Glacial Lakes in the Himalayas Using Satellite Remote Sensing
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The Indian Space Research Organisation (ISRO) recently conducted an extensive analysis of glacial lakes in the catchments of Indian Himalayan river basins. Leveraging satellite remote sensing technology, ISRO’s study sheds light on the expansion of these lakes and the associated risks.
Key Findings:
Expansion of Glacial Lakes: ISRO examined satellite data archives spanning four decades (1984 to 2023) to assess changes in the glaciated environment. Among the 2,431 lakes larger than 10 hectares identified during 2016-17, 676 glacial lakes had significantly expanded since 1984. Glacial lakes are expanding due to the retreat of glaciers, which is accelerating due to global warming.
Geographical Distribution: 130 of the 676 lakes are situated in India, specifically in the: Indus basin (65 lakes), Ganga basin (7 lakes), Brahmaputra basin (58 lakes).
Formation of Glacial Lakes: The movement of glaciers causes erosion, creating depressions in the surrounding topography. As glaciers retreat, meltwater accumulates in these depressions, giving rise to glacial lakes.
ISRO categorized glacial lakes into four types:
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- Moraine-dammed: Formed when water is dammed by moraine (debris left during glacier movement).
- Ice-dammed: Formed when water is dammed by ice.
- Erosion-based: Formed when water is dammed by erosion-created depressions.
- Others: Additional categories based on formation mechanisms.
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Risks and Impacts: While glacial lakes serve as crucial freshwater sources for rivers, they also pose significant risks. Glacial Lake Outburst Floods (GLOFs) occur when these lakes release large volumes of meltwater due to natural dam failure. GLOFs can lead to sudden and severe flooding downstream, impacting infrastructure and settlements.
ISRO’s satellite-based analysis provides valuable insights into glacial lake dynamics, glacier retreat rates, and the risks associated with GLOFs.