In News:

• In recent years, Glacial Lake Outburst Floods (GLOFs) have emerged as a critical concern in the Himalayan region, particularly affecting countries like India, Nepal, Bhutan, and China.
• The July 8, 2025, GLOF in Nepal—which washed away a China-built bridge and crippled hydropower plants supplying 8% of Nepal’s electricity—has drawn urgent attention to the increasing frequency and severity of such events.
• For India, especially in the Indian Himalayan Region (IHR), GLOFs pose an escalating risk to lives, infrastructure, and ecological systems due to climate change and unregulated development.

What is a Glacial Lake Outburst Flood (GLOF)?

A GLOF is the sudden, catastrophic release of water from a glacial lake—typically dammed by ice or moraine (glacial debris). The floodwaters often cause massive downstream destruction, marked by:

• Extremely high discharge volumes
• Destructive debris flows
• Short warning times

Types of Glacial Lakes in the Himalayas

• Supraglacial Lakes: Form on the surface of glaciers due to meltwater accumulation. Highly unstable during summer.
  • Example: Cirenma Co in Tibet (1981), July 2024 Nepal GLOF.
• Moraine-Dammed Lakes: Form at glacier snouts, blocked by weak debris. Most vulnerable to outbursts.
  • Example: South Lhonak (Sikkim), Tsho Rolpa (Nepal), Shako Cho (Sikkim)

Causes of GLOFs

Natural Triggers

• Glacial Retreat: Rising temperatures accelerate glacial melt, enlarging lakes.
• Ice or Rock Avalanches: Sudden falls into lakes displace water and rupture dams.
• Cloudbursts & Heavy Rainfall: Rapid rise in water levels increases pressure on dams.
• Seismic Activity: Earthquakes can destabilize moraine dams.
• Internal Piping: Seepage within dams weakens structural integrity over time.

Anthropogenic Factors

• Climate Change: Human-induced warming accelerates glacial melt.
• Unregulated Development: Construction near glacial zones—e.g., hydropower—exacerbates risk.
  • Example: Teesta-III dam destruction in 2023.

Impacts of GLOFs

On Human Life and Infrastructure

• Casualties: Kedarnath (2013) and Sikkim (2023) GLOFs caused hundreds of deaths.
• Hydropower & Transport Damage: Washed-out roads, bridges, and dams; loss of electricity and connectivity.
• Displacement & Livelihood Loss: Long-term socio-economic disruption in affected regions.

On Environment

• River Course Changes & Silting: Raised riverbeds and reduced flood-carrying capacity.
  • Teesta river rose several meters post-2023 flood.
• Habitat Loss & Biodiversity Decline: Ecological imbalance in alpine and riparian zones.
• Long-Term Ecosystem Stress: Sedimentation affects water quality and ecosystem resilience.

The Situation in India

India’s Himalayan arc—covering J&K, Ladakh, Himachal Pradesh, Uttarakhand, Sikkim, and Arunachal Pradesh—houses:

• 28,000 glacial lakes
• 7,500 lakes above 4,500 m altitude
• 11 major river basins

Yet, the region lacks sufficient monitoring infrastructure and early warning systems, primarily due to remoteness and hostile terrain.

Notable GLOF events:

• Kedarnath (2013): Triggered by cloudburst and glacial melt.
• South Lhonak (2023): Avalanche-triggered breach, damaging a $2 billion hydro project.

India’s Institutional Response to GLOF Risks

1. National Disaster Management Authority (NDMA) Initiatives

India has transitioned from reactive relief to proactive risk mitigation, through:

• National GLOF Programme: A ?150 crore initiative targeting 195 high-risk lakes.
• Committee on Disaster Risk Reduction (CoDRR): Coordinates central and state agencies, scientific institutions, and communities.

2. Five-Pronged Strategy

1. Hazard Assessment: Classification of lakes by size, dam type, and downstream threat.
2. Automated Weather & Water Stations (AWWS): Real-time monitoring (e.g., in Sikkim).
3. Early Warning Systems (EWS): ITBP-led manual alerts; multilingual digital alerts in pilot stages.
4. Engineering Interventions:
   • Bathymetry and ERT scans
   • Artificial channels and retention structures
5. Community Engagement:
   • Sensitization on religious and ecological concerns.
   • Involving locals in scientific expeditions for credibility and access.

Technological Interventions

• SAR Interferometry: Satellite-based technique to detect micro-slope changes.
• Electrical Resistivity Tomography (ERT): Detects ice-cores under moraine dams.
• Unmanned Aerial Vehicles (UAVs): High-resolution terrain mapping.
• Remote Sensing: Tracks surface area growth of glacial lakes (but is post-facto).

Status of Mitigation Efforts

• Expeditions to 40 high-risk lakes in 2024 across J&K, Ladakh, HP, UK, Sikkim, and Arunachal Pradesh yielded positive outcomes.
• Installation of AWWS at lakes in Sikkim providing 10-minute interval data and daily lake imagery.
• ITBP trained for early alerts in absence of automated systems.
• More stations and expeditions are planned post-monsoon 2025.

Transboundary Challenges

• Many GLOF-prone lakes lie in Tibet, with rivers flowing into Nepal, Bhutan, and India.
• Nepal has faced multiple transboundary GLOFs recently (2024–25), with little to no warning from China.
• Example: July 8, 2025 GLOF from Tibet triggered floods in Nepal, destroying infrastructure.
• Past major GLOFs: Cirenma Co (1981), Dig Tsho (1985), Tama Pokhari (1998).

Policy Recommendations

• Strengthen Early Warning Systems: Expand AWWS and EWS coverage, integrate with mobile alerts.
• Transboundary Collaboration: Create shared protocols for upstream monitoring and data exchange with China, Nepal, and Bhutan.
• Integrate Climate Adaptation in Planning: Include GLOF risk in disaster risk reduction and infrastructure resilience planning.
• Ban Critical Infrastructure: Avoid siting major installations near vulnerable glacial zones.
• Promote Indigenous Technology: Invest in SAR, ERT, and AI-based modelling to predict GLOF risks.
• Community-Led Risk Reduction: Involve local populations in monitoring, response planning, and implementation.