THEY NOW have a number. The lake that was formed upstream of the Rishi Ganga river after the February 7 flash floods in Uttarakhand’s Chamoli district, holding the potential of a fresh deluge, is between 8 metres and 9 metres in depth at different points, and contains about 50,000 cubic metres of water.
In a joint operation Saturday, an Indian Air Force Advanced Light Helicopter winched divers from the Indian Navy into the lake to measure its depth. As the helicopter hovered 14,000 ft above sea level, the divers plunged into the ice-cold water with handheld echo sounders to calculate the depth. In a release, the Navy noted the complexity of the operation, including holding the choppers steady in the difficult terrain.
According to a Navy official, the operation lasted around half-an-hour, starting with the take-off from Joshimath to reach the lake, positioning of the helicopter over it, the dive into the waters to record the depth at several spots, and the return to Joshimath.
Following the operation, Uttarakhand officials said, they assessed the amount of water held in the lake at 50,000 cubic metres. An official said the Navy had measured depth at five spots in the lake, and calculated the average depth at around 8 metres.
“The data is important as earlier we were not able to assess the volume of water in the lake,” said Ridhim Aggarwal, DIG, State Disaster Response Force (SDRF), and…