An assessment of the spatial and temporal dynamics of landslide hazards and their implications on communities in Kabale District.

Abstract

Landslide occurrences in Kabale district is on the increase in the last 10 years. These threaten livelihood and can impact on the ecosystem services and benefits to communities. In this study, the spatial and temporal dynamics of landslide hazards were assessed; factors that underpin landslide sites characterized in order to evaluate the damage associated with landslides and how people cope. Landslide scars were mapped using a Global Positioning System (GPS). The Geographical Information System (GIS) tools were used to create a landslide map in areas prone to landslide hazards. Terrain parameters such as slope angle, slope aspect and slope curvature were also assessed for their significance in landslide occurrences. Social surveys were administered to understand community perceptions on landslides in Bukinda Sub County. The perceived main (40%) triggering factor identified was heavy rainfall, followed by steep slopes (30%), soil type 18%, vegetation type (5%), temperature (4%) and 3% mentioned clearing of vegetation, stone quarrying (33%), road construction (20%), 47% mentioned cultivation on steep slopes as a preparatory factor, 24% of the respondents had lost property due to landslides, 23% had their gardens destroyed, 11% reported damage to infrastructure and 10% reported destruction of houses. Detailed GIS analysis revealed that most landslides (59%) occur on the convex slopes compared to concave slopes (41%). However, when subjected to a statistical test, no significant difference (P>0.05) related to slope curvature was detected. Most (58%) of the landslides occurrences were on upper slope sections and 22% on middle and lower sections respectively. Similarly, the difference in distribution related to slope position was not found to be statistically significant. The majority (61%) of landslides occurred in areas with sandy loam compared to loam (33%) and sandy clay loam soils (6%). Slopes with gradient above 30% significantly (P<0.05) had more landslide scars. It is recommended that sites with slope gradients >30%, below 2000 meters above sea level which be deliberately targeted for focused land conservation measures that enhance stability and improve soil organic matter. In particular, adequate vegetative cover during rainy seasons is required to mitigate the situations and reduce slope failures.