Geomorphic, geo-tectonic and hydrologic attributes and landslide susceptibility

Abstract

Occurrences of landslides are affected by geomorphic, tectonic and hydrologic parameters. Balason river basin of Darjeeling Himalaya exhibits these parameters which are being analyzed in regard to landslide occurrences. In the present work, we carried out an overlay analysis of various data layers such as elevation, slope, geology, geomorphology, soil, rainfall, drainage density and drainage frequency with the landslide distribution data layer to assess the probability of different classes of landslide causative factors. Frequency ratio (FR) values for each class were estimated considering both landslide affected pixels and total pixels of a class. The result showed that, those areas which were characterized by elevation of 1065–1257 m, slope of 36–89°, south facing slope, high concave area, lineament density of 1.22–2.29, 20–40 m distance from lineament, NDVI of 0.16–0.21, drainage density of 620.17–741.51, 100–150 m distance from drainage, SPI of 12.34–13.14, TWI of −19.41 to −17.59 and rainfall of 2560–2618 mm were registered with high frequency ratio and high landslide probability. In addition, the probability of landslide occurrences is also high in Darjeeling gneiss, lower hill, human settlement and fine loamy to coarse loamy soil textural area.