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Assessing Cohesion, Friction Angle and Slope Instability in the Shivkhola Watershed of Darjiling Himalaya

Author Affiliations

  • 1 Department of Geography, University of Gour Banga, Malda-732103, West Bengal, INDIA

Int. Res. J. Earth Sci., Volume 3, Issue (8), Pages 1-7, August,25 (2015)

Abstract

The study of soil strength properties is of very much important to assess the slope instability in the mountain area. Himalayan mountain range characterized by most fragile lithological composition. This fragile lithology is the outcome of heavy compressive forces resulting from the convergence of two solid slabs i.e. Indian Plate and Eurasian Plate. Hence, the upper part of the slope materials up to the weathered limit or weathered front is of low shear strength and very much prone to failure. Cohesion (c) and friction angle (φ) are the two significant parameters of soil and on the basis of these properties the stability and instability of the slope segment can be assessed. The present study area of the Shivkhola watershed of Darjiling Himalaya is dominated by slope instability. To indentify the potential landslide locations, a landslide inventory map was prepared in consultation with Topo-sheet, Google Earth Image, Satellite image (LISS III 2010) and intensive field investigation with GPS. The soil samples were collected from 50 locations considering 0.25 sq. km surface and tested in the laboratory to estimate cohesion and stress parameters. Based on cohesion and major principal stress and minor principal stress a Mohr Stress Circle was developed to determine friction angle. Finally the spatial distribution of cohesion and friction angle and their integration with landslide distribution was accomplished on GIS platform incorporating pixels affected by landslide and pixels not-affected by landslide in each class of the prepared data layers.

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