Landslide susceptibility mapping using GIS and weighted overlay method: a case study from NW Himalayas, Pakistan

Landslide susceptibility map is very important for engineers, geologist, and land use planner for prevention and mitigation of landslide hazard in the area. This paper presents landslide susceptibility analysis for the part of tehsil Balakot, NW Himalayas, Pakistan. In this study, topographical, geological and remote sensing data were collected and processed using geographic information system (GIS) and ERDAS Imagine software. Nine influential causative factors for landslide occurrence were used for this purpose. The causative factors that influence the landslide occurrence include slope, aspect, curvature, elevation, lithology, land cover, faults, road network, and hydrology. These factors were analyzed for construction of thematic data layers. Numerical weight for each factor was assigned by the Analytic Hierarchy Process (AHP) using Pairwise Comparison Method. The landslide susceptibility indices were derived using weighted overlay method (WOM). As a result, landslide susceptibility map was produced in GIS. The susceptibility map classified the study area into very high, high, moderate, and low susceptible zones. The results of the susceptibility mapping were verified using the landslide occurrence. The verification results revealed 76 % accuracy. The validated results showed good agreement between landslide occurrence and produced susceptibility map of the area. Susceptibility map prepared by weighted overlay method is validated for landslide hazard, mitigations, and land use planning for future construction in the area.