Glacier retreat, dynamics and bed overdeepenings of Parkachik Glacier, Ladakh Himalaya, India

This study describes the morphological and dynamic changes of Parkachik Glacier, Suru River valley, Ladakh Himalaya, India. We used medium-resolution satellite images; CORONA KH-4, Landsat and Sentinel-2A from 1971-2021, and field surveys between 2015 and 2021. In addition, we used the laminar flow-based Himalayan Glacier Thickness Mapper and provide results for recent margin fluctuations, surface ice velocity, ice thickness, and identified glacier-bed overdeepenings. The results revealed that overall the glacier retreated by -210.5 +/- 80m with an average rate of 4 +/- 1ma(-1) between 1971 and 2021. Whereas a field study suggested that the glacier retreat increased to -123 +/- 72m at an average rate of -20 +/- 12ma(-1) between 2015 and 2021. Surface ice velocity was estimated using COSI-Corr on the Landsat data. Surface ice velocity in the lower ablation zone was 45 +/- 2ma-(1) in 1999-2000 and 32 +/- 1ma(-1) in 2020-2021, thus reduced by 28%. Further, the maximum thickness of the glacier is estimated to be similar to 441m in the accumulation zone, while for glacier tongue it is similar to 44 m. The simulation results suggest that if the glacier continues to retreat at a similar rate, three lakes of different dimensions may form in subglacial overdeepenings.