Chamoli disaster due to avalanche

Source: The Hindu

What is the News?

The Geological Survey of India has come out with a report. It suggests that the disaster which hit Chamoli district of Uttarakhand was possibly due to an avalanche.

Note: An avalanche (also called a snowslide) is a rapid flow of snow down a slope, such as a hill or a mountain. Avalanches can happen due to various factors such as increased precipitation or snowpack weakening or by external means such as humans, animals, and earthquakes.

Background:

• In February 2021, a part of the Nanda Devi glacier broke off and flooded the Rishiganga river in Chamoli district of Uttarakhand.
• It led to massive flooding in the region that damaged many villages in its path and claimed at least 72 lives and 200 missings.
• The flood also wiped out two hydroelectric power projects on their way.

Why did this disaster happen? According to the Geological Survey of India report, the disaster happened due to:

• A large mass of snow, ice, and rock avalanche along with a hanging mass of rock had crashed into the Raunthi Garh valley floor.
• Due to this, it crushed the combination of rock, snow, and ice causing a rapid flow downstream of Raunthi Garh and into the Rishiganga valley leading to the flash flood.
• The flash flood, in turn, destroyed the 13.2 MW Rishiganga power plant and damaged the 520 MW Tapovan-Vishnugad hydel power project, in which tunnels several workers had been fatally trapped.

Major Factor behind this Flash Flood:

• A major contributory factor for this flash flood was the unusually warm weather in the region. (heavy snowfall followed by a sudden warmer climate).
• This may have possibly triggered this huge snow and rock avalanche/ landslide, causing a sudden domino effect of flash floods downstream.

Note: The report has found no evidence of a Glacial Lake Outburst Flood (GLOF) having caused the Chamoli Disaster.