'High risk' of lake breaching and causing second flood, warns China

China has expressed concern that a lake formed after a recent landslide near the Nepal-Tibet border may breach its banks, potentially triggering another flood downstream. This warning follows a deadly flash flood in the same area on Wednesday, which scientists attribute to the collapse of a mountain glacier into a river. As of Friday, around 2.5 million cubic meters of water had accumulated in the lake, with an estimated three million cubic meters expected to flow in over the next few days, raising concerns about a high risk of breach.

However, experts suggest that the lake could drain naturally over time. The barrier lake, created by debris damming a river, has formed at the confluence of the Chhochen Khola and Purepu Tsangpo rivers, near the Langtang Lirung peak where the glacier collapse is believed to have originated. It is located several kilometers upstream from Gyirong Port, a major land crossing connecting Nepal and China.

On Thursday, the lake began to overflow. By Friday morning, a Chinese military drone captured footage of an avalanche depositing 50,000 cubic meters of ice debris into the lake. Authorities issued warnings and prepared for emergency evacuations, but rescue operations were suspended due to the lake's ongoing overflow. By Friday afternoon, state media reported that the risk from the upstream barrier lake had subsided, and rescue efforts resumed.

Geoscientist Jakob Steiner from the University of Graz noted that while the lake could still breach, it is uncertain if all the material from the mountain had been transported into the lake. If more material were to enter or avalanche further upstream, it could pose a significant problem. Chinese state media have also warned of heavy rainfall and storms in the region, increasing the likelihood of the lake swelling.

Experts caution that authorities should remain vigilant for potential secondary waves and post-disaster landslides, as the valley walls have been weakened by erosion. However, Steiner believes it is unlikely that the Chinese authorities could prevent the lake from overflowing, as there are no suitable roads to transport heavy machinery to the site. The melting season is expected to end by October, reducing the risk of further overflow.