Landslides are the most destructive geological hazard in the hilly regions. For systematic landslide mitigation and management, landslide evaluation and hazard zonation is required. Over the past few decades several techniques have been developed that can be used for landslide evaluation and zonation. These techniques can broadly be classified into qualitative and quantitative approaches. Qualitative approaches include geomorphological analysis and heuristic techniques whereas quantitative approaches include statistical, artificial intelligence and deterministic techniques. In quantitative techniques prediction for landslide susceptibility is based on the actual realistic data and interpretations. Further, the quantitative techniques also overcome the subjectivity of qualitative approaches. Each of these techniques may consider different causative factors and utilizes various means for factor evaluation and analysis. When compared, each of these techniques has its own advantage and disadvantage over other techniques. The selection of appropriate technique for landslide hazard evaluation and zonation is very crucial. The factors that need to be considered to adopt an appropriate approach are; investigation purpose, the extent of the area to be covered, the type of mapping units, the scale of map to be produced, type of data to be used, type of landslides, availability of resources, capability and skill set of an evaluator and the accessibility to the study area. The main aim of this article is to present a comprehensive review on various techniques and approaches available for landslide susceptibility and hazard zonation mapping. Further, attempt is also made to assess the effectiveness of these techniques in landslide hazard zonation studies.

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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.