Landslide Hazard Mapping Using Gis And Remote Sensing Techniques: The Case Of Arbegona Woreda, Sidama Region, Ethiopia

Abstract

Arbegona area is located in southern parts of the Ethiopian highlands around 349 km from Addis Ababa, the capital city of Ethiopia. The area is a part of southern Ethiopian highlands, it is characterized by rugged topography with deep-cut gorges, weathered volcanic rocks, heavy rainfall and active surface processes. Because of the aforementioned conditions, the area becomes prone to landslide hazards. The previously occurred landslides in the study area have caused widespread damage. The main objective of this study is to evaluate landslide hazard and prepare a landslide hazard zonation map of Arbegona Woreda. The evaluation is conducted by applying GIS-based multi-criteria analysis. Landslide inventory map was firstly developed from 209 active and passive landslide scarps using intensive fieldwork and Google Earth image interpretation. These landslide locations were randomly divided into 70% training and 30% validation datasets. In this case study, the following landslide conditioning factors were evaluated: slope, aspect, drainage density, lineament density, geology, land use land cover and soil type. The thematic data layers representing various factors were, generated using GIS and remote sensing techniques. Using Analytical Hierarchy Processes, the weight of each factor was calculated and assigned in GIS. By adding the aforementioned landslide conditioning factors, a landslide hazard map, was produced by weighted overlay method. The result showed that 8.06% of the study area falls in very high, 29.24% in high, 43.88% in moderate, 11.79% in low and 7.03% in the very low hazard zone. Finally, the resulted landslide hazard maps have been validated and verified using the area under the curve and landslide inventory data. The result showed that the landslide hazard map agreed well with areas that had recently experienced a landslide. The landslide hazard map showed that southeastern, northwestern and southern parts of the study area are more prone to landslides than other parts. The correlation between landslide occurrence and causative factors was carried out to examine their relationship. Based on the landslide hazard zone various mitigation measures were recommended for the stabilization of unstable areas. The landslide hazard zonation map can be used for preliminary land use planning and hazard mitigation purposes in the study area.