What is Glacial Lake outburst? Is it the cause of Chamoli Tragedy?

11 February 2021.

Introdcuction:

 What triggered the breach — whether there was an avalanche in the area recently or whether the lake breach was the result of construction, anthropological activities, climate change etc. Investigation is still on.  This incident is also being seen as the Glacial Lake Outburst flood.

About Glacial Lake Outburst Flood(GLOF)

• GLOF — a breach in a glacier which is not very unusual.
• When glaciers retreat, they leave a space which becomes a glacial lake being filled with water.
• When such a lake breaches, it is known as glacial lake outburst flood.
• A type of the outburst flood which occurs when the dam comprising a glacial lake fails.
• The failure of the dam can happen because of water pressure, erosion, earthquake, avalanche in rock or heavy snow or volcanic eruptions under the ice.
• It can also occur because of the huge displacement of water in a glacial lake because of collapse of any glacier into it.
• Other reasons for the glacial burst include the construction activities, anthropological activities and climate change.

Subglacial Lake:

• It is a lake found under a glacier.
•  It is usually formed beneath an ice cap or ice sheet.
• It is formed at the boundary between ice and the underlying bedrock.
• At this boundary, the gravitational pressure decreases the pressure melting point of ice.

Proglacial Lakes

• The Proglacial lakes are the lakes formed at the tips of the glacial as a result of the retreating glaciers.
• They are often bound by sediments and boulders In the Himalayas, majority of the glaciers are known to be receding.
• So, there are several proglacial lakes in the regions.
• Breach in the boundaries of the proglacial lakes can lead to large amounts of water to rush down to nearby streams and rivers.
• The water gains the momentum on its way by coming in contact with the sediments, rocks and other materials.
• This causes flooding downstream.

Avalanche

An avalanche is falling masses of snow and ice which gathers pace as it comes down the slope. 

Cloudburst:

It is a sudden, very heavy rainfall accompanied by a thunderstorm.