Mangan, 1st Sept: A scientific team has completed a major expedition to South Lhonak Lake and nearby glacial lakes in North Sikkim from August 26 to September 1, 2025. The mission focused on assessing the condition of South Lhonak and other high-altitude lakes that could trigger GLOFs (Glacial Lake Outburst Floods) in the future, similar to the devastating flood that had earlier struck Sikkim.
Key Findings from the Expedition
- South Lhonak Lake (17,200 ft): Scientists studied the lake’s depth (bathymetry), checked water pressure, and collected mud and soil left after the flood. These studies will help to know how much water the lake holds and how safe it is.
- Changsang Lake (18,100 ft): The team mapped the lake and examined the moraine — the natural wall of rocks and soil holding the lake water. If this wall breaks, it can release large amounts of water suddenly.
- Yuleh Khangse Lake: Preparations began to study this lake above Lashar Valley. This is part of a larger plan to monitor more lakes in high-altitude areas.
- Teamwork of Experts: The mission included scientists from Himachal Pradesh, NIH (National Institute of Hydrology), CWC (Central Water Commission), DGRE (Defence Geoinformatics Research Establishment), and GSI (Geological Survey of India).
- Focus on Safety: The main goal of the mission is to improve early warning systems and prevent disasters by understanding the risks better.

What is a GLOF?
- Glacial Lake Outburst Flood (GLOF): When a lake formed by melting glaciers suddenly bursts and floods downstream.
- This happens if the natural wall (moraine) holding the water breaks due to heavy rain, earthquake, or glacier melting.
- Example: The South Lhonak flood that happened earlier in Sikkim.
Click Here for Details report about the Expedition 2025
What is a Moraine?
- A moraine is a pile of rocks, mud, and soil left behind by glaciers.
- Many glacial lakes are held back by these moraines, which are not very strong. If they collapse, floods occur.

Are There Chances of Another GLOF?
- The study does not say there is an immediate danger, but it shows these lakes are sensitive and risky.
- Scientists are checking them closely because the chances of a similar GLOF in the future cannot be ignored.
- That is why continuous monitoring, safety planning, and early warning systems are being developed.
Why This Matters
The Himalayas are full of glacial lakes, and climate change is melting glaciers faster. This increases the amount of water stored in these lakes and raises the chances of floods. Monitoring and preparedness are the only ways to keep communities safe.
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