Mass Movement Hazard and Exposure in the Himalaya

Himalaya is experiencing frequent catastrophic mass movement events such as avalanches and landslides, causing loss of human lives and infrastructure. Millions of people reside in critical zones potentially exposed to such catastrophes. Despite this, a comprehensive assessment of mass movement exposure is lacking at a regional scale. Here, we developed a novel method of determining mass movement trajectories and applied it to the Himalayan Mountain ranges for the first time to quantify the exposure of infrastructure, waterways, roadways, and population in six mountain ranges, including Hindu Kush, Karakoram, western Himalaya, eastern Himalaya, central Himalaya, and Hengduan Shan. Our results reveal that the exposure of buildings and roadways to mass movements is highest in Karakoram, whereas central Himalaya has the highest exposed waterways. The hotspots of exposed roadways are concentrated in Nepal, the North Indian states of Uttarakhand, Himachal Pradesh, the Union Territory of Ladakh, and China's Sichuan Province. Our analysis shows that the population in the central Himalaya is currently at the highest exposure to mass movement impacts. Projected future populations based on Shared Socio‐economic and Representative Concentration Pathways suggest that changing settlement patterns and emission scenarios will significantly influence the potential impact of these events on the human population. Assessment of anticipated secondary hazards (glacial lake outburst floods) shows an increase in probable headward impacts of mass movements on glacial lakes in the future. Our findings will support researchers, policymakers, stakeholders, and local governments in identifying critical areas that require detailed investigation for risk reduction and mitigation. Plain Language Summary Avalanches and landslides are common in mountainous terrain like the Himalaya. Failure of the steep slopes can threaten infrastructure and population in the downstream regions. Also, such failures in glaciated terrain can potentially impact high‐altitude lakes, thereby leading to downstream flooding. The assessment carried out in this study covering the mountain ranges in the Hindukush Karakoram Himalaya identifies the exposed elements, including buildings, roadways, waterways, population, and glacial lakes to potential mass movements. Further, downstream impact from glacial lake outburst depends on the location of the lake with respect to the mass movement impact direction, that is, stri