Overflowing Temporary Lake Sparks New Flood Alert in Nepal

Authorities in Nepal have issued a high-level flood warning along the Trishuli River after a newly formed lake in the upper reaches of the Bhotekoshi River began overflowing, sending increasing amounts of water downstream.

Nepal’s Flood Forecasting Division said the lake was created after the river was blocked by a landslide and debris in an area where a major flood occurred on August 26.

The division urged residents living along the Trishuli River corridor, extending as far as Muglin, to remain on high alert and move to safer locations until further notice.

“According to information received from the Ministry of Foreign Affairs, the lake formed after the river was blocked has filled up and water has started flowing out,” the division said in a warning issued on Friday.

Officials stressed that the lake has not burst. Instead, the volume of water flowing out of the lake has increased, causing water levels in the river downstream to rise.

Shanti Mahat, a spokesperson for Nepal’s National Disaster Risk Reduction and Management Authority, said the flood generated by the overflowing lake was reported to be about six times smaller than the flood recorded on Wednesday.

Nevertheless, authorities have urged people living near the river to remain vigilant as water levels rise.

The newly formed lake covers an estimated 0.11 square kilometres. Authorities said this is roughly equivalent to a body of water about 200 metres wide and 550 metres long.

Nepal is highly vulnerable to floods and landslides during the annual monsoon season, when intense rainfall can rapidly destabilise mountain slopes and raise river levels.

The Trishuli River is one of Nepal’s major river systems and flows through densely populated areas before joining other rivers that form the Narayani system.

Its downstream corridor includes settlements, roads and other critical infrastructure.

Authorities have advised residents and travellers along the river to avoid riverbanks and other potentially hazardous areas and to follow official evacuation and safety instructions.

The warning comes as Nepal continues to monitor the effects of heavy monsoon-related flooding and landslides across its mountainous terrain.