On the morning of 26 August 2026, a series of flash floods and debris flows destroyed the Gyirong Port on the China–Nepal border and struck dozens of settlements along a 72 km (45 mi) stretch of the Trishuli River in Nepal. These events are also known as the 2026 Nepal-China floods, Bhotekoshi flood, or Rasuwa flood.
At least 1,455 deaths and 5,285 missing persons in Nepal, and 43 deaths and 519 missing in the Tibet Autonomous Region of China were reported. The flood carried the bodies of some victims 250 km (160 mi) away into neighbouring India.
The precipitating geological event, initially reported as a glacier collapse in the Langtang region of the Himalayas, caused a chain reaction whose tremors were detected by seismometers worldwide, with magnitudes reaching 5.2. According to experts at the National Society for Earthquake Technology–Nepal (NSET), the University of Reading and Newcastle University, the flood was triggered by a large rock-ice avalanche originating from the Lirung massif, involving glacier ice and rock, which transformed into a highly mobile, long-runout debris flow and generated destructive downstream flooding.
Background
Geography and history
The Trishuli River is joined by the Lhende Khola (also known as Lende River or Donglin Tsangpo in Lhasa Tibetan), which originates in Gyirong County, Tibet Autonomous Region before entering Nepal. It then flows past Dhunche, downstream from which it forms part of the Trishuli River system.
The flash floods and mudslides occurred around the China–Nepal border crossing at Gyirong Port, a strategic border crossing connecting Nepal's Rasuwa District and Gyirong County, located at the confluence of the Trishuli and Lhende Khola rivers. The crossing saw large amounts of daily traffic related to both commerce and tourism, especially the pilgrimage tour to Mount Kailash, a holy site in Bon, Buddhism, Hinduism and Jainism. The Gyirong crossing accounted for 30% of all Nepal-China trade before the disaster, and more than 100,000 people had used the crossing in the first half of 2026 according to Chinese media.
Since 1900, dozens of floods have occurred near the border between Nepal and China. Langtang Lirung, opposite the site of the 2026 landslide, experienced a major glacier collapse and debris avalanche triggered by the April and May 2015 Nepal earthquakes. The landslide in the Langtang valley destroyed and buried several villages, killing over 350 people. A July 2025 flood caused by a glacial lake outburst washed away the bridge at the border crossing.
Analysis of satellite imagery found that from 8 January 2026 to 18 August 2026, the glacier north of Langtang Lirung moved around 10 millimetres per month, but the rate accelerated in the weeks prior to the glacier's collapse.
Climate change
Climate change contributes to the melting of permafrost, which in turn increases the likelihood of glacier collapses. Alton C. Byers, a senior research associate at the Institute of Arctic and Alpine Research, University of Colorado Boulder, said, "Permafrost has been the cryospheric glue that's held the rock and the ice and the glaciers together for millennia, and now we're getting increasing evidence that it's being weakened by warming trends."
Researchers quoted by the BBC, CNN, and NPR said climate change probably increased the likelihood of the event. Nepal foreign minister Shisir Khanal called for increased global response to climate change and stated that Nepal was bearing a disproportionate share of its consequences.
Early warning systems
Chinese and Nepali scientists have maintained a flash flood early warning system for years, which the South China Morning Post credited with consistently preventing casualties. The system did not detect the August 2026 flood in time as the water level monitors were configured for detecting monsoon and perennial floods. Upstream monitoring stations in Nepal were swept away by the flooding before alerts could be sent. A senior fellow at the Stimson Center remarked that the affected region was a monitoring "blind spot" and that geologists paid little attention to it.
After the 2025 floods, Chinese authorities in Gyirong County took a number of measures in preparation for a new glacial lake outburst flood. The local government updated emergency plans, set up a sentry system monitoring water level changes, constructed flood prevention structures such as a new flood wall, dikes and channels, trained local officials in "glacial lake outburst defense", and simulated an emergency evacuation of villagers. The August 2026 flood, which was caused by a different event than the system was built to anticipate, overwhelmed these defenses within minutes.
The incident began at around 08:37 NPT. At 09:00, the Nepalese Department of Hydrology and Meteorology was informed of the flood by the District Administrative Officer in Rasuwa, by which time several communications towers had been destroyed and door-to-door warnings were being sent. The first text alerts were sent out by 09:15, with 679,295 warning text messages sent within one minute. Authorities issued flood warnings for communities along rivers in the Nepali districts of Rasuwa, Nuwakot, Dhading, Gorkha, and Chitwan.
Cause
No rain was reported on the morning of 26 August at the Rasuwa district headquarters.
A seismic event measuring 5.2 occurred at 02:52 UTC (08:37 NPT; 10:52 BJT) and was centred just north of Langtang Lirung, a mountain in Langtang National Park. The seismic event was initially believed to be an earthquake; later analysis by the United States Geological Survey (USGS) indicated that the seismic event did not precede the collapse but was rather generated by the collapse itself. The USGS' analysis found that the long-period seismic waves were consistent with a glacier collapse. The GFZ Helmholtz Centre for Geosciences (GFZ), in Potsdam, Germany, recorded an event measuring 5.7 that was consistent with a landslide with a timestamp identical to the USGS. Other early analyses suspected a glacial lake outburst flood (GLOF).
A second landslide event was identified by USGS three hours after the first by analyzing low-frequency seismic waves. The second landslide was recorded as a Ms 4.2 seismic event.
Seven minutes after (vis. 2026 Nepal floods timeline) the seismic event, a surveillance camera captured floodwaters destroying the Gyirong Port border crossing. Geomorphologists quoted by the BBC and NPR proposed that the collapsed portion of a glacier fell thousands of metres and melted from the velocity and friction of the impact. The meltwater and rocks then displaced the river in the valley.
There were indications of heavy water flow almost immediately after the seismic waves were detected. The combination of the two near-simultaneous signals, and review of the first satellite imagery, led researchers to conclude that a glacier located around 64 kilometres (40 mi) north of the capital city Kathmandu and some 15 km (9.3 mi) east of where the flood was first noticed, measuring 600 metres (2,000 ft) in width may have fallen 1,200 metres (4,000 ft), in what is known as a glacier collapse (also called an ice avalanche). According to Daniel Shugar, a geologist at the University of Calgary in Canada who reviewed satellite imagery after the event, a 0.2 km2 (49-acre) piece of ice and rock broke off at about 5.2 km (3.2 mi) above sea level and fell vertically about 1.2 km (0.75 mi) to the valley below.
Satellite images and seismology confirm that a glacier collapsed near Langtang Lirung, which itself is a likely result of destabilisation by tectonic uplift and climate warming. Compared to GLOFs, glacier collapse floods are less frequent in the region, but more destructive. The collapsed glacial material was believed to have originated from an altitude of 5,200–5,400 m (17,100–17,700 ft) and had a size of around 197×106–492×106 m3 (7.0×109–17.4×109 ft3). It then moved north-westwards before shifting west.
The debris flowed up to some 100 km (62 mi) downstream. Seismometers over 100 kilometres (62 mi) away recorded seismic tremors caused by the floods.
Risk of further flooding
Two barrier lakes formed following the glacier collapse. On 27 August, Chinese authorities warned that one of the lakes with a volume of 2×106 m3 (71×106 ft3) had formed near the confluence of the Chhochen Khola and Purepu Tsangpo rivers, adding that the possibility of a breach was high due to an expected water inflow of 3×106 m3 (110×106 ft3) until 30 August. The lake overflowed slightly on 28 August, prompting Chinese authorities to briefly pause rescue operations and warn about the potential for additional flooding. The barrier lake slowly drained out and was largely empty by 30 August. The other lake was situated at a high elevation, near where the glacier collapsed. Flood warning notices were sent on 30 August after Chinese authorities reported increased water flow upstream.
Casualties
As of 5 October, at least 1,455 people died, 9,287 were injured, and 5,285 were missing in Nepal. Among the missing were 650 foreign nationals from 38 countries. As of 1 October, 112 bodies had been identified.
As of 16 September, 43 people died and 519 were missing in Tibet. Among the missing in Tibet include 261 foreign nationals from 23 countries. This includes 104 Nepali nationals.
Among the missing in Nepal include 189 Indians, 188 Nepali tourists, 65 Americans, 55 Malaysians, 54 Ukrainians, 37 Chinese, 33 Australians, 33 Latvians, 32 British, and 30 Canadians. The Chinese Ministry of Foreign Affairs reported nearly 100 Chinese citizens in Nepal missing. Australia's foreign minister said on 27 August that at least 34 of the missing were pilgrims. A group of 77 Isha Foundation pilgrims from 19 different nationalities traveling to Tibet were at Gyirong Port during the flash flood. The South Korean Foreign Ministry reported 9 citizens working at a hydropower plant construction site went missing.
At least 147 government officials, including eight local elected representatives, 32 local government employees, 11 teachers, 25 police officers, 13 Armed Police Force personnel, 45 Nepali Army personnel, 15 customs office employees, and 4 immigration office employees were reported missing. Around 622 students were also unaccounted for. An estimated 300 trade and transportation workers and 200 workers in the tourism industry were reported missing. Over 900 people involved in 12 hydropower projects were reported missing, with 500 believed to be trapped in tunnels. At the Upper Trishuli 1 Hydroelectric Project, at least 576 workers were reported missing, with around 300 trapped inside the project's tunnel. On September 7, the Nepal Army estimated that 121 people were trapped inside hydropower tunnels.
UNICEF estimated that over 84,000 people were impacted by the floods, including 32,021 children. UN spokesperson Stéphane Dujarric stated that an estimated 2,600 children younger than 5 required treatment for severe wasting and 10,500 pregnant and breastfeeding women required nutrition assistance. The Ministry of Health and Food Safety estimated that 1,500 children had moderate acute malnutrition by October 2026. Around 540 children were separated from a parent and 102 children were orphaned by the floods. UN Women estimated that 157,050 women and girls were impacted by the floods and 43,000 women and girls were in need of humanitarian aid.
The flood carried the bodies of some victims 250 km (160 mi) away, with bodies recovered as far downstream as Nawalparasi District in Nepal and Kushinagar and Maharajganj districts in Uttar Pradesh, India.
Damage
It was estimated that the resulting debris traveled at a speed of around 52 m/s (190 km/h; 120 mph), while analysis of satellite images suggests that discolorations caused by the flood reached an elevation of 800 m (2,600 ft) in a valley some 7 km (4.3 mi) from the origin. Following the flood, more than 1.5 m (4 ft 11 in) of silt was deposited in the main disaster zone. The United Nations Development Programme estimated that the flooding generated 2.2 million tonnes of debris, including 556,200 tonnes of building debris.
Floodwaters reached settlements as high as 80 metres (270 ft) above the river level.
Nepal
In Nepal, residential areas and infrastructure, including roads, sustained extensive damage. The districts of Rasuwa, Nuwakot, Dhading, Gorkha, and Chitwan were impacted by the flooding. Around 7,570 houses were destroyed, along with seven health facilities and 30 cultural sites. In Nuwakot, floodwater entered areas including Timure, Dhunche, Mailung, Syafrubesi, Betrawati, Trishuli, and Devighat. An estimate by the Nepal government reported that the floods caused over रू 277.79 billion (US$1.8 billion) in damages and रू 136.27 billion (US$883 million) in economic losses. A Rapid Damage and Needs Assessment report estimated that rebuilding costs would be around रू 723.67 billion (US$4.78 billion). A report estimated that immediate relief and short-term reconstruction costs would be रू 8.74 billion and long-term reconstruction would cost रू 714.58 billion.