Satopanth and Bhagirath Kharak Glacier snowline (blue dots) on Oct. 8, 2020 (Sentinel image) mean elevation is 5350 m. T=Terminus location and blue line is flowline with distance from terminus in km.

Satopanth and Bhagirath Kharak Glacier are located at the headwaters of the Alaknanda River, Uttarakhand, India and have until recently shared a terminus. Glacier runoff is an important contribution to the 400 MW Vishnuprayag and 330 MW Alaknanda Hydroproject. Recent glacier behavior summarized by Thapliyal et al (2023)indicates retreat rates For Satopanth of 23.5 m/year and for Bhagirath Kharak of 18.5 m/year from 1968-2017. They also report a reduction of snowcover during a period of warming from 2000-2020. They considered the accumulation zone to be from 4500 m to 5600 m. Here we examine Sentinel images from Oct. 8, 2020 and Oct. 8 2023 indicating the snowline at 5350 m and 5250 m respectively. On Satopanth Glacier the glacier is 14 km long with ~87% of that length in the ablation zone both years. On Bhagirath Kharak Glacier the glacier is 16.5 km long with ~90% of its length in the ablation zone both years. A glacier needs more than 50% of its area to be in the accumulation zone, which means a snowline in the 4600 m range. The higher snowlines in recent years will drive an increased glacier loss. Below 4600 m debris cover dominates. Shah et al (2019) estimated mean sub-debris ablation ranges between 1.5±0.2 to 1.7±0.3 cm/day leading to thinning of this zone of the glacier.

Satopanth and Bhagirath Kharak Glacier snowline (blue dots) on Oct. 8, 2023 (Sentinel image- mean elevation is 5250 m. T=Terminus location. 90% of the length of each glacier is in the ablation zone.

Vishnuprayag Hydropower Plant a 400 MW run of river project 18 km downstream of Satopanth Glacier.