China and Nepal have warned of a renewed risk of catastrophic flooding in the Himalayas after this week’s disaster killed hundreds and left nearly 1,000 people missing on both sides of the border, including as many as 540 foreigners from 31 countries.

Two dangerous barrier lakes have formed on either side of the border. On the Chinese side, aerial footage showed water accumulating in a basin with no visible outlet, submerging vegetation and pressing against a barrier of debris and rock.

Chinese authorities have mobilized an eight-member engineering team to conduct aerial surveys and create 3D models of the danger zone. The lake is about 150 meters long and 40–50 meters deep, holding an estimated 1.5–2 million cubic meters of water.

The risk is being compounded by continued rainfall and unstable terrain around the Gyirong border area, where soil and rock have been loosened. Rain is forecast to continue over the coming week.

Authorities estimate that another three million cubic meters of water will flow into the dammed lake over the next three days, significantly increasing the risk of a breach, with peak flow expected around 1 September.

Engineers plan to excavate a drainage channel at a lower point of the natural dam to reduce the water level. The work is complicated by difficult access, isolated cliffs and steep terrain.

(Reuters, max)