Modeling of Flash Floods in Wadi Systems Using a Robust Shallow Water Model—Case Study El Gouna, Egypt

Abstract

Flash floods as a result of extreme rainfall events occur in different regions all over the world and often cause losses of human life and severe damages to settlements and the environment. The Red Sea region of Egypt is affected by flash floods almost every year leading to losses of human life and infrastructure damages. The lack of data and the highly random occurrence of these extreme events make the management of flash floods very difficult. In the future, the frequency and intensity of extreme rainfalls might increase due to climate change and measures to reduce the risk of flooding have to be realized urgently. To investigate flash floods in Wadi Bili, a shallow water model of the region of El Gouna was established. In preparatory work, sensitivity studies were carried out for an idealized catchment. The inflow from upstream was found to be the most important parameter. The model of El Gouna was set up using a DEM and the flash flood event of 9 March 2014 was simulated by implementing the measured data of rainfall and runoff. The simulation results include the distribution of water depths and flow velocities in the computational domain at different time steps. The results are plausible in terms of flooding areas and ranges of water levels and flow velocities. Later on, the model will be applied to investigate different scenarios of structural measures to protect the city of El Gouna against flash floods, e.g., dams, canals, basins, and local measures for buildings.