Landslide vulnerability mapping using multi-criteria decision-making approaches: in Gacho Babba District, Gamo Highlands Southern Ethiopia

Abstract

The landslide has been a life-threatening natural disaster in most districts of Gamo Highlands. This study was conducted to assess the status of landslide vulnerability in the Gacho Baba district of the Gamo zone in southern Ethiopia. The Geographic Information System Analytical Hierarchy Process and Weighted Linear Combination multi-criteria decision-making approaches were applied. Eight causative factors of landslide, namely, slope, elevation, aspect, distance from the stream, drainage density, soil type, distance from the road, and land use/cover were considered. The weight values of each causative factor were determined by previous studies, field observations, and experts’ judgment. The calculated weight of each causative factor is the slope (23%), elevation (21%), aspect (8%), stream distance and drainage density each (12%), soil type and road length each (9%), and land use/cover (6%). Moreover, the Consistency Index (0.13) and Consistency Ratio (0.08%) were calculated with acceptable values for comparison to weighted overlay analysis to produce a landslide vulnerability map of the study area. The result shows that the vast majority of the study district (86.6%) falls within a very high to moderate landslide susceptibility class and only (13.4%) falls within a very low and low susceptibility. This indicates that almost all the 11 villages in the district, are found within the high to moderate landslide vulnerability class which alerts responsible community and zonal disaster risk prevention and related offices to take action on the identified causative factors to reduce the occurrences of landslide hazard in the study district.