Assessment of Hazard and Contributing Factors of Landslides in Abay Gorge in Ethiopia

Abstract

Main road 3, a major arterial road in Ethiopia, steeply climbs nearly 1,500 m over 40 km through the Abay Gorge. It is plagued by landslides in the rainy season from June to September. Some of these are up to 2-km wide and would jeopardize this vital link. To fundamentally solve this problem it is necessary to implement appropriate countermeasures after clarifying the mechanisms that trigger landslides in this stretch of road. In this paper, we discuss the hazard of each landslide and identified the factors to clarify the mechanisms. A quantification theory, which is a type of multivariate statistical analysis, is adopted as the assessment method in this paper. The theory assesses the hazard of each landslide according to disaster causes such as topographic features and geological conditions, and landslide history. The results are represented as a category score, which is a coefficient that correlates to the contribution of each item; and the score is directly influenced by the dependent variable. According to the results of the landslide hazard assessment, we have not only determined unique factors of landslides, but have also ranked them from A (extremely high hazard) to E (lowest hazard) in the Abay Gorge. As a result, fourteen landslides were assigned to rank A. Assessing hazards and identifying mechanisms of landslides enable the most appropriate countermeasures to be implemented.