GIS-based analytical hierarchy process for comprehensive flood hazard and risk assessment in the Juba River Basin, Somalia

In data-scarce regions like the Juba River Basin, Somalia, the absence of high-resolution hydrological monitoring hinders effective disaster management. This study develops a comprehensive flood risk assessment framework by integrating the Analytical Hierarchy Process (MCDM-AHP) with Geographic Information Systems (GIS). Twelve parameters were selected and categorized into Hazard (n = 7) and Vulnerability (n = 5) indices. Geophysical factors included elevation, slope, and soil type, while socio-economic exposure was assessed through population density and land use. All data were standardized to a 30 m resolution to ensure spatial consistency during the weighted overlay process. Results indicate that 21,345 km 2 (approximately 13.5%) of the basin falls within “High” to “Very High” hazard zones, primarily in the downstream reaches near Bardhere and Jilib. The vulnerability analysis reveals that 18% of the basin’s population resides in high-risk zones. Validation of the model using 65 historical flood points yielded an Area Under the Curve (AUC) of 0.938 (93.8% accuracy), demonstrating a high degree of reliability in predicting flood-prone areas. This study provides a spatially explicit tool for prioritizing flood mitigation infrastructure and enhancing early warning systems in the Juba River Basin, offering a replicable methodology for other data-limited transboundary watersheds.