A GIS approach for Landslide Hazard Zonation in the Lesser Himalaya

Geodynamically active Himalaya is the youngest mountain belt in the world and tectonically pro-active in nature, therefore, always associated with the distressing hazards. Landslides are one of the most devastating natural hazards which result ~ 32000 fatalities and 50 billion USD damage every year worldwide. Almost 90% landslide risk and fatalities can be avoided if effective measures are taken before its occurrence. Landslide hazard zonation (LHZ) is a crucial tool for assessing the likelihood of landslide occurrences in any specific regions. This study delves into the LHZ of a 134.7 km ² area, focusing on critical causative factors such as slope, aspect, lithology, Land Use/Land Cover (LULC), road-buffer and drainage systems. A comprehensive LHZ conducted firstly along the NH-109K from Karnaprayag to Gwaldam in Chamoli district of Uttarakhand, India using Geographic information technique (GIS). The LHZ classification resulted in five distinct zones, notably, the moderate-hazard zone encompasses highest 47% of the area, followed by the Low-hazard zone at 28%, the high-hazard zone at 21%, very high-hazard zone at 2% and very low-hazard zone 2%. To enhance the reliability of the study, 51 past landslides were compiled from GSI, NRSC and NASA’s grided inventory data. Aftermath it is found that 39 past landslide occurrences were situated within the very high and high-hazard zones, 9 in the moderate hazard zone and 3 in the low and very low-hazard zones. The receiver operating characteristic (ROC) curve yielded a commendable quality with an 87.1% area under the curve (AUC). In summary, this research underscores the importance of LHZ in assessing and mitigating landslide risks along a stretch of the NH-109K using GIS tool. The findings provide valuable insights for informed decision- making in infrastructure development and risk management, contributing to the sustainable growth and protection of the region's livelihood.