Potential Landslide Vulnerability Zonation Using Integrated Analytic Hierarchy Process and GIS Technique of Upper Rangit Catchment Area, West Sikkim, India

Landslides have become a serious hazard in mountainous region where exhaustive storm rainfall is common. The intensity of landslide hazard is not only depending upon storm rainfall and physical factors but also depends upon several anthropogenic activities or land use practices. The aim and objective of this paper are to highlight the landslide vulnerability with the help of analytical hierarchy process and geographic information system (GIS) tools. Weighted overlay analysis method was used for assessing landslide vulnerability of upper Rangit catchment area, West Sikkim, India, within the GIS environment. Weights and rank are assigned on the basis of influence of landslide occurrence. Factors selected for this study include rock type, geomorphology, slope, aspect, drainage density, soil type and land use and land cover. The landslide vulnerability map will provide valuable information to the local government for planning and management in future. Higher weight was assigned for greater influence and lower weight was assigned for lesser influence of landslide. Southern part and middle part of the region have very high vulnerability of landslide in comparison with the northern region, but the region having much anthropogenic activities towards the south became more vulnerable. It has been observed that 38.48% of the area is at very low vulnerability, 32.26% is at low vulnerability, 18.16% at medium vulnerability, 8.56% at high vulnerability and 2.53% at very high vulnerability.