Landslide Hazard Zonation Using Expert Evaluation Technique: A Case Study of the Area Between Gohatsion Town and The Abay (Blue Nile) River, Central Ethiopia

Abstract

The area between Gohatsion town and the Abay River in Central Ethiopia is witnessing severe problems of landslides during rainy seasons. These landslides in the area affect the safe functioning of the road, which is an essential link between Addis Ababa and the northwestern part of the country. In the present study, an attempt is made to delineate the area into landslide hazard zones (lhz). The landslide hazard zonation was carried out by “Landslide Hazard Evaluation Factor” (lhef) rating scheme. The lhef is an expert evaluation technique that is based on the observational past experience gained over causative factors and their contribution for instability of slopes in the area. The causative factors responsible for landslide activity, which were considered during the present study, are: relative relief, slope morphometry, geology, groundwater and land use/ land cover. The information pertaining to these causative factors was collected from the field and analyzed as per the lhef scheme. The evaluated lhz revealed that most of the study area falls within the moderate and high hazard zones. The existing road that links Addis Ababa with the northwestern part of the country mostly passes through high hazard zones and some of it passes through moderate hazard zones. This seems to be the main reason for frequent landslides along the road during the rainy season. Thus, it is imperative to conduct detailed investigations to suggest proper remedial measures for slope stabilization along the road section or to realign the road section to avoid such critical slope sections.