Flood Risk Evaluation Using AHP-Based Model and GIS Technique: A Case Study of Ethiope East and West Local Government Areas, Nigeria

Ethiope, two of the local government areas (LGAs) in Delta State, Nigeria, is at risk of severe flooding disasters resulting from climate changes-rising temperatures and changing precipitation patterns. This study adopted the analytic hierarchy process (AHP) model and soil conservation services curve number (SCS-CN) method to assess flood risks in Ethiope. We integrated seven factors under two criteria: hazards and vulnerability. Five risk scales were developed to represent flood risk likelihood. Results revealed that Ethiope LGAs are highly flood prone. Seven towns were at high risk of flooding (13.4%), while four towns were at very high risk of flooding (10.6%). The soil type was found to be largely homogenous though with higher degree of spatiotemporal variation in infiltration rate and moisture level. The volumetric analysis showed that surface runoff during the peak months of September in the subcatchments exceeded 2800 million cubic meters-which usually results in flooding. This novel approach to predicting flood risk proves highly effective and can be advanced further to study other deltas characterized by a stable hydrological flow regime. Analytical findings call on the authority to develop coping strategies for future flood occurrences and actively map out empirically established areas for intervention efforts.