Landslide Susceptibility Mapping and Its Driving Factors in Kamonyi District of Rwanda

This study investigates the use of remote sensing and GIS techniques to generate a landslide susceptibility map and examine the factors contributing to landslides in the Kamonyi district located in the Southern Province of Rwanda. The Weighted Overlay Analysis (WOA) approach has been applied, enhanced by the Analytic Hierarchy Process (AHP), to combine various geospatial factors influencing landslide occurrence. These factors include elevation, slope angle, aspect, curvature, the topographic wetness index (TWI), stream power index (SPI), proximity to roads, proximity to rivers, land use and land cover (LULC), normalized difference vegetation index (NDVI), soil texture, and rainfall. GIS and remote sensing tools were employed to carry out a multi-criteria analysis, assign appropriate weights to the factors, and produce the final landslide susceptibility map. The findings emphasized the key factors that contribute to landslide susceptibility and were ranked based on the assigned weights. The slope (22.5%), rainfall (18.3%), land use and land cover (LULC) (13.6%), and soil texture (10.4%) were identified as factors mostly influencing landslide occurrence in the area while factors such as proximity to roads (7.8%), elevation (6.3%), topographic wetness index (TWI) (5.2%), and proximity to rivers (4.6%) were found to have a moderate influence. NDVI (3.9%), stream power index (SPI) (3.1%), curvature (2.8%), and aspect (1.5%) were found to have a lesser influence on landslide susceptibility in the Kamonyi district. The landslide susceptibility map displayed varying degrees of risk across the district, with 2.5% categorized as very high susceptibility, 16.9% as high susceptibility, 52.7% as moderate susceptibility, 27.2% as low susceptibility, and 0.7% as very low susceptibility. The areas with high and very high susceptibility were predominantly located in the northern and central regions of the district, whereas the southern areas mainly exhibited low and very low susceptibility. The results of this study provide crucial information for land use planning, risk reduction, and disaster management in both Kamonyi district and Rwanda overall. It is recommended that policymakers and local authorities focus on the high-risk zones for focused and effective interventions.