Landslide susceptibility mapping using frequency ratio model: the case of Gamo highland, South Ethiopia

Abstract

Landslide is the most frequently occurring geo-hazard in mountainous terrains of the world. It affects human life, infrastructures, landscapes, and human properties as well as their day-to-day activities. In the current study area which is found in the Gamo Zone of south Ethiopia, recurrent landslide hazards have occurred. To minimize this landslide hazard on human life and their properties, landslide susceptibility mapping is an important step for environmental planning. For this purpose, 1554 landslides and 9 landslide causative factors (both conditioning and triggering factors) were used. Each thematic layer has different classes and some of these classes influence landslide occurrence more than others. The most influencing factor classes which were identified by the frequency ratio model include slope classes between12 and 45°; convex and concave classes of the curvature; aspect classes of north, northeast, south, and southwest directions; and elevation classes in between 2118 and 2492 m. The distances factors, proximity to streams, and lineaments 0–100 m and 0–200 m respectively have a very high on landslide occurrences. Land use/land cover factor has different classes and they have different levels of direct and indirect influences on landslide occurrences. The landslide susceptibility map was classified as very low, low, moderate, high, and very high classes each accounting for 17.8%, 29.19%, 28.55%, 17.52%, and 6.91% of the area respectively. To evaluate the reliability of this model, the landslide susceptibility map was verified using a receiver operating characteristic (ROC) curve with a value of 82% and through field observation. Therefore, this can be used by local, zonal, regional, and federal governments for land use planning, disaster prevention, and mitigation as it offers first-hand information.