Experts have cast doubts on reports that said the flood in Dharali village was caused by a cloudburst. Rainfall data showed that in nearby Harsil, only about 6.5 mm of rain was recorded on Tuesday. In 24 hours, a total of 9 mm was recorded in Harsil and 11 mm was recorded in Bhatwari.
Scientists are examining the possibilities of an avalanche, glacier burst or lake breach upstream that may have caused the landslide.
Rohit Thapliyal, senior scientist at IMD’s regional centre, said that only very light rain was observed in the affected area in over 24 hours. “The highest rainfall recorded anywhere in the district was just 27 mm at the district headquarters,” he said.
The recorded numbers were nowhere near enough to meet the category of a cloudburst.
What is a cloudburst?
A cloud burst is a sudden rainfall that happens in a short period. Metrologists define it as an event that occurs in a area concentrated to 30 sq km or less with a rainfall rate of over 100 mm of rainfall in an hour.
Flash flood likely to have been caused by a glacial lake outburst flood
According to another IMD official who spoke to The Times of India, “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).”
A glacial lake outburst flood is a catastrophic flood that is usually caused by the failure of a dam that contains a glacial lake. A glacial lake is formed when the meltwater of a glacier accumulates in one area and is dammed by ice and debris. The rapid release of water from the lake, which is often caused by the dam weakening, can cause downstream flash flooding and avalanches.
Dharali is home to glacier lakes
Satellite images of the area showed that large glaciers and at least two glacial lakes were 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 said. The Raini disaster occurred after a rock-ice avalanche triggered floods that destroyed the Rishiganga hydel project and damaged the Tapovan Vishugad power plant, which resulted in more than 200 deaths.
However, Shardul Gusain, District Disaster Management Officer of Uttarkashi, argues that at least three cloudbursts were recorded in the region. "Initial indications point to cloudbursts as the trigger," he said, adding, "More clarity is expected once new data arrives in the morning. At this point, we cannot rule anything out. The weather was relatively calm the previous day, with only light rainfall. But in the mountains, the weather can change in an instant. He also says that Dharali, Harsil, and Sukhi, all saw cloudburst events.
Uttarakhand is home to at least 1266 glacial lakes that range from small ponds to large reservoirs, and many of them pose a threat to communities living downstream, according to the Wadia Institute of Himalayan Geology.
About 13 glacial lakes have been identified by the national disaster management authority as high risk, and five are considered extremely dangerous.
More rain in Uttarkhand
Meanwhile, the Indian Meteorological Department has issued an orange alert as rains are expected to continue in Uttarakhand till August 10 2025.
The weather department has issued an orange alert in Uttarkashi, Dehradun, Nainital, Chamoli, Champawat, Udham Singh Nagar, Bageshwar, Tehri, Haridwar, and Pithorgarh.
Over 174 mm of rain in 24 hours is to be expected in some parts of the state, including Maldevta, which is considered to be under very heavy rainfall or excessive rainfall by the meteorological department. Excessive rainfall creates a possibility of flooding and landslides in hilly areas.
64.5–115.5 mm of rain is just considered to be “heavy rainfall” and may cause general waterlogging and strong flow in drains.
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A rainfall recorded at 204.5 mm or more is considered “Extremely heavy rainfall” and will cause severe flooding, structural damage, and the possibility of loss of life.
The torrential rains have pushed the water levels higher in rivers in the state and have caused flood like condistions in many parts
Five people have been killed and hundreds have gone missing after a flash flood swamped the Dharali village in Uttarkashi, Uttarakhand. Rescue operations are underway, and about 150 persons have already been rescued.
