Risk assessment of flash flood and soil erosion impacts on electrical infrastructures in overcrowded mountainous urban areas under climate change

Abstract

Risk management of flash floods in arid mountainous cities is challenged by the lack of proper data and the unreadiness of infrastructures to handle large floods. Climate projections predict increasing frequency of extreme droughts and floods over these arid zones aggravating the impacts of flash floods by increasing the hardness of the topsoil, making it less efficient at absorbing rain water. This study assesses the hazards of steadily increasing flash floods on voltage towers around Makkah city using hydrological modeling to simulate flow velocity and volume and erosion intensity of floods. Hydrological modeling estimated the maximum discharge rates at Wadi Numan and Wadi Al-Sharaya outlets as 3142 and 2543 m3/s, respectively. Extreme soil erosion rates are encountered in the lower reaches of these basins (11% of the total area) and severe erosion rates (3.6%) were reported in the planned voltage tower path. Catchment's lower reaches are proved highly vulnerable to soil erosion due to the lack of vegetation cover and high flow accumulations. The study alarms revisiting the risk management policies for infrastructure projects in arid mountainous cities considering the climate change impacts on increasing the frequency of unprecedented droughts and floods and their aggravated destructive impacts.