China warns of high risk as barrier lake threatens second flood near Nepal border

China has issued a warning that a barrier lake formed after a landslide near the Nepal‑Tibet border could burst, potentially causing a second flood downstream. The alert follows a deadly flash flood that struck the region on Wednesday, killing hundreds and leaving many missing.

According to CCTV, the lake, which sits at the confluence of the Chhochen Khola and Purepu Tsangpo rivers, holds an estimated 2.5 million cubic metres of water as of Friday morning. Officials say that between Thursday and Saturday an additional three million cubic metres of water is expected to enter the lake, creating a “high risk of breach.” The lake has already begun to overflow, the Ministry of Water Resources reported, and the area has received heavy rainfall.

Engineering teams dispatched by Chinese authorities are monitoring the lake’s water level and atmospheric conditions. CCTV footage shows emergency workers stranded at a village about 7 km (4 miles) from Gyirong Port, the main land crossing between Nepal and China that was inundated by Wednesday’s flood. The continuous overflow of the barrier lake threatens new floods or debris flows, forcing search and rescue operations to halt near the border.

The barrier lake lies in the same region as Langtang Lirung, the peak whose glacier is believed to have collapsed into the river and triggered the Wednesday flood. Nepali authorities have warned of similar risks along the Bhote Koshi and Trishuli rivers and urged residents to stay away from the waterways until further notice.

Scientists attribute the Wednesday flash flood to the sudden collapse of a glacier near Langtang Lirung. The debris damming the river created a temporary lake that, when breached, released a surge of water and mud downstream. The flood devastated communities in both Nepal and Tibet, with the Tibetan side reporting more than 550 missing persons, nearly half of whom are foreign nationals. In Nepal, hundreds of people have died and many remain missing.

China’s warning comes as the barrier lake’s capacity is rapidly filling. The ministry’s statement that the lake is “overflowing non‑stop” underscores the urgency of the situation. If the dam fails, the resulting torrent could travel downstream, potentially affecting the same areas that were already devastated by the earlier flood.

The Chinese government has mobilized emergency services to the region, but the terrain and ongoing water flow have hampered relief efforts. Local authorities in both countries are coordinating to monitor river levels and to assess the stability of the debris dam.

The incident highlights the vulnerability of Himalayan communities to glacial and landslide hazards, especially in the context of climate change and increased precipitation. International experts have called for improved monitoring of glacial lakes and debris dams, as well as better communication between neighboring countries to mitigate the risk of secondary disasters.

In summary, China warns that a barrier lake formed after a recent landslide could burst, posing a high risk of a second flood downstream. The lake holds 2.5 million cubic metres of water, with an expected influx of three million more cubic metres over the next few days. The region has already experienced a deadly flash flood, and authorities have halted rescue operations due to the threat of further flooding. The situation remains fluid, with emergency teams monitoring water levels and atmospheric conditions, while Nepali officials advise residents to stay clear of the affected rivers.