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Mahesh

04/04/24 12:20 PM IST

Glacial Lake Outburst Floods

In News
  • The Uttarakhand government has constituted two teams of experts to evaluate the risk posed by five potentially hazardous glacial lakes in the region.
About GLOF
  • GLOFs are disaster events caused by the abrupt discharge of water from glacial lakes — large bodies of water that sit in front of, on top of, or beneath a melting glacier.
  • As a glacier withdraws, it leaves behind a depression that gets filled with meltwater, thereby forming a lake.
  • The more the glacier recedes, the bigger and more dangerous the lake becomes.
  • Such lakes are mostly dammed by unstable ice or sediment composed of loose rock and debris.
  • In case the boundary around them breaks, huge amounts of water rush down the side of the mountains, which could cause flooding in the downstream areas — this is referred to as a GLOF event.
  • GLOFs can be triggered by various reasons, including glacial calving, where sizable ice chunks detach from the glacier into the lake, inducing sudden water displacement.
  • Incidents such as avalanches or landslides can also impact the stability of the boundary around a glacial lake, leading to its failure, and the rapid discharge of water.
  • GLOFs can unleash large volumes of water, sediment, and debris downstream with formidable force and velocity.
  • The floodwaters can submerge valleys, obliterate infrastructure such as roads, bridges, and buildings, and result in significant loss of life and livelihoods.
Rise in GLOFs
  • In recent years, there has been a rise in GLOF events in the Himalayan region as soaring global temperatures have increased glacier melting.
  • Rapid infrastructure development in vulnerable areas has also contributed to the spike in such incidents.
  • Since 1980, in the Himalayan region, particularly in southeastern Tibet and the China-Nepal border area, GLOFs have become more frequent.
  • Approximately 6,353 sq km of land could be at risk from potential GLOFs, posing threats to 55,808 buildings, 105 hydropower projects, 194 sq km of farmland, 5,005 km of roads, and 4,038 bridges in the region.
  • About 3 million people in India and 2 million in Pakistan face the risk of GLOFs.
  • While the number and size of glacial lakes in these areas (India and Pakistan) isn’t as large as in places like the Pacific Northwest or Tibet, it’s that extremely large population and the fact that they are highly vulnerable that mean Pakistan and India have some of the highest GLOF danger globally.
Situation in Uttarakhand
  • Uttarakhand has witnessed two major GLOF events in the past few years.
  • The first took place in June 2013, which affected large parts of the state — Kedarnath valley was the worst hit, where thousands of people died.
  • The second occurred in February 2021, when Chamoli district was hit by flash floods due to the bursting of a glacier lake.
  • As mentioned earlier, Uttarakhand has 13 glacial lakes which are prone to GLOF. Based on the analysis of available data and research from various technical institutions, these lakes have been categorised into three risk levels: ‘A’, ‘B’, and ‘C’.
  • Five highly sensitive glacial lakes fall into the ‘A’ category.
  • These include Vasudhara Tal in the Dhauliganga basin in Chamoli district, and four lakes in Pithoragarh district — Maban Lake in Lassar Yangti Valley, Pyungru Lake in the Darma basin, an unclassified lake in the Darma basin, and another unclassified lake in Kuthi Yangti Valley.
  • The rising surface temperatures could worsen the situation in Uttarakhand. The state’s annual average maximum temperature may increase by 1.6-1.9 degree Celsius between 2021-2050.
Source- Indian Express

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