In a joint operation, an Indian Air Force Advanced Light Helicopter (ALH) winched Navy’s divers to measure the depth of a glacial lake formed upstream of Tapovan in Uttarakhand following the devastating flash flood, the Navy said on Sunday. Over 65 people were killed and 139 are missing after a glacial disaster in the state's Chamoli district on February 7. The artificial lake was formed over Rishiganga after the calamity.
The operation by the naval divers took place at a height of 14,000 feet above the mean sea level on Saturday.
"The Naval divers undertook the challenging task of winching down from the helo and recording of depth using a handheld echo sounder (depth measuring equipment) in the near freezing waters. Throughout the evolution, the IAF pilots maintained accurate positioning in the difficult terrain," the Navy said.
The data will help scientists determine the pressure on the mud wall of the dam.
The lake is 400 metres in length, 25 metres wide and 60 metres deep. The water catchment not being natural the administration urgently needed to assess the condition of the catchment by measuring the depth of water. "With no road access and time criticality Indian Navy diving team were quickly mobilised onboard the IAF ALH," the Navy said.
After the formation of a lake following the Uttarakhand floods, there has been a rise in the Rishiganga-Dhauliganga riverbeds which may pose a fresh threat to Chamoli district. The riverbeds of Dhauliganga and Rishiganga have risen by few metres at Tapovan.
"We have noticed considerable rise in riverbeds after the floods which is a big issue before us," said a top NTPC official.