Development of Methodology for Identification of Landslide Susceptible areas along NH-10 from Singtam to Gangtok, East Sikkim using GIS based Modelling

Around the world, landslides are a common phenomenon or natural disaster. The NH-10 has been chosen for identification and examinations of slope failure processes in order to better understand the impact of landslides and mass movements in the Sikkim region. The NH-10 is the only communication system in this region and called as a life line of the state that also fulfills the demands of defense forces working in border areas. The 18 km stretch of NH-10 between Singtam and Gangtok has been chosen for the current research. This road length is affected by various types of mass movements. Geology, hydrology, seismicity, engineering behaviour of slope forming material, etc. are the main reasons of this mass movement. Besides these, the study area is also affected by heavy rainstorms and alteration of geometry of slope which consequently results different types of slope failure phenomenon. Geologically, the area is made up of mainly quartzite and phyllite which belongs to Goruba than and Reyong Formations of the Daling Group. Further, an attempt has also been made to mark the landslide prone areas along the road with help of different types of thematic maps. The study involved preparation of various thematic maps for geo-factors. A weighted multiclass index overlay method was used to categorise the landslide susceptible slopes. The input thematic maps integrated through a knowledge-driven integration technique. The Author (s) have prepared the Digital Elevation Map, Slope map, Aspect map, Drainage map, lineament map and landslide susceptible map using ALOS PALSAR DEM on Arc GIS 10.5 software.