scholarly journals Hydrological assessment of flash flood hazards and the constructed mitigation measures in Wadis affecting Ain Al Soukhna, Northwest Gulf of Suez, Egypt

2021 ◽  
Author(s):  
Hanaa Megahed ◽  
Mohammed El Bastawesy
Keyword(s):  
Flash Flood ◽  
Flow Direction ◽  
Anthropogenic Activities ◽  
Flash Floods ◽  
Alluvial Fan ◽  
Mitigation Measures ◽  
Optical Remote Sensing ◽  
Gulf Of Suez ◽  
Flood Hazards ◽  
Industrial Zone

Considerable stretches of barren coastal areas of the Gulf of Suez and the Red Sea have been covered by various anthropogenic activities during the past few decades. Several dykes have been erected on the wadi beds constituting the catchment of Wadi Ghuwaiba, which encloses the industrial zone of Ain Al Soukhna on its large alluvial fan. The multitude of optical remote sensing data, Digital Elevation Model (DEM) and thematic geological data have been integrated into Geographic Information System (GIS) to estimate the hydrological parameters of flash floods, pathways and storage capabilities of the constructed dykes upstream of the industrial zone. Due to the absence of rainfall/runoff data for these ungagged wadis, a semi-distributed hydrological model was developed using the extracted morphometric parameters from the DEM from the analyses of satellite images. Manning equation was used to compute the open channel flow velocities, and the spatial functionalities into GIS were used to estimate the cumulative flow times. Next, the catchments were subdivided into cascading time-area zones using the derivatives of flow direction, accumulation and length from the DEM. Then, the spatially distributed unit hydrograph was computed using a hypothetical rainfall distribution and runoff coefficients, and the obtained time-area zones. The dykes have been visited in the field to measure the distribution of entrapped sediment loads due to the accumulation of torrential flows in these specific areas. The magnitudes of flash floods developed from an effective rainfall of 20 mm will not be fully contained in the storage areas of these dykes and overflows will reach the industrial zone via uncontrolled pathways, thus the area is prone to flash flood vulnerability and additional mitigation measures are still needed. The slack deposits are accumulating with notable rates and have reached 60 cm in some areas. It is strongly recommended to construct a conveying channel downstream of the dykes to collect the surplus overflow and discharge it into the Gulf of Suez via a well-defined channel-pathway

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

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.

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

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.

scholarly journals Risk Perception, Risk Communication, and Mitigation Actions of Flash Floods: Results from a Survey in Three Types of Communities

2021 ◽  
Vol 13 (22) ◽  
pp. 12389
Author(s):  
Ming Zhong ◽  
Lu Xiao ◽  
Qian Zhang ◽  
Tao Jiang
Keyword(s):  
Risk Perception ◽  
Risk Communication ◽  
Rural Community ◽  
Risk Perceptions ◽  
Flash Flood ◽  
Protective Action ◽  
Community Resilience ◽  
Flash Floods ◽  
Flood Hazards ◽  
Flood Warnings

In order to improve the decision-making of risk management and enhance community resilience to flash floods, the perception of risks, communication of warnings, and mitigation actions concerning flash floods were investigated in this study. The survey involves 280 participants from three types of communities in flash flood-prone areas. Results show that: (i) About 55.4% of community participants misperceived or underestimated the risk of flash floods, especially in the suburban communities, and people had misconceptions about the safety of crossing fast-flowing water, even though most of them had experienced flash flood hazards. (ii) In total, 67.9% of participants indicated that they had at some point received a flash flood warning. The perception of accuracy was related to trust in flash flood warnings, but they were different constructs for some individuals. Moreover, residents in the rural community and suburban community reported a closer social communication with neighbors, which would greatly influence inhabitants’ attitudes and behaviors towards the flash flood warnings and mitigation actions. (iii) Most of the participants indicated they would take some protective action when they received a warning. Risk perceptions and risk communications influence the mitigation actions in the community. Significant variables in the rural community and non-rural community were explored, and some important suggestions are highlighted. These findings suggest that risk perception and risk communication in neighborhoods help people to decide what action to take in the given scenarios, contribute to enhancing the community resilience, and contribute to coping with future flash floods in a more specific and effective way.

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

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.

scholarly journals Natural Disasters Versus Anthropogenic Activities in Nepal Himalayas: Case Study from Ghatte Khola , Myagdi

2019 ◽  
Vol 1 (1) ◽  
pp. 65-70 ◽  
Author(s):  
Narayan Gurung
Keyword(s):  
Debris Flow ◽  
Natural Disasters ◽  
Debris Flows ◽  
Flash Flood ◽  
Anthropogenic Activities ◽  
Alluvial Fan ◽  
Electric Power Station ◽  
Natural Dynamics ◽  
The Right

In the Himalayas, geo-hazards are natural events occurring more or less frequently and of a greater or lesser magnitude. But when natural hazards affect people and property, then it becomes disasters. It’s believed that natural disasters as such do not exist. Everything is just natural hazard and anything can turn into disasters due to anthropogenic activities. Thus, natural phenomenons are hazards while disasters are anthropogenic. In this regard, a case study was being conducted in the Ghatte Khola (Dana) of Myagdi District in Western Central Nepal, where in a context of growing population and haphazard construction of infrastructures, natural dynamics have turned into disasters. The Ghatte Khola is an intermittent, right bank tributary of the Kali Gandaki, which behaves occasionally as a debris flow, in relation with slope instabilities that affect its upstream catchment. The debris flows are usually triggered during heavy cloudbursts, and can cause damages and losses downstream, along the wide alluvial fan built at the tributary junction and upon which Dana village (Myagdi District) is settled. Inhabitants are aware of this ephemeral, yet threatening behaviour of the stream that may also affect the Kali Gandaki valley upstream from the confluence (Lat. 28°32'22" N and Long. 83°39'03" E). The Ghatte Khola is often affected by debris flows bringing sediment fluxes that are eroding its banks every year. A motor bridge was being built over Ghatte Khola near the confluence with Kali Gandaki and further, a large electric power station is being built on the right bank of Ghatte Khola. Sadly, the bridge was washed away by the flash flood in Ghattekhola on 25th May 2019. This study was focused on vulnerability of these man made infrastructures and their future on Ghatte Khola debris flow dynamics, with hazard that might occasionally transform into disaster.  

scholarly journals Modeling Flash Floods and Induced Recharge into Alluvial Aquifers Using Multi-Temporal Remote Sensing and Electrical Resistivity Imaging

2020 ◽  
Vol 12 (23) ◽  
pp. 10204
Author(s):  
Omnia El-Saadawy ◽  
Ahmed Gaber ◽  
Abdullah Othman ◽  
Abotalib Z. Abotalib ◽  
Mohammed El Bastawesy ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Electrical Resistivity ◽  
Flash Flood ◽  
Flood Hazard ◽  
Flash Floods ◽  
Water Infiltration ◽  
Mitigation Measures ◽  
Aquifer Recharge ◽  
Basin Scale ◽  
Alluvium Aquifer

Flash flood hazard assessments, mitigation measures, and water harvesting efforts in desert environments are often challenged by data scarcity on the basin scale. The present study, using the Wadi Atfeh catchment as a test site, integrates remote sensing datasets with field and geoelectrical measurements to assess flash flood hazards, suggest mitigation measures, and to examine the recharge to the alluvium aquifer. The estimated peak discharge of the 13 March 2020 flood event was 97 m3/h, which exceeded the capacity of the culverts beneath the Eastern Military Highway (64 m3/h), and a new dam was suggested, where 75% of the catchment could be controlled. The monitoring of water infiltration into the alluvium aquifer using time-lapse electrical resistivity measurements along a fixed profile showed a limited connection between the wetted surficial sediments and the water table. Throughflow is probably the main source of recharge to the aquifer rather than vertical infiltration at the basin outlet. The findings suggest further measures to avoid the negative impacts of flash floods at the Wadi Atfeh catchment and similar basins in the Eastern Desert of Egypt. Furthermore, future hydrological studies in desert environments should take into consideration the major role of the throughflow in alluvium aquifer recharge.

scholarly journals An improved rainfall-threshold approach for robust prediction and warning of flood and flash flood hazards

2020 ◽  
Author(s):  
Geraldo Moura Ramos Filho ◽  
Victor Hugo Rabelo Coelho ◽  
Emerson da Silva Freitas ◽  
Yunqing Xuan ◽  
Cristiano das Neves Almeida
Keyword(s):  
Rainfall Intensity ◽  
Flash Flood ◽  
Flash Floods ◽  
Rainfall Threshold ◽  
Probability Of Detection ◽  
False Alarms ◽  
Flood Hazards ◽  
Number Of False Alarms ◽  
Antecedent Precipitation ◽  
Hydrological Hazards

Abstract This paper presents an improved method of using threshold of peak rainfall intensity for robust flood/flash flood evaluation and warnings in the state of São Paulo, Brazil. The improvements involve the use of two tolerance levels and the delineating of an intermediate threshold by incorporating an exponential curve that relates rainfall intensity and Antecedent Precipitation Index (API). The application of the tolerance levels presents an average increase of 14% in the Probability of Detection (POD) of flood and flash flood occurrences above the upper threshold. Moreover, a considerable exclusion (63%) of non-occurrences of floods and flash floods in between the two thresholds significantly reduce the number of false alarms. The intermediate threshold using the exponential curves also exhibits improvements for almost all time steps of both hydrological hazards, with the best results found for floods correlating 8-h peak intensity and 8 days API, with POD and Positive Predictive Value (PPV) values equal to 81% and 82%, respectively. This study provides strong indications that the new proposed rainfall threshold-based approach can help reduce the uncertainties in predicting the occurrences of floods and flash floods.

scholarly journals Hydrogeomorphological analysis and modelling for a comprehensive understanding of flash-flood damage processes: the 9 October 2018 event in northeastern Mallorca

2020 ◽  
Vol 20 (8) ◽  
pp. 2195-2220
Author(s):  
Joan Estrany ◽  
Maurici Ruiz-Pérez ◽  
Raphael Mutzner ◽  
Josep Fortesa ◽  
Beatriz Nácher-Rodríguez ◽  
...  
Keyword(s):  
Global Change ◽  
Flash Flood ◽  
Warning System ◽  
Flash Floods ◽  
Flood Damage ◽  
Hydrological Modelling ◽  
Mitigation Measures ◽  
Management Service ◽  
Catchment Scale ◽  
Effective Prevention

Abstract. A flash-flood event hit the northeastern part of Mallorca on 9 October 2018, causing 13 casualties. Mallorca is prone to catastrophic flash floods acting on a scenario of deep landscape transformation caused by Mediterranean tourist resorts. As global change may exacerbate devastating flash floods, analyses of catastrophic events are crucial to support effective prevention and mitigation measures. Field-based remote-sensing and modelling techniques were used in this study to evaluate rainfall–runoff processes at the catchment scale linked to hydrological modelling. Continuous streamflow monitoring data revealed a peak discharge of 442 m3 s−1 with an unprecedented runoff response. This exceptional behaviour triggered the natural disaster as a combination of heavy rainfall (249 mm in 10 h), karstic features and land cover disturbances in the Begura de Salma River catchment (23 km2). Topography-based connectivity indices and geomorphic change detection were used as rapid post-catastrophe decision-making tools, playing a key role during the rescue search. These hydrogeomorphological precision techniques were combined with the Copernicus Emergency Management Service and “ground-based” damage assessment, which showed very accurately the damage-driving factors in the village of Sant Llorenç des Cardassar. The main challenges in the future are to readapt hydrological modelling to global change scenarios, implement an early flash-flood warning system and take adaptive and resilient measures on the catchment scale.

scholarly journals Hydrogeomorphological analysis and modelling for a comprehensive understanding of flash-flood damaging processes: The 9th October 2018 event in North-eastern Mallorca

2019 ◽  
Author(s):  
Joan Estrany ◽  
Maurici Ruiz-Pérez ◽  
Raphael Mutzner ◽  
Josep Fortesa ◽  
Beatriz Nácher-Rodríguez ◽  
...  
Keyword(s):  
Global Change ◽  
Flash Flood ◽  
Warning System ◽  
Flash Floods ◽  
Hydrological Modelling ◽  
Mitigation Measures ◽  
Catchment Scale ◽  
Effective Prevention ◽  
Flood Warning ◽  
Karstic Features

Abstract. A flash-flood event hit in the 9th October 2018 the northeastern part of Mallorca Island, causing 13 casualties. This island is prone to catastrophic flash floods acting on a scenario that illustrates the deep landscape transformation of Mediterranean tourist resorts. As global change may exacerbate devastating flash floods, comprehensive analyses of catastrophic events are crucial to support effective prevention and mitigation measures. Field-based, remote-sense and modelling techniques were used in this study to evaluate rainfall-runoff processes at catchment scale linked to hydrological modelling. Continuous streamflow monitoring data revealed a peak discharge 442 m3 s−1 with an unprecedented runoff response (lag time, 15’). This very flashy behaviour triggered the natural disaster as a combination of heavy rainfall (246 mm in 10 h), karstic features and land cover disturbances in the Begura de Saumà River catchment (i.e., 23 km2). Topography-based connectivity index and geomorphic change detection were used as a rapid post-catastrophe decision-making tool, playing a key role during the rescue searching tasks. These hydrogeomorphological precision techniques were also applied in combination with Copernicus EMS and ground-based damage assessment illustrating with high accuracy the damage driving factors in the village of Sant Llorenç des Cardassar. The main challenges in the future are to readapt hydrological modelling to global change scenarios, implement an early flash flood warning system and apply adaptive and resilient measures at catchment scale.

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