Flood vulnerability assessment and mapping in selected communities of Langtang South Nigeria, using analytical hierarchy process and geographic information system

Flooding is a devastating natural disaster that disproportionately affects vulnerable communities with significant effect on their socio-economic well-being. This study used an integrated approach that combined a geographic information system and the analytical hierarchy process (AHP) to evaluate flood vulnerability in selected communities in Langtang South, Nigeria. Five main factors contributing to flooding, including elevation, slope, distance to a river, rainfall, and land use/land cover, were used in the analysis. Using AHP, each factor was assigned a weight based on its significance in causing floods, with a pairwise comparison matrix used to determine their relative importance. Rainfall was identified as the most significant contributor (52.9%), followed by elevation (22.8%), land use/land cover (13.7%), proximity to rivers (7.2%), and slope (3.4%). The resulting vulnerability map classified 0.2% of the study area as very low, 8.0% as low, 42.1% as moderate, 40.0% as high and 9.7% as very high vulnerability. Additionally, community members participated in focus group discussions to gain a thorough understanding of the impact on the ground. The findings from the discussions revealed that rainfall is the primary cause of floods, and that arable farmlands were the most heavily and frequently damaged assets, which has a significant negative impact on their agriculture-dependent livelihoods. The study concludes that communities located along riverbanks with low elevations are the most vulnerable to flooding. The findings highlight the critical need for extensive flood control strategies and targeted interventions in the area.