Spatio-temporal dynamics of landslides in the sedimentary terrain: a case of Siwalik zone of Babai watershed, Nepal

Abstract

Topographical, geological and hydrological attributes of mountainous region play significant role for landslide occurrence. In this study, the spatial and temporal behaviors of landslides in the Siwalik zone of Babai watershed are evaluated on the basis of topographical, geological and hydrological attributes. For this work, polygon based landslide spatial inventory and spatio-temporal inventory from the years 2010 to 2019 were prepared by using Santeniel-2, USGS and temporal series of Google earth images. Further analysis of landslides including the numbers, area and other geometrical parameters were carried out using Q-GIS. The geological map prepared by the Department of Mines and Geology of Nepal government was referred and validated from the field. The precipitation data was obtained from department of hydrology and meteorology, Government of Nepal. The state of activity of landslides was evaluated in different geological formations in temporal basis. The result shows that the landslides in study area are highly dynamic in nature showing reactivation, expansion and even self stabilization in some parts. The new and active landslides are identified every year in every geological formation since a decade. It is also found that the hanging wall of the thrust zone is more sensitive for the distribution of medium to large scale landslides. The total annual rainfall shows positive correlation with the landslide frequency. The study will be useful for the researchers and policy makers to understand landslide mechanics and to manage the safe settlements in the area.