Sikkim's Lhonak lake had a half-built warning system for glacial floods

Scientists and government authorities were in the process of installing an early warning system for potential glacial floods at a Himalayan Lake in northeast India when it breached its banks this week, resulting in tragic consequences. Sikkim, characterised by its rugged terrain, plunged into chaos as floods triggered by heavy rainfall and an avalanche claimed at least 18 lives. This was one of the worst disasters in the region in the past five decades with more than 100 people remained missing till Thursday. Officials involved in the project told Reuters that the initial phase of the warning system, which included a camera to monitor the water level of Lhonak Lake and weather instruments, had been installed just last month. Should the warning system have been fully operational, it had the potential to provide residents with more time to evacuate, according to scientists. They said that typical glacial early warning systems can offer residents anywhere from a few minutes to an hour of advance notice. Details of the Lhonak Lake warning system have not previously been reported. “It’s quite absurd, really,” said geoscientist Simon Allen of the University of Zurich who is involved with the project. “The fact it happened just two weeks after our team was there was completely bad luck”. He said they planned to add a tripwire sensor that would trigger if the lake was about to burst. That would typically be connected to an alert system or siren that would warn residents to immediately evacuate to higher ground. “The Indian government was not prepared to do that this year, so it was being done as a two-step process,” he said. The monitoring devices were supposed to send data to authorities, but the camera lost power for an unknown reason in late September, according to a source at the Swiss embassy, which supported the project. As climate change warms high mountain regions, many communities are facing dangerous glacial lake outburst floods (GLOFs). Lakes holding water from melted glaciers can overfill after heavy rain and burst, sending torrents rushing down mountain valleys. More than 200 such lakes now pose a very high hazard to Himalayan communities in India, Pakistan, China, Nepal and Bhutan, according to 2022 research. In recent years, glacial flood early warning systems have been deployed in Nepal, Pakistan, and Bhutan. The early warning systems at Lhonak Lake, and another at nearby Shako Cho in Sikkim, were to be among the first in India for glacial lake outburst floods, sources told Reuters. Scientists have for years said the two lakes are at risk of outburst floods, but the design process and search for funding caused time to pass without progress. India plans to install early warning systems at several other glacial lakes, said Kamal Kishore, a senior official at India’s National Disaster Management Authority (NDMA). He did not answer further questions on the Lhonak project. However, Farooq Azam, a glaciologist at the Indian Institute of Technology Indore, noted that even if the system had been in place, the potential benefits were not clearcut. “Such kind of events are so fast that even if we have some kind of early warning system … we may only gain some minutes, maybe an hour,” he said. The Lhonak Lake as other glacial lakes are large bodies of water sitting on top of, or beneath a melting glacier. As they grow larger, they become more dangerous. This is because they are blocked by ice or sediment of loose rock and debris. If and when the boundary breaks, huge amounts of water rush down mountains at phenomenal speeds, causing flooding in the downstream areas. With inputs from Reuters.