What is Glacial Lake Outburst Flood?

A severe Glacial Lake Outburst Flood in Nepal caused infrastructure damage. With similar vulnerabilities in the Indian Himalayas, India is intensifying mitigation & cross-border warning efforts.

What is Glacial Lake Outburst Flood (GLOF)?

A Glacial Lake Outburst Flood occurs when water trapped in a glacial lake suddenly breaches its boundary often due to avalanches, landslides, or earthquakes, causing massive downstream flooding.
- GLOF can be triggered by several reasons, including earthquakes, heavy rains and ice avalanches.
Glacial Retreat: Hindu Kush Himalaya lost over 40% glacial mass in 40 years (ICIMOD).
Lake Formation: Over 5,000 glacial lakes identified in Indian Himalayas (ISRO).
Warming Impact: Region warming at 0.3°C per decade, double the global rate (ICIMOD).
Event Surge: GLOFs rose from 2 to 30 per decade (UNEP).

Credits: Science Direct

Glacial Lakes

Glacial lakes form when a glacier erodes the land, and the depression is filled by glacial meltwater.
It typically forms at the foot of a glacier but may form on, in, or under it.
As glacial lakes grow larger, they become more dangerous because glacial lakes are mostly dammed by unstable ice or sediment.

Credits: Research Gate

What is a Cloudburst?

A cloudburst is a localised but intense rainfall activity. However, not all instances of very heavy rainfall, are cloudbursts. Rainfall of 10 cm or more in an hour over a roughly 10 km x 10 km area is classified as a cloudburst.
During a cloudburst event, a place receives about 10% of its annual rainfall within an hour.
While it can occur in plains, the phenomenon is most common in hilly regions.
In hilly regions, the local topology, wind systems, and temperature gradients between the lower and upper atmosphere facilitate the occurrence of such events. Because of the terrain of hilly regions, cloudbrusts often trigger landslides and flash floods, causing extensive destruction downstream.

Flash Flood

A flash flood is a sudden, intense flooding event triggered by heavy rain, storms, dam failures, or similar factors, leading to a rapid and overwhelming surge of water.
Flash floods can occur within minutes or hours of the triggering event.
They are characterised by their high intensity, short duration, and the potential for significant damage and danger to life and property.

India’s Multi-Pronged GLOF Mitigation Approach

Proactive Risk Reduction: Led by the National Disaster Management Authority (NDMA), India has moved from post-disaster relief to a coordinated, preventive approach.
National GLOF Risk Mitigation Programme: Launched with a $20 million outlay, initially covering 56 glacial lakes, now expanded to 195, categorised into four risk levels.
Core Components of the Programme:
- Hazard Assessment: Scientific expeditions to high-risk lakes.
- Early Warning Systems (EWS): Installation of Automated Weather and Water Stations (AWWS).
- Risk Mitigation: Construction of water drawdown channels and flow retention structures.
- Advanced Technology: Use of SAR Interferometry for slope stability & Electrical Resistivity Tomography (ERT) for detecting ice cores beneath moraine dams.
Remote Sensing: Satellite, drone-based monitoring of lake size and shoreline; bathymetry used to estimate water volume and risk potential.
Capacity Building: Indo-Tibetan Border Police (ITBP) trained to provide manual early warnings.
- Community training, mock drills, & awareness campaigns in vulnerable districts to support timely evacuation.

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Challenges in GLOF Risk Management

Data Deficits: Remote glacial lakes are inaccessible for much of the year due to altitude and terrain.
Climate Change: 2023 and 2024 were the hottest years globally, accelerating glacial melt & increasing lake volume & pressure.
Technological Gaps: Limited use of Indian scientific tools and private innovations hampers Himalayan risk management.
- Gaps remain in automated monitoring, early warning systems, and timely satellite imaging.

Way Forward

Incentivise Indigenous Tech: Launch a Challenge Fund under Start-up India to develop affordable, rugged sensors for real-time glacial lake monitoring.
GLOF Audits: Include GLOF risk assessments using satellite and geophysical tools in all Detailed Project Reports (DPRs) of hydropower and road projects.
Cross-Border Alert Systems: Build real-time GLOF data-sharing mechanisms with Nepal, Bhutan and China.
Community-Based Response: Pilot volunteer forces in remote hamlets for lake monitoring, traditional forecasting, and emergency response, blending local knowledge with scientific systems.

A proactive, tech-enabled, & community-driven approach guided by NDMA’s motto “A Culture of Preparedness, A Commitment to Safe Future” is vital to mitigate GLOF risks in a climate-sensitive Himalaya. Strengthening regional cooperation & indigenous innovation will ensure long-term resilience and preparedness.

Reference: The Hindu | PMFIAS: Glacial Lake Outburst Flood

PMF IAS Pathfinder for Mains – Question 269

Q. The frequency of Glacial Lake Outburst Floods is increasing due to climate change-driven glacial melt. Discuss the reasons for GLOF and highlight the mechanisms for preparedness to reduce the risk during such events. (150 Words) (10 Marks)

Approach

Introduction: Provide a brief definition of GLOFs, highlighting the most vulnerable area.
Body: Write reasons for GLOF and the mechanisms for preparedness to reduce the risk during.
Conclusion: Emphasis on a multi-pronged approach to effectively manage GLOF risks.