DEHRADUN: Geologist Naresh Rana of Hemwati Nandan Bahuguna Garhwal University, who was among the first experts to notice the new lake formation at the site of the floods, told TOI that while an avalanche may have acted as a trigger, water accumulated inside the glacier was the “real culprit”.
“Glaciers often have accumulated water inside their crevasses or in small sub-glacial lakes. In this case, the water must have reached its saturation point. Any avalanche or landslide may disturb the glacier’s process and break its reservoir, leading to a sudden increase in water outflow. Then it flows along with heavy sediments at a rapid speed along a steep slope.” He added that “had it been just an avalanche, it would have stayed confined to the valley.” “It was the accumulated water inside the glacier, punctured by an avalanche, that caused the river to swell, leading to flash floods.”
Meanwhile, scientists of Wadia Institute of Himalayan Geology said a chunk of hanging glacier, around 500m in length, had broken off and fallen into the Raunthi river, causing ‘an explosion like sound.’ This was at 2:30am. Over the next eight hours, a slurry of ice, water and boulders ended up in Rishiganga, triggering the flash flood.