New inventory and dynamics of glacial lakes in Alaknanda basin, Uttarakhand, India from 1990 to 2020: A multi-temporal landsat analysis

Glacial lakes are critical components of high-altitude mountainous regions in the Himalayas. In recent years, glaciers have rapidly receded due to climate change, resulting in the formation of glacial lakes with substantial risks for downstream communities and infrastructure. The present study uses Landsat satellite data to create a comprehensive glacial lake inventory in the Alaknanda Basin, focusing on spatiotemporal changes between 1990 and 2020. The study has recorded 73 glacial lakes (≥0.003 km²) with a total surface area of 2.538 ± 0.037 km² in 2020. The mean depth and volume of glacial lakes were assessed as 7.17 m and 0.432 x 10⁶m³, respectively. During 1990–2020, the total glacial lake area has increased from 0.748 ± 0.020 km² to 2.538 ± 0.037 km² with a growth of ∼1.790 km² (239%; 7.97% a⁻¹). Additionally, 15 common glacial lakes have shown significant growth rates of 91.24% (3.04% a^-1). Among all the glacial lakes, tiny lakes (<0.02 km²) have shown the maximum growth in both numbers (+33) and area (477.92%; 15.93% a⁻¹). Moraine-dammed lakes have expanded more rapidly in terms of number (+27), while supraglacial lakes have exhibited a higher rate of areal (1771.71%; 59.06% a⁻¹) expansion. Based on the current inventory, flood hazard studies in the Alaknanda Basin can be carried out for a better understanding of glacial-climate related dynamics.