Syllabus: GS-III & V: Natural Disaster

Why in the News?

• Recent studies by the Centre for Earth Sciences and Himalaya Studies (CESHS) highlight rapid glacier melting in Arunachal Pradesh.

• The Khangri glacier in Tawang is of particular concern, increasing the risk of Glacial Lake Outburst Floods (GLOFs).

What are GLOFs?

• A Glacial Lake Outburst Flood (GLOF) is a sudden release of meltwater from a moraine- or ice-dam glacial lake due to dam failure.

• This results in catastrophic downstream flooding.

Key Features

• Sudden release of water.

• Rapid events, lasting hours to days.

• River discharge often 10x higher than normal flow.

Causes of GLOFs

1. Avalanches & Landslides – Sudden slope failures displacing lake water (e.g., 2021 Chamoli disaster).

2. Heavy Rainfall/Snowmelt – Unusual rainfall or warming triggers overtopping (e.g., 2013 Kedarnath floods).

3. Cascading Events – Overflow from upstream lakes causes downstream breaches.

4. Earthquakes – Seismic activity destabilises dams.

5. Ice Melt in Dams – Rising temperatures weaken moraine-ice dams.

6. Blocked Subsurface Outflows – Blocked drainage raises water pressure.

7. Long-Term Erosion – Natural degradation of moraine dams.

Impacts of GLOFs

• Loss of Life & Property – Hundreds killed, thousands displaced in the Himalayas.

• Infrastructure Damage – Roads, bridges, and hydropower projects like Teesta III destroyed.

• Environmental Impact – Severe erosion, habitat loss, water pollution.

• Landscape Alteration – Past mega-floods permanently changed valley systems.

Proneness of Arunachal Pradesh

• Over 100 glaciers lost in the last three decades.

• Expansion of pro-glacial lakes near retreating glaciers.

• Weak natural composition of dams (sand, ice, debris, pebbles).

• Hotspot zones:

  • Khangri glacier, Tawang.

  • Gorichen range.

  • Glaciers in West Kameng & Upper Subansiri.

Steps Taken by the Government

• National GLOF Risk Mitigation Project (NGRMP), 2024:

  • Early warning systems & automatic weather stations.

  • Satellite-based glacial lake inventory (ISRO).

  • Strengthening local disaster preparedness.

• International Cooperation – ICIMOD, ESA, USGS, NOAA monitoring support.

• NDMA Guidelines – Focus on community awareness and training.

Mitigation Strategies

Structural Measures

• Controlled drainage channels/tunnels.

• Siphoning to lower lake water levels.

• Dam reinforcement with rock/concrete.

• Spillways & check dams to manage outflow.

Non-Structural Measures

• Early Warning Systems – Satellite sensors + last-mile alerts.

• Risk mapping of vulnerable valleys.

• Community preparedness – evacuation drills.

• Policy – Restrict construction in floodplains.

• Research – SAR technology, climate models.

• Climate action – Limit warming to <1.5°C.

Way Forward

• Speed up NGRMP implementation with modern tools.

• Promote community-based disaster management using local knowledge.

• Ensure cross-border cooperation (Nepal, Bhutan, China) for data-sharing.

• Mainstream GLOF preparedness in hydropower and infrastructure planning.

• Launch awareness campaigns on climate risks.

Conclusion

• GLOFs are a growing climate-induced disaster in the fragile Himalayas.

• Arunachal Pradesh, with its rapidly retreating glaciers, is at high risk.

• Combining technology, infrastructure, and community preparedness is essential.

• GLOF management must be treated as both a climate adaptation priority and a developmental necessity to safeguard lives and strategic assets in the Northeast.

Q. “Glacial Lake Outburst Floods (GLOFs) are emerging as a climate-driven disaster in the Himalayas. Analyse their causes, impacts, and Arunachal Pradesh’s vulnerabilities. Suggest mitigation measures for sustainable development.”
(15 marks / 250 words)