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Chamoli flash foods: Experts intrigued by the place and timing

TV Jayan New Delhi | Updated on February 08, 2021

Scientists are intrigued by the flash floods that occurred in Chamoli district in Uttarakhand, which resulted in the death of 18 people and around 200 people missing on Sunday, as the glacial regionis said to be more stable and such freak events are least expected in the middle of a winter season.

“Nobody really knows what exactly went wrong there. We were not expecting this to happen at this time of the season and that also in this area actually,” said Thamban Meloth, a senior scientist at the Goa-based National Centre for Polar and Ocean Research (NCPOR).

Apart from the human casualties, the flash floods near Joshimath in Chamoli district in Uttarakhand resulted in the partial or total destruction of two hydropower projects in Rishiganga and Tapovan.

Avalanche

Glacial lake outbursts can happen in a climate warming scenario when glaciers start retreating. This produces more water, leading to the formation of lakes. Such lakes are vulnerable when there is an avalanche or a cloud burst like what happened in Kedarnath in 2013, said Meloth, who has been studying Himalayan glaciers for quite some time.

“In Tapovan, there is no available records suggesting that such a lake is existing. As per the information coming up, it could be probably due to an avalanche initiated by a landslide in the upper reaches. People are looking at high resolution satellite data for the last couple of days to understand what would have happened,” said the NCPOR scientist.

Anil Kulkarni, a scientist at the Davecha Centre for Climate Change at the Indian Institute of Science in Bengaluru, on the other hand said he and his team have identified as many as 26 glacial lakes in the Alaknanda basin and that one of them is very close to the region where the flash flood has taken place. “We knew that this is a potential lake, which can cause a flash flood,” said Kulkarni, who has been using remote sensing to study Himalayan glaciers for more than two decades.

“Since Sunday, a lot of people have been saying there was a landslide even though such landslides normally do not happen in the middle of a winter,” said Kulkarni, adding that if it did happen it may have led to draining of water from this lake in the terminus region of the Nandadevi glacier.

But he said it would be difficult to say if the bursting of this lake led to the flash floods. “It is a bit difficult to ascertain whether water from the lake has flown out. Since this is winter time, the top layer of water would be frozen, and on top of it, it is still snowing. Knowing whether there is still water beneath (in the lake) will be difficult to know (from satellite imageries),” said Kulkarni.

Naresh Chandra Pant, professor of geology at the University of Delhi, said global warming could have also played a role. “As global warming takes place and if there is less snow precipitation, the top surface of the glacier would not get consolidated with fresh snow. This thinning of the top leads to a disequilibrium of body of melted water which is trapped inside the glacier. This becomes amenable to bursting. When that happens there is a quick release of water which carried another materials such as debris,” said Pant. This is the only possible explanation in the scientific context, said Pant, who is also a member of the Scientific Committee on Antarctic Research.

Published on February 08, 2021

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