At 08:37 on the morning of 26 August 2026, an ice-and-rock mass broke away from a glaciated cliff on the north side of Langtang Lirung, a peak of about 7,200 m in Langtang National Park in Nepal, close to the border with China. The debris ran north into the Lhende Khola, the tributary that meets the Bhote Koshi at the Rasuwagadhi border crossing, and blocked it. The blockage gave way, and the flood travelled roughly 100 km down the Bhote Koshi and the Trishuli. By 11:22 on 28 August, Nepal Police had recovered 475 bodies.
The flood destroyed Nepal's principal overland route to Tibet. 42 km of the Betrawati to Rasuwagadhi road was cut at multiple points, with a further 16 km toward the border swept away. The Miteri Bridge at the crossing was washed out 8 months after it reopened, and the Rasuwagadhi customs office and dry port were reduced to riverbed. The Humanitarian OpenStreetMap Team's damage assessment of the corridor records 32 of 39 bridges washed out and 4,977 damaged buildings among 633,208 assessed footprints.
Where the dead were found is the fact that shapes everything the response does next. Of the 469 bodies recovered by the morning of 28 August, 12 were in Rasuwa, the district the flood struck first. 178 were in Chitwan, more than 150 km downstream.
The surge carried people the length of the river system. Rasuwa, where the flood entered Nepal, accounts for 12 of the 469 bodies recovered by 07:00 on 28 August. Chitwan, more than 150 km downstream on the Narayani, accounts for 178. The district hit hardest is reachable only by helicopter and has 87 telecommunications towers out of service, so its recorded figures describe the difficulty of reaching it.
What set the flood off
The United States Geological Survey published its first solution for the event as a magnitude 4.4 earthquake, with an origin time of 02:52 UTC, 08:37 Nepal time. It replaced that solution the same day and now states plainly that no earthquake had occurred. The catalogue entry is a magnitude 5.2 landslide, and USGS reached that reading from nearby seismic stations, long-period seismic waves and satellite imagery. A second landslide followed about 3 hours later, at 11:45, carrying energy equivalent to a magnitude 4.2 earthquake.
USGS locates the source in a glaciated mountain cliff on the north side of Langtang Lirung and titles its assessment the 2026 Nepal Debris Avalanche and Flash Flood. It describes glacial debris carrying water and ice that melted as the mass moved downslope, picking up more material until it became a fast-moving flood laden with boulders and rubble. How far the mass fell is unsettled. Dan Shugar read the drop as about 1,200 m from the first day's satellite imagery; Jakob Steiner read it as a fall from 5,100 m to 3,000 m, and later analyses put it above 2,000 m.
The downstream record matches that reading. ICIMOD measured the Trishuli rising 9 m in 30 minutes at Galchhi and about 7 m over a similar period at Malekhu. The Nepal Red Cross Society field report estimated flood waves of 8 to 10 m. A technical report cited at the Asia Pacific humanitarian logistics working group put about 20 million m3 of additional water into the river as the dam gave way.
On a glacial lake, USGS says nothing at all. The rulings come from elsewhere. Dave Petley, writing in AGU's Eos, states that there is no evidence this was a glacial lake outburst flood, and attributes the water to ice melted by the collapse's own energy, water held in the sediment it entrained, and the river itself. ICIMOD called the cause unconfirmed on 26 August, and Kathmandu University's Rijan Bhakta Kayastha said it could take several days to establish whether a glacial lake had also burst. PRISM reports an ice-and-rock avalanche that blocked the Lhende Khola and then failed, and leaves the term GLOF to the sources that use it.
The name assigned to this event determines which hazard gets monitored. ICIMOD, the Government of Nepal and UNDP classify 47 glacial lakes in the basin as potentially dangerous, including 21 inside Nepal and 25 across the border in Tibet. A monitoring programme built around lake outbursts watches water. A programme built around slope failure watches ice and rock on steep ground, which is what the seismic record describes here. Several hydrological monitoring stations were damaged or washed away in the flood, so whichever hazard is chosen, the corridor now has less warning capacity than it had on 25 August.
PRISM's climate profile for Nepal, read from CRED EM-DAT on 28 August 2026, records 80 disasters between 2000 and 2025. 38 of them were floods and 17 were wet mass movements. Glacial lake outburst floods appear twice in 26 years. Monsoon rainfall was running at 109.4% of its long-term average on the platform's latest reading, 174.12 mm against 169.98 mm. Meteorologists ruled out heavy local rainfall as the cause in Rasuwa itself, and the 9 m rise at Galchhi arrived as a single pulse off the mountain.
The same mountain has done this before. USGS records that a large debris avalanche off Langtang Lirung in 2015, set off by the magnitude 7.8 Gorkha earthquake, buried a village and killed more than 200 people.
The Lhende Khola has now flooded twice in 14 months, in ICIMOD's phrasing. On 8 July 2025 a supraglacial lake on the Purepu glacier drained into the upper Lhende catchment, killed at least 9 people in Rasuwa and swept away the Miteri Bridge. Nepal's NDRRMA placed that lake about 35 km upstream of the Nepal-China border, and the Department of Hydrology and Meteorology published its position inside Gyirong county in Tibet. The two floods share a river and a set of destroyed structures, and their mechanisms differ: the 2025 flood was confirmed as a glacial lake outburst on Sentinel imagery, and for 26 August 2026 no source has identified a lake that emptied.
The Miteri Bridge was rebuilt with Chinese support as a 91 m Bailey structure rated to 55 tonnes and reopened on 1 January 2026. The road behind it was upgraded to two lanes with Chinese government financing. The corridor was restored along the same alignment, and on 26 August the river took it again.
The sequence
The whole event fits between 08:37 on 26 August and the last count on the morning of 28 August. The strip below carries that window on one line. Colour marks the 3 phases, the ghosted curve behind it is the confirmed death toll, and each dot opens the event beneath.
Times are Nepal Standard Time. The strip is spaced to keep the first hour legible, so it is not linear in elapsed time; each event carries its real clock time. Sources: USGS, ICIMOD, NDRRMA, Nepal Police, UNICEF, IFRC, BBC and Chinese state media, 26 to 28 August 2026. The 26 August sequence is reconstructed from seismic timing and downstream gauge readings.
The toll and its distribution
The confirmed toll rose from 7 to 475 in 48 hours. Each step in that curve marks a place search teams reached for the first time, or a stretch of river they worked downstream. NDRRMA's sixth status report on 28 August put the figure at 472 dead and 73 injured; Nepal Police, counting bodies recovered, reported 475 by 11:22 the same morning.
Nepal Police, NDRRMA and Office of the Prime Minister bulletins, compiled by PRISM, 28 August 2026. The series mixes issuing bodies; NDRRMA's sixth status report separately gave 472 dead and 73 injured. Figures are provisional and expected to rise.
73 injured against 472 dead is an unusual ratio. In most sudden-onset disasters the injured outnumber the dead by a wide margin. A high-energy debris flood explains part of it, and the rest sits in the districts that cannot yet report.
Nepal Police district bulletin, 28 August 2026, via OnlineKhabar.
The shape of that chart is the story of the flood. Rasuwa, where the water entered Nepal, has 12 recovered bodies. Chitwan, where the Trishuli has already joined the Narayani and the valley is wide and populous, has 178. Nawalparasi East, further downstream again, has 110. The surge kept its lethal force well past the mountain front, and it met far more people once it left it.
Registers of the missing
Nepal maintains 3 separate registers of the missing. NDRRMA compiles district reports and gives 977, of whom 517 are foreign nationals, 127 Nepali travellers, 86 security personnel, 15 customs staff and 4 immigration officers. The Ministry of Foreign Affairs runs consular liaison and registered 596 foreign nationals from 33 countries by 20:00 on 27 August. The Nepal Tourism Board works from trekking and travel manifests and gives 667 travellers, 540 of them foreign. Across the border, Gyirong County in Tibet reports 558 missing, including 260 foreign nationals.
NDRRMA, Nepal Ministry of Foreign Affairs, Nepal Tourism Board and Gyirong County authorities. These registers are not additive; see the note below.
Each register is built on a different basis and each has a known direction of error. Consular registers run high because an enquiry is opened for every person reported. Manifest counts run high because a whole group is listed when contact is lost with one member. Kailash Mansarovar pilgrims crossing at Rasuwagadhi and Gyirong can appear in both national lists at once. Combined totals of more than 1,500 are in circulation; they are sums of unreconciled lists. These registers list people who are out of contact, in districts where 87 telecommunications towers are down. 84 Indian nationals, 4 South Koreans, 3 Americans and 2 Russians have already been recovered alive.
The corridor
The Rasuwagadhi crossing carries about USD 600 million of trade a year and is Nepal's principal overland link to China. On 26 August the flood removed it. As Data Friendly Space records in its rapid situation overview, the customs office at Timure lost contact with 15 employees, 9 commercial bank branches in Rasuwa were swept away with 26 staff unaccounted for, and the Department of Roads confirmed the entire 42 km road from Betrawati to the crossing destroyed at multiple points. 200 to 300 containers were destroyed or swept away, including more than 700 electric vehicles awaiting clearance.
Humanitarian OpenStreetMap Team damage layers for the Nepal flash flood, August 2026: 39 assessed bridges and 4,977 damaged buildings within a 90.11 km2 corridor. Mapped by PRISM, with districts assigned from Nepal's common operational administrative boundaries; building points are grouped into roughly 1 km cells and sized by count. Basemap: Esri World Light Gray.
Along the assessed corridor, 32 of 39 bridges were washed out, 3 were damaged and 4 survived. The gradient runs with distance from the source. Every one of the 16 assessed crossings in Rasuwa went, including the Miteri Bridge, which sits on the border line itself and falls outside any Nepali administrative unit. 11 of 13 went in Nuwakot, 5 of 7 in Dhading and none of the 3 in Gorkha. Of the 20 structures with a recorded span, 1,630 m of 2,135 m is gone.
Humanitarian OpenStreetMap Team bridge damage layer, August 2026, aggregated by PRISM to district using Nepal's common operational administrative boundaries. NDRRMA separately reports 35 motorable and 45 suspension bridges damaged nationally; the two counts measure different things.
Humanitarian OpenStreetMap Team damage assessment of Overture building footprints, August 2026, joined by PRISM to Nepal's common operational administrative boundaries. A further 85 damaged buildings fall outside any mapped unit. No official building damage count had been published at the time of writing.
The two charts point in opposite directions, and the reason is physical. At the border the flood still carried enough energy to remove structures outright, and there were few of them to remove. 2,544 of the 4,977 damaged buildings stand in Bidur, the Nuwakot district headquarters 34 km south of the border, where the valley opens and settlement is dense. Gosaikunda, the Rasuwa unit that took the first impact, accounts for 1,042. The body recovery pattern corroborates it: the flood did its worst work to infrastructure at the top of the corridor and to people at the bottom.
| Sector | Reported damage | Status |
|---|---|---|
| Roads | 42 km of the Betrawati to Rasuwagadhi road destroyed, plus 16 km toward the border; roads blocked across 9 districts | Severed |
| Bridges | 35 motorable and 45 suspension bridges damaged nationally (NDRRMA); 32 of 39 assessed crossings washed out (HOT) | Severed |
| Electricity | Supply halted in Rasuwa; the 220 kV Trishuli 3B Hub substation destroyed and six transmission lines disrupted | Out |
| Telecoms | 87 towers out of service across Rasuwa, Nuwakot, Dhading and Chitwan, 60 of them Nepal Telecom and 27 Ncell | Degraded |
| Hydropower | Official estimates of capacity affected ranged from about 360 MW to 901 MW within 48 hours, depending on whether projects under construction were counted | Contested |
| Trade | Rasuwagadhi customs and dry port destroyed; 200 to 300 containers lost; the crossing handles about USD 600 million a year | Closed |
| Preliminary cost | About NPR 200 billion (roughly USD 1.3 billion) for roads and bridges, per the Minister for Physical Infrastructure | Provisional |
The hydropower figures moved 4 times in 2 days. A consolidated assessment identified 14 affected projects with a combined capacity of about 748 MW, 9 operational at 354 MW and 5 under construction at 394 MW. The Ministry of Energy first put 754.02 MW inside the damage zone, then described about 431 MW as lost. The Nepal Electricity Authority counted 12 operating plants totalling 431.1 MW shut down and 15 under construction totalling 470 MW damaged. A later ministry statement gave close to 360 MW damaged, nearly 8% of Nepal's roughly 4,300 MW installed base. The range is what the record supports at this stage. Nepal supplied 600 MW to India over the past 6 months and had planned 500 MW more this year.
What Rasuwa cannot report
Rasuwa is now reachable only by air. 15 helicopters carry the entire rescue, medical evacuation and relief effort into the district, and the weather governs how often they fly. 87 telecommunications towers are out of service, so needs reported at ward level have no route to district authorities. Morgue capacity in Rasuwa and Nuwakot was exceeded on 27 August and bodies were moved to district hospitals downstream, which slows identification and lengthens the wait for families.
NDRRMA's itemised missing categories account for 749 of the 977 on its register, leaving 228 unclassified. The itemised categories cover travellers and officials, so the remainder is largely resident population. 10,000 households were identified as needing immediate relief on 26 August, and no figure for people displaced has been published. Nepal recorded 890,437 new disaster displacements between 2016 and 2025 in the IDMC database that PRISM serves, so the absence of a number for this event is the largest open question in the response.
What has been committed
UNICEF appealed for USD 17.2 million on 27 August, reporting more than 17,000 children in need across Rasuwa, Nuwakot and Dhading, 18 schools destroyed and 20 damaged, about 10,000 children needing education support, and at least 4 health facilities damaged. WFP requires USD 4 million and is distributing high-energy BP-5 biscuits as the first ration. The UN released USD 2 million from CERF for emergency medical care, shelter and water, and the IFRC allocated nearly CHF 1 million to the Nepal Red Cross Society. China committed CNY 120 million for Gyirong County.
| Actor | Amount | Purpose |
|---|---|---|
| UNICEF | USD 17.2m | Emergency response and early recovery for children |
| WFP | USD 4m | Initial food response, requirement |
| UN CERF | USD 2m | Emergency medical care, shelter and water |
| IFRC DREF | CHF ~1m | Nepal Red Cross Society operations |
| China | CNY 120m | Relief in Gyirong County, Tibet |
That is about USD 24 million in published appeals and allocations against a preliminary damage estimate of about USD 1.3 billion for roads and bridges alone. The appeals cover immediate relief. Reconstruction of the corridor has not been costed, and no consolidated flash appeal had been launched by 28 August. Cluster activation was discussed at the Asia Pacific logistics working group on 27 August without being confirmed.
IDMC Global Internal Displacement Database, served through PRISM, read 28 August 2026. No displacement figure has been published for this event.
Nepal's decadal record gives the scale a displacement figure for this event would sit against. 2017 alone accounts for 383,904 new displacements, and 2023 for 110,349. The corridor's population is smaller than either, and the households in Rasuwa whose land the river took are not counted anywhere yet.
The hazard upstream
The mechanism that produced this flood has left a second one behind it. China's Ministry of Water Resources reported on 27 August that a barrier lake had formed near the confluence of the Chhochen Khola and the Purepu Tsangpo, close to the border, holding about 2 million m3 and already overtopping, with a further 3 million m3 expected to enter over the following 3 days. By 28 August the reservoir had topped 2.5 million m3, and a Chinese engineering team surveyed it at about 150 m long and 40 to 50 m deep, with peak flow expected around 1 September and a plan to excavate a drainage channel at a low point in the dam. Accounts of which side of the border the lake sits on conflict, and the mapped confluence sits within tens of metres of the boundary.
Downstream, the effects reached India. Authorities in Bihar opened the Valmikinagar Barrage on the Gandak as a precaution and prepared to evacuate up to 12,000 people, according to the situation overview.
Search and recovery operations in Nepal were suspended on 28 August when the lake began to overflow, and NDRRMA has warned rescue workers and residents away from the riverbanks. Every figure in this update was compiled before that suspension took effect. The count of the recovered will resume when the upstream hazard allows it.
- USGS Landslide Hazards Program, the 2026 Nepal Debris Avalanche and Flash Flood event page.
- USGS, catalogue entry for the magnitude 5.2 landslide.
- Data Friendly Space, Nepal flash floods rapid situation overview, 27 August 2026.
- ICIMOD, press release on the Rasuwa flash flood.
- Nepali Times, central Nepal flood, the day after.
- The Kathmandu Post, how the Bhotekoshi flood unfolded over 10 hours.
- Dave Petley, The Landslide Blog, AGU Eos, on the contested trigger.
- UNICEF, flash floods in Nepal leave more than 17,000 children in need.
- WFP, Nepal floods external situation report #1.
- IFRC GO, Nepal Red Cross Society field report on the Rasuwa flood.
- Logistics Cluster, ad-hoc regional call on the Nepal flood emergency.
- The Kathmandu Post and OnlineKhabar, rolling coverage.
Nepal's disaster record, INFORM Risk profile, rainfall anomaly and agricultural hotspot status are tracked live on PRISM and updated from source.
What the next 10 days require
Publish a displacement figure
10,000 households were identified as needing relief on 26 August and no displacement number has followed. Shelter, cash and site planning all wait on it, and the caseload in Rasuwa includes households whose land is now riverbed.
Deconflict the missing-persons registers
NDRRMA, the Foreign Ministry, the Tourism Board and Gyirong County hold four overlapping lists. A single deconflicted register, agreed with China, would give families one answer and stop combined totals from circulating as fact.
Resource an air-supported assessment in Rasuwa
The district closest to the flood has the fewest recorded casualties and the least working telecommunications. Treat its figures as incomplete and fund the helicopter hours needed to verify needs ward by ward.
Assess the corridor against slope failure as well as lake outburst
The Rasuwagadhi route was rebuilt on the same alignment after July 2025 and lost again in 13 months. Reconstruction planning needs a hazard assessment covering ice and rock on steep ground, and it needs the hydrological stations the flood destroyed put back.
The Bhote Koshi corridor was rebuilt once and has now failed twice inside 13 months. What changes the outcome the third time is a reconstruction plan that reads the mountain as the source of the hazard, an early-warning network that survives the event it warns about, and a count of the displaced that lets the response reach the people still on the riverbank.