A GIS-based landslide susceptibility assessment and mapping around the Aba Libanos area, Northwestern Ethiopia

Abstract

The geological hazards caused by natural and manmade activities pose serious property damage, loss of life, and changes in the earth’s features. In this work, GIS-based landslide susceptibility mapping was carried out using the Analytical Hierarchy Process (AHP) and Frequency Ratio (FR) methods for the Chemoga River Sub-Basin (CRSB), in the Aba Libanos area in Northwestern Ethiopia. To produce a susceptibility map, eight influencing factors were selected. They are elevation, slope, aspect, Lithology, land use land cover, curvature, distance to drainage, and distance lineaments. All those influencing factors were statistically analyzed to decide their relationship to past landslides. The relationships between the observed landslide areas and these eight related factors were identified using GIS-based statistical models including AHP and FR. Detailed fieldwork (lithological description and mapping, geological structural measurements, and taking considerations for the impact of each influencing factor on the occurrence of landslides in the area) was conducted to interpret and produce the various maps of the study area. The AHP modeling susceptibility map of the study area was 9.6%, 15.4%, 29.7%, 27.8%, and 17.5% very low, low, moderate, high, and very high respectively. Similarly, based on the value of FR, the study area was classified into five susceptibility zones, 20.7%, 14.6%, 13.0%, 18.6%, and 33.0% very low, low, moderate, high, and very high respectively. Both results showed that steep side slopes and lineaments are very high landslide susceptibility zones. Lastly, the landslide susceptibility maps produced from the two models were validated with detailed fieldwork measurements and observation. Prediction accuracy of these maps that the landslide inventory map was overlaid on the AHP and FR maps. Both susceptibility maps show almost similar results and mainly, introduced some parts of the study areas of the Chemoga river sub-basin (CRSB) as landslide-prone areas.