Understanding Glacial Lake Outburst Floods in India

Glacial Lake Outburst Floods (GLOFs) – FAQs

1. What is a Glacial Lake Outburst Flood (GLOF)?

A GLOF is a sudden release of water from a glacial lake due to dam failure caused by melting glaciers, landslides, earthquakes, or ice avalanches. It often results in flash floods downstream.
Example: The Kedarnath flood in 2013 was partly caused by a glacial lake breach.

2. Why is India at risk from GLOF events?

India has over 9,000 glacial lakes, with 200+ considered potentially dangerous. These are mostly located in the Himalayan states like Uttarakhand, Sikkim, Himachal Pradesh, and Arunachal Pradesh.
Example: The South Lhonak Lake in Sikkim is monitored due to high risk of overflow.

3. How are GLOFs linked to climate change?

Rising global temperatures accelerate glacier melt, leading to the formation and expansion of glacial lakes, increasing the risk of dam failure.
Example: Melting Himalayan glaciers are enlarging lake volumes every year.

4. How are GLOF-prone lakes monitored in India?

• Satellite mapping: National Remote Sensing Centre (NRSC) monitors glacial lakes via satellites.
• Early warning systems: Sensors, automated sirens, and wireless alerts are tested in high-risk areas.

Example: NRSC data helped identify South Lhonak Lake as high risk, enabling preventive planning.

5. How is the National Disaster Management Authority (NDMA) reducing risks?

• Risk zonation
• Lake volume analysis
• Integrated disaster preparedness

Example: NDMA’s 2020 guidelines recommend using Synthetic Aperture Radar (SAR) to predict breaches.

6. What is the role of international cooperation in GLOF preparedness?

Shared rivers mean upstream GLOFs (e.g., in China or Nepal) can affect Indian regions. Cooperation is needed for information exchange and early warnings.
Example: Lack of timely communication from China about overflowing lakes can delay India’s response time.

7. Are there efforts to reduce water volume in glacial lakes?

Yes, through artificial drainage, siphoning, and controlled breach techniques.
Example: In Sikkim, controlled drainage of South Lhonak Lake has been proposed to reduce risk.

8. What kind of damages do GLOFs cause?

GLOFs can destroy roads, bridges, hydropower plants, and villages.
Example: The 2013 Kedarnath floods destroyed infrastructure and killed over 5,000 people.

9. What technologies are being used to predict or prevent GLOFs?

• SAR Interferometry for monitoring lake changes
• Weather forecasting and AI-based flood simulations

Example: ISRO uses SAR to detect deformations in moraine dams.

10. What else should be done to prevent GLOF disasters?

• Regular glacial lake audits
• Installation of sirens and cameras
• Local capacity building and drills
• Improved road, bridge, and dam design in mountain areas

Example: NDMA recommends district-level disaster plans for GLOF-prone regions.