Flooding is a natural calamity that causes widespread devastation, including severe infrastructure destruction, significant economic consequences, and social disturbances around the world, particularly in the Sinai region. Wadi Ked is one of Sinai, Egypt's, most vulnerable districts to flood hazards, and it is the location used for this study. This study aims to create a map of flood-prone areas in Wadi Ked by combining Geographic Information System (GIS) technology and multi-criteria decision-making (MCDM) techniques, utilizing the Analytical Hierarchy Process (AHP) methodology. To achieve the study's goal, flood-related factors such as elevation, slope, distance to roads, distance from streams, annual rainfall, drainage density, topographic wetness index, land use and land cover, normalized difference vegetation index, soil type, and curvature were weighted and overlaid. The results show that 26.91% of the areas studied have a low sensitivity to flooding, whereas roughly 73.09% of the area is moderately to very highly vulnerable to flooding. The study proposed a dam with a height of 30 m, a width of 0.416 km, and a lake capacity of 31.74 million cubic meters (MCM). The surface runoff volumes from 50-and 100-year storms in sub-basins 1–5 are 23.07 MCM and 29.66 MCM, respectively. Model validation was performed by comparing susceptibility maps generated from literature-based and expert-based AHP weights, revealing a 98% spatial agreement and a Kappa coefficient of 0.995, confirming the model's robustness. This study offers value to decision-makers and planners by utilizing morphometric properties and flash flood risk maps to identify suitable locations for dams.