Review of Dam Design to handle Glacial Lake Outburst Floods (GLOFs)

Syllabus: Geography/ Disaster Management

Source: PIB

Context: Following the Teesta-III Hydroelectric dam collapse in October 2023, the Central Water Commission (CWC) is reviewing the design flood of vulnerable dams to ensure they can handle Glacial Lake Outburst Floods (GLOFs)

What are Glaciers?

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.

What is Glacial Lake Outbursts (GLO)?

A Glacial Lake Outburst (GLO) occurs when a glacial lake, formed by melting ice and snow, suddenly releases a large volume of water. This can happen due to the failure of natural ice or moraine dams holding the lake, often triggered by factors like heavy rainfall, earthquakes, or the melting of surrounding ice. The sudden release of water can lead to devastating floods downstream, causing significant damage to communities, infrastructure, and ecosystems.

Reasons for Glacial Lake Outburst Floods (GLOFs):

• Geological: Earthquakes, breaches of moraine dams.

• Morphological: Mass movements into glacial lakes, water seepage through glacial structures.

• Physical: Excessive precipitation, cryoseism (non-tectonic seismic events in the glacial cryosphere).

• Anthropogenic: Climate change and global warming.

Mounting GLOF Risks in the Himalayas:

• Glacial Retreat: Rising temperatures lead to accelerated glacial melt, creating glacial lakes. The increased volume of water in these lakes raises the risk of GLOFs, threatening downstream communities.

• Glacial Lake Dynamics: The formation of moraine-dammed lakes, often unstable, poses a significant risk. When the moraine dam weakens or breaches due to factors like earthquakes or increased meltwater pressure, it can trigger a GLOF.

India’s Vulnerability to GLOFs:

• ISRO’s Atlas: Identified over 28,000 glacial lakes in the Himalayan basins.

• Sikkim: 733 glacial lakes identified; 10 classified as vulnerable.

• Uttarakhand: 13 out of 486 glacial lakes are vulnerable.

• Jammu and Kashmir: Highest number of vulnerable lakes, with significant threats also in Arunachal Pradesh and Sikkim.

Urgent Call for heightened awareness and proactive measures:

• Preventing Catastrophic Floods: GLO events can unleash massive floods downstream, causing loss of life, extensive damage to infrastructure, and economic devastation. For instance, the 1994 GLO in the Bhutanese Himalayas resulted in a catastrophic flood disaster.

• For instance, the 1994 GLO in the Bhutanese Himalayas resulted in a catastrophic flood disaster.

• Safeguarding Vulnerable Communities: Many communities reside in downstream areas of glacial lakes, making them highly vulnerable to GLO events. Effective awareness measures are essential to protect these communities from harm.

• Effective awareness measures are essential to protect these communities from harm.

• Threat to Livelihoods: Many communities in the Himalayan region depend on agriculture and livestock farming. GLOFs can damage agricultural fields, threaten livestock, and disrupt livelihoods, leading to food insecurity.

• Preserving environmental integrity: GLO events disrupt ecosystems downstream, leading to long-term environmental damage. Mitigation efforts aim to minimize such ecological impacts and maintain environmental balance.

• Mitigation efforts aim to minimize such ecological impacts and maintain environmental balance.

• Infrastructure Resilience: Designing infrastructure with resilience against GLOFs, such as building protective barriers and establishing safe evacuation routes, is essential to minimize the impact on vulnerable communities.

• Community Engagement: Raising awareness and involving local communities in disaster preparedness and response strategies is pivotal. Communities need to be equipped with the knowledge and tools to protect themselves during GLOF events.

NDMA guidelines in mitigating the risks associated with GLOFs:

Guideline | Details

1. 1.Identifying Potentially Dangerous Lakes | Use field observations, historical data, geomorphologic and geotechnical analysis.
2. 2.Use of Technology | Promote synthetic-aperture radar imagery for detecting changes in water bodies and develop remote monitoring methods.
3. 3.Channelling Potential Floods | Implement controlled breaching, pumping, siphoning, or creating tunnels through barriers.
4. 4.Uniform Codes for Construction Activity | Develop frameworks for construction and land use planning in vulnerable zones.
5. 5.Enhancing Early Warning Systems (EWS) | Increase the number of operational GLOF EWS; currently, only a few exist in the Himalayas.
6. 6.Training Local Manpower | Train locals for search and rescue, shelter planning, and relief distribution.
7. 7.Comprehensive Alarm Systems | Combine acoustic alarms with modern communication technologies like smartphones.

Measures to Mitigate GLOF Disasters:

• Monitoring: Intensify meteorological monitoring and real-time data collection at glacier lakes and downstream rivers.

• Technology: Use satellites and drones for regular monitoring of glacier lakes.

• Safety Standards: Revise and enforce strict safety standards for infrastructure in mountainous areas.

• Construction Regulation: Apply stringent quality control and regulations for construction near rivers.

• Scientific Research: Expand research on glacier behaviour and climate change impacts in the Himalayas.

Conclusion

By understanding these risks and implementing comprehensive mitigation strategies, we can reduce the potential devastation caused by GLO events, protect vulnerable communities, and preserve the environment, ultimately contributing to a more resilient and sustainable future.

Mains Links:

Dam failures are always catastrophic, especially on the downstream side, resulting in a colossal loss of life and property. Analyze the various causes of dam failures. Give two examples of large dam failures. (UPSC 2023)