Experts suggest a glacier collapse may have triggered recent landslides and floods in Uttarkashi, with further analysis needed to confirm the cause.
Did a glacier collapse cause the three landslides and flash floods in Uttarkashi on Tuesday? Experts are now veering around to this view.
“There are indications that a glacial snout at 6,700 m detached some days ago and large glacio fluvial debris deposits collected. Incessant rain over the past few days is believed to have led to loosening of the debris. Once critical mass was crossed, the massive collection of debris cascaded downstream with water in the Kheer Ganga, accelerating due to the steep gradient upto Dharali,” said Safi Ahsan Rizvi, advisor (mitigation), National Disaster Management Authority, and executive director, National Institute of Disaster Management.
He added that the scientific analysis that can establish this is incomplete.
But this is very likely, added another expert. “The disaster area is in the periglacial zone. Involvement of a glacier is likely,” said Anil Kulkarni, distinguished visiting scientist, Divecha Center for Climate Change, Indian Institute of Science.
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“Satellite images from September 2022 show there is glacier moraine upstream of the channel feeding Kheer Ganga. If there is continuous rain, a lake may have formed behind the end moraine ridge. The lake might have formed due to a landslide near the outlet. That may have overflowed with all the debris flowing into the channel,” he added.
The Wadia Institute of Himalayan Geology has also not ruled out the involvement of a glacier, but said that there is little data to establish any theory right now.
“Because of non-availability of ground-truthing and adequate satellite data, all of us are extrapolating at the moment. Someone said it was a cloud burst, and of course it is a possibility. Landslides are also a possibility because we do see some evidence of old landslides there. Glacial lake outburst flood (GLOF) is a possibility because there is a glacier and there is a snout and moraine so there is a possibility of a small pond being formed there which then breached leading to the floods. Landslides could have also led to a lake formation. None of us can confirm what the reason is unless we get to see satellite images of a pond that has now disappeared,” said Vineet Kumar Gahalaut, director, Wadia Institute of Himalayan Geology.
A glacial lake outburst flood (GLOF) is a release of meltwater from a moraine- or ice-dam glacial lake due to dam failure.
The state is no stranger to glacial disasters. On February 7, 2021, a failure of huge rock mass along with dislodgement of a glacier caused an air blast and dust clouds in the higher reaches of Garhwal Himalaya (Nanda Devi ranges). This event brought an unprecedented level of debris flow in the Raunthi Gadhera, Rishiganga, and Dhauliganga river valley in the Joshimath block of the Chamoli district, according to NDMA, killing over 200 workers who were stuck in tunnel of the under construction Tapovan Vishnugad Hydropower project.
Meanwhile, bad weather continued in the state, although the rainfall is likely to reduce in intensity from Thursday, according to the India Meteorological Department.
The article originally appeared on Hindustan Times
