Mains Practice Questions

Introduction

Glacial Lake Outburst Floods (GLOFs) occur when a glacial lake suddenly releases a massive volume of water, often due to the failure of a natural dam or other containing structure.

• These events can unleash destructive floods, carrying enormous amounts of water, sediment, and debris downstream at high speeds.
• In recent years, the frequency and intensity of GLOFs in the Himalayas have increased, primarily due to climate change and its cascading effects on the fragile mountain ecosystem.

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Causes of GLOFs in the Himalayas:

• Climate Change and Global Warming: Climate change is accelerating glacial melting in the Himalayas, leading to the rapid formation and expansion of glacial lakes.
  • Rising temperatures or erratic rainfalls cause ice to melt at unprecedented rates, increasing the volume of water in these lakes.
  • A prime example is the 2013 Uttarakhand Floods.
• Cloudburst: Intense rainfall events, often referred to as cloudbursts, can rapidly increase water levels in glacial lakes, leading to instability and potential breaches in the moraine dams.
  • A prime example is the June 2023 GLOF in North Sikkim.
• Seismic Activity: The Himalayan region's high seismic activity poses a constant threat to glacial lake stability.
  • Earthquakes can damage natural dams, trigger landslides into lakes, or cause sudden shifts in glacial structures.
  • The 2015 Nepal earthquake, for instance, caused significant changes in numerous glacial lakes across the region, substantially increasing GLOF risks in its aftermath.
• Avalanches and Landslides: Mountainous terrain makes the Himalayas prone to avalanches and landslides, which can have catastrophic effects on glacial lakes.
  • These events can cause sudden water displacement or breach containment structures.
  • A tragic example occurred in 2021 Uttarakhand's Chamoli district, where a landslide triggered a devastating GLOF.
• Weak Moraine Dams: Many Himalayan glacial lakes are contained by natural moraine dams, formed from loose glacial debris.
  • These structures are often inherently weak and prone to failure, especially when subjected to additional stressors.
  • The 1985 Dig Tsho GLOF in Nepal serves as a classic example, where the failure of a weak moraine dam led to a catastrophic flood event.

Mitigation Measures:

• Early Warning Systems (EWS): Implementing well structured Early Warning Systems like use of Synthetic-Aperture Radar imagery is crucial for GLOF risk mitigation.
  • These systems involve real-time monitoring of glacial lakes, automated alert mechanisms, and community-based warning networks.
• Controlled Lake Drainage: Proactive management of glacial lake water levels through controlled drainage can significantly reduce GLOF risks.
  • This involves carefully planned engineering interventions to gradually lower lake volumes to safer levels.
• Infrastructure Reinforcement: Strengthening existing man-made dams and constructing protective structures through Uniform Codes for Construction Activity along with balancing hydropower development can enhance resilience against GLOFs.
  • This includes techniques like reinforcing moraine dams, building spillways, and constructing flood protection barriers.
• Community-based Disaster Preparedness: Empowering local communities with knowledge and skills for GLOF preparedness is essential.
  • This involves conducting regular drills, creating evacuation plans, and establishing community-led monitoring systems.
• Transboundary Cooperation: Given the cross-border nature of many Himalayan glacial systems, international cooperation is vital for effective GLOF management.
  • This includes sharing data, coordinating monitoring efforts, and jointly developing mitigation strategies.

Conclusion

The threat of Glacial Lake Outburst Floods in the Himalayas demands urgent and comprehensive action. Long-term mitigation requires sustained international cooperation, continued research, and integration of GLOF management into broader climate adaptation plans.