Integrated assessment of glacial lake outburst flood hazard using remote sensing and 2D hydrodynamic modelling in the Chenab Basin, Western Himalaya

Rapid glacier retreat in the Western Himalaya caused by climate change has substantially transformed glacier and glacial-lake systems, increasing the likelihood of glacial lake outburst floods (GLOFs). This study provides an integrated multi-decadal assessment of glacier dynamics, glacial lake evolution, potentially dangerous glacial lakes (PDGLs) and downstream GLOF hazards in the Chenab Basin during 2000–2025 using multi-sensor satellite observations, empirical hazard assessment and two-dimensional hydrodynamic modelling. Landsat-derived glacier extent, normalized difference snow index (NDSI), normalized difference water index (NDWI), and glacial lake inventories were validated with Google Earth and existing datasets. The results indicate significant glacier retreat, especially after 2010, accompanied by rapid expansion of glacial lakes and a shift toward larger proglacial lakes with higher outburst potential. In 2025, 289 glacial lakes covering 9.71 km2 were identified, including 12 high-hazard lakes. Hydrodynamic simulations of Gepang Gath, Samundar Tapu, and Khawar lakes revealed highly variable flood magnitudes and downstream impacts controlled by lake volume and breach dynamics.