NDMA Guidelines on Glacial Lake Outburst Flood (GLOF)

Context: A massive glacier burst at Chamoli in Uttarakhand yet again bringing back our focus to the dangers of climate change.

Relevance:
Prelims: Glaciers and rivers
Mains: GS-I, GS-III- About GLOF, Disaster preparedness and mitigation.

• Parts of Uttarakhand recently witnessed massive flooding after a chunk of the Nanda Devi glacier broke off at Joshimath in the Tapovan-Reni area of Chamoli District.
• The glacial break led to a massive Flash Flood in Dhauli Ganga and Alaknanda Rivers, damaging houses and the nearby Rishiganga power project. 

  
  

  

• Local authorities have described it as a glacial burst.
  • But it is unclear whether there was an avalanche in the area recently or whether the lake breach was the result of construction, anthropological activities, climate change, etc.
  • Scientists say this probably means that a gigantic chunk of ice broke away from a glacier and caused the water level in the associated glacial lake to abruptly rise and possibly trigger a “moraine breach event” — the breach of a natural dam made from rock and debris that has been holding the water back.

• Past experiences:
  • 2013 Kedarnath calamity, the glacier break caused large-scale devastation in the upper reaches of the ecologically fragile Himalaya.
  • Another example: In 1929, a GLOF from the Chong Khumdan Glacier in the Karakoram caused flooding on the Indus River 1,200 km downstream 

    

• Identify and Mapping Dangerous Lakes:
  • Potentially dangerous lakes are often identified.
  • This identification are going to be supported by field observations, past events, geomorphologic and geotechnical characteristics, etc.
• Use of Technology:
  • It is recommended to utilize the Synthetic-Aperture Radar imagery.
  • It will automatically detect changes in water bodies, including new lake formations, during the monsoon months.
• Structural Measures:
  • It recommends reducing the number of water with various methods to manage lakes structurally.
  • Methods are pumping or siphoning out water and making a tunnel through the moraine barrier or under an ice dam.
  • Constructions and development in High prone areas should be prohibited. it's a very efficient means to reduce risks at no cost.
• Land Use Planning:
  • Land use planning regulations need to be developed.
  • In downstream areas, Infrastructure development should be monitored before, during, and after the construction.
• Empowered Local Manpower:
  • Apart from specialized forces like NDRF, ITBP, and the military, there is a requirement for trained local manpower.
  • They can assist in planning and fixing emergency shelters, distributing relief packages, identifying missing people, and addressing the requirement for food, healthcare, water, sanitation, etc.
• Early Warning System:
  • A robust early warning system in vulnerable zones should be put in place.
• Emergency response team:
  • Quick Reaction Medical Teams, mobile field hospitals, Accident Relief Medical Vans, and heli-ambulances should be found out in areas inaccessible by roads.

• How can the GLOF risk be reduced?
  • As per the NDMA guidelines that risk reduction has to begin with identifying and mapping such lakes, taking structural measures to prevent their sudden breach, and establishing a mechanism to save lives and property in times of a breach.
  • Potentially dangerous lakes can be identified based on field observations, records of past events, geomorphologic and geotechnical characteristics of the lake/dam and surroundings, and other physical conditions.
  • NDMA has recommended the use of Synthetic-Aperture Radar imagery to automatically detect changes in water bodies, including new lake formations, during the monsoon months. Methods and protocols could also be developed to allow remote monitoring of lake bodies from space.
  • To manage lakes structurally, the NDMA recommends reducing the volume of water with methods such as controlled breaching, pumping or siphoning out water, and making a tunnel through the moraine barrier or under an ice dam.
• How well is India prepared?
  • While some work on the identification of such lakes has been done by Central Water Commission (CWC), other aspects are still a work in progress like:
    • A robust early warning system, and
    • A broad framework for infrastructure development, construction and
    • Excavation in vulnerable zones.
  • In contrast to other countries, there are no uniform codes for excavation, construction, and grading codes in India.
  • Restricting constructions and development in GLOF/LLOF prone areas is a very efficient means to reduce risks at no cost.
  • The guidelines say the construction of any habitation should be prohibited in the high hazard zone.
    • Existing buildings are to be relocated to a safer nearby region and all the resources for the relocation have to be managed by Central/State governments.
    • New infrastructures in the medium hazard zone have to be accompanied by specific protection measures.
  • The guidelines emphasize the importance of land use planning:
    • There are no widely accepted procedures or regulations in India for land use planning in the GLOF/LLOF prone areas.
    • Such regulations need to be developed.
    • There should be monitoring systems prior to, during, and after the construction of infrastructure and settlements in the downstream area.
• Are there early warning systems in place?
  • The number of implemented and operational GLOF EWS is still very small, even on a global scale.
  • In the Himalayan region, there are three reported instances (two in Nepal and one in China) of implementation of sensor- and monitoring-based technical systems for GLOF early warning.
  • India, though, has a remarkable history of successful warnings in relation to Landslide Lake Outburst Floods (LLOFs), dating back to the 19th century.
  • In 1894, a landslide in Gohna, Uttarakhand dammed the main river.
    • On July 5 that year, the engineer in charge estimated the lake would overflow the dam in mid-August, which eventually happened.
  • Despite the devastating impact of the flood, including washing away of most buildings along the river and severe destruction in Srinagar, no victims were reported, thanks to the precise prediction and the early warning to the population.
    • This was made possible by the installation of a telephone line between the lake and the downstream towns of Chamoli, Srinagar etc.

• The threat from moraine-dammed GLOFs is typically greatest during periods of glacier retreat, whereas ice-dammed GLOFs are highest during periods of glacier growth.
• However, because moraine dams are normally destroyed in lake outbursts, the number of GLOFs will likely start to decrease over time, as the capacity for storing glacial meltwater is gradually lost.
• Therefore, we might expect the number of moraine-dammed GLOFs to increase as mountain glaciers continue to shrink worldwide.
• Importantly, the general global trend of glacier shrinkage through the 20th and 21st centuries has seen the number and size of glacial lakes increase, at the same time as human activities have expanded further into glaciated catchments.
• The study of how GLOFs occur and their impacts is therefore important for future hazard mitigation.