DEHRADUN: The recent devastating deluge in Uttarakhand's Dharali village, which caused widespread destruction, may not have been triggered by a cloudburst, according to meteorological data and scientific experts. Instead, researchers point to more complex hydrological and geological factors behind the disaster.
Meteorological records show that the area received only 8 to 10 mm of rainfall on the afternoon of the catastrophe and the preceding night—far below the 100 mm threshold required to classify an event as a cloudburst. Scientists now propose alternative explanations, including the formation of temporary lakes due to landslides blocking river flow, glacial or rockfall disturbances, or sudden flash floods.
Retired glaciologist Dr DP Dobhal of Wadia Institute of Himalayan Geology outlined three potential causes for the Khirganga River flood. "The devastating flood likely stemmed from three primary causes," he said. "First, accumulated glacial sediment from two small glaciers above Khirganga may have been washed down by heavy rainfall." He continued, "Second, a landslide could have blocked the river, forming a temporary dam that later burst." He also noted human encroachment as a factor: "It's widely known this is a river path, yet settlements have emerged there."
Dr Dobhal, who has extensively studied the Gangotri Glacier, also warned of shifting rainfall patterns in the Himalayas. "The entire region above 6,000 feet is filled with loose sediment. Previously, these areas experienced gentle, prolonged rain. Now, we witness intense bursts lasting only 20 minutes, followed by cessation. This is an extremely dangerous situation, with rainfall now even reaching the snowline." He emphasized the need for aerial surveys to determine whether the disaster resulted from a glacier burst or a blocked river breach.
Supporting this assessment, Dr Manish Mehta, a senior scientist at the Wadia Institute, said, "The true cause of this disaster can only be fully understood once satellite images become available." He noted that past studies suggest possibilities such as glacial lake outbursts, landslide-induced floods, or sudden flash floods as plausible triggers.
The findings underscore the growing complexity of Himalayan disasters, where traditional explanations like cloudbursts may not always apply, necessitating deeper scientific investigation into evolving climatic and geological risks.