Scientists continue to be uncertain about the downstream impact of a pool of water that is building up at the spot in the Rishiganga river from where the avalanche on Sunday first struck Raini village, destroying a hydroelectric plant as well as damaging and trapping workers in the Tapovan dam downstream.
The pool of water has been formed, as The Hindu reported on Thursday, because the flow of the Rishiganga was obstructed at its confluence with another stream, the Raunthi stream, owing to a huge pile of rock, debris and snow there. This pile is part of the debris that avalanched on Sunday from the breaking of a rock slope on a glacier.
The Uttarakhand police have tweeted that the length of this new stretch is about 350 meters.
“There is a natural obstruction that has formed but it is like a dam that is holding up water. My colleagues had seen the build-up as part of an aerial survey. It looks like some of the water has already started to flow over this dam but we don’t know if there will be enough pressure to cause another flood,” said Kalachand Sain, Director, Wadia Institute of Himalayan Geology, Dehradun.
With relief operations — now on its sixth day — downstream near the Tapovan hydropower project to salvage some workers still reportedly trapped in the tunnels of the dam, a new flood or new debris rolling down could impede relief work.
Naresh Rana, Geologist, HNB Garwahal University, Srinagar Garwahal, saw the dam on Thursday and reported its presence to media outlets. “The water has started trickling down since last evening. I think there is no reason to panic. Rishiganga is a river and at some point, the water would have flowed down. But we need a constant vigil so that we can send a warning downstream in case of sudden increase in its volume,” he told The Hindu in a phone conversation.
A State Disaster Response Force (SDRF) team had been sent to the spot where the lake had formed after the snow avalanche. “The SDRF team has reached the location. It will try to determine if there is any disaster threat due to the lake formation. It will also prepare a temporary helipad for the scientists to be flown in. The DRDO scientists are currently examining the development using aerial and satellite pictures,” a senior Uttarakhand police officer told The Hindu .
