Geospatial Flood Susceptibility Mapping in Ekeremor Local Government Area, Bayelsa State, Nigeria, Using Multi-Criteria Decision Analysis

Flooding constitutes one of the most significant environmental hazards affecting coastal communities in the Niger Delta, Nigeria, owing to the combined influence of river overflow, intense rainfall, tidal inundation, and low-lying terrain. This study assessed flood susceptibility in Ekeremor Local Government Area, Bayelsa State, using a Geographic Information System (GIS)-based Multi-Criteria Decision Analysis (MCDA) framework integrating the Analytical Hierarchy Process (AHP) and Weighted Linear Combination (WLC). Seven flood conditioning factors, namely elevation, slope, rainfall, soil, distance to river, distance to coastline, and land use/land cover (LULC), were selected based on their influence on flood occurrence. The factors were standardized and weighted using the AHP, with pairwise comparisons yielding a Consistency Ratio (CR) of 0.036, indicating acceptable consistency in the assigned criterion weights. The weighted factors were integrated using the WLC technique to generate a Flood Susceptibility Index (FSI), which was subsequently classified into five susceptibility classes: Very Low, Low, Moderate, High, and Very High. The results revealed that 544.09 km² (30.19%) of the study area falls within the Very High flood susceptibility class, while 135.86 km² (7.54%) is classified as High susceptibility. Moderate, Very Low, and Low susceptibility classes occupy 402.94 km² (22.36%), 361.74 km² (20.07%), and 357.49 km² (19.84%), respectively. Collectively, the High and Very High susceptibility classes account for 679.95 km² (37.73%) of the Local Government Area, indicating extensive exposure to flood hazards. Settlement overlay analysis further identified 156 settlements within the Very High susceptibility class, 41 settlements within the High class, 85 settlements within the Moderate class, 34 settlements within the Low class, and 73 settlements within the Very Low class. The observed spatial pattern demonstrates that flood susceptibility in Ekeremor is primarily controlled by the interaction of low elevation, gentle slopes, proximity to river channels, coastal influence, high rainfall, poorly drained soils, and land use characteristics. The generated flood susceptibility map provides a reliable spatial decision-support tool for flood risk reduction, sustainable land use planning, infrastructure development, disaster preparedness, and climate adaptation within Ekeremor Local Government Area and similar coastal environments in the Niger Delta.