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Sultan Qaboos University (2018)

Flood Risk Assessment for Wadi Mayh Catchment Area in Muscat Governorate

Al Azri Fathiya

Titre : Flood Risk Assessment for Wadi Mayh Catchment Area in Muscat Governorate

Auteur : Al Azri Fathiya

Université de soutenance : Sultan Qaboos University

Grade : Master of Science (MS) Civil and Architecural Engineering 2018

Résumé
The aim of this study is to develop flood risk maps for Wadi May which has length of 25 km and drainage area of 771 km2 by combining the hydrological, hydraulic simulation and ArcGIS. To achieve this aim, a Digital Elevation Model (DEM) with 5 m resolution was used to delineate the sub-watershed’ boundaries and extract their physical characteristics. The frequency analysis for 15 rainfall events of 6-hour duration was used to predict the rainfall depth for various return periods of 5, 10, 25, 50 and 100 years using Extreme Value Type 1 probability distribution. The wadi peak flows that correspond to each rainfall depth were estimated using the watershed modelling system (WMS v.9.1). Then the water profiles and inundations for various peak flows of the wadi were also generated using the Engineering Centre -River Analysis System (HEC-RAS) via entering the geometric data of the wadi that extracted through HEC-Geo-RAS. _ By using the Geographical Information System (GIS) spatial data for water depth, velocity and inundations maps for the study area generated from HEC-RAS. The results of the study show that the highest water depth and velocity for 100 year return period flood reach to about 7 m and 7.1 m/s respectively. However, the highest water depth and velocity found for a 5 year return period flood is about 4.8 m and 5 m/s respectively. In addition to this, the flood inundation layer for various return periods was superimposed on the plots, buildings and road layers through Arc-GIS. The results showed that there were more than 15 buildings, 290 plots and 3 roads are affected by a 5 year return period flood and this impact is even increased with the increase in the flood return period. The outcomes of this study could be used as a sample or a model to be applied to different Omani cities. The results of this work are very useful for city planners, helping them to take decisions regarding urban planning, infrastructures and water resources design projects. _ This study suggests that a sensitivity analysis on using different rainfall event durations could be implemented to improve the results. Furthermore, climate change incorporation and future projections for the risk maps could also contribute significantly to the future floods scenarios.

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Page publiée le 24 novembre 2019