Watch: Why rescuers fear new barrier lake could cause another Nepal-Tibet flood

Chinese authorities have issued an urgent warning indicating a high risk that a newly formed barrier lake near the Nepal-Tibet border could breach its banks, potentially triggering a second devastating flood for downstream communities.

The alert follows a deadly flash flood that struck the same high-altitude region on Wednesday. Scientific analyses revealed that the initial flood was triggered by the sudden collapse of a mountain glacier into a river, which propelled a destructive surge of water, rock, and mud through the surrounding valley.

The severe movement of earth and ice produced a major landslide that subsequently blocked the river's natural flow, impounding water and creating a precarious barrier lake. Regional disaster management agencies warn that if the natural dam gives way under increasing hydraulic pressure, a secondary outburst flood will sweep down the mountain corridor, compounding the destruction already caused by Wednesday's event.

The situation poses a critical hazard to a sensitive cross-border area where river systems originating in the Tibetan Plateau flow southward into Nepal. In these narrow Himalayan valleys, remote villages, vital bridge crossings, and essential transport routes are situated close to the riverbed, placing them in the direct line of any prospective floodwaters.

Rescue workers and geological experts are actively monitoring the site to evaluate the stability of the landslide dam. However, mitigation efforts face severe logistical challenges due to the extreme conditions of the region. High altitudes, steep topography, unpredictable weather, and unstable ground severely hinder the movement of heavy machinery and emergency personnel required to safely breach or drain the impounded water.

Barrier lakes formed by landslides are recognized by geologists as highly volatile environmental hazards. Because these dams consist of loose, uncompacted rock and soil rather than solid bedrock, they are prone to sudden and catastrophic failures. The risk is further heightened if water levels continue to rise rapidly or if additional landslips fall into the newly formed reservoir.

The ongoing threat of a second flood has complicated relief operations following Wednesday's initial disaster. Emergency response teams operating in the border area remain on high alert, while local officials evaluate safety conditions and prepare contingency plans, including potential evacuations for downstream residents. Scientific monitoring of the water body continues as authorities seek ways to avert a secondary catastrophe.