Mass balance and morphological evolution of the Dokriani Glacier,central Himalaya,India during 1999-2014

• 作者: Purushottam Kumar Garg Jairam Singh Yadav Santosh Kumar Rai Aparna Shukla
• 来源期刊: 地学前缘（英文版）
• 年，卷（期）: 2022,（1）
• 所属期刊栏目: Research Paper
• 页码范围: 255-267
• 页数: 13页
• 语种: 英文

摘要

Glaciological mass balance (MB) is considered the most direct,undelayed and unfiltered response of the glaciers to climatic perturbations.However,it may inherit errors associated with stake under-representation,averaging over the entire glacier and human bias.Therefore,proper validation of glacio-logical MB with geodetic MB is highly recommended by the World Glacier Monitoring Service (WGMS).The present study focuses on the Dokriani Glacier,central Himalaya which is one of the bench-mark gla-ciers in the region and has glaciological MB records from 1993 to 2013 with intermittent gaps.In the pre-sent study,firstly the glaciological MB series is extended to 2014 i.e.,field-based MB for one more year is computed and,to compare with it,the geodetic MB is computed for the 1999-2014 period using high resolution Cartosat-1 digital elevation model (DEM) and SRTM DEM.Finally,the study assesses the regio-nal representation of the Dokriani Glacier in terms of MB and evaluates the influence of the MB regime on its morphological evolution.Results show that the average glaciological MB (-0.34 ± 0.2 m water equiv-alent (w.e.) y-1) is more negative than the geodetic MB (-0.23 ± 0.1 m w.e.y-1) for the 1999-2014 per-iod.This is likely because of the partial representation of glacier margins in the glaciological MB,where melting is strikingly low owing to thick debris cover (＞30 cm).In contrast,geodetic MB considers all mar-ginal pixels leading to a comparatively low MB.A comparative assessment shows that the MB of Dokriani Glacier is less negative (possibly due to its huge accumulation area) than most other glacier-specific and regional MBs,restricting it to be a representative glacier in the region.Moreover,continuous negative MB has brought a peculiar change in the epiglacial morphology in the lower tongue of the glacier as differ-ential debris thickness-induced differential melting has turned the glacier surface into a concave one.This concavity has led to development of a large (10-20 m deep) supraglacial channel which is expanding incessantly.The supraglacial channel is also connected with the snout wall and accelerates terminus dis-integration.Given the total thickness of about 30-50 m in the lower glacier tongue,downwasting at its current pace,deepening/widening of supraglacial channel coupled with rapid terminus retreat may lead to the complete vanishing of the lower one km glacier tongue.