Two days after a glacier collapse sent a catastrophic flood roaring through parts of Nepal and Tibet on Wednesday, a newly formed river has broken the banks, and a renewed flood threat is looming. The river breach on Friday halted rescue operations in the area after flash floods and mudslides caused by glacial collapse from the Himalayas led to 469 confirmed deaths. More than 1,000 people remain missing across Nepal and China’s Tibet.
A lake has formed by the buildup of debris at the border of Nepal and China at the flood site, and as it continues to rise, it increases the flood risk. On Friday, officials in Nepal’s Rasuwa district said they had been notified that the barrier lake had begun to overflow. He added that it is currently unclear how high the water level is.
We can see that the level of water in the river is rising.” Scientists say this disaster has created not one but two new lakes. One has formed high up near the glacier, where meltwater is now trapped. The other, much larger and more dangerous lake sits on a river in Nepal, where a huge landslide blocked the valley and dammed the river.
Nepali and Chinese authorities warned on Thursday that the lower lake had formed due to the buildup of debris at the site of the flood. The lake is rising in level, which means it can burst, Nepal’s National Disaster Risk Reduction and Management Authority (NDRRMA) warned. Chinese authorities said they have mobilised an engineering team comprising eight members to carry out aerial surveys and 3D modelling of the barrier lake in Nepal, Chinese state broadcaster CCTV reported on Friday.
However, there are challenges when it comes to accessing the site. The lake is near the confluence of the Chhochen Khola and Purepu Tsangpo rivers on the Lhende river system in Nepal. It is flowing upstream of the Bhotekoshi and Trishuli rivers that carry water south towards Kathmandu, the Kathmandu Post reported.
The glacial collapse which resulted in the Wednesday flash floods also caused mudslides, pushing rock, ice, mud and debris into river systems. The ice-rock avalanche deposited a huge volume of rock, ice and debris in the river valley, blocking or severely constricting the drainage,” Pawan Bhattarai, assistant professor at the civil engineering department of Nepal’s Kathmandu-based Tribhuvan University, told Al Jazeera. Satellite imagery and even some Chinese media reports has confirmed the barrier lake.” These immense piles of debris blocked river channels, creating a natural dam and hence causing this lake to form.
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