Susceptibility Analysis of Flash Flood in Jeddah City, Saudi Arabia, Using a GIS-Based Analytical Hierarchy Process

Abstract

Floods rank among the most devastating natural hazards on Earth, posing significant threats to human society across various geographies, including arid regions such as Saudi Arabia. In Saudi Arabia, Jeddah is the second largest city in terms of population with more than 4.5 million residents. The city experiences long and arid summers and short, dry, and windy winters. As the severity and frequency of floods continue to increase, there is a growing demand for improved flood risk assessment to mitigate damage to lives and properties. Given the complex nature of flood evaluation and prediction, a systematic criteria-based methodology, such as the Analytical Hierarchy Process (AHP), offers a robust solution. This study integrates the AHP with a Geographic Information System (GIS) to model flash flood risk hazards in Jeddah, Saudi Arabia. Key parameters for this evaluation included precipitation, elevation, slope, proximity to drainage networks, land cover, and lithology. A pairwise comparison was conducted to rank these criteria by order of magnitude in flood contribution. Four susceptibility grades – ranging from Low to Very High – were identified to represent flood hazard likelihood. The findings show that the eastern and central parts of Jeddah, particularly areas leading to the coast, are identified as the most vulnerable areas to flash flooding due to their proximity to natural water channels and their low-lying, intermittent topography, which creates valleys. Obviously, the rapid urbanization of Jeddah contributes also to flash flooding caused by seasonal downpours. Local authority should develop coping strategies, such as widening drainage systems and reducing paved surface areas in highly susceptible zones, to mitigate future flood risks effectively.