Geoenvironmental GIS development to investigate Landslides and Slope Instability along Frontal zone of Central Himalaya

The Frontal Himalayan terrain comprises of Lesser Himalaya and Siwalik Hills; is highly susceptible to landslide disaster due to active tectonics, scrappy geology, steep slope, and reshaping geomorphology. Besides that, hydrological impacts of land use degradation and climate change enhancing the vulnerability of the terrain. Keep in view this; the Dabka watershed, falls in frontal zone of central Himalaya has been selected for case illustration. Geospatial analysis advocates that the areas of the most stressed geo-environment (comprises of very steep slopes above 30°, geology of Lower Krol and Lariakanta formation, geomorphology of moist areas and debris sites and land use of barren land) have high density (5–10 landsides km²) of landslides whereas the areas of least stressed geo-environment (comprises of gentle slopes below 10°, geology of Kailakhan and Siwalik formation, geomorphology of depositional terraces and land use of dense forest) have low density of landslides (2 landsides km²). Out of total 340 landslides in the region, 198 are active landsides whereas 51 and 91 are reactivated and old landsides respectively. Geospatial analysis of landslide areas reveals that across the region total 804.33 ​ha land has been degraded by landslides which account for 11.65% of the total area of the Dabka watershed. The wedge failure analysis suggests that there are 3–4 sets of rock joints across the region and most of the sites are unsafe as their safety factors are less than 1.