Flood risk assessment in Limbe (Cameroon) using a GIS weighed sum method

Climate change, urbanization, and land subsidence are increasing risks of dangerous and costly flooding in Africa’s coastal regions. As the intensity and the number of flooding occurrences increase, real-time solutions for flood risks and hazards mapping are required to assess flooding and its potential impacts on the environment and humans. Flood risk mapping has become an important tool for assessing flood risks in coastal areas to guide planning and mitigation efforts by local officials. However, this tool has not been leveraged to support flood risk analysis. Using GIS weighted sum method, this study mapped and assessed flood risk zones in Limbe, Cameroon, by utilizing a Shuttle Radar Topography Mission-Digital Elevation Model (SRTM-DEM). Flood risk zones were delineated based on several environmental factors, including precipitation, elevation, slope, soil texture, land use/land cover, and flow accumulation. The findings classified about 50% of land in Limbe as having either high or very high vulnerability to flooding. The highest risk areas were concentrated in the upstream and downstream areas of Ejengele and Limbe Rivers. Only about 9% of Limbe was classified as very low risk, suggesting that most of the land area is susceptible to flooding. The study reveals that more than 90% of the Limbe’s urban areas are in flood-prone areas, which requires special attention from stakeholders to take necessary steps toward the preparation and mitigation of extreme flood events. The resulting flood risk maps provide vital information for urban and risk management planning professionals.