Two Decades of Glacier and Glacial Lake Change in the Dhauladhar Mountain Range, Himachal Himalayas, India (2000–2020)

This study represents a first of its kind effort in generating a comprehensive database of glaciers (74) and glacial lakes (43) in the Dhauladhar Mountain Range (DMR) located in the Himachal Himalaya region using cloud-free remote sensing data during 2000–2020. The database was constructed by utilizing satellite imagery with varying resolutions, including Landsat 7 ETM + (2000; 30/15 m), Sentinel 2A (2020; 10 m), LISS IV (2020; 5.8 m), and Planet Scope (2020; 3 m). Furthermore, by utilizing slope-dependent numerical approaches, power scaling methods, and modelling techniques (GlabTop2 and HIGTHIM), an attempt has been undertaken to assess the glacier ice thickness, volume and water stored in the DMR. The overall extent of glaciers has exhibited a decline from 50.8 (± 4.38 km 2 ) to 42.84 (± 0.83 km 2 ) during the course of the past two decades (2000–2020), resulting in a total reduction of 7.98 ± 4.45 km 2 (~ 15.71 ± 8.76%). Nevertheless, while considering glacier lakes, there has been an observed increase in both number and size. Specifically, the number of glacier lakes has risen from 36 (with an average area of 0.91 ± 0.36 km 2 ) in 2000 to 43 (with an average area of 1.18 ± 0.08 km 2 ) in 2020. This represents a growth rate of 19.45% in terms of number and 29 ± 40.5% in terms of size. The presence of seven newly formed lakes can be attributed to their proglacial nature, indicating and providing evidence for the retreat of the glacier that previously occupied the area. The estimation of ice thickness utilizing the GlabTop2 and HIGTHIM models indicates a range of ice thickness from 9 ± 0.9 to 111.69 ± 11.7 m, with mean values of 36.51 ± 3.63 and 33.37 ± 4.32 m, respectively. The estimated volume and mass of glacier ice are reported as 10.4 ± 0.24 km 3 and 9.36 ± 0.22 gigatons, respectively. Our meteorological trend analysis suggests that temperature increases with a slope of 0.023 °K a −1 and precipitation decrease with a slope of 1.425 mm a −1 between 1940 and 2022. Increased accumulation season temperature (winter time) is the primary cause for the reduction of glacier coverage. This study provides a comprehensive assessment of glacier dynamics and their impact on water supply. The generated glacier lake inventory assumes significance specifically for the stakeholders in the formulation of a complete risk assessment strategy for future glacier lake outburst floods.