Glacial Lake Outburst Flood (GLOF)

Why in news?

Recently scientists from the International Centre for Integrated Mountain Development (ICIMOD) found that supraglacial lake melting is also a reason for glacial lake outburst.

What are glacial lake outbreak floods?

• Glacial lakes – A glacial lake is a body of water that originates from a glacier.
• Formation – It usually forms in front of, on top of, or beneath a melting glacier.
• Classification - ISRO classifies, glacial lakes into 4 broad categories based on their formation
  • Moraine-dammed glacial lakes
  • Ice-dammed glacial lakes
  • Erosion-based glacial lakes
  • Other glacial lakes.
• Glacial lake outburst flood (GLOF) - It occurs when water is suddenly released from a lake fed by a melting glacier.
• Vulnerable regions – Hindukush Himalayas, Andes, Alaska and Alps mountainous regions

• Recent incidents
  • Nepal (Limi)
  • Afghanistan (Andorab valley)
  • Pakistan (Chitral, Hunza)

What are its causes?

• Climatic Reasons - Sustained warming plays a key role in the formation and gradual expansion of glacial lakes.
• Draining of supraglacial lakes – Recent GLOF events have occurred due to the draining of newly formed (supraglacial) ice-dammed glacial lakes.
• Short term heat variations - Extreme Short-term temperature   can also trigger sudden events such as ice avalanches, ice calving, or slope failures related to thawing of permafrost.

Permafrost is any type of ground from soil to sediment to rock that has been frozen continuously for a minimum of two years

• Glacial overflow - Severe rapid glacier movement caused due to Sudden movement of ice over a relatively short time.
• Glacial retreat - Hindu Kush Himalayas has given rise to the formation of numerous new glacial lakes due to climate change occurring in most parts of the region.

• 
• Structural weakness of moraines - Unconnected and weak moraines, which are unstable, can collapse due to structural weakness.
• Seismic exertion - Sudden structural change in glacier can be created due to tectonic movements in mountainous region.
• Anthropogenic reasons - Extensive mining, deforestation, hydropower projects, unregulated urbanization.
• Greenhouse gas emission can also alter drainage patterns.

What are the steps taken by India to prevent GLOFs?

• Sendai Framework (2015-2030) – It is a global blueprint for disaster risk reduction and prevention.
• Coalition for Disaster Resilient Infrastructure (CDRI) - CDRI is an international climate initiative by India in 2019 to promote resilient climate-proof critical infrastructure in member countries.
• National Disaster Management Authority (NDMA) - NDMA, headed by the Prime Minister of India, is the apex body for Disaster Management in India.
• Institutional mechanism- Central Water Commission (CWC)/ National Remote Sensing Agency (NRSA)/ State governments also check for landslides and blockages in rivers with the help of satellite imageries.
• Aapda Mitra – Launched in 2016, it is a central sector scheme implemented by NDMA to train community volunteers in disaster response in selected 30 most flood prone districts of 25 states including Sikkim.
• Doppler radars - The India Meteorological Department (IMD) has been using Doppler radars, a flash floods forecasting and warning systems

What measures can be taken?

• Regular monitoring – Regular analysis and updating potentially dangerous glacial lakes inventories, analysing smaller, short-lived ice dammed lakes can be done.

Potentially dangerous Glacial lakes can increase the vulnerability of GLOF. Nepal has 25, Tibet autonomous region of China has 21 and India has 1 potentially dangerous Lake.

• Encompassing the process - The processes involved in glacier retreat and lake formation should be incorporated in monitoring methodology for more dynamic and accurate hazard assessment.
• Technological solutions - Synthetic-Aperture Radar imagery can be used to automatically detect changes in water bodies, new lake formations.
• High Density Polyethylene (HDPE) pipes- In 2016, Sikkim used HDPE pipes to reduce water levels in South Lhonak Lake.
• Risk assessment- Researchers need to continuously monitor the lakes for signs of instability and potential outburst events, this includes using satellite imagery and developing models to predict GLOF risk.
• Uniform construction guidelines - Developing a uniform framework for infrastructure development, construction, and excavation.
• Early Warning Systems (EWS) - Development of new EWS  and enhancing existing EWS can be done in vulnerable areas.
• Research - Continued research into glacial dynamics, climate change impacts, and GLOF mitigation strategies is necessary to develop innovative approaches that reduce GLOF risk.

Reference

Down To Earth| Glacial Lake Outburst Floods