Dharali landslide: Not cloudburst, glacier collapse or lake burst may have caused destruction

The flash flood that ravaged Dharali village in Uttarkashi on Tuesday was likely triggered by a glacier collapse or a glacial lake outburst, not a cloudburst as initially believed, The Times of India reported, citing experts analysing satellite imagery and meteorological data.

As rescue operations continue, scientists are examining signs of a possible avalanche, glacier burst, or lake breach upstream that may have unleashed the sudden torrent.

Rainfall figures recorded by the India Meteorological Department (IMD) cast doubt on the cloudburst theory. Harsil registered only 6.5 mm of rain on Tuesday, with a 24-hour total of 9 mm in Harsil and 11 mm in Bhatwari, far below the levels typically associated with cloudburst-triggered flooding.

“Only very light to light rain was observed in the affected area over 24 hours,” said Rohit Thapliyal, senior scientist at IMD’s regional centre. “The highest rainfall recorded anywhere in the district was just 27 mm at the district headquarters.” Another IMD official told TOI, “This amount of rainfall is too little to cause such severe flooding. It points to a high-impact event like a glacier burst or a GLOF (glacial lake outburst flood).”

According to the report, satellite images revealed large glaciers and at least two glacial lakes located directly above the affected region.

“There is a glacier right above the Kheer Gad stream. A sudden water release—whether from a glacial lake outburst or a glacier burst, could easily trigger a high-energy flash flood, similar to the Raini disaster in Chamoli in February 2021,” one of the scientists explained.

The 2021 Raini tragedy was caused by a rock-ice avalanche, which led to catastrophic flooding that destroyed the Rishiganga hydel project, severely damaged the Tapovan-Vishnugad power plant, and killed more than 200 people.

The Wadia Institute of Himalayan Geology notes that Uttarakhand is home to 1,266 glacial lakes, ranging from small ponds to large reservoirs, many of which pose serious threats to downstream communities.

The National Disaster Management Authority has identified 13 glacial lakes as high-risk, including five considered extremely dangerous.