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Abstract:
The debris-covered glaciers' (DCGs) evolution is complicated and differs significantly from the debris-free ones. Though the impact of supraglacial debris in altering the glacier processes and response is recognized, it is irregularly investigated in the Himalaya. DCGs (relative to the debris-free ones) frequently develop geomorphic features like ice-cliffs and supraglacial ponds, which enhance the localized melting of the glacier surface and ultimately affect the runoff variability. Therefore, to comprehend the morphological evolution and the distinctive behaviour of the DCGs relative to their cleaner counterparts, it is crucial to investigate them. Accordingly, the present study focused on multiparametric and multitemporal assessment of the Lalung glacier (area: 44 km2, length: 13 km), western Himalaya from 1971-2018 using geospatial techniques. Lalung is a north-east facing, DCG, with 17% of the glacier area covered with debris. Results suggest a retreat of 630 m (rate: 13 ma-1), with an overall glacier shrinkage of 5% and debris accumulation of 30% during 1971-2018. The end of summer snow line altitude has increased by 303 ±58 (Standard deviation) m during 1977-2018. The glacier has slowed down by 0.4% during 1993-2018 and shown a mass loss of -0.96 m.w.e a-1 during 2000-2017. The decadal analysis revealed a doubling of retreat and shrinkage rates (19 ma-1 and 0.06 km2a-1) post-2000. The overall glacier status suggests its degenerative pattern, which is in sync with the other western Himalayan glaciers. Meanwhile, the enhanced glacier degenerationpost-2000 may be attributed to the differential debris distribution and densification of geomorphic attributes such as ice cliffs.
