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The influence of debris cover and glacial lakes on the recession of glaciers in Sikkim Himalaya, India


Basnett, Smriti; Kulkarni, Anil V; Bolch, Tobias (2013). The influence of debris cover and glacial lakes on the recession of glaciers in Sikkim Himalaya, India. Journal of Glaciology, 59(218):1035-1046.

Abstract

We investigated area changes in glaciers covering an area of 200 km2 in the Tista basin, Sikkim, Eastern Indian Himalaya, between 1990 and 2010 using Landsat Thematic Mapper (TM) and Indian Remote-sensing Satellite (IRS) images and related the changes to debris cover, supraglacial lakes and moraine-dam lakes. The glaciers lost an area of 3.3`0.8% between 1989/90 and 2010. More detailed analysis revealed an area loss of 2.00 ` 0.82, 2.56 ` 0.61 and 2.28 ` 2.01 km2 for the periods 1989–97, 1997–2004/05 and 2004–2009/10, respectively. This indicates an accelerated retreat of glaciers after 1997. On further analysis, we observed (1) the formation and expansion of supraglacial lakes on many debris-covered glaciers and (2) the merging of these lakes over time, leading to the development of large moraine-dam lakes. We also observed that debris-covered glaciers with lakes lose a greater area than debris-covered glaciers without lakes and debris-free glaciers. The climatic data for 24 years (1987–2011), measured at the Gangtok meteorological station (1812 m a.s.l.), showed that the region experienced a 1.08C rise in the summer minimum temperature and a 2.08C rise in the winter minimum temperature, indicating hotter summers and warmer winters. There was no significant trend in the total annual precipitation. We find that glacier retreat is caused mainly by a temperature increase and that debris-covered glaciers can retreat at a faster rate than debris-free glaciers, if associated with lakes.

We investigated area changes in glaciers covering an area of 200 km2 in the Tista basin, Sikkim, Eastern Indian Himalaya, between 1990 and 2010 using Landsat Thematic Mapper (TM) and Indian Remote-sensing Satellite (IRS) images and related the changes to debris cover, supraglacial lakes and moraine-dam lakes. The glaciers lost an area of 3.3`0.8% between 1989/90 and 2010. More detailed analysis revealed an area loss of 2.00 ` 0.82, 2.56 ` 0.61 and 2.28 ` 2.01 km2 for the periods 1989–97, 1997–2004/05 and 2004–2009/10, respectively. This indicates an accelerated retreat of glaciers after 1997. On further analysis, we observed (1) the formation and expansion of supraglacial lakes on many debris-covered glaciers and (2) the merging of these lakes over time, leading to the development of large moraine-dam lakes. We also observed that debris-covered glaciers with lakes lose a greater area than debris-covered glaciers without lakes and debris-free glaciers. The climatic data for 24 years (1987–2011), measured at the Gangtok meteorological station (1812 m a.s.l.), showed that the region experienced a 1.08C rise in the summer minimum temperature and a 2.08C rise in the winter minimum temperature, indicating hotter summers and warmer winters. There was no significant trend in the total annual precipitation. We find that glacier retreat is caused mainly by a temperature increase and that debris-covered glaciers can retreat at a faster rate than debris-free glaciers, if associated with lakes.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Geography
Dewey Decimal Classification:910 Geography & travel
Language:English
Date:2013
Deposited On:17 Dec 2013 08:22
Last Modified:05 Apr 2016 17:15
Publisher:International Glaciological Society
ISSN:0022-1430
Publisher DOI:https://doi.org/10.3189/2013JoG12J184
Permanent URL: https://doi.org/10.5167/uzh-86634

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