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Expansion of Glacial Lakes in Himalayan Region


Recent satellite monitoring data from the Indian Space Research Organisation (ISRO) has revealed a significant expansion of glacial lakes in the Himalayan region between 1984 and 2023. This expansion raises concerns about potential risks for downstream areas, highlighting the need for further attention and monitoring of glacial dynamics in the region.


GS I: Geography

Dimensions of the Article:

  1. Observations on Himalayan Glacial Expansion by ISRO
  2. Factors Contributing to Glacial Lake Expansion in the Himalayas
  3. Glacial Lakes
  4. Path Forward for Glacial Lake Management in the Himalayas

Observations on Himalayan Glacial Expansion by ISRO

Expansion Trends of Glacial Lakes

  • ISRO’s assessment reveals significant growth in 676 glacial lakes out of 2,431 identified lakes larger than 10 hectares during 2016-17.
  • Within India, 130 of these expanded lakes are situated, with 65, 7, and 58 lakes found in the Indus, Ganga, and Brahmaputra River basins, respectively.
  • Notably, 601 lakes, comprising 89% of the total, have expanded more than twice their original size. An additional 10 lakes have grown by 1.5 to 2 times, while 65 lakes have expanded by 1.5 times.
  • Elevation-wise analysis indicates that 314 lakes are positioned in the 4,000 to 5,000 m range, and 296 lakes are located above 5,000 m elevation.
  • An exemplary case is the Ghepang Ghat glacial lake in the Indus River Basin, situated at an elevation of 4,068 m in Himachal Pradesh, India, which has witnessed a 178% enlargement from 36.49 to 101.30 hectares between 1989 and 2022.
Classification and Quantity of Glacial Lakes
  • Moraine-dammed (307): Formed when accumulated rocks and debris block valleys, creating natural dams.
  • Ice-dammed (8): Result from glaciers acting as dams.
  • Erosion (265): Occupying depressions carved into bedrock by glaciers.

Factors Contributing to Glacial Lake Expansion in the Himalayas

Climate-Related Influences

  • Climatic warming in the Himalayas is causing glacier melt, resulting in increased inflow into existing lakes, thus expanding their size.
  • Melting glaciers expose new land surfaces, facilitating the formation of additional glacial lakes.

Natural Phenomena

  • Natural barriers like moraines, formed by glacier retreat, weaken over time, potentially leading to Glacial Lake Outburst Floods (GLOFs) upon collapse.
  • Alterations in precipitation patterns, including heightened rainfall and snowfall, augment water input into glacial lakes, promoting expansion.
  • Thawing permafrost due to rising temperatures creates depressions that collect water, aiding in glacial lake enlargement.

Human-Induced Factors

  • Human activities such as infrastructure development, mining, and deforestation indirectly contribute to glacial lake expansion by exacerbating climate change and altering drainage patterns.

Glacial Lakes

  • Glacial lakes, exemplified by South Lhonak Lake, are expansive bodies of water situated in proximity to, on top of, or beneath a melting glacier.
  • These lakes, as they expand, become progressively hazardous due to their containment by unstable ice or sediment comprising loose rock and debris.
  • A breach in the boundary surrounding these lakes can result in the rapid release of vast volumes of water down mountain slopes, leading to downstream flooding, an event termed as a glacial lake outburst flood (GLOF).

Causes Behind GLOF

Triggering Factors

  • GLOFs can be precipitated by various factors, including seismic activity such as earthquakes, extraordinarily heavy rainfall, and ice avalanches.
  • Given their typical presence in steep, mountainous terrains, occurrences like landslides or ice avalanches have the potential to directly impact these lakes.
  • The result is the displacement of water, causing it to surpass the natural dam and inundate areas downstream.

Notable Incident

  • In 2013, a catastrophic event unfolded in Uttarakhand’s Kedarnath region, marked by flash floods and a consequential GLOF.
  • The Chorabari Tal glacial lake was responsible for this incident, resulting in the loss of thousands of lives.

Path Forward for Glacial Lake Management in the Himalayas

Addressing Climate Change

  • Mitigating greenhouse gas emissions globally is paramount to address the root cause of glacial melt and retreat.
  • This requires concerted efforts to transition to renewable energy sources, enhance energy efficiency, and enact policies to curb carbon emissions across various sectors.

Early Warning Systems and Monitoring

  • Developing and implementing early warning systems is crucial for monitoring glacial lakes, weather forecasting, and disseminating timely alerts to at-risk communities.

Engineering Measures for Risk Reduction

  • Implementing engineering measures to stabilize and manage glacial lakes can mitigate the risk of Glacial Lake Outburst Floods (GLOFs).
  • Infrastructure such as spillways, drainage channels, and dams can be constructed to control water levels and prevent uncontrolled water releases.

Natural Ecosystem Restoration

  • Restoring and conserving natural ecosystems like wetlands and forests can regulate water flow, providing additional benefits such as habitat conservation and carbon sequestration.

Community Engagement and Capacity Building

  • Involving local communities in risk assessment, planning, and decision-making processes is essential for effective glacial lake management.
  • Building local capacity for disaster preparedness, including training in emergency response and evacuation procedures, can enhance community resilience to GLOFs and other hazards.

International Cooperation

  • Given the transboundary nature of many glacial lakes in the Himalayas, international cooperation is vital for effective management and risk reduction.
  • Collaborative efforts among countries sharing glacier-fed river basins can facilitate information sharing, joint monitoring, and coordinated action to address common challenges.

-Source: The Hindu

May 2024