Fast-Growing Glacial Lake in Uttarakhand Himalayas Raises Worries

• 09 Mar 2024

Why in News?

According to the scientists at Dehradun-based Wadia Institute of Himalayan Geology (WIHG), the Bhilangana glacial lake situated in the Bhagirathi catchment has grown to about 0.38 sq km area in the last 47 years and can pose a potential threat to people downstream.

Key Points

• Glacial lakes form when the vast sheet of glaciers starts melting and the melt water gets accumulated.
  • As the global temperatures rise and climate change intensifies, many of the glaciers have also begun to withdraw at a rapid rate, triggering the formation of numerous such glacial lakes, which, if unstable, can send torrents of water downstream and wreak disastrous floods.
• Studies show that over a thousand such glacial lakes have formed in the Uttarakhand Himalayas, but their understanding is limited due to lack of adequate ground-based studies.
  • 13 such glacial lakes are identified in Uttarakhand that are moraine-dammed lakes and around ten glaciers which are being continuously monitored, as they may pose threat to people downstream.
  • Similar to this was experienced in 2013 in Kedarnath, 2021 in the Rishiganga- Dhauliganga glacial avalanche, and more recently in Sikkim’s South Lhonak Lake.
• According to the Geological Survey of India (GSI), there are about 9,575 glaciers in the Indian Himalayan Region (IHR), only 980 of them lie in the north-western state of Uttarakhand and the most sensitive ones are being continuously monitored by the team.
• The largest glacier in Uttarakhand Himalayas, Gangotri Glacier with a length of nearly 30 kms is retreating at a rate of about 15-20 metres per year.

Wadia Institute of Himalayan Geology (WIHG)

• The Wadia Institute of Himalayan Geology is an autonomous research Institute of the Department of Science & Technology.
• Established in June, 1968 as a small nucleus in two rooms of the Botany Department, Delhi University, the Institute was shifted to DehraDun during April, 1976.

Glacial Lake Outburst Flood (GLOF)

• It is a type of catastrophic flood that occurs when the dam containing a glacial lake fails, releasing a large volume of water.
• This type of flood is typically caused by rapid melting of glaciers or the buildup of water in the lake due to heavy precipitation or the inflow of meltwater.
• In February 2021, Chamoli district in Uttarakhand witnessed flash floods which are suspected to have been caused by GLOFs.
• Causes:
  • 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.
  • 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.

Moraine-Dammed Lake

• A moraine-dammed lake occurs when the terminal moraine has prevented some meltwater from leaving the valley.
• When a glacier retreats, there is a space left over between the retreating glacier and the piece that stayed intact which holds leftover debris (moraine).
• Meltwater from both glaciers seep into this space creating a ribbon-shaped lake due to the pattern of ice melt.
• This ice melt may cause a glacier lake outburst flood, leading to severe damage to the environment and communities nearby.