Spatial variability of slope movements in central and western Nepal Himalaya: Evaluating large-scale landslides to cut-slopes

Abstract

Spatial variability of slope movements is common in the Himalayan terrain of central and western Nepal Himalaya due to the intricate topography, differential geo-environment, and frequent rainstorms. The process of mass movements in the Himalaya has been described in the past by many researchers. The spatial variability of slope movement phenomena is scale dependent and is affected by causative and triggering processes. The limited researchers delivered output to understand the scale-dependent spatial variability resulting from the causative and triggering mechanism of slope movement phenomena. This study has presented a rigorous scientific examination of the spatial variability of slope movements, focusing on large-scale landslides to cut slopes across the central and western regions of the Nepal Himalaya. To achieve this, a multidisciplinary approach was employed, encompassing geospatial analysis, remote sensing, and field investigations. High-resolution satellite imagery was utilized to identify and map slope movement features, while digital terrain analysis techniques aided in quantifying their characteristics. This approach quantitatively analyzed slope movement distribution, frequency, and characteristics in terms of various geo-environmental settings. The findings reveal diverse patterns of slope movements influenced by complex interactions between geological factors, geomorphology, triggering factors, and anthropogenic activities. Geological and geomorphological heterogeneity play roles differently in the spatial distribution of slope movements. Moreover, rainfall distribution and peak ground acceleration act similarly for the scale dependency phenomena of slope movement. The spatial variation concerning the causative and triggering variables signify the scale-dependency nature of slope movement processes. This study has provided insights into the scale dependency and spatially variable nature of slope movement events due to variations in causative and triggering mechanisms in the Nepal Himalaya.