No abstract

The Hindu Kush range of northern Pakistan has a large variety of Alpine and valley glaciers. These glaciers are subjected to volumetric changes owing to a host of factors (i.e., altitude, slope, glacier types, and aspect). The geodetic survey and eld-based data are not available for assessment of glacier's ELA for the Hindu Kush due to rough topography and rigorous climate. However, the mass balance of the alpine and valley glaciers can be obtained through Equilibrium Line Altitude (ELA) and Accumulation Area Ratio (AAR). Therefore, this study deals with the estimation of ELA, the hypsometrically controlled methods based on AAR and Accumulation Area Balance Ratio (AABR). The various ratio of AAR and AABR is applied to obtain the glacier ELAs of valley glaciers. AAR-ELAs are estimated based on ratios between 0.4-0.8 with 0.05 interval a d 0.67-4.4 with 0.01 for AABR-ELAs Moreover, the glacier contours with the interval of 50 m ± 5 m are employed for these estimations. This technique adjusted glacier hypsometry and area with the constant AAR ratio (rather than constant glacier area) to calculate the ELA variations. The results show that for AAR (0.5), 50m ELA declined from 5409 to 5359 m and reducing 4% the geometric area. The maximum decrease of 150 m ELA for these glaciers is reported for the AAR-AABR ratio 0.1-4.4, showing a signi cant decrease. The estimated decrease in the glacier area of Hindu-Kush glaciers is extremely variable speci cally in Phargam, Khorabohr and Gordoghan.

The Hindu Kush range of northern Pakistan has a large variety of Alpine and valley glaciers. These glaciers are subjected to volumetric changes owing to a host of factors (i.e., altitude, slope, glacier types, and aspect). The geodetic survey and field-based data are not available for assessment of glacier’s ELA for the Hindu Kush due to rough topography and rigorous climate. However, the mass balance of the alpine and valley glaciers can be obtained through Equilibrium Line Altitude (ELA) and Accumulation Area Ratio (AAR). Therefore, this study deals with the estimation of ELA, the hypsometrically controlled methods based on AAR and Accumulation Area Balance Ratio (AABR). The various ratio of AAR and AABR is applied to obtain the glacier ELAs of valley glaciers. AAR-ELAs are estimated based on ratios between 0.4–0.8 with 0.05 interval a d 0.67–4.4 with 0.01 for AABR-ELAs Moreover, the glacier contours with the interval of 50 m ± 5 m are employed for these estimations. This technique adjusted glacier hypsometry and area with the constant AAR ratio (rather than constant glacier area) to calculate the ELA variations. The results show that for AAR (0.5), 50m ELA declined from 5409 to 5359 m and reducing 4% the geometric area. The maximum decrease of 150 m ELA for these glaciers is reported for the AAR-AABR ratio 0.1–4.4, showing a significant decrease. The estimated decrease in the glacier area of Hindu-Kush glaciers is extremely variable specifically in Phargam, Khorabohr and Gordoghan.

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.