Assessing the impact of land use on triggering landslides: A case of Sabaragamuwa Province, Sri Lanka

Landslide is a result of a complex spatial-temporal interaction of geological, geomorphological, climate and land use factors. Dynamics of geological, geomorphological and climate factors expands over relatively longer periods whilst land use change in short run. Hence, land use has a significant influence on landslide frequency and distribution, even in a short time span. However, limited studies have been carried out to investigate the relative contributions of the changes of different land use types in triggering landslides. This study has analyzed land use changes occurred in Sabaragamuwa Province, Sri Lanka over a period of ten years and assessed the effect of specific land use changes on landslides. The study is executed in four phases. Firstly, study mapped locations of landslides in QGIS environment. For this purpose, the study used secondary data which has been obtained from National Building Research Organization, Sri Lanka. Then the study analyzed the land use changes at landslide occurrence locations including a range of spatial buffer zone areas. MOLUSCE (Modules for Land Use Change Evaluation) plugin in QGIS was utilized to identify the land use changes in each spatial buffer zone area. Thirdly, the study computed the magnitude of landslide damage of each location based on five criteria as number of deaths, number of injured people, number of partial damaged houses, number of fully damaged houses and number of affected people. Then, the study analyzed the relationship between the magnitude of a landslide damage and land use changes. For this purpose, the study utilized spatial analysis tools in QGIS environment. The results revealed that land use changes such as forest to rubber, rubber-to-garden, rubber-to-any, tea-to-rubber, tea-to-any, forest-to-any have reported a greater influence on frequency of occurrence and the magnitude of landslide damage. These findings provide useful inputs to minimize landslides in the fields of land use planning and disaster management.