Landslide Vulnerability Zones and Their Driving Factors in Rwanda: A Case of Gakenke District

الملخص

Landslides are recognised as devastating and deleterious natural disasters which are contemporary substantial threats to communities, exerting profound impacts on human lives, infrastructure, and the environment. In this line, Gakenke is one of the districts in Rwanda that has experienced landslide events damaging ample property, infrastructure, and the environment. Hence, this study aimed at geo-modelling and visualising the landslide vulnerability zones and determining the local factors that mostly drive landslide vulnerability. Primary data were collected through field observation and expert knowledge. In contrast, secondary data were collected from historical landslide records, meteorological institutions, and satellite images, where a set of factors was deduced. Using an integrated approach, this study integrated remote sensing techniques, Geographic Information Systems (GIS), and the Analytical Hierarchy Process (AHP) to model and geo-visualize landslide vulnerable zones, determining the risk levels considering a set of independent variables subdivided into topographical, meteorological, geological, hydrological, and land use factors. The results of the first objective revealed slope (26.83%), rainfall (21.23%, soil texture (15.51%, and distance from roads (11.21%) as the most influential factors to landslide vulnerability in the study area. In addition, distance from the river (8.47%) and land use land cover (5.74%) exhibited moderate influence, while normalised difference vegetation index (4.03%), topographic wetness index (3.01%), aspect (2.1%), and curvature (1.59%) disclosed a low influence. The study results for the second objective showed that 18.12% of the area was classified as very high and highly vulnerable zones, mainly western and northern regions. Moderately vulnerable areas covered 60.7% of the central and eastern regions, while low and very low vulnerable zones comprised 21.2%, mainly in southern and south-eastern regions. This highlights the heterogeneous distribution across the district, emphasising the need for tailored mitigation strategies. These findings informed the development of tailored, community-driven resilience planning strategies that address the specific vulnerabilities and leverage local resources and knowledge. Therefore, a reforestation program, toe protection walls, terraces, and provision of proper drainage with check dams in very high and highly vulnerable areas, accompanied by relocating residents from these areas, particularly those living on hilltops, roads, and river sides, are recommended.  These measures are essential for protecting vulnerable populations and enhancing community resilience against natural disasters in the district.