Uttarakhand Glacier Burst: What is Glacial Outburst & How does it occur?

Uttarakhand Glacier Burst: A large piece of Nanda Devi glacier broke off on a chilly winter morning of February and fell into a river, triggering an avalanche and glacial lake outburst flood (GLOF).

Created On: Feb 8, 2021 17:30 ISTModified On: Feb 15, 2021 18:37 IST
Uttarakhand Glacier Burst

Another massive tragedy struck Uttarakhand on February 7, 2021 when a glacier burst took place in Chamoli district of the state. A large piece of Nanda Devi glacier broke off on a chilly winter morning of February and fell into a river, triggering an avalanche and glacial lake outburst flood (GLOF) in Dhauli Ganga, Rishi Ganga and Alaknanda rivers. Over 150 people are feared missing after the flash flood. This is a second massive blow for the Himalayan state after the 2013 Kedarnath Tragedy.

Two hydroelectric power projects, namely, NTPC’s Tapovan-Vishnugad hydel project and Rishi Ganga Hydel Project got completely washed away along with five bridges and scores of houses after the waters came rushing in.

Know here what caused the Uttarakhand Glacier Burst and what is meant by Glacial Outburst:

What is Glacial Outburst?

When glaciers break off, the space underneath them develops into a glacial lake filled with water. The breaking off of the glacial lake is termed as Glacial Lake Outburst Flood (GLOF) or glacial outburst. The glacial outburst occur when the water level of lake rises or when the glacier retreats. The occurrence of GLOF is very rare.

Some experts are calling the Uttarakhand glacier burst as the GLOF. However, the researchers and scientists are yet to investigate the real reason behind the incident.

What causes Glacier Outburst?

Earthquakes, erosion, volcanic eruptions, build of water pressure or an avalanche of heavy snow can cause the glaciers to burst. The glacier outburst can also happen after the displacement of massive water pocket in a glacial lake when an adjacent glacier retreats into it.

What led to the Uttarakhand glacier burst?

In case of Uttarakhand glacier burst tragedy, it is not yet clearly known that what caused the outburst of Nanda Devi glacier. As per the experts, the breaking off of this huge chunk of Nanda Devi glacier into the Dhauli Ganga river is a rare incident as the Google Earth images and satellite did not show any glacial lake underneath the glacier that broke off.

Usually, Glacial Lakes are formed beneath the big glaciers and flow within these massive ice sheets. At times, these lakes create enough pressure causing the glacier chunks to break off. The glacial lakes are not like usual lakes; they comprise ice boulders that have potential of bursting the glacier banks.

In Uttarakhand glacier burst case, it is believed that the water pockets might have developed within the Nanda Devi glacier that led to this incident. Some experts also link this tragedy to climate change and global warming. High temperatures and less of snowfall can lead to increase in melting of glaciers, causing glacial lake water to rise beyond the levels.

A 2019 study published in the Science Advances journal had warned that the Himalayan glaciers are melting at an alarming speed and the 2013 Kedarnath-like tragedy may occur again. The study had warned that glaciers of the Himalayas have been melting twice as fast since the beginning of this century due to the climate change.

The study was based on satellite observations of 40 years across India, Nepal, Bhutan and China.

The study showed that glaciers have been losing half of their ice every year and the formation of glacial lakes had increased by 50% since 2000. The formation of increased number of glacial lakes pose an existential threat to Himalayan glaciers and the rivers flowing from near them.

Is Uttarakhand Glacier Burst similar to 2013 Kedarnath tragedy?

The 2013 Kedarnath tragedy was caused by the cloudbursts that led to severe floods and landslides. In case of Uttarakhand Glacier Burst, it is yet to know what actually triggered the glacier burst at Chamoli district of Uttarakhand.

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