UTTARAKHAND GLACIAL LAKE BURST OR AVALANCHE

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For : GS-3: DISASTER MANAGEMENT

CONTEXT:

A glacial lake burst, a cloud burst or an avalanche, the effects of climate change or' development-Scientists are not sure what caused the sudden water surge near Chamoli in Uttarakhand on Sunday morning, which briefly raised fears of a repeat of the 2013 disaster in the state.

INCIDENT DETAILS:

A glacier break in Uttarakhand's Chamoli district triggered huge flooding on Sunday followed by the evacuation of thousands - living near Alaknanda and Dhauliganga rivers - to safety.
The flooding damaged nearby Rishiganga and NTPC power plants. Officials said over 100 labourers working in the power plant are feared dead.
Five NDRF teams - one from Dehradun and four from Delhi - have been mobilised for the rescue operation. The Army has committed six columns, each with 100 soldiers. In addition, one Advanced Light Helicopter (ALH) and two Cheetah helicopters are also operating.

REASON FOR FLOODING DUE TO GLACIAL LAKE BREACH

Glacial lake outburst flood: Being most talked about was what glaciologists like to call a GLOF, or glacial lake outburst flood. It is a reference to flooding caused downstream due to a breach in a glacial lake.
Retreating glaciers, like several in the Himalayas, usually result in the formation of lakes at their tips, called proglacial lakes, often bound only by sediments and boulders.
Breach of Lake: If the boundaries of these lakes are breached, it can lead to large amounts of water rushing down to nearby streams and rivers, gathering momentum on the way by picking up sediments, rocks and other material, and resulting in flooding downstream.
Intensity: It depends on the size of the proglacial lake that burst, and location.

SUDDEN SURPIRSE:

Timing: The surprise is also because of timing — a possible reason for the sudden rush of water, like a cloudburst, is not expected at this time of the year.
Rare event: “Cloudburst would be a rare event during this time of the year. It does look like a GLOF event right now.”
Makeshift dam-like situation: “It is possible that an avalanche or a landslide created an obstruction in the flow of the river or streams in the upper mountains, resulting in a makeshift dam-like situation.
- When the pressure of the flowing water became large, the dam probably gave away, leading to a sudden gush of water.
Climate change: Then there are also issues to consider, like climate change or disproportionate construction in a fragile ecosystem, which were supposed to have contributed significantly to the 2013 disaster as well.

SOURCE: INDIAN EXPRESS

MCQs.

Q. Which of the following can cause the sudden water surge in downstream in Glacial region?

Select the correct answer from the code given below.

ANS: D