Characterization of Landslides in Lesser Himalayan Region: A Case Study of Gambhar River Catchment

In India, 15% of land territory (0.49 million square kilometers) is affected by landslides. The tectonically active Himalayan region exhibits the highest frequency of landslides (NDMA National disaster management guidelines, Management of landslides and snow avalanches, A publication of the National Disaster Management Authority, Government of India, 2009). Landslides are triggered by natural as well as anthropogenic activities; and their frequency is usually higher in the hilly terrain. Present study aims to examine nature, types, surficial material involved, location and impact of landslides in Gambhar River Catchment. Use of Multitemporal Satellite imageries, DEM, Landslide Vector data inventory of Geological survey of India, Topograhical maps of survey of India, Soil map of NBSS and Data collected through field survey. An integrated methodology was adopted to prepare landslide inventory over a period of 20 years were delineated from satellite imageries. After the procurement of satellite imageries these were pre-processed using atmospheric correction techniques, co-registration of datasets, layer-stacking, mosaicking, clipping of study area, contrast and texture analysis and image segmentation. Images were classified using unsupervised classification techniques via ISODATA algorithm to examine different features. The geological and soil maps were digitized to create a geodatabase on these parameters. The analysis of landslide occurrence shows that it is prone to such hazard and therefore warrants a thorough examination of nature, types, occurrence patterns, surficial characteristics, and causes of slope failure. The catchment is affected by 14 types of landslides; the majority belongs to debris slide; rock slides and translational slides. About 9% are composite slides trigged by multiple processes. The occurrence of landslides is due to both natural and anthropogenic factors.