Spatiotemporal glacier dynamics over the Rulung and Gyama massifs, Ladakh (2000–2018): Influences of topographic and climatic factors

Long-term observations of glacier dynamics are crucial for understanding past climatic shifts and assessing current glacier conditions. The Ladakh region, known for its high-altitude arid landscape, amasses about 40% of Indian glacier wealth, which is vital for local communities who rely on meltwater for their water needs. However, human-induced warming has accelerated glacier depletion globally, including in the Trans-Himalayas. Despite its importance, Ladakh remains underrepresented in glaciological research, highlighting the need for continued studies on glacier dynamics in the region. Glacier velocity and mass balance is interlinked with each other and is a manifestation of mass change in the glacier system. This study aims to present inter-annual glacier velocity over the Rulung and Gyama massifs of Karzok range, Ladakh using the global dataset i.e. ITS_LIVE which is available from 1980s to 2018, calculated using multiple satellite missions. Furthermore, mass balance calculations are performed to quantify changes in glacier mass. This study also evaluates the influence of both climatic and topographic factors on glacier dynamics. The Rulung and Gyama massifs contain 52 and 100 glaciers, respectively, covering total areas of 22.2 ± 1.4 km² and 44.9 ± 2.7 km². Notably, the glaciers in both massifs are relatively small, with average sizes of 0.39 km² for Rulung and 0.45 km² for Gyama. Consequently, the magnitude of glacier velocity is also low. The surface velocity of Rulung Glacier ranges from 0.37 ± 0.21 m/y to 8.17 ± 2.80 m/y, with an average of 2.33 ± 1.63 m/y. In contrast, the velocity of Gyama Glacier varies from 0.40 ± 0.11 m/y to 6.53 ± 3.32 m/y, with an average of 1.73 ± 0.70 m/y. Over the study period, the velocity across both massifs exhibited a decreasing trend, with an average slowdown of 0.05 m/y (31%) in Rulung and 0.01 m/y (8%) in Gyama. Both glaciers show a negative mass balance, with rates of -0.17 ± 0.03 m w.e./y for Rulung and -0.07 ± 0.01 m w.e./y for Gyama. The observed slowdown in glacier velocity and the associated mass loss can be attributed to sustained warming in the region and an erratic precipitation pattern, both of which primarily govern glacier dynamics. The decreasing velocity and negative mass balance are interlinked, as reduced flow rates often correlate with a loss of glacier mass, further accelerating the retreat and thinning of glaciers. Additionally, regional heterogeneity in velocity patterns can be explained by topographic factors, which exert a significant influence on glacier dynamics The overall decline in both glacier velocity and mass balance highlights the ongoing depletion of glaciers in the region, posing a substantial threat to water security and increasing the risk of natural hazards to communities living in close proximity to the glaciers. The study recommends timely attention towards depleting glaciers to better manage the important water resources. 

Keywords: Glacier changes, remote sensing, glacier mass balance, glacier velocity, climate change, Karzok Range, Ladakh Himalaya