Impact of geomorphometric parameters on landslide occurrence and distribution in Yamuna River Basin, North-Western Himalaya, India

Abstract Landscape evolution is a dynamic process controlled by several geomorphic parameters along with geology, tectonics and climatic condition of the area. The Himalayan mountain belt is highly geodynamic with immature topography which offer one of the best places to study the impact of geomorphotectonic characteristics on the occurrence and distribution of landslides along with tectonically modified geomorphic features. The morphotectonic study of the drainage basin is extensively utilized to analyze the landscape evolution in the study area along with impact of neotectonic activity in landscape evolution. The study shows that the Yamuna River, originating from the mighty Himalayas, flows downslope by adjusting its course due to ongoing tectonic activities, underlying structures, and climatic factors. Active tectonics play important role in modifying the landscape and impacting the occurrence and distribution of landslides. The characteristics of rainfall induced landslides have been studied in relation to morphotectonic parameters. The analysis shows that the probability density of landslides was highest in the range of 25o-30o and that landslide size increased up to 20o-25o slope angle, decreasing on further increase in slope angle. The study also shows that slope angle merely controls number of landslides rather than size of the landslides. Landslides were mostly restricted to South facing slopes. About 91% of the landslide occur in the drainage density range of 1.2 to 2.1 km/km2 while landslides show very low occurrence in either lower (< 1.2) or higher (> 2.1) drainage density. The present analysis can be very helpful in landslide risk reduction and landslide hazard zonation and probably to plan critical locations for installation of early warning signals.