEWS) using the TIGGE database is tested in the Huai River basin in east-central China. It is the first early flood warning system in China that uses the massive TIGGE database cascaded with river catchment models, the Xinanjiang hydrologic model and a 1-D hydraulic model, to predict river discharge and flood inundation. The NEWS algorithm is also designed to provide web-based services to a broad spectrum of end-users. The latter presents challenges as both databases and proprietary codes reside in different locations and converge at dissimilar times. NEWS will thus make use of a ready-to-run grid system that makes distributed computing and data resources available in a seamless and secure way. An ability to run or function on different operating systems and provide an interface or front that is accessible to broad spectrum of end-users is additional requirement. The aim is to achieve robust interoperability through strong security and workflow capabilities. A physical network diagram and a work flow scheme of all the models, codes and databases used to achieve the NEWS algorithm are presented. They constitute a first step in the development of a platform for providing real time flood forecasting services on the web to mitigate 21st century weather phenomena.

Living together flash-floods: the Versilia (Italy) case study

NASA Astrophysics Data System (ADS)

Caporali, Enrica; Pileggi, Tiziana; Gruntfest, Eve; Ruin, Isabelle; Federici, Giorgio

2010-05-01

The phenomena involved in extreme flash-flood events are complex and their prediction is affected by a given degree of uncertainty that makes the warning communication very difficult to achieve. The promotion of the natural hazards perception and the improvement in warning communication, aimed at human life losses reduction, became extremely important to accomplish. As a case study the Versilia river basin, in North - West Tuscany, Central Italy, prone to frequent flash-flood events, is considered. In the area, as stated from Santini (a local historian of XIX century), since 1386 existed special statutes, imposing rivers maintenance for protection against floods. Historical data testify also that the biggest flood events have occurred in the years 1774, 1885, 1902 and 1996. The last event is the one deeply analyzed and better documented. It was exceptional, the consequences on the population were dramatic, and the effects on building and infrastructures were catastrophic. With reference to the Versilia region, a geographic database for flood risk assessment, integrating diachronic data with the results of hydrological and sedimentological modeling, and integrating different competencies, is implemented. The purpose is to provide valuable aid to flash-floods prediction, risk assessment, structural and non-structural mitigation measures. As a first attempt, the combination of all the information available on the history of floods of Versilia region and model results, together with human exposure to flash-flood risk, is also explored. The aim is to investigate the detailed hydrometeorological circumstances that lead to accidental casualties and to better understand the predominant physical factors of risk. In the framework of enhancing natural hazards perception, a very particular educational experience, dedicated to the personnel that work on the territory with different roles and in different fields (i.e. municipal and provincial police, national forest body, voluntary associations, etc.), that in the early warning and in emergency states can be involved in the warning system and the Civil Protection Activities, is also described. The Versilia area, in the days around last Christmas (25-28 December 2009), has been hit again by a series of intense weather events. The rainfall and instability data, as well as the interventions, of these last events, have been acquired and are being processing. The aim is to analyze and verify the impacts on the territory and on the population, also in terms of communities' behavior, risk perception and capacity to cope.

An operational real-time flood forecasting system in Southern Italy

NASA Astrophysics Data System (ADS)

Ortiz, Enrique; Coccia, Gabriele; Todini, Ezio

2015-04-01

A real-time flood forecasting system has been operating since year 2012 as a non-structural measure for mitigating the flood risk in Campania Region (Southern Italy), within the Sele river basin (3.240 km2). The Sele Flood Forecasting System (SFFS) has been built within the FEWS (Flood Early Warning System) platform developed by Deltares and it assimilates the numerical weather predictions of the COSMO LAM family: the deterministic COSMO-LAMI I2, the deterministic COSMO-LAMI I7 and the ensemble numerical weather predictions COSMO-LEPS (16 members). Sele FFS is composed by a cascade of three main models. The first model is a fully continuous physically based distributed hydrological model, named TOPKAPI-eXtended (Idrologia&Ambiente s.r.l., Naples, Italy), simulating the dominant processes controlling the soil water dynamics, runoff generation and discharge with a spatial resolution of 250 m. The second module is a set of Neural-Networks (ANN) built for forecasting the river stages at a set of monitored cross-sections. The third component is a Model Conditional Processor (MCP), which provides the predictive uncertainty (i.e., the probability of occurrence of a future flood event) within the framework of a multi-temporal forecast, according to the most recent advancements on this topic (Coccia and Todini, HESS, 2011). The MCP provides information about the probability of exceedance of a maximum river stage within the forecast lead time, by means of a discrete time function representing the variation of cumulative probability of exceeding a river stage during the forecast lead time and the distribution of the time occurrence of the flood peak, starting from one or more model forecasts. This work shows the Sele FFS performance after two years of operation, evidencing the added-values that can provide to a flood early warning and emergency management system.

An experimental operative system for shallow landslide and flash flood warning based on rainfall thresholds and soil moisture modelling

NASA Astrophysics Data System (ADS)

Brigandı, G.; Aronica, G. T.; Basile, G.; Pasotti, L.; Panebianco, M.

2012-04-01

On November 2011 a thunderstorms became almost exceptional over the North-East part of the Sicily Region (Italy) producing local heavy rainfall, mud-debris flow and flash flooding. The storm was concentrated on the Tyrrhenian sea coast near the city of Barcellona within the Longano catchment. Main focus of the paper is to present an experimental operative system for alerting extreme hydrometeorological events by using a methodology based on the combined use of rainfall thresholds, soil moisture indexes and quantitative precipitation forecasting. As matter of fact, shallow landslide and flash flood warning is a key element to improve the Civil Protection achievements to mitigate damages and safeguard the security of people. It is a rather complicated task, particularly in those catchments with flashy response where even brief anticipations are important and welcomed. It is well known how the triggering of shallow landslides is strongly influenced by the initial soil moisture conditions of catchments. Therefore, the early warning system here applied is based on the combined use of rainfall thresholds, derived both for flash flood and for landslide, and soil moisture conditions; the system is composed of several basic component related to antecedent soil moisture conditions, real-time rainfall monitoring and antecedent rainfall. Soil moisture conditions were estimated using an Antecedent Precipitation Index (API), similar to this widely used for defining soil moisture conditions via Antecedent Moisture conditions index AMC. Rainfall threshold for landslides were derived using historical and statistical analysis. Finally, rainfall thresholds for flash flooding were derived using an Instantaneous Unit Hydrograph based lumped rainfall-runoff model with the SCS-CN routine for net rainfall. After the implementation and calibration of the model, a testing phase was carried out by using real data collected for the November 2001 event in the Longano catchment. Moreover, in order to test the capability of the system to forecast thise event, Quantitative Precipitation Forecasting provided by the SILAM (Sicily Limited Area Model), a meteorological model run by SIAS (Sicilian Agrometeorological Service) with a forecast horizon up to 144 hours, have been used to run the system.

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.

Boosting flood warning schemes with fast emulator of detailed hydrodynamic models

NASA Astrophysics Data System (ADS)

Bellos, V.; Carbajal, J. P.; Leitao, J. P.

2017-12-01

Floods are among the most destructive catastrophic events and their frequency has incremented over the last decades. To reduce flood impact and risks, flood warning schemes are installed in flood prone areas. Frequently, these schemes are based on numerical models which quickly provide predictions of water levels and other relevant observables. However, the high complexity of flood wave propagation in the real world and the need of accurate predictions in urban environments or in floodplains hinders the use of detailed simulators. This sets the difficulty, we need fast predictions that meet the accuracy requirements. Most physics based detailed simulators although accurate, will not fulfill the speed demand. Even if High Performance Computing techniques are used (the magnitude of required simulation time is minutes/hours). As a consequence, most flood warning schemes are based in coarse ad-hoc approximations that cannot take advantage a detailed hydrodynamic simulation. In this work, we present a methodology for developing a flood warning scheme using an Gaussian Processes based emulator of a detailed hydrodynamic model. The methodology consists of two main stages: 1) offline stage to build the emulator; 2) online stage using the emulator to predict and generate warnings. The offline stage consists of the following steps: a) definition of the critical sites of the area under study, and the specification of the observables to predict at those sites, e.g. water depth, flow velocity, etc.; b) generation of a detailed simulation dataset to train the emulator; c) calibration of the required parameters (if measurements are available). The online stage is carried on using the emulator to predict the relevant observables quickly, and the detailed simulator is used in parallel to verify key predictions of the emulator. The speed gain given by the emulator allows also to quantify uncertainty in predictions using ensemble methods. The above methodology is applied in real world scenario.

Application of Virtual Rain and Stream Gauge Information Service for Improved Flood Early Warning System in Lower Mekong Countries

NASA Astrophysics Data System (ADS)

Basnayake, S. B.; Jayasinghe, S.; Meechaiya, C.; Markert, K. N.; Lee, H.; Towashiraporn, P.; Anderson, E.; Okeowo, M. A.

2017-12-01

Asia is the most vulnerable region in the world to hydro-meteorological extreme events, exacerbated by climate variability and change. Impacts of floods have been on the rapid increase in the recent decades. Myanmar is one of the most vulnerable countries in the lower Mekong region due to its socioeconomic situation (eg; Nargis in 2008, monsoon floods in 2015, etc). Early warning is an effective way to prepare for hydro-meteorological hazards, to minimize disaster risks; however, early warning systems in Myanmar are seriously hampered by limited observation networks. The Virtual Rain and Stream Gauge Information Service (VRSGIS) has been developed by SERVIR-Mekong program of Asian Disaster Preparedness Center (ADPC) to address these gaps and to provide dense, satellite-based rainfall and water level data, which are calibrated and validated with available in-situ observations. This service would enhance decision making in lower Mekong countries, including Myanmar, to minimize impacts of impending disasters. This service contains rainfall data from GPM IMERG and GSMap, CMORPH, TRMM, and CHIRPS, and water levels for 15 locations using Jason-2/3 altimetry. The virtual daily rainfall data sets are being calibrated with Gamma distribution method and are made publicly accessible through a user-friendly web interface.This paper presents a case study of satellite-derived rainfall data accessed from VRSGIS for hydrological modeling in Myanmar, to estimate inundation areas in Kalay township area of Chindwin River basin during the country's worst flood in 2015. Twelve out of fourteen States of Myanmar were severely affected, 103 people were killed, and one million were displaced due to heavy rains associated with Komen cyclone. The aforementioned rainfall data products are used as inputs for HEC-HMS hydrological runoff model to calculate river flows along Chindwin River, and HEC-RAS hydraulic model is used to estimate inundation areas in downstream including Kalay township area. Model results (inundations) are compared with the estimates of water levels of Jason 2/3 measurements from two locations along the river. The results encourage us to use satellite-derived rainfall data over upstream areas to improve flood modeling, which contributes to improved flood early warning in Myanmar and other lower Mekong countries.

Flood disaster preparedness: a retrospect from Grand Forks, North Dakota.

PubMed

Siders, C; Jacobson, R

1998-01-01

Natural disasters often come without warning. The clinical, financial, and business risks can be enormous. Grand Forks' (ND) healthcare systems experienced a flooding disaster of unprecedented proportions in April of 1997. Planned and practiced disaster and evacuation procedures can significantly reduce a healthcare facilities' risk to life, health, and safety. This article retrospectively analyzes disaster preparation and the complete evacuation of the facilities' patients.

Towards flash-flood prediction in the dry Dead Sea region utilizing radar rainfall information

NASA Astrophysics Data System (ADS)

Morin, Efrat; Jacoby, Yael; Navon, Shilo; Bet-Halachmi, Erez

2009-07-01

Flash-flood warning models can save lives and protect various kinds of infrastructure. In dry climate regions, rainfall is highly variable and can be of high-intensity. Since rain gauge networks in such areas are sparse, rainfall information derived from weather radar systems can provide useful input for flash-flood models. This paper presents a flash-flood warning model which utilizes radar rainfall data and applies it to two catchments that drain into the dry Dead Sea region. Radar-based quantitative precipitation estimates (QPEs) were derived using a rain gauge adjustment approach, either on a daily basis (allowing the adjustment factor to change over time, assuming available real-time gauge data) or using a constant factor value (derived from rain gauge data) over the entire period of the analysis. The QPEs served as input for a continuous hydrological model that represents the main hydrological processes in the region, namely infiltration, flow routing and transmission losses. The infiltration function is applied in a distributed mode while the routing and transmission loss functions are applied in a lumped mode. Model parameters were found by calibration based on the 5 years of data for one of the catchments. Validation was performed for a subsequent 5-year period for the same catchment and then for an entire 10-year record for the second catchment. The probability of detection and false alarm rates for the validation cases were reasonable. Probabilistic flash-flood prediction is presented applying Monte Carlo simulations with an uncertainty range for the QPEs and model parameters. With low probability thresholds, one can maintain more than 70% detection with no more than 30% false alarms. The study demonstrates that a flash-flood warning model is feasible for catchments in the area studied.

Towards flash flood prediction in the dry Dead Sea region utilizing radar rainfall information

NASA Astrophysics Data System (ADS)

Morin, E.; Jacoby, Y.; Navon, S.; Bet-Halachmi, E.

2009-04-01

Flash-flood warning models can save lives and protect various kinds of infrastructure. In dry climate regions, rainfall is highly variable and can be of high-intensity. Since rain gauge networks in such areas are sparse, rainfall information derived from weather radar systems can provide useful input for flash-flood models. This paper presents a flash-flood warning model utilizing radar rainfall data and applies it to two catchments that drain into the dry Dead Sea region. Radar-based quantitative precipitation estimates (QPEs) were derived using a rain gauge adjustment approach, either on a daily basis (allowing the adjustment factor to change over time, assuming available real-time gauge data) or using a constant factor value (derived from rain gauge data) over the entire period of the analysis. The QPEs served as input for a continuous hydrological model that represents the main hydrological processes in the region, namely infiltration, flow routing and transmission losses. The infiltration function is applied in a distributed mode while the routing and transmission loss functions are applied in a lumped mode. Model parameters were found by calibration based on five years of data for one of the catchments. Validation was performed for a subsequent five-year period for the same catchment and then for an entire ten year record for the second catchment. The probability of detection and false alarm rates for the validation cases were reasonable. Probabilistic flash-flood prediction is presented applying Monte Carlo simulations with an uncertainty range for the QPEs and model parameters. With low probability thresholds, one can maintain more than 70% detection with no more than 30% false alarms. The study demonstrates that a flash-flood-warning model is feasible for catchments in the area studied.

The new Euskalmet coastal-maritime warning system

NASA Astrophysics Data System (ADS)

Gaztelumendi, Santiago; Egaña, Joseba; Liria, Pedro; Gonzalez, Manuel; Aranda, José Antonio; Anitua, Pedro

2016-06-01

This work presents the main characteristics of the Basque Meteorology Agency (Euskalmet) maritime-coastal risk warning system, with special emphasis on the latest updates, including a clear differentiation on specific warning messages addressing sea conditions for navigation purposes in the first 2 nautical miles, and expected coastal impacts. Some details of the warning bulletin for maritime and coastal risk situations are also presented, together with other communication products and strategies used in coastal and maritime severe episodes at the Basque coast. Today, three different aspects are included in the coastal-maritime risk warning system in Basque Country, related to the main potential severe events that affecting coastal activities. - "Galerna" risk relates to a sudden wind reversal that can severely affect coastal navigation and recreational activities. - "Navigation" risk relates to severe sea state conditions for 0-2 miles, affecting different navigation activities. - "Coastal impact" risk relates to adverse wave characteristics and tidal surges that induce flooding events and different impacts in littoral areas.

Colombia Mi Pronostico Flood Application: Updating and Improving the Mi Pronostico Flood Web Application to Include an Assessment of Flood Risk

NASA Technical Reports Server (NTRS)

Rushley, Stephanie; Carter, Matthew; Chiou, Charles; Farmer, Richard; Haywood, Kevin; Pototzky, Anthony, Jr.; White, Adam; Winker, Daniel

2014-01-01

Colombia is a country with highly variable terrain, from the Andes Mountains to plains and coastal areas, many of these areas are prone to flooding disasters. To identify these risk areas NASA's Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) was used to construct a digital elevation model (DEM) for the study region. The preliminary risk assessment was applied to a pilot study area, the La Mosca River basin. Precipitation data from the National Aeronautics and Space Administration (NASA) Tropical Rainfall Measuring Mission (TRMM)'s near-real-time rainfall products as well as precipitation data from the Instituto de Hidrologia, Meteorologia y Estudios Ambientales (the Institute of Hydrology, Meteorology and Environmental Studies, IDEAM) and stations in the La Mosca River Basin were used to create rainfall distribution maps for the region. Using the precipitation data and the ASTER DEM, the web application, Mi Pronóstico, run by IDEAM, was updated to include an interactive map which currently allows users to search for a location and view the vulnerability and current weather and flooding conditions. The geospatial information was linked to an early warning system in Mi Pronóstico that can alert the public of flood warnings and identify locations of nearby shelters.

Mortality from flash floods: a review of national weather service reports, 1969-81.

PubMed Central

French, J; Ing, R; Von Allmen, S; Wood, R

1983-01-01

Of all weather-related disasters that occur in the United States, floods are the main cause of death, and most flood-related deaths are attributed to flash floods. Whenever a weather-related disaster involves 30 or more deaths or more than $100 million in property damage, the National Weather Service (NWS) forms a survey team to investigate the disaster and write a report of findings. All NWS survey reports on flash floods issued during 1969-81 were reviewed to determine the mortality resulting from such floods, the effect of warnings on mortality, and the circumstances contributing to death. A total of 1,185 deaths were associated with 32 flash floods, an average of 37 deaths per flash flood. The highest average number of deaths per event was associated with the four flash floods in which dams broke after heavy rains. Although there were 18 flash floods in 1977-81 and only 14 in 1969-76, the number of deaths was 2 1/2 times greater during the earlier period. More than twice as many deaths were associated with flash floods for which the survey team considered the warnings inadequate than with those with warnings considered adequate. Ninety-three percent of the deaths were due to drowning and 42 percent of these drownings were car related. The other drownings occurred in homes, at campsites, or when persons were crossing bridges and streams. The need for monitoring dams during periods of heavy rainfall is highlighted. PMID:6419273

Characterizing Global Flood Wave Travel Times to Optimize the Utility of Near Real-Time Satellite Remote Sensing Products

NASA Astrophysics Data System (ADS)

Allen, G. H.; David, C. H.; Andreadis, K. M.; Emery, C. M.; Famiglietti, J. S.

2017-12-01

Earth observing satellites provide valuable near real-time (NRT) information about flood occurrence and magnitude worldwide. This NRT information can be used in early flood warning systems and other flood management applications to save lives and mitigate flood damage. However, these NRT products are only useful to early flood warning systems if they are quickly made available, with sufficient time for flood mitigation actions to be implemented. More specifically, NRT data latency, or the time period between the satellite observation and when the user has access to the information, must be less than the time it takes a flood to travel from the flood observation location to a given downstream point of interest. Yet the paradigm that "lower latency is always better" may not necessarily hold true in river systems due to tradeoffs between data latency and data quality. Further, the existence of statistical breaks in the global distribution of flood wave travel time (i.e. a jagged statistical distribution) would represent preferable latencies for river-observation NRT remote sensing products. Here we present a global analysis of flood wave velocity (i.e. flow celerity) and travel time. We apply a simple kinematic wave model to a global hydrography dataset and calculate flow wave celerity and travel time during bankfull flow conditions. Bankfull flow corresponds to the condition of maximum celerity and thus we present the "worst-case scenario" minimum flow wave travel time. We conduct a similar analysis with respect to the time it takes flood waves to reach the next downstream city, as well as the next downstream reservoir. Finally, we conduct these same analyses, but with regards to the technical capabilities of the planned Surface Water and Ocean Topography (SWOT) satellite mission, which is anticipated to provide waterbody elevation and extent measurements at an unprecedented spatial and temporal resolution. We validate these results with discharge records from paired USGS gauge stations located along a diverse collection of river reaches. These results provide a scientific rationale for optimizing the utility of existing and future NRT river-observation products.

Development of a flood early warning system and communication with end-users: the Vipava/Vipacco case study in the KULTURisk FP7 project

NASA Astrophysics Data System (ADS)

Grossi, Giovanna; Caronna, Paolo; Ranzi, Roberto

2014-05-01

Within the framework of risk communication, the goal of an early warning system is to support the interaction between technicians and authorities (and subsequently population) as a prevention measure. The methodology proposed in the KULTURisk FP7 project aimed to build a closer collaboration between these actors, in the perspective of promoting pro-active actions to mitigate the effects of flood hazards. The transnational (Slovenia/ Italy) Soča/Isonzo case study focused on this concept of cooperation between stakeholders and hydrological forecasters. The DIMOSHONG_VIP hydrological model was calibrated for the Vipava/Vipacco River (650 km2), a tributary of the Soča/Isonzo River, on the basis of flood events occurred between 1998 and 2012. The European Centre for Medium-Range Weather Forecasts (ECMWF) provided the past meteorological forecasts, both deterministic (1 forecast) and probabilistic (51 ensemble members). The resolution of the ECMWF grid is currently about 15 km (Deterministic-DET) and 30 km (Ensemble Prediction System-EPS). A verification was conducted to validate the flood-forecast outputs of the DIMOSHONG_VIP+ECMWF early warning system. Basic descriptive statistics, like event probability, probability of a forecast occurrence and frequency bias were determined. Some performance measures were calculated, such as hit rate (probability of detection) and false alarm rate (probability of false detection). Relative Opening Characteristic (ROC) curves were generated both for deterministic and probabilistic forecasts. These analysis showed a good performance of the early warning system, in respect of the small size of the sample. A particular attention was spent to the design of flood-forecasting output charts, involving and inquiring stakeholders (Alto Adriatico River Basin Authority), hydrology specialists in the field, and common people. Graph types for both forecasted precipitation and discharge were set. Three different risk thresholds were identified ("attention", "pre-alarm" or "alert", "alarm"), with an "icon-style" representation, suitable for communication to civil protection stakeholders or the public. Aiming at showing probabilistic representations in a "user-friendly" way, we opted for the visualization of the single deterministic forecasted hydrograph together with the 5%, 25%, 50%, 75% and 95% percentiles bands of the Hydrological Ensemble Prediction System (HEPS). HEPS is generally used for 3-5 days hydrological forecasts, while the error due to incorrect initial data is comparable to the error due to the lower resolution with respect to the deterministic forecast. In the short term forecasting (12-48 hours) the HEPS-members show obviously a similar tendency; in this case, considering its higher resolution, the deterministic forecast is expected to be more effective. The plot of different forecasts in the same chart allows the use of model outputs from 4/5 days to few hours before a potential flood event. This framework was built to help a stakeholder, like a mayor, a civil protection authority, etc, in the flood control and management operations, and was designed to be included in a wider decision support system.

Establishing a rainfall threshold for flash flood warnings in China's mountainous areas based on a distributed hydrological model

NASA Astrophysics Data System (ADS)

Miao, Qinghua; Yang, Dawen; Yang, Hanbo; Li, Zhe

2016-10-01

Flash flooding is one of the most common natural hazards in China, particularly in mountainous areas, and usually causes heavy damage and casualties. However, the forecasting of flash flooding in mountainous regions remains challenging because of the short response time and limited monitoring capacity. This paper aims to establish a strategy for flash flood warnings in mountainous ungauged catchments across humid, semi-humid and semi-arid regions of China. First, we implement a geomorphology-based hydrological model (GBHM) in four mountainous catchments with drainage areas that ranges from 493 to 1601 km2. The results show that the GBHM can simulate flash floods appropriately in these four study catchments. We propose a method to determine the rainfall threshold for flood warning by using frequency analysis and binary classification based on long-term GBHM simulations that are forced by historical rainfall data to create a practically easy and straightforward approach for flash flood forecasting in ungauged mountainous catchments with drainage areas from tens to hundreds of square kilometers. The results show that the rainfall threshold value decreases significantly with increasing antecedent soil moisture in humid regions, while this value decreases slightly with increasing soil moisture in semi-humid and semi-arid regions. We also find that accumulative rainfall over a certain time span (or rainfall over a long time span) is an appropriate threshold for flash flood warnings in humid regions because the runoff is dominated by excess saturation. However, the rainfall intensity (or rainfall over a short time span) is more suitable in semi-humid and semi-arid regions because excess infiltration dominates the runoff in these regions. We conduct a comprehensive evaluation of the rainfall threshold and find that the proposed method produces reasonably accurate flash flood warnings in the study catchments. An evaluation of the performance at uncalibrated interior points in the four gauged catchments provides results that are indicative of the expected performance at ungauged locations. We also find that insufficient historical data lengths (13 years with a 5-year flood return period in this study) may introduce uncertainty in the estimation of the flood/rainfall threshold because of the small number of flood events that are used in binary classification. A data sample that contains enough flood events (10 events suggested in the present study) that exceed the threshold value is necessary to obtain acceptable results from binary classification.

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.

Bill spurs efforts to improve forecasting of inland flooding from tropical storms

NASA Astrophysics Data System (ADS)

Showstack, Randy

Newly-enacted U.S. legislation to reduce the threat of inland flooding from tropical storms could provide a "laser beam" focus to dealing with this natural hazard, according to Rep. Bob Etheridge (D-N.C.), the chief sponsor of the bill.The Tropical Cyclone Inland Forecasting Improvement and Warning System Development Act, (PL. 107-253), signed into law on 29 October, authorizes the National Oceanic and Atmospheric Administration's U.S. Weather Research Program (USWRP) to improve the capability to accurately forecast inland flooding from tropical storms through research and modeling.

Silent Warning: Understanding the National Terrorism Advisory System

DTIC Science & Technology

2014-12-01

Business ( New York: Harper Business, 2011), 185–197. xiv ACKNOWLEDGMENTS Completing this Naval...Advisory System (HSAS). This new system “effectively communicates information about terrorist threats by providing timely, detailed information to the...occurrence of threat, such as hurricanes, earthquakes , floods, etc. Deliberate 10 Homeland Security Advisory System: Threat Codes and Public

Flood Risk Assessment and Forecasting for the Ganges-Brahmaputra-Meghna River Basins

NASA Astrophysics Data System (ADS)

Hopson, T. M.; Priya, S.; Young, W.; Avasthi, A.; Clayton, T. D.; Brakenridge, G. R.; Birkett, C. M.; Riddle, E. E.; Broman, D.; Boehnert, J.; Sampson, K. M.; Kettner, A.; Singh, D.

2017-12-01

During the 2017 South Asia monsoon, torrential rains and catastrophic floods affected more than 45 million people, including 16 million children, across the Ganges-Brahmaputra-Meghna (GBM) basins. The basin is recognized as one of the world's most disaster-prone regions, with severe floods occurring almost annually causing extreme loss of life and property. In light of this vulnerability, the World Bank and collaborators have contributed toward reducing future flood impacts through recent developments to improve operational preparedness for such events, as well as efforts in more general preparedness and resilience building through planning based on detailed risk assessments. With respect to improved event-specific flood preparedness through operational warnings, we discuss a new forecasting system that provides probability-based flood forecasts developed for more than 85 GBM locations. Forecasts are available online, along with near-real-time data maps of rainfall (predicted and actual) and river levels. The new system uses multiple data sets and multiple models to enhance forecasting skill, and provides improved forecasts up to 16 days in advance of the arrival of high waters. These longer lead times provide the opportunity to save both lives and livelihoods. With sufficient advance notice, for example, farmers can harvest a threatened rice crop or move vulnerable livestock to higher ground. Importantly, the forecasts not only predict future water levels but indicate the level of confidence in each forecast. Knowing whether the probability of a danger-level flood is 10 percent or 90 percent helps people to decide what, if any, action to take. With respect to efforts in general preparedness and resilience building, we also present a recent flood risk assessment, and how it provides, for the first time, a numbers-based view of the impacts of different size floods across the Ganges basin. The findings help identify priority areas for tackling flood risks (for example, relocating levees, improving flood warning systems, or boosting overall economic resilience). The assessment includes the locations and numbers of people at risk, as well as the locations and value of buildings, roads and railways, and crops at risk. An accompanying atlas includes easy-to-use risk maps and tables for the Ganges basins.

A digital simulation of message traffic for natural disaster warning communications satellite

NASA Technical Reports Server (NTRS)

Hein, G. F.; Stevenson, S. M.

1972-01-01

Various types of weather communications are required to alert industries and the general public about the impending occurrence of tornados, hurricanes, snowstorms, floods, etc. A natural disaster warning satellite system has been proposed for meeting the communications requirements of the National Oceanic and Atmospheric Administration. Message traffic for a communications satellite was simulated with a digital computer in order to determine the number of communications channels to meet system requirements. Poisson inputs are used for arrivals and an exponential distribution is used for service.

A Bayesian-Based System to Assess Wave-Driven Flooding Hazards on Coral Reef-Lined Coasts

NASA Astrophysics Data System (ADS)

Pearson, S. G.; Storlazzi, C. D.; van Dongeren, A. R.; Tissier, M. F. S.; Reniers, A. J. H. M.

2017-12-01

Many low-elevation, coral reef-lined, tropical coasts are vulnerable to the effects of climate change, sea level rise, and wave-induced flooding. The considerable morphological diversity of these coasts and the variability of the hydrodynamic forcing that they are exposed to make predicting wave-induced flooding a challenge. A process-based wave-resolving hydrodynamic model (XBeach Non-Hydrostatic, "XBNH") was used to create a large synthetic database for use in a "Bayesian Estimator for Wave Attack in Reef Environments" (BEWARE), relating incident hydrodynamics and coral reef geomorphology to coastal flooding hazards on reef-lined coasts. Building on previous work, BEWARE improves system understanding of reef hydrodynamics by examining the intrinsic reef and extrinsic forcing factors controlling runup and flooding on reef-lined coasts. The Bayesian estimator has high predictive skill for the XBNH model outputs that are flooding indicators, and was validated for a number of available field cases. It was found that, in order to accurately predict flooding hazards, water depth over the reef flat, incident wave conditions, and reef flat width are the most essential factors, whereas other factors such as beach slope and bed friction due to the presence or absence of corals are less important. BEWARE is a potentially powerful tool for use in early warning systems or risk assessment studies, and can be used to make projections about how wave-induced flooding on coral reef-lined coasts may change due to climate change.