A GIS approach for landslide hazard zonation in the lesser Himalaya

Geo-dynamically active Himalaya is the youngest mountain belt in the world. Himalaya is tectonically pro-active in nature, therefore, always associated with the distressing hazards. Landslides are one of the most devastating natural hazards. According to World Bank, landslides result ~ 32,000 fatalities and 50 billion USD damage every year worldwide. Brabb (Proposal for worldwide landslide hazard maps, 2003) mentioned that 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 specific regions. This study delves into the LHZ of a 134.7 km2 area along NH-109K, focusing on critical causative factors such as slope, aspect, lithology, rainfall, 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 high-hazard zone encompasses 36% of the area, followed by very high hazard zone 28%, very low hazard zone at 16%, low hazard zone at 12% and moderate hazard zone at 8%. Enhance the reliability of the study, 576 landslide inventories of last five years, were compiled from Bhukosh (an open data archive of Geological Survey of India). The receiver operating characteristic (ROC) curve yielded a commendable quality with an 95.3% 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. LHZ map provides valuable insights for informed decision- making in infrastructure development and risk management, contributing to the sustainable growth and protection of the region's livelihood.