Syllabus
GS Paper I – Geographical features and their location-changes in critical geographical features (including water-bodies and ice-caps) and in flora and fauna and the effects of such changes.
Context
With the monsoon season setting in, the Uttarakhand State Disaster Management Department (USDMA) is set to do a vulnerability study of the 13 glacial lakes, five of them in “high risk zone” from the coming month.
Glacial lakes in the Himalayas
Introduction
Glacial lakes in the Himalayas have drawn attention due to climate change impacts on glaciation and melting. These lakes influence snowmelt runoff, stream discharge, water resources, and the risk of glacial lake outburst floods (GLOFs). Recent studies employ machine learning and geospatial analysis to track glacial lakes over decades, revealing spatial and temporal patterns. The accelerated melting of glaciers in the Himalayas has led to the formation and expansion of these lakes, creating hundreds of new ones. If natural dams fail, the resulting floods could threaten communities downstream.
Glacial Lake formation processes
Glacial Lakes
- Glacial lakes form in depressions or hollows created by glacier movement. They vary in size and are commonly found in mountainous regions and areas previously covered by glaciers.
Formation Processes
- Glacial Erosion:
- Erosion by Ice Movement: Glaciers shape the landscape through plucking and abrasion, resulting in depressions and valleys that later fill with water.
- Cirque Formation: Glacial erosion creates cirques, which can hold tarns (small mountain lakes).
- Glacial Deposition:
- Moraines: Debris carried by glaciers accumulates at their margins, forming natural dams that create lakes.
- Kettle Formation: Blocks of ice embedded in glacial till melt, forming kettle lakes.
- Ice Melt and Retreat:
- Proglacial Lakes: These lakes form as glaciers melt and retreat, leaving behind depressions that fill with meltwater.
ISRO’s Observations on Glacial Lake Expansion
- Satellite Monitoring Data (1984-2023):
- ISRO’s satellite data reveals significant expansion of glacial lakes in the Himalayan region during this period.
- Lake Expansion Statistics:
- Out of 2,431 lakes larger than 10 hectares identified in 2016-17, 676 glacial lakes have notably expanded since 1984.
- Within India, 130 of these lakes are situated in the Indus, Ganga, and Brahmaputra River basins.
- Expansion Magnitude:
- 601 lakes (89%) have expanded more than twice, while 10 lakes grew between 1.5 to 2 times, and 65 lakes expanded by 1.5 times.
- Elevation Distribution:
- 314 lakes are located in the 4,000 to 5,000 m elevation range, and 296 lakes are above 5,000 m elevation.
- Case Study: Ghepang Ghat Glacial Lake:
- Located in the Indus River Basin at an elevation of 4,068 m in Himachal Pradesh, this lake increased in size by 178%, from 36.49 to 101.30 hectares between 1989 and 2022.
Causes of Glacial Lake Expansion
- Global Warming: Rising temperatures lead to glacier melting, feeding existing glacial lakes and causing expansion.
- Retreating Glaciers: Melting glaciers expose new land surfaces, allowing for the formation of new glacial lakes.
- Weakening Moraines: Natural rock and debris dams (moraines) weaken as glaciers shrink, potentially triggering Glacial Lake Outburst Floods (GLOFs).
- Increased Precipitation: Altered precipitation patterns contribute to lake expansion by providing more water.
- Permafrost Thaw: Thawing permafrost creates depressions that collect water, contributing to lake growth.
- Human Activities: Infrastructure development and other activities alter natural drainage patterns, indirectly promoting glacial lake expansion.
Threats Associated with Glacial Lakes
- Glacial Lake Outburst Floods (GLOFs):
- GLOFs occur when water breaches natural moraines or ice dams, releasing a rapid downstream flood.
- These sudden floods pose significant risks to human lives in downstream communities.
- Infrastructure Damage:
- Bridges, roads, and hydropower plants are vulnerable to destruction during GLOFs.
- Environmental Degradation:
- Habitat Loss: Expanding glacial lakes submerge terrestrial habitats, affecting local flora and fauna.
- Water Quality: Increased sediment and debris impact ecosystems and human water use.
- Water Resource Impacts:
- Seasonal Water Supply: Unpredictable lake changes affect downstream water availability.
- Hydropower: Variable water flow impacts hydropower project reliability and safety.
- Socioeconomic Challenges:
- Livelihoods: Agriculture and livestock communities face loss of arable land and grazing areas.
- Displacement: Destroyed homes and infrastructure lead to social and economic challenges.
- Climate Feedback Loop:
- Larger glacial lakes absorb more solar radiation, accelerating glacier melt.
- Geopolitical Concerns:
- Transboundary lakes affect international water agreements and may lead to tensions between countries.
Way forward
- Early Warning Systems:
- Implement robust early warning systems that monitor glacial lakes and provide timely alerts to downstream communities.
- Utilize satellite imagery, remote sensing, and real-time data to detect changes in lake size and water levels.
- Risk Assessment and Mapping:
- Improve understanding of glacier and glacial lake dynamics.
- Analyze past GLOF events to assess future risks and plan mitigation strategies.
- Structural Measures:
- Construct controlled breaching structures or tunnels to lower water volume behind moraine dams.
- Pump out excess water strategically to reduce the risk of sudden dam failure.
- Community Resilience:
- Build resilience in vulnerable communities through awareness campaigns, emergency preparedness plans, and sustainable land use practices.
- Prioritize disaster risk reduction as an integral part of development planning.
Conclusion
The expansion of glacial lakes in the Himalayas presents significant risks to both the environment and human communities. Combining advanced monitoring technologies, engineering solutions, community readiness, and effective policies is essential to mitigate these risks and safeguard vulnerable ecosystems and populations.
Source: The Hindu
Related PYQ
Explain the mechanism and occurrence of cloudburst in the context of the Indian subcontinent. Discuss two recent examples. [UPSC Civil Services Exam – 2022 Mains]
Practice Question
What strategies can be employed to address the risks posed by the expansion of glacial lakes in the Himalayas? Provide relevant examples. [150 words]