Flooding from Glacial Lakes

In News

• According to a new study, around 15 million people across the world face the risk of sudden and deadly flooding from Glacial lakes.

What are Glacial Lakes?

• A glacial lake is a body of water that originates from a glacier. It typically forms at the foot of a glacier but may form on, in, or under it.
• They are commonly divided into two main groups: ice-contact lakes which are characterized by the presence of glacier ice terminating in lake water and distal lakes which are somewhat distant, but still influenced by, the presence of glaciers and/or ice sheets.

What are Glacial Lake Outbursts?

• As glacial lakes grow larger in size, they become more dangerous because they are mostly dammed by unstable ice or sediment composed of loose rock and debris. 
• In case the boundary around them breaks, huge amounts of water rush down the side of the mountains, which could cause flooding in the downstream areas. This is called glacial lake outburst floods or GLOF.
• These lakes are often found in steep, mountainous regions, which means landslides or ice avalanches can sometimes fall directly into the lakes and displace the water, causing it to over-top the natural dam and flood downstream.
• In 2013 Uttarakhand’s Kedarnath witnessed flash floods along with a GLOF caused by the Chorabari Tal glacial lake, killing thousands of people.

Major Findings of the Study

• Increase in the number of GLOFs: Flooding from glacial lakes are expanding and rising in numbers due to global warming.
  • More than half of those who could be impacted live in four countries: India, Pakistan, Peru and China.
  • 15 million people live within the 50 km danger zone of glacial lakes.
• Most exposed population: Populations in High Mountains Asia (HMA) — a region stretching from the Hindu Kush all the way to the eastern Himalayas — are the most exposed and on average live closest to glacial lakes with around one million people living within 10 km of a glacial lake.
• India and Pakistan: India and Pakistan make up one-third of the total number of people globally exposed to GLOFs — around three million people in India and around two million people in Pakistan
  • The number and size of glacial lakes in these areas aren’t as large as in places like the Pacific Northwest or Tibet, but they are highly vulnerable and densely populated which makes that the highest GLOF region globally.  Khyber Pakhtunkhwa in Pakistan is the most dangerous catchment in the world.
• Peru: Peru ranks third globally in danger levels. In the past two decades, due to climate change, glacial lakes across the Andes have increased by 93 per cent, in comparison to 37 per cent in high-mountain Asia. 

National Disaster Management Agency (NDMA) Guidelines

• These guidelines aim to enable concerned ministries or departments of State/UT, central governments and other stakeholders to take concerted action for preparedness, prevention, mitigation, and response to GLOFs. 
• These Guidelines also emphasize awareness and capacity building of the relevant stakeholders. 
• These guidelines also direct the government to focus on research and development in the GLOF. 

Way Ahead

• Limiting climate change and keeping warming under 1.5 degree Celsius is a big step as this will help slow the growth of glacial lakes, but a certain amount of ice loss is already ‘locked in’ – if we stopped all emissions today GLOF hazard will continue to increase for several decades.
• There is a need to find effective measures by working with national and regional governments, as well as communities themselves. 

IE