Prioritization of subwatersheds flood sensitivity using fuzzy analytical hierarchy process (FAHP) method: A case study of the Drâa basin

Flash floodsare major natural hazard in dry regions like the Drâa basin. This study aimed to compare the flood risk prioritization in three subwatersheds (Upper Drâa, Middle Drâa, and Lower Drâa) using GIS and DEM-derived morphometric parameters. In this study, a multi-criteria GIS-based analysis method, named Fuzzy Analytical Hierarchy Process (FAHP), was use to ranking the subwatersheds according to flood sensitivity based on ten morphometric parameters. These parameters are: compactness index (Kg), basin relief (H), length of the basin (Lb), specific elevation gain (Ds), slope Index (Ig), stream frequency (Fs), drainage density (Dd), gradient Ratio (Rg), time of water concentration (Tc), and torrentiality coefficient (Tcoef). The results show that the Lower Drâa is the most sensitive to floods due to steep slopes and high drainage density. This study helps us to identify areas with a priority for flood risk management.