A day after a flash flood ravaged Dharali village in Uttarkashi district, new evidence is shifting focus away from the initial assumption of a cloudburst. Instead, experts are now pointing toward a more dangerous cause — a glacial lake outburst flood (GLOF) or glacier collapse.
Early theories attributed the sudden deluge to a cloudburst, a common occurrence in Uttarakhand during the monsoon. However, recent data from the India Meteorological Department (IMD) indicates that rainfall in the region was only light to moderate. The heaviest precipitation in the district headquarters was just 27 mm, far below the threshold required to define a cloudburst.
IMD’s forecast for the area continues to predict “light to moderate rainfall, with isolated very heavy showers likely during the afternoon and night hours.” However, this falls short of the 100 mm-per-hour intensity typically required to classify an event as a cloudburst.
Satellite Imagery and Scientific Input Point to Glacial Trigger
Satellite images examined after the flood reveal the presence of large glaciers and at least two glacial lakes upstream of Dharali, located directly above where the disaster began. This has led scientists to propose that the sudden release of water from one of these lakes, or a glacier collapse, could have unleashed a torrent of water and debris down the Kheer Gad stream.
The aajtak.in quoted glaciologist Dr DP Dobhal who said, “A cloudburst typically means over 100 mm of rainfall in an hour. However, IMD data shows that only 8–10 mm of rain was recorded from the night of August 4 till 8:30 AM on August 5. The flash flood occurred later in the afternoon, suggesting that a cloudburst was likely not the cause.”
In contrast, Shardul Gusain, District Disaster Management Officer of Uttarkashi, maintained that three cloudburst incidents were recorded in the region — Dharali, Harsil, and near Sukhi Top. “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.”
Rising Threat of Glacial Lake Outburst Floods in Uttarakhand
A glacial lake outburst flood occurs when water dammed by glacial ice or a moraine is suddenly released, unleashing enormous volumes of water downstream. These floods can destroy villages, infrastructure, and disrupt power supply within hours.
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Uttarakhand has over 1,260 glacial lakes, and 13 of them are classified as high-risk (Category A) by the National Disaster Management Authority (NDMA). These vulnerable lakes are increasingly concerning for disaster response teams, especially as climate-induced glacial melt accelerates.
The incident echoes the 2021 Chamoli disaster in Raini, where a similar rock-ice avalanche caused a deadly flood. As rescue efforts continue in Dharali and experts study new data, the need for real-time monitoring and early warning systems around glacial lakes has never been more urgent.
