Hydroclimatic controls on glacier mass balance in the Gangotri region, western Himalaya: a multi-temporal geodetic assessment

Glaciers in the Gangotri region have experienced sustained retreat and mass loss, raising concerns for regional water security. This study presents a multi-temporal geodetic mass-balance assessment of 302 glaciers in the Gangotri region for 2002–2019. Advanced Spaceborne Thermal Emission and Reflection Radiometer-derived digital elevation models, Inter-mission Time Series of Land Ice Velocity and Elevation glacier velocity data, and European Centre for Medium-Range Weather Forecasts Reanalysis v5-Land data were integrated to quantify glacier mass loss, elevation change, ice-surface velocity, and climatic variability. Results indicate a cumulative loss of −4.65 ± 0.03 m w.e. with massloss rates increasing from −0.29 ± 0.03 to −0.42 ± 0.03 m w.e. a−1. The massloss coincided with generally warmer climatic conditions and highly variable precipitation over the region. Higher-elevation glaciers showed lower losses, while declining ice velocities indicate possible dynamic adjustment, interpreted cautiously given known data limitations. These findings support continued glacier monitoring and water-resource assessment.