Introduction: The Indian Space Research Organisation (ISRO) has analyzed satellite imagery of the Indian Himalayan river basins from 1984 to 2023, revealing that more than 27% of identified glacial lakes have expanded since 1984.
Key Findings:
- Expanding Glacial Lakes: Among the 2,431 lakes larger than 10 hectares identified during 2016-17, around 676 glacial lakes have notably expanded since 1984.
- Expansion Details: Out of these 676 lakes:
- 601 lakes have more than doubled in size.
- 10 lakes have grown between 1.5 to 2 times.
- 65 lakes have expanded by 1.5 times.
- Location: 130 of these lakes are within India, with:
- 65 in the Indus river basin.
- 7 in the Ganga river basin.
- 58 in the Brahmaputra river basin.
- Expansion Details: Out of these 676 lakes:
- Elevation-Based Analysis:
- 314 lakes are in the 4,000 to 5,000 meters elevation range.
- 296 lakes are above 5,000 meters.
- Classification of Glacial Lakes:
- Moraine-dammed: 307 expanding lakes.
- Erosion: 265 expanding lakes.
- Other Glacial Lakes: 96 expanding lakes.
- Ice-dammed: 8 expanding lakes.
Case Study:
- Ghepang Ghat Glacial Lake: Located in the Indus River Basin at an elevation of 4,068 meters in Himachal Pradesh, this lake increased by 178% in size (from 36.49 to 101.30 hectares) between 1989 and 2022, with an annual growth rate of about 1.96 hectares.
Significance of Glacial Lakes:
- Vital Freshwater Sources: These lakes, formed by melting glaciers, are crucial freshwater sources for Himalayan rivers.
- Risk of Glacial Lake Outburst Floods (GLOFs): GLOFs pose significant risks, occurring when glacial lakes release large volumes of meltwater due to the failure of natural dams.
Additional Insights:
- The satellite-derived analyses provide crucial information for:
- Assessing environmental impacts.
- Developing strategies for GLOF risk management.
- Climate change adaptation in glacial environments.
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