New lake on Nepal-China border poses fresh flood threat
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A newly formed barrier lake on the Nepal-China border is threatening to trigger another flood, two days after a glacial collapse caused flash floods and mudslides that killed 469 people and left more than 1,000 missing across Nepal and Tibet.
The lake formed after a massive landslide pushed rock, ice, mud and other debris into a river, creating a natural dam.
Nepali officials said on Friday that the lake had begun overflowing, forcing rescue operations in the hard-hit Rasuwa district to briefly pause before they resumed.
Scientists say the disaster appears to have created two lakes. One formed at high altitude near the collapsed glacier in China, where meltwater has become trapped. The second, larger lake formed on Nepal's Lhende river after a landslide blocked the valley.
The lake is near the confluence of the Chhochen Khola and Purepu Tsangpo rivers and lies upstream of the Bhotekoshi and Trishuli rivers, which flow south towards Kathmandu.
China's Ministry of Water Resources estimated that the lake contained 1.5 to 2 million cubic metres of water on Thursday and warned that another three million cubic metres could flow into it over three days. If the natural dam of rock and mud fails, a sudden outburst could send water, sediment and boulders downstream with little warning.
Nepal's disaster management authority has warned that the rising lake could burst. China has deployed an eight-member engineering team to conduct aerial surveys and 3D modelling, but steep cliffs and difficult terrain are complicating access.
Scientists say the natural dam itself could not have been prevented, but better satellite monitoring, river monitoring, early warnings and coordinated Nepal-China evacuation systems could reduce the risks.
Similar cascading events have occurred in the Himalayas, including Nepal's destructive 2012 Seti flood. Glacial collapses and glacial lake outburst floods have also occurred in Tibet and northern Pakistan in recent years.
The World Health Organization said six health facilities had been damaged and eight health workers were missing. Nepal has said it does not currently require foreign search and rescue assistance.