Assessment of Landslide Risk in Ethiopia: Distributions, Causes, and Impacts

Abstract

The complex geological and geomorphological settings of Ethiopia, consisted of highland plateaus, escarpments, deeply dissected valleys, and flat lowlands, are results of multiple episodes of orogenesis, peneplanation, crustal up-doming, faulting, and emplacement of huge volumes of lava. The broad elevation contrast raging from about −125 m to 4550 m Above Mean Sea Level (AMSL) is an important factor in determining the climate regimes, vegetation types, and even popula-tions' lifestyles. In Ethiopia landslides, mostly manifested as rockfall, earth slide, debris, and mudflow, are among the major geohazard problems that immensely affects life, infrastructures, and the natural environment. They widely occur in the central, S-SW, and N-NW highland regions. This study discusses the distributions, causes, and impacts of landslides and presents a susceptibility zoning map produced applying the weighted overlay analysis method in the ArcGIS environment. For this purpose, key parameters (lithology, elevation, rainfall, slope angel, land use-land cover, and aspect) were selected and assigned weights by considering their contributions to slope failures. Correlations with inventory data have shown very good matching, where more than 90% of the observed data fall in areas categorized either as moderate, high, or very high susceptible zones, where appropriate risk assessments could be mandatory before approval of major projects.