Authorities are closely monitoring the lake, rainfall and downstream areas, while identifying communities that could be at risk.
The death toll from the devastating flash floods along Nepal’s border with Tibet has risen to 469, Nepal Police said on Friday, as rescue teams continue searching for people missing after a torrent of water, mud and debris swept through the region earlier this week. Massive landslides and flooding struck the mountainous border area on Wednesday, causing widespread destruction across northern Nepal and parts of Tibet. Rescue and evacuation operations have continued, with military personnel and helicopters deployed to reach affected communities and search for survivors.
The disaster has also raised fears of further flooding after China issued a Level-IV emergency alert over a newly formed barrier lake near the confluence of the Chhochen Khola and Purepu Tsangpo rivers. The rivers originate in Tibet and flow into Nepal as part of the Bhote Koshi river system. China’s Ministry of Water Resources said the lake had accumulated around two million cubic metres of water by Thursday morning. Forecasts suggested inflows could reach about three million cubic metres over the following three days amid continued rainfall, raising the risk that the lake could breach and send more water downstream. Authorities are closely monitoring the lake, rainfall and downstream areas, while identifying communities that could be at risk. The potential impact includes areas around Gyirong Port on the China-Nepal border.
China has also deployed satellites, drones and unmanned aerial vehicles to support rescue and assessment operations. Satellite imagery is being used to assess the affected areas, while high-definition and thermal imaging equipment is helping rescue teams identify priority search zones and locate possible survivors in vegetation and mud-covered areas.
The flooding was initially thought to have been triggered by an earthquake, but the US Geological Survey said the disaster was caused by a "glacial collapse". The collapse was powerful enough to register as a magnitude 5.2 event as the glacier hit the valley floor, according to USGS data. Scientists believe the collapse sent huge amounts of ice, rock and sediment into the river system, triggering catastrophic downstream flooding. Mike Searle, professor of Earth sciences at Oxford University, said the sequence may have involved a landslide blocking the river before the accumulated water burst through in a massive flood.
The disaster sent a wall of mud and water through northern Nepal, destroying buildings, roads and vehicles. Severe flooding was reported along the Bhote Koshi, Trishuli and Narayani rivers, while deaths were also reported on the Tibetan side of the border. Scientists are continuing to examine satellite imagery, rainfall data and evidence of possible river blockages to establish exactly how the disaster unfolded.
