Assessing landslide vulnerability from soil characteristics—a GIS-based analysis

Abstract

Hilly regions are prone to landslides that cause heavy losses of life and properties every year. A number of researches and analyses are carried out in the GIS environment to identify landslide vulnerability in the region. The important conditioning factors identified by the researchers are slope, geological, geomorphologic features, and land use coupled with triggering factors like rainfall and a few of the anthropogenic activities. Soil forms the uppermost part of the earth crust, and it is expected that various soil characteristics like depth, surface texture, depth texture, soil erosion, hydraulic conductivity, stoniness, etc., play significant roles in causing landslide in the area. These factors have been ignored so far by most researchers while identifying landslide hazard-prone areas. This paper attempts to assess the vulnerability status in parts of East Sikkim, India, by integrating the influence of the various soil attributes. A composite index called soil stability value was determined by aggregating the weights assigned to different soil parameters. Finally, based on the soil stability values, the study area was classified into least vulnerable, moderately vulnerable, and most vulnerable zones of landslide occurrences. Comparison between the vulnerability zones and the actual landslide occurrences yielded a 90% agreement with the density of landslides in the most vulnerable zone, demonstrating the efficacy of soil characteristics as potential indicators of landslide events.