Analytical hierarchy process (AHP) based landslide susceptibility mapping of Kaligandaki hydro-catchment of Syangja, Nepal

Abstract

Landslide problems are abundant in the mountainous areas of Nepal. This study aims to prepare landslide susceptibility map (LSM)using Analytical Hierarchy Process (AHP) method of the Kaligandaki hydro-catchment, Syangja, Nepal. Eight factor maps viz. slope, aspect, distance to stream/river, lithology, distance to faults, precipitation, land use and distance to road were used for preparing thematic layers. Weight for each factor was assigned using AHP depending on its influence on the landslide occurrence. The LSM was obtained with combination of weighted thematic layers and reclassified into five susceptible classes namely, very low (VL), low (L), moderate (M), high (H) and very high(VH).Altogether 27 landslide incidents were recorded by inventory approach. The result showed that about 40% of the study area is highly susceptible for landslide occurrence. The study revealed that higher slope (>30o) with combination of lithological factor has higher effect on landslide occurrence. Similarly, west facing slopes were found to be more susceptible to landslide occurrence in comparison to other aspects. The majority of the landslides were found near proximity of roads and streams/rivers. Finally, the landslide hazard zonation map was crossed with the landslide distribution map and the model applicability was confirmed by determining the per hazard class percent of area covered by the landslide. Further, the effectiveness of the map was also confirmed by the high statistically significant value of a chi-square test. The LSM can be useful for the decision-makers and planners in choosing suitable locations for the development works like road network, drainage network, drinking water, etc.