A new danger has interrupted rescue operations after the severe flood that struck the Himalayan border region between Nepal and China two days ago: a lake formed by a landslide on the Tibetan slope has begun to overflow, threatening the same areas already devastated by the surge and forcing rescuers to withdraw temporarily.
The report was carried by Deutsche Welle, which cited Nepalese authorities and Chinese sources. Narendra Pariyar, the senior-most civil official in Rasuwa district, said he had received “a communication that the lake has broken its banks” and observed a rise in river levels. Images and eyewitness accounts collected by international media show residents fleeing to higher hills to seek safety.
The phenomenon is the result of a landslide caused by the collapse of a glacier: debris and rock material blocked the upstream watercourse, creating an artificial reservoir above the point where the flood originated. According to Beijing, cited by CCTV and reported by DW, the lake contained roughly 2 million cubic metres of water at the time of measurement and is estimated to receive another 3 million over the next three days — a total volume of about 5 million cubic metres, equivalent to more than 1,200 Olympic swimming pools.
The size and location of the basin explain the new emergency: the debris dam is more than 10 kilometres from the Gyirong border crossing, the place initially struck by the flood, and sits at an elevation roughly 1,000 metres higher than the border post. Surveys by Chinese engineers indicate the lake is about 150 metres long with an estimated depth between 40 and 50 metres, although precise measurements are difficult because of fractured terrain.
The hydraulic alert prompted immediate measures: Chinese rescue personnel were evacuated to an area deemed safe and Nepalese authorities suspended search operations for at least 90 minutes, according to Reuters and relayed by DW. The interruption slowed searches for hundreds of people still missing after the initial catastrophe.
Official figures provided by Nepal, also cited by DW, list 469 confirmed deaths, up from the earlier count of 390. China has not updated its official toll, which before the latest developments stood at three deaths in the Tibet Autonomous Region. Authorities in both countries have also reported that more than 1,000 people remain unaccounted for: among them up to 540 are believed to be foreign nationals from more than 30 countries, though these figures remain approximate and subject to verification.
The operational picture on the ground is complex. Persistent rainfall forecast over the next days risks further feeding the basin and destabilising the rock faces and slopes around the lake, increasing the danger of additional flows and collapses. In response, China has sent an engineering team of eight experts tasked with flying over the area, collecting data and producing three-dimensional models of the site to plan mitigation interventions.
Statements by engineer Chen Hanxiao, reported by Chinese state television and cited by DW, underline the difficulty of the operation: the glacier collapse created multiple isolated cliffs and steep scarps around the lake perimeter. The general strategy outlined is to excavate a drainage channel at the lowest point of the debris dam, but the channel’s dimensions and slope will depend on hydraulic calculations and on how quickly the lake continues to fill.
The practical consequences of the overflow are immediate and severe. In Nepal, the suspension of searches reduces the chances of finding survivors in the critical hours after the event; many border infrastructures, villages and road links are damaged or impassable; and the presence of numerous foreign nationals among the missing complicates logistics and identification, involving embassies and consular services.
At the regional level, the event highlights the increasingly evident risks associated with glacier degradation and extreme precipitation in mountain areas. Experts note that the combination of glacier collapse, heavy rain and landslides can quickly create unstable temporary basins with potentially destructive downstream surges. However, the information available at present comes primarily from official Chinese and Nepalese sources compiled and summarised by international media; the lack of independent on-site surveys limits the possibility of a more detailed and timely assessment.
Open questions remain. It is not yet clear precisely if or when a discharge channel can be opened safely, nor what the final extent of the lake’s filling will be if rains intensify. There are also no synchronized updates from the two administrations on any joint cross-border coordination measures or large-scale international assistance.
The situation underscores the urgency of rapid but calibrated responses: protecting downstream lives requires both complex technical decisions — such as designing a controlled drainage — and coordinated communications and evacuations. In the meantime, rescuers must balance the need to continue searches with the growing risk posed by a possible collapse of the debris dam.
The next 48–72 hours will be decisive for the emergency’s evolution: the combination of lake level, rainfall intensity and engineers’ capacity to intervene will determine whether the new basin can be drained gradually or will cause another devastating downstream wave. Nepalese and Chinese authorities have both intensified monitoring activities, but the exact scale of the damage and the final toll of dead and missing can be confirmed only when conditions allow full resumption of rescue and inspection operations on the ground.