Spatio-temporal change in the glaciers of Astore Basin (North-Western Himalaya), between 2016 and 2021 by using Sentinel-2 satellite data

Abstract

Abstract The Pakistani Himalayan glaciers are major component of freshwater environment. However, previous studies suggest that their existence is under direct of global warming. we estimated the glacier dynamics of Bazin, Chhongpher and Chongra glaciers in Astore Basin (Northwestern Himalaya) in terms of Equilibrium Line Altitude (ELA), snout variation position and statistical analysis of climate trends assessment between 2016 and 2021. A quaterly trend analysis was carried out on climate data (temperature, precipitation, river discharge) to evaluate the climate pattern in the Astore Basin. The net retreating change is higher in the Bazin glacier (2.1 sqkm) as compared to the Chhongpher (1.1 Sqkm) and Chongra (1.2 Sqkm) glaciers. A maximum retreat of the snout position was observed as 1595 m in Bazin glacier, 3260 m in Chhongpher glacier, and 960 m in Chongra glacier. In the Astore Basin of the Himalaya region we applied the accumulation area ratio (AAR) and accumulation area balance ratio (AABR) for ELA calculation. Two parameters are provided to determine AAR-ELAs with 0.05 interval between 0.4 and 0.8 and AABR-ELAs with 0.01 interval between 0.9 and 4.4. A 200 m ELA decrease from 6021 to 5821 m of Bazin glacier adjusted its geometries for constant AAR of 0.4–0.45, by reducing ~ 8% area. Furthermore, it is concluded that the value of ELAs is extremely dependent on the rebuilt three dimensional glacier surfaces.