A sudden flash flood swept through the Bhote Koshi River on Wednesday, 26 August, causing widespread destruction across the Nepal-China border region, with four Armed Police Force (APF) personnel reported missing and at least 15 hydropower projects damaged. The surge, which began at around 9 am, has triggered high-alert warnings across five districts in central Nepal.

Personnel Missing, Contact Lost

APF Deputy Inspector General Netra Bahadur Karki confirmed that the four missing personnel were deployed at a border outpost in northern Rasuwa district and have been out of contact since the flood struck. 'The border post itself has not been damaged,' Karki said, adding that authorities have yet to determine whether the missing personnel were directly affected by the floodwaters.

Additionally, unconfirmed reports in local media indicate that 14 Rasuwa customs office staff are also out of contact, though this has not been officially verified.

Infrastructure Damage Across Rasuwa

The Timure market area, Timure Customs Office, and parts of Syabrubesi near the Nepal-China border are among the localities reported to have suffered major damage. Roads, hydropower facilities, electricity transmission lines, and substations have all reportedly been affected, according to officials.

The Nepal Electricity Authority (NEA) said the floods damaged the Rasuwagadhi, Chilime, Trishuli-3A, and Trishuli-3B power projects, the 220 kV Trishuli-3B Hub substation, as well as the Trishuli and Devighat hydropower plants and several distribution structures. Power supply has been disrupted across affected areas, with the NEA stating that all necessary efforts are underway to restore electricity as soon as possible.

According to Nepal's Independent Power Producers' Association, preliminary data indicates that 15 hydropower projects — 10 operational and five under construction — have been affected by the flood.

GLOF in Tibet the Likely Trigger

Hydrological experts have raised the possibility that the flooding was caused by a Glacial Lake Outburst Flood (GLOF) originating in Tibet, rather than heavy rainfall within Nepal. The sudden rise in the Bhote Koshi is believed to have originated in the Tibet region, officials said.

The Department of Hydrology and Meteorology, in coordination with Chinese counterparts, is analysing satellite imagery to establish the precise source of the surge. This comes amid growing scientific concern over accelerating glacial melt in the Himalayan region, which has increased the frequency and severity of GLOF events in Nepal over recent years.

Downstream Threat and Evacuation Orders

Officials have warned that floodwaters could pose a serious threat to downstream communities as the Bhote Koshi flows into the Trishuli River, moving toward Nuwakot and other central Nepal districts. High-alert warnings have been issued for riverbank settlements in Rasuwa, Nuwakot, Dhading, Gorkha, and Chitwan districts.

Residents in low-lying and riverside areas have been advised to relocate immediately to higher ground. Authorities have also urged the public to avoid unnecessary travel along the Prithvi Highway and other riverside routes. District-level disaster management authorities are coordinating rescue operations and mobilising emergency resources across the affected zones.