Flash flood simulations for an Egyptian city - mitigation measures and impact of infiltration

The quantification of model structure uncertainty on hydraulic models is very important for flash flood simulations. The choice of an appropriate model structure complexity and assessment of the impacts due to infrastructure failure can have a huge impact on the simulation results. To assess the risk of flash floods, coupled hydraulic models, including 1D-sewer drainage and 2D-surface run-off models are required for urban areas because they include the bidirectional water exchange, which occurs between sewer and overland flow in a city [1]. By including various model components, we create different model structures. For example, modelling the inflow to the city with the 2D surface-runoff or with the delineated 1D model; including the sewer system or use a surrogate as an alternative; modifying the connectivity of manholes and pumps; or representing the drainage system failures during flood events. As the coupling pattern becomes complex, quantifying the model structure uncertainty is essential for the model structure evaluation. If one model component leads to higher model uncertainty, it is reasonable to conclude that the new component has a large impact in our model and therefore needs to be accounted for; if one component has a less impact in the overall uncertainty, then the model structure can be simplified, by removing that model component. In this study, we set up seven different model structures [2] for the German city of Simbach. By comparison with two inflow calculation types (1D-delineated inflow or 2D-catchment), the existence of drainage system and infrastructure failures, the Model Uncertainty Factor (MUF) is calculated to quantify the model structure uncertainties and further trade-off values with Parameter Uncertainty Factor (PUF) [3]. Finally, we can obtain a more efficient hydraulic model with the essential model structure for urban flash flood simulation. &#160; <ol>1. Leandro, J., Chen, A. S., Djordjevic, S., and Dragan, S. (2009). "A comparison of 1D/1D and 1D/2D coupled hydraulic models for urban flood simulation." Journal of Hydraulic Engineering-ASCE, 6(1):495-504.</ol> <ol>2. Leandro, J., Schumann, A., and Pfister, A. (2016). A step towards considering the spatial heterogeneity of urban, key features in urban hydrology flood modelling. J. Hydrol., Elsevier, 535 (4), 356-365.</ol> <ol>3. Van Zelm, R., Huijbregts, M.A.J. (2013). Quantifying the trade-off between parameter and model structure uncertainty in life cycle impact assessment, Environ. Sci. Technol., 47(16), pp. 9274-9280.</ol> &#160;

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Integrated Strategies for the Management of Wadi Flash Floods in the Middle East and North Africa (MENA) Arid Zones: The ISFF Project

10.1007/978-981-16-2904-4_1 ◽

2021 ◽

pp. 3-34

Author(s):

Sameh A. Kantoush ◽

Mohamed Saber ◽

Mohammed Abdel-Fattah ◽

Tetsuya Sumi

Keyword(s):

Middle East ◽

North Africa ◽

Flash Flood ◽

Rapid Development ◽

Flash Floods ◽

Mitigation Measures ◽

Mena Region ◽

Main Research ◽

Rainfall Occurrence ◽

High Flood

AbstractSustainable management of wadi flash flood (WFF) risks is desperately needed to secure development in wadi systems. Due to rapid flow generation with sudden high flood peaks, spatiotemporal variability of rainfall occurrence, and poorly sited rapid development, most Middle East and North Africa (MENA) region have no comprehensive proper protection from WFFs. In arid regions, single mitigation measures, including storage dams, recharge dams, artificial lakes and embankments, are implemented, although soft mitigation measures are not dominant, such as early warning systems. The single management strategy under climate change impacts is not adequate to reduce flash flood risks; an integrated strategy is required. The objective of the international symposium on flash floods (ISFF) project has been to develop scientific understanding of WFFs in wadi systems; monitor, model, and mitigate; issue warnings; and plan urban development by discussing and networking the strategies in the MENA region. To achieve this goal, the project defines priorities for future research challenges and potential projects for WFFs. This chapter provides a state-of-the-art scientific basis in terms of integrated flash flood management. Further, priorities are defined for the main research gaps, and the emerging research methodologies can contribute to guide the management of WFFs in such regions.

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Hydrological problems of flash floods and the encroachment of wastewater affecting the urban areas in Greater Cairo, Egypt, using remote sensing and GIS techniques

Bulletin of the National Research Centre ◽

10.1186/s42269-020-00442-5 ◽

2020 ◽

Vol 44 (1) ◽

Author(s):

Hanaa A. Megahed ◽

Mohammed A. El Bastawesy

Keyword(s):

Remote Sensing ◽

Urban Areas ◽

Satellite Images ◽

Flash Flood ◽

Flow Direction ◽

Flash Floods ◽

Mitigation Measures ◽

Water Volume ◽

Gis Techniques ◽

Greater Cairo

Abstract Background This paper discusses the hydrological problems assessment of flash floods and the encroachment of wastewater in selected urban areas of Greater Cairo using remote sensing and geographic information system (GIS) techniques. The integration of hydrogeological and geomorphological analyses with the fieldwork of drainage basins (Wadi Degla) hosting these urban areas endeavors to provide the optimum mitigation measures that can be feasibly taken to achieve sustainability of the urban areas and water resources available. Results Landsat 5 and Sentinel-2 satellite images were obtained shortly before and after flash flood events and were downloaded and analyzed to define the active channels, urban interference, storage areas, and the natural depressions response. The quantitative flash flood estimates include total GSMap meteorological data sets, parameters of rainfall depths from remote sensing data, active channel area from satellite images, and storage areas that flooded. In GIS, digital elevation model was used to estimate the hydrographic parameters: flow direction within the catchment, flow accumulation, time zone of the catchment, and estimating of the water volume in the largely inundated depressions. Conclusions Based on the results obtained from the study of available satellite images, it has been shown that there are two significant hydrological problems, including the lack of flash flood mitigation measures for urban areas, as the wastewater depressions and sanitary facilities are dotting in the downstream areas.

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Flash Flood Simulations Based on Shallow Water Equations to Investigate Protection Measures for El Gouna, Egypt

10.29007/kh16 ◽

2018 ◽

Author(s):

Ester Marafini ◽

Franziska Tügel ◽

Ilhan Özgen ◽

Reinhard Hinkelmann ◽

Michele La Rocca

Keyword(s):

Shallow Water ◽

Flash Flood ◽

Flash Floods ◽

Flood Event ◽

Water Model ◽

Protection Measures ◽

Environmental Disasters ◽

Whole Process ◽

Flood Simulations ◽

The City

Severe and sudden events like flash floods are considered to be one of the most hazardous environmental disasters. Therefore, predicting the whole process of flooding is fundamental to prevent urban damages. In this context, the simulation of flash floods is an important tool to analyse the flow processes in order to find solutions to the problem. In this work, a case study of the flash flood event of 9th March 2014 in the city of El Gouna in Egypt was carried out using the Hydroinformatics Modeling System (hms), a two-dimensional (2D) shallow water model developed at the Chair of Water Resources Management and Modeling of Hydrosystems, Technische Universität Berlin. The flooding processes are simulated in great detail on unstructured grids. The aim of this work is to investigate the flow field around the settlement of the study area, when structures such as storage basins and dams are adopted as protection measures for the city. Different scenarios are analyzed to find out the most suitable one, which is able to minimize the risk during the flash flood event.

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Flash Flood Modeling and Mitigation in Arid and Semiarid Basins: Case Studies from Oman and Brazil

10.1007/978-981-16-2904-4_13 ◽

2021 ◽

pp. 355-381

Author(s):

Mohamed Saber ◽

Sameh A. Kantoush ◽

Mohammed Abdel-Fattah ◽

Tetsuya Sumi ◽

Jose Andres Moya ◽

...

Keyword(s):

Case Studies ◽

Arid Regions ◽

Flash Flood ◽

Flash Floods ◽

Mitigation Measures ◽

Comprehensive Overview ◽

Semiarid Regions ◽

Climatic Regions ◽

Average Water ◽

Arid And Semiarid

AbstractThe behaviors and impacts of flash floods (FF) are different based on the climatic regions. To understand such difference, two case studies were selected for the analysis: Wadi Uday, Oman and Sume Basin, Paraiba, Brazil. The rainfall-runoff inundation model (RRI) was used to simulate the discharge and flood inundation of the recent flood events to understand the severity and frequency of flash floods to better assess the current mitigation measures. The current FF situations in arid and semiarid basins were analyzed, and the hazards associated with flood phenomenon were assessed for various calculated rainfall return periods using RRI model. To this end, a flash flood index (average water depth per total basin area) was calculated as a basis to understand the impact of flash floods. A coupling of this index with the FF histories was included to provide a comprehensive overview of the FF vulnerability of arid and semiarid basins. We concluded that FFs tend to be more severe and extreme in arid regions than in semiarid regions, despite the lower frequency of FFs and the water scarcity in arid regions. Distributed dams also proved to be more effective in preventing FFs in arid regions than in semiarid regions.

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Sensitivity of flash-flood simulations on the volume, the intensity, and the localization of rainfall in the Cévennes-Vivarais region (France)

Water Resources Research ◽

10.1029/2008wr006906 ◽

2009 ◽

Vol 45 (10) ◽

Cited By ~ 33

Author(s):

G.-M. Saulnier ◽

M. Le Lay

Keyword(s):

Flash Flood ◽

Flood Simulations

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Assessing the impact of resolution and soil datasets on flash-flood modelling

Hydrology and Earth System Sciences ◽

10.5194/hess-23-1801-2019 ◽

2019 ◽

Vol 23 (3) ◽

pp. 1801-1818 ◽

Cited By ~ 3

Author(s):

Alexane Lovat ◽

Béatrice Vincendon ◽

Véronique Ducrocq

Keyword(s):

Land Cover ◽

Soil Texture ◽

Flash Flood ◽

Grid Cell ◽

Coupled System ◽

High Water ◽

Catchment Scale ◽

Flood Modelling ◽

Flood Simulations ◽

The Impact

Abstract. The present study assesses the impacts of two grid resolutions and the descriptors of soil texture and land cover on flash-flood modelling at local and basin scales. The ISBA-TOP coupled system, which is dedicated to Mediterranean flash-flood simulations, is used with two grid-cell sizes (300 and 1000 m), two soil texture datasets, and two land use databases to model 12 past flash-flood events in southeastern France. The skill of the hydrological simulations is assessed using conventional data (discharge measurements from operational networks) and proxy data such as post-event surveys and high-water marks. The results show significant differences between the experiments in terms of both the simulated river discharge and the spatial runoff, whether at the catchment scale or at the local scale. The spatial resolution has the largest impact on the hydrological simulations. In this study, it is also shown that the soil texture has a larger impact on the results than the land cover.

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The Role of Hazard and Vulnerability in Modulating Economic Damages of Inland Floods in the United States Using a Survey-Based Dataset

Sustainability ◽

10.3390/su11133754 ◽

2019 ◽

Vol 11 (13) ◽

pp. 3754 ◽

Cited By ~ 2

Author(s):

Zhou ◽

Su ◽

Leng ◽

Peng

Keyword(s):

United States ◽

Flash Flood ◽

Unit Cost ◽

Heavy Rain ◽

The United States ◽

Mitigation Measures ◽

Economic Losses ◽

Vulnerability Indicators ◽

The Difference ◽

Economic Damages

This study investigates the trends in economic damages caused by three types of inland floods (flash flood, flood, and heavy rain) in the United States and the variations in related hazard and vulnerability indicators between 1996 and 2016. We explore the underlying mechanisms based on a survey-based dataset maintained by the National Oceanic and Atmospheric Administration (NOAA) National Weather Service. An annual average of 6518 flood occurrences was reported, which caused economic damages of 3351 million USD per year. Flash flood and flood contributed to 53% and 32% of total occurrences and was associated with a larger share of damaging events (SDE). Results show that the higher impacts by flood and flash flood on property and crop are partly attributed to the greater intensity of rainfall. In addition, flood has the highest unit cost of damages. Notably, despite an upward tendency in economic damages by flash floods, no evident change trend is observed for inland floods as a whole. Further analysis shows changes in economic damages by heavy rain and flash flood are mainly governed by the increased annual frequency and hazard intensity, but the change of trend in their vulnerability indicators (i.e., SDE and Damage Per Event (DPE)) is not obvious. Regarding floods, it was not possible to attribute the variations in economic losses to hazard and vulnerability, as no significant tendency is found except for an increasing SDE. Despite limitations of length of records, data collection, and methodology, the difference in economic impacts and the related hazard and vulnerability revealed in this study can help better target future adaptation and mitigation measures.

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Evaluation of Hydrological and Hydraulic Models Applied in Typical Mediterranean Ungauged Watersheds Using Post-Flash-Flood Measurements

Hydrology ◽

10.3390/hydrology7010012 ◽

2020 ◽

Vol 7 (1) ◽

pp. 12 ◽

Cited By ~ 4

Author(s):

Aristeidis Kastridis ◽

Dimitrios Stathis

Keyword(s):

Goodness Of Fit ◽

Flash Flood ◽

Hydraulic Models ◽

Rain Gauges ◽

Critical Success ◽

Small Watersheds ◽

Flood Simulations ◽

Flood Generation ◽

Analysis System ◽

Ungauged Watersheds

In this paper, three different flash floods episodes were analyzed, which occurred in October 2006, February 2010, and June 2018 in the Chalkidiki peninsula (North Greece). The Soil Conservation Service (SCS) model and a revised assessment of the CN parameter were applied to estimate the flood hydrographs, and Hydrologic Engineering Center’s-River Analysis System (HEC-RAS) software was used for the flood simulations. Initially, hydrological and hydraulic models were calibrated at Vatonias watershed (240.90 km2, North Greece), where three rain gauges and one water level station are located. Vatonias is located very close to the Stavros ungauged watersheds and presents similar geomorphology and land use conditions. The effectiveness and accuracy of the methodology were validated using post-flash-flood measurements. The root mean square error goodness of fit was used to compare the observed and simulated flood depths. Critical success index was calculated for the assessment of the accuracy of observed and modeled flooded areas. The results showed that the dense forest vegetation was not capable of preventing the flash flood generation or reducing the peak discharge, especially in small watersheds characterized by short concentration times. The main cause of flash flood generation was the human interference that influenced the hydraulic characteristics of streams and floodplains. The revised assessment of the CN parameter enhanced the estimation and spatial distribution of CN over the entire watershed. The results revealed that the proposed methodology could be a very useful tool to researchers and policy makers for flood risk assessment of higher accuracy and effectiveness in ungauged Mediterranean watersheds.

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