Abstract Pakistan’s Karakoram region has a large variety of glacier types. Equilibrium line altitude (ELA) of alpine or valley glaciers represents mass balance. Field observations for estimation of ELA of the majority of Karakoram’s glaciers are not available due to rugged glacier-covered terrains and lack of climatic data above 5000 masl. Therefore, we applied the hypsometrically controlled accumulation area ratio (AAR) and accumulation area balance ratio (AABR) methods for ELA estimation and glacier–climate reconstructions in the Shigar River Basin of the Karakoram region. Constrained by mountain topography, larger size and type of glaciers, several ranges of ELA are calculated and implemented for several ratios. Two parameters (ratio and interval) are provided to calculate AAR-ELAs between 0.4 and 0.8 with 0.05 interval and AABR-ELAs between 0.9 and 4.4 with 0.01 interval. By providing constant AAR (rather than constant glacier area), this approach adjusted glacier geometries (area) to future ELA variations. For constant AAR of 0.4–0.45, a 90-m ELA decrease from 5769 to 5679 m of Baltoro glacier adjusted its geometries by reducing ~ 5% area. The highest decrease of 140-m ELA of the same glacier is reported for constant AAR of 0.7–0.75, revealing a significant loss of 8% geometries. The projected geometry losses for all these glaciers are highly variable, with top-heavy glaciers (Biafo and Baltoro) projected to experience the major losses in glacier-ice area. It is concluded that the quality of ELAs is highly dependent on the reconstructed three-dimensional glacier surfaces.
Northern latitudes of Pakistan are warming at faster rate as compared to the rest of the country. It has induced irregular and sudden glacier fluctuations leading to the progression of glacial lakes, and thus enhancing the risk of Glacier Lake Outbursts Floods (GLOF) in the mountain systems of Pakistan. Lack of up-to-date inventory, classification, and susceptibility profiles of glacier lakes and newly formed GLOFs, are few factors which pose huge hindrance towards disaster preparedness and risk reduction strategies in Pakistan. This study aims to bridge the existing gap in data and knowledge by exploiting satellite observations, and efforts are made to compile and update glacier lake inventories. GLOF susceptibility assessment is evaluated by using Analytical Hierarchy Process (AHP), a multicriteria structured technique based on three susceptibility contributing factors: Geographic, topographic, and climatic. A total of 294 glacial lakes are delineated with a total area of 7.85 ± 0.31 km2 for the year 2018. Analysis has identified six glacier lakes as potential GLOF and met the pre-established criteria of damaging GLOFs. The historical background of earlier GLOF events is utilized to validate the anticipated approach and found this method appropriate for first order detection and prioritization of potential GLOFs in Northern Pakistan.
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