Lhonak Lake
Why In News ?
- Recent flash floods in north Sikkim resulted from the bursting of the South Lhonak Lake. This flood occurred due to continuous rain and rising water level in Teesta river.
Important Fact:
- Glaciers are large masses of ice that form from the accumulation and compaction of snow over long periods. They flow slowly downhill under their weight and gravity, shaping the landscape and playing a crucial role in Earth’s climate and hydrology by storing and releasing freshwater.
- Glaciers cover ∼10% of the Earth’s land surface, but they are shrinking rapidly across most parts of the world, leading to cascading impacts on downstream systems.
- An international team of researchers conducted a study two years ago and warned that South Lonak Lake in Sikkim could burst in the future and significantly affect the downstream area.
In the context of Glacial Lake Outburst Flood (GLOF):
- According to NDMA (National Disaster Management Authority), glacial retreat due to climate change occurring in most parts of the Hindu Kush Himalayas has given rise to the formation of numerous new glacial lakes, which are the major cause of GLOFs.
- Glacial lakes, like South Lhonak Lake, form in front of, on, or beneath melting glaciers.
- As they grow, they become more dangerous, often dammed by unstable ice or sediment.
- If the dam breaks, a huge amount of water flows downstream, causing floods and this is called GLOF..
- These floods can be triggered by a number of factors, including changes in the volume of the glacier, changes in the water level of the lake, and earthquakes.
Reasons why South Lonak Lake is vulnerable to GLOF:
- With the rising global temperatures, glaciers in Sikkim Himalayan have been melting rapidly, giving rise to many glacier lakes and expanding the already existing ones in the region.
- According to the Sikkim State Disaster Management Authority (SDMA), there are currently more than 300 glacial lakes in Sikkim Himalayan, and 10 (including South Lhonak Lake) have been identified as vulnerable to outburst floods.
- Lhonak has grown nearly 1.5 times and South Lhonak nearly 2.5 times their initial size in 1989.
- An earthquake of magnitude 4.9 in 1991 near the parent glacier feeding the South Lhonak Lake and the recent earthquake (6.9) in 2011 may have weakened the boundaries of the lake.
Source – The Hindu
