NEWS
Nepal’s Glacier Flood Repeats a Himalayan Tunnel Disaster
Nepal’s Rasuwa flood has again packed hydropower tunnels with mud, repeating Chamoli 2021, while a new barrier lake threatens another surge.
Wednesday’s flash flood in Nepal’s Rasuwa district has killed at least 579 people and packed hydropower tunnels with mud.
The collapse began on the north face of Langtang Lirung and ran into Tibet and down the Trishuli. Nepal’s disaster authority said 1,924 people were still missing as of Friday evening, and a new lake upstream is still a threat.
Ice and Rock Dropped a Kilometre Into the Lhende
At 8:37 a.m. on 26 August, seismic stations recorded a magnitude 5.2 event near the Nepal-China border. The United States Geological Survey later said that signal was a glacial collapse in Langtang National Park, not a tectonic quake that set a slope moving.
Dan Shugar, who studies mountain hazards, told reporters that satellite frames showed the lower part of a glacier breaking off at about 5,200 metres and crashing onto the valley floor about 1,200 metres below. Kristen Cook, a geomorphologist at Université Grenoble Alpes, said the rock the glacier sat on gave way, and millions of tonnes of rock and ice went with it.
That mass entered the Lhende Khola, a tributary that feeds the Bhote Koshi and then the Trishuli. Debris briefly dammed the channel. When the plug failed, a surge of water, ice, mud and boulders headed south through Rasuwa. ICIMOD, the Kathmandu-based mountain science centre, said the Trishuli at Galchhi rose as much as nine metres in 30 minutes, and the river at Malekhu climbed about seven metres in the same span.
Timure and Syaphrubesi were among the first settlements hit. A helicopter pilot who later flew over Timure told the Kathmandu Post the village had gone out of sight. Further down, the flood reached Nuwakot and Dhading. Early talk of a glacial-lake outburst has faded as the satellite record has pointed to an ice-rock avalanche, then a short-lived blockage, then a breach.
Dave Petley, writing for the American Geophysical Union’s Eos, called the quake story a misreading of the data. The seismic pulse, he said, was almost certainly the avalanche and debris flow itself. That point has been slow to land. Clips of the surge keep being captioned as an earthquake, which is how the first hours of this disaster were written.
The Army Is Still Digging in a Power Tunnel
Nepal’s army pulled 350 workers and local people out of a hydropower tunnel on Friday, the Prime Minister’s Office said, and more than 100 were still inside. Sixty-three of those brought out were Indian nationals, India Today reported. Army spokesperson Raja Ram Basnet told AFP the trapped group was in the tunnel at the Trishuli 3A plant in Rasuwa, and that two helicopters had been sent even though crews could barely find the entrances.
Video released by the Prime Minister’s Office shows soldiers in hard hats dragging people through a bore coated in grey slurry. Other footage from construction sites along the river shows crews running as the wave accelerates toward a dam. Suraj Sigdel, Nepal country director for Mercy Corps, told PBS News Hour his team held back from ground zero after fresh flood alerts, because a lake was forming on the Tibetan side of the border and could spill.
The missing list is not mostly villagers from the first bend of the river. The National Disaster Risk Reduction and Management Authority’s Friday evening update, as reported by The Tribune, put people from hydropower projects at the centre of it.
WHO IS STILL LISTED MISSING
- Hydropower crews: The Friday update listed 933 people from hydroelectric projects among the missing, The Tribune reported from the NDRRMA tally.
- Foreign nationals: 517 visitors remain unaccounted for, a figure repeated across the authority’s Friday bulletins.
- Nepalis back home: 127 citizens who live abroad and were visiting Nepal are on the same list.
- Security and border staff: The tally includes 45 army personnel, 28 police, 13 Armed Police Force members, 15 customs staff and 15 immigration staff.
Those numbers will move as phones come back and bodies are identified. Being listed missing in a valley with no power and no road is not the same as being confirmed dead, and Nepal Police have said as much. The weight of the hydro figure is still the story inside the story. The people who were on shift in the tunnels and yards sit at the top of the contact list.
A $647 Million Plant Had Been Rated Low Risk
The flood ran through one of Nepal’s densest power corridors. The Nepal Electricity Authority said the water damaged 11 hydropower projects totalling 405 megawatts and a 25-megawatt solar plant, about 430 megawatts in all. NEA spokesperson Rajan Dhakal said the 111-megawatt Rasuwagadhi plant, nearest the Tibet border, had its powerhouse and substation destroyed.
The biggest unfinished site is Upper Trishuli-1. Korean coverage and Chinese energy trade reports put the plant at about 84 percent complete, with commercial running planned for next year, and said more than 90 percent of its cofferdam was wrecked. Yoon Jang-hyun of Korea South-East Power Co. described that damage on Korean television. Doosan Enerbility is the builder. Nine lenders, including the IFC, the Asian Development Bank and the Asian Infrastructure Investment Bank, put credit into the $647 million venture.
The IFC’s own disclosure describes a 216 MW run-of-river hydropower project meant to lift Nepal’s domestic supply by about a third against 2018 levels, with roughly 40 percent of its 1,427 gigawatt-hours due in the dry months when the lights used to go out. The ADB’s project page is blunter about what the studies missed. A climate-risk review concluded that climate risks were low. The same page then records that extreme rain and a glacial-lake outburst in 2025 already damaged works under construction and changed the river’s shape.
SBS in Seoul reported that the 2018 disaster plan for the plant named glacial-lake floods as a main natural hazard in Nepal, then judged the nearest lake far enough away to matter little. Doosan had already reinforced upstream warnings after last year’s flood and ran evacuation drills twice in 2026. The cofferdam still went.
PLANTS HIT ALONG THE BHOTE KOSHI AND TRISHULI
| Facility | Capacity | What NEA and site reports say |
|---|---|---|
| Rasuwagadhi | 111 MW | Powerhouse and substation destroyed, nearest the border |
| Upper Trishuli-1 | 216 MW, unfinished | Cofferdam about 90 percent gone, Korean-led, 84 percent built |
| Upper Trishuli 3A | about 60 MW | Tunnel rescue; army still hunting the last 100 people |
| Chilime | 22 MW | Community-owned plant in the same corridor |
| Trishuli and Devighat | 24 MW and 14 MW | Older stations further downstream, plus a 220 kV hub at 3B |
Urja Khabar, citing the NEA, also named Sanjen, Langtang, Mailung and other smaller sites among the 11. Independent Power Producer Association Nepal put three unfinished projects totalling 342 megawatts in the damage column, Upper Trishuli-1 among them. This is the valley Nepal has been betting on to keep winter imports down.
Chamoli Hit the Same Hydropower Tunnels in 2021
On 7 February 2021, a rock-and-ice avalanche came off the north face of Ronti Peak in India’s Chamoli district. Shugar and dozens of co-authors, writing in Science, found that about 27 million cubic metres of rock and ice fell, turned into a debris flow, and wrecked two hydropower projects. More than 200 people were killed or listed missing. Most were labourers at the Tapovan-Vishnugad works and the smaller Rishiganga plant upstream.
Rescuers spent days in a tunnel filled with slush. A few men who had been inside a shorter bore survived by hanging from iron rods and sitting on an excavator until the Indo-Tibetan Border Police broke an emergency door. Others never came out. Families later took death certificates for men whose bodies were never found. The science paper’s last turn could have been filed from Rasuwa this week.
The intersection of the hazard cascade with downvalley infrastructure resulted in a disaster, which highlights key questions about adequate monitoring and sustainable development in the Himalaya as well as other remote, high-mountain environments.
D. H. Shugar and colleagues, Science, 2021
Rasuwa is that intersection again. The drop, the debris flow, the plants in the gorge, the crews in the tunnel, and the argument over whether a quake or a glacier did it all showed up on cue. One difference is the count of people walked out of a bore this time. Chamoli did not give the army that number.
The Lhende already had a recent dress rehearsal. On 8 July 2025, floodwater from the same Tibetan tributary killed at least nine people and left 19 missing, Urja Khabar recalled, and it took out the Miteri Bridge and damaged the Rasuwagadhi dry port. The ADB page’s 2025 outburst is the lenders’ own record of that season. Fourteen months later the bigger collapse came down the same line.
The New Lake Can Still Break
Debris from Wednesday’s surge blocked the channel again. China’s Ministry of Water Resources said a barrier lake formed at the confluence of the Chhochen Khola and Purepu Tsangpo, several kilometres above Gyirong Port, the main land crossing into Nepal. CCTV put the water at 2.5 million cubic metres on Friday, up from 1.5 to 2 million a day earlier. An eight-member Chinese engineering team measured a dam about 150 metres long and 40 to 50 metres high.
THE LAKE, AS OF FRIDAY
- Volume: About 2.5 million cubic metres held behind the debris, CCTV said.
- Inflow warning: Officials said another 3 million cubic metres could arrive over three days, with peak flow around 1 September.
- Fresh ice: A Chinese military drone on Friday morning filmed an avalanche that dumped an estimated 50,000 cubic metres of ice into the lake.
- Rescue pause: Overflow on Friday morning halted searches; by afternoon state media said the risk was manageable and work resumed.
Jakob Steiner, a geoscientist at the University of Graz who has worked on lake bursts in Nepal, told the BBC the remaining slope is still loose. If more rock drops into the lake, he said, “then we have a problem.” He also said China is unlikely to drain it with machines, because there is no road for excavators. Mohd Farooq Azam, a glacio-hydrologist at ICIMOD, warned that any extra water could undercut already scoured valley walls and start new slides. Both men said the pond might empty slowly on its own, as some Chamoli and Dharali lakes have, and Steiner noted that melt eases by October.
Separate from that barrier, Indian NDMA official Krishna Vatsa told The Hindu that two new lakes have formed near the scar, about 19.80 hectares and 7.28 hectares, with no volume yet. Satellogic imagery from 27 August showed a lake of about 20.25 hectares in the high Lhende. Nepal’s NDRRMA has told people to stay off the rivers. Police in the mud towns have been riding through with the same shout.
Most Bodies Were Found Far Down the Trishuli
Only 12 of the 579 recovered bodies were in Rasuwa, the district where the water first hit. Nepal Police said 233 were taken from Chitwan, 154 from Nawalparasi East, 46 from Gorkha, 40 from Dhading, 37 from Nuwakot, 30 from Tanahun and 27 from Nawalparasi West. The flood carried people tens of kilometres down the Trishuli and into the Narayani. Morgues in Chitwan filled. Temporary identification centres went up. PTI reported 1,545 injured and stranded people rescued, and a wider tally of 4,451 brought out of the affected belt.
Gyirong Port on the Chinese side was buried to the eaves. Photographs circulating after the flood show the customs roof sitting in a field of silt where a road used to be. China has confirmed five deaths in Gyirong County and 558 missing, nearly half of them foreigners, according to state media. Li Qiang, China’s premier, went to the site on Thursday. On Nepal’s side the missing foreigners include, in earlier police breakdowns, large groups of Indians and smaller groups from the United States, Ukraine, Malaysia, Australia and Britain. Those national splits have not been republished with the Friday 1,924 figure, so they should be read as a Thursday snapshot.
Kathmandu has said its own army and police are enough and has declined to bring in foreign rescue teams, Sigdel told PBS, because extra flags would tangle the command. Other help is coming anyway. The United Nations, India, South Korea and the United Kingdom have offered supplies or money. The U.S. State Department said it is sending $500,000. The Red Cross has said it needs more than $30 million for the response. Nepal’s government has started releasing local relief funds.
Indira Adhikari, an evacuated resident, told PBS through an interpreter that her house was full of mud and that walking out was hard enough for the young. Maddie Tamong, a mother, said she had already accepted that both her children were gone, then found them scratched but alive after crossing leech-filled jungle. Those are the stories that will keep arriving as the phones come back. The 100 people still in the tunnel, and the lake that is still rising, are the ones that are not finished.
