Estimation of Glacier Equilibrium Line Altitude in the Hunza River Basin of Northern Karakoram, Pakistan

Abstract

Hunza River Basin (research region) in the Karakoram Himalaya is distinctive for a variety of reasons. Firstly, the glaciated areas have a greater mean altitude as compared to other glaciated landscapes in the Karakoram, Secondly, the basin is occupied by both debris and clean ice glaciers. Thirdly, the glaciated region is more vulnerable to the mountain communities living downstream. It is very crucial to comprehend the strength of the topography or morphology of the surface and the likely effects of changing glacial ice, which can alter how material is transported from higher to lower elevations. For those living downstream, the ice masses and snow of the Hunza River Basin (HRB) provide a vital source of fresh water. These readily available ice and snow masses are significantly impacted by changing climatic conditions. There are many kinds of glaciers in Pakistan's Karakoram region like Alpine or valley glaciers. Due to climate change, these glaciers may have an impact on the population living downstream through avalanches and surge occurrences. Therefore, it is crucial to monitor the glaciers. Equilibrium line altitude (ELA) is a measure of mass balance. Due to the rough terrain covered in glaciers and the paucity of climate data above 5000 masl, field measurements for the measurement of ELA of most of the Karakorum glaciers are not easily accessible. However, in this study we used the hypsometrically controlled accumulation area ratio AAR (0.6) and accumulation area balance ratio AABR (2.24) techniques to estimate ELAs and reconstruct the relation between climate and glacier data in the Hunza River Basin of the Karakoram region. This method adjusted glacier geometry (area) to future ELA shifts by applying recommended AAR rather than constant glacier area. Batura Glacier's geometry was altered by 32% by a 380m ELA decrease from 5049- 4668 m with a steady AAR of 0.6-0.45. The biggest losses in glacier-ice area are anticipated for top-heavy glaciers (Hisper, Batura and Kukuar), whose expected geometrical losses are widely varied. It is determined that the reconstructed three-dimensional glacier surfaces have a significant impact on the quality of ELAs.