China-Nepal rescue efforts face new threat as barrier lake overflows
Rescue operations along the China-Nepal border have been paused as a newly formed barrier lake begins overflowing, raising fears of fresh flash floods and landslides in a region already devastated by Wednesday's landslide and torrential flooding. The lake, holding an estimated 1,000 Olympic swimming pools' worth of water, formed after debris dammed the river upstream of the Gyirong border port, a critical disaster zone.
Authorities in both countries halted helicopter rescues in Nepal's Rasuwa district and ground operations near the port on Friday, citing the immediate risk posed by the overflowing lake. Chinese state broadcaster CCTV reported that the lake has been overflowing non-stop, making it too dangerous for teams to reach priority search areas.
“There is a very real possibility that it could trigger new flash floods or landslides, so it is extremely dangerous to proceed to the areas that have been identified as priorities for search and rescue operations,” CCTV reported.
What is a barrier lake and why is it dangerous?
A barrier lake forms when a landslide or debris flow dams a river, creating a body of water that can grow rapidly. If the natural dam fails, the sudden release of water can cause catastrophic flooding downstream. In this case, the lake is located about 10 kilometers upstream of the Gyirong port, and its volume has been expanding, reaching a storage capacity of over 2.5 million cubic meters by Friday afternoon.
Chen Hanxiao, a member of the monitoring team dispatched by China Anneng Engineering Rescue Lhasa Base, told CCTV that the barrier stretching about 150 meters long and 40 to 50 meters high is unstable. “The rocks and soil along the area are currently loose. During the assessment operation, secondary collapses occurred several times above the barrier,” he said, adding that safety personnel would withdraw immediately if significant displacement was detected.
How are authorities monitoring the risk?
Chinese authorities have deployed teams to monitor the lake and analyze the risks, adapting rescue plans accordingly. A top government official in Nepal's Rasuwa district confirmed that Chinese officials shared information about the overflow. Meanwhile, experts are also tracking a second barrier lake that formed just below the fracture in the glacier that broke on Wednesday, which triggered the initial disaster.
Austin Lord, a senior fellow at the Stimson Center think tank, said that breaches of either lake could cause a small flood in the same flow path as the initial event, rather than a major catastrophe. “They're growing in volume. They're not insignificant, but they're not to the extent that if they failed they could trigger an event on the scale that we saw,” Lord told CNN. However, he warned that ongoing rain could increase the water volume, putting more pressure on the dams and raising the risk of a breach.
What are the main concerns for rescue teams?
The immediate concern is the safety of rescue personnel operating in the river corridor, which remains vulnerable to sudden flooding. The challenge in the coming days will be managing the lakes' growth as weather systems continue to bring rain. Rescue teams are currently waiting at a village several kilometers from the Gyirong port, as roads remain blocked by thick mud and debris.
The situation underscores the delicate balance between urgent humanitarian needs and the unpredictable nature of geological hazards in the region. Authorities are prioritizing data collection and risk assessment to inform their next steps, but the window for rescue operations may be narrowing as the lakes continue to swell.
Frequently asked questions about the barrier lake and rescue efforts
What caused the initial disaster on the China-Nepal border?
The disaster was triggered by a powerful landslide and torrential flooding on Wednesday, which devastated the area near the Gyirong border port and Nepal's Rasuwa district. The landslide also broke a glacier, leading to the formation of the barrier lakes.
Why have rescue efforts been paused?
Rescue operations were paused due to the risk of new flash floods or landslides from the overflowing barrier lake. The unstable natural dam could collapse, endangering both rescue teams and survivors in the area.
How are authorities responding to the new threat?
Chinese and Nepalese authorities are monitoring the lakes closely, with teams dispatched to measure the barriers and assess risks. They are also sharing information across the border and adapting rescue plans based on real-time data.
What could happen if the barrier lakes breach?
If either lake breaches, it could trigger a small flood in the same flow path as the initial event. While not expected to be as catastrophic as Wednesday's disaster, it would still pose a significant danger to anyone in the river corridor, including rescue personnel.