Two days after a massive glacier collapse triggered a catastrophic flood in Nepal and Tibet, a newly formed river has breached the banks, raising concerns of a renewed and potentially devastating flood. 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 and more than 1,000 missing individuals 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.
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. 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.
On Friday, officials in Nepal’s Rasuwa district said they had been notified that the barrier lake had begun to overflow. ‘We can see that the level of water in the river is rising,’ Narendra Pariyar, Rasuwa’s most senior bureaucrat, said. He added that it is currently unclear how high the water level is. ‘We do not know how big it is and how high is its water level. We can see that the level of water in the river is rising.’
Scientists suggest 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.
The lake 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 glacial collapse which resulted in the Wednesday flash floods also caused mudslides, pushing rock, ice, mud and debris into river systems. These immense piles of debris blocked river channels, creating a natural dam and hence causing this lake to form.
China’s Ministry of Water Resources estimated on Thursday that the lake is holding about 1.5 to 2 million cubic metres of water and warned that about 3 million cubic metres more could flow in over three days. This is equivalent of about 1,200 Olympic-sized swimming pools.
“It is a threat, because if a formed lake suddenly breaches it may cause another flood; it may mobilise the sediments that will hamper search and rescue operation and will also put dangers to those surviving in the hydro tunnels,” Khadka said.
Rescue efforts have been impeded due to the floods and mudslides.
In the hard-hit Rasuwa district, they were paused on Friday since the barrier lake broke its banks. However, after the brief pause, the efforts were resumed. China’s state broadcaster CCTV said on Friday that the risks from the overflowing barrier lake were “manageable”.
According to a World Health Organization official on Friday, six health facilities have been damaged by the floods, and eight health workers are missing.
Nepal has said it does not need help from abroad.
“The offer for help is natural. Our security agencies are doing the search and rescue operation. For now we don’t require such help,” Lok Bahadur Chhetri, Foreign Ministry spokesperson, said on Friday.
While this exact barrier river has not formed before, glacial collapse and glacial lake outburst floods have happened before in the Himalayas. Simply put, a glacial collapse refers to when a large mass of glacier ice detaches from its bed.
This sometimes involves millions of cubic metres of ice, rock and water, which can transform into a highly mobile ice-rich avalanche or debris flow.
Glacial lake outburst floods (GLOF) refer to the sudden and catastrophic release of vast volumes of water from melting glacier-fed lakes.
In July 2016, the lower part of a valley glacier in Tibet’s Aru Range detached, sending about 68 million cubic metres of ice down the mountain and killing nine herders and hundreds of animals. This was located in far western Tibet, near the Pangong Tso region along the India-China border. Two months later, a nearby glacier collapsed, releasing about 83 million cubic metres of ice.
In November 2022, about 40 million cubic metres of glacier ice detached from the Bukadaban Feng glacier in the Kunlun Mountains on the northern edge of the Tibetan Plateau, in China’s Qinghai province. An ice avalanche crashed into a lake below, creating a 13-meter (42ft) high wave, according to analysis by the European Space Agency.”
This means that if the lake causes a flood, the flood will pick up mud and rocks, making the water even more destructive and making it harder for teams to search for the missing.”
Source: Al Jazeera
