How catastrophic flash flood unfolded at remote Nepal-China border point

By Soutik Biswas, India Correspondent and Phanindra Dahal, BBC Nepali.

Key points

• As well as citizens of Britain, Canada, Australia and Italy, among the foreign nationals recorded leaving Nepal that morning were 32 Indians, 12 Chinese nationals and nine Americans.
• When a 21-member Chinese rescue team reached Gyirong on 28 August, one rescuer informed Reuters: "As far as the eye could see, there was nothing but ruins."
• Among those at the Chinese immigration facility was a group of 77 pilgrims associated with the Isha Foundation, returning from Mount Kailash.
• While four individuals had registered their entry into Nepal, electronic records show that 89 Nepali and foreign nationals had cleared immigration to leave Nepal for Tibet.
• The immigration office stood at Ghatte Khola Bazar, regarding 1.5km north of Timure.

Notably, a dark wall appears from behind the buildings at Gyirong, on the Chinese side of the Nepal-Tibet border. At first, it looks almost like a black cloud. Then it gathers shape and speed: water, mud, boulders, ice and rock surging down the valley. The timestamp on the CCTV footage reads 10: 59: 53 local time.

What happened in the minutes that followed is still tough to reconstruct. But fragments of video and satellite imagery from before and after the disaster have begun to reveal the scale of the destruction. Much of the border complex appears to have been swept away, with buildings that once crowded the valley floor simply gone.

Gyirong was one of the places devastated by the floods that tore through the region on 26 August.

Just throughout the frontier, at Rasuwagadhi in Nepal's Rasuwa district, the destruction was additionally extensive. The Friendship Bridge linking Nepal and China was swept away, along with Nepal's immigration and customs facilities. Timure, the small trading settlement clustered around the crossing, was devastated.

"This is a historic travel route between Kathmandu and Tibet. The area is geologically vulnerable, characterised by deep gorges and steep rivers that flow at high velocity, carry heavy sediment and can bring down massive boulders, " states Ajay Dixit, a Kathmandu-based hydrologist.

In practice, the route remains an significant gateway between Nepal and China. It is a place where pilgrims heading towards Mount Kailash cross paths with traders travelling between Nepal and China, truck drivers, customs authorities, tourists and residents who live along the border.

On the morning of the flood, more than 100 Indians may have been in or around the crossing. At least 275 Indians remain missing in Nepal, according to India's foreign ministry.

Nepal's Department of Immigration has been trying to reconstruct who passed through Rasuwagadhi in the final hours before the disaster.

Meanwhile, the immigration system recorded its final transaction at 8: 35: 03am local time (10: 52am Tibet time), less than 10 minutes before the torrent appeared on the CCTV footage at Gyirong.

Four immigration employees, including the head of the Rasuwagadhi office, went missing in the floods. His body was afterwards recovered far downstream. The female official who recorded the final transactions is still missing.

Tika Ram Pokharel, a senior immigration assistant at Rasuwagadhi, was the only member of his office known to have survived. He had travelled to Kathmandu to sit an exam that day.

But he notes the electronic records capture only part of what was happening at the border that morning.

Notably, the immigration office stood at Ghatte Khola Bazar, regarding 1.5km north of Timure. From there, it was another 2km to the Friendship Bridge marking the border with Tibet. Along that stretch were shops, hotels and parking areas where travellers and vehicles gathered before crossing.

In practice, the Nepalese immigration office opened at 08: 00, Pokharel notes. Once travellers had cleared immigration, they could continue towards the border or wait in the area before crossing.

When Pokharel called a colleague at 08: 20 that morning, he was informed the crossing was unusually busy. While others arriving from the Chinese side were additionally in the area, around 300 to 400 individuals were waiting to leave Nepal for Tibet, he states.

"Those who completed the immigration formalities that morning, I don't think were able to complete their immigration process on the Chinese side, " Pokharel informed the BBC.

Pokharel notes it took 15 to 20 minutes to walk from the Nepalese immigration office to the bridge after travellers had cleared immigration.

While those travelling in groups or by bus would often wait for everyone to clear immigration before moving on together, travellers arriving late the previous afternoon sometimes had to wait until the border reopened the next morning.

That makes it tough to know where those 89 residents were when the flood struck.

At 8: 37am – less than two minutes after the immigration system recorded its final transaction – seismic instruments detected movement in the mountains above the border, according to a timeline compiled by Nepal's Centre of Hydrology and Water Resources Research. Researchers afterwards attributed the signal to the collapse of part of a glacier that triggered the flood.

China remarked the mudslide reached the border crossing from its origin in around seven minutes.

Individuals at the crossing could have been making their way towards the bridge, waiting in Ghatte Khola or preparing to cross towards the Chinese facility. Exactly where each person was remains unclear.

And Ghatte Khola itself was far more than a waiting area. Pokharel notes 50 to 60 houses stood there, alongside hotels, local businesses and four hydropower offices.

It was additionally the final stop for buses from Kathmandu, and a base for drivers, helpers, tourist guides and cargo workers waiting for customs clearance. Travellers heading into Tibet often queued there from the previous day. "My 40-50 close friends are missing, " Pokharel remarked.

Pokharel believes the toll there could be far higher than official figures suggest, estimating that "2, 000 to 2, 500 people" may have been caught in the flood. The figure is his estimate and has not been independently verified.

For context, the immigration office itself stood regarding 100 metres above the river, Pokharel states. But during the flood, the water appeared to surge even higher. He initially hoped his missing colleagues might have escaped to grazing land a number of kilometres away.

For some of the Indian pilgrims at the border, the morning had begun almost casually. They created video calls and reels for relatives back home, showing them the mountains as they waited for the Chinese immigration office to open.

Sudipto Bhattacharya was receiving messages from his wife, Subhrasree Chakraborty. This person was travelling with a group of more than 60 individuals. At 07: 57 Nepal time, she sent him a photograph of the departure stamp in her passport: Nepalese immigration was done.

Six minutes afterwards, at 08: 03, she sent another message: "We are waiting to enter China." Then the messages ceased.

Among those at the Chinese immigration facility was a group of 77 pilgrims associated with the Isha Foundation, returning from Mount Kailash. They, along with three staff members, were unaccounted for after the flood swept through the area.

Notably, the crossing had only lately recovered from another major flood. In July 2025, flooding shut Rasuwagadhi for almost six months. It reopened on 1 January after China built a temporary bridge.

Traffic had since returned. While Nepali immigration records show 53, 742 arrivals and departures at Rasuwagadhi in the year to mid-July, chinese border authorities say more than 100, 000 individuals had passed through Gyirong by June. The two figures are based on different reporting periods and counting systems, making a direct comparison tough.

Indians were the largest group recorded at the Nepali immigration point, followed by Nepalis and Chinese.

Gyirong had additionally become one of the main arteries linking Nepal and China.

Posh Kumar Pandey, chairman emeritus of the Kathmandu-based South Asia Watch on Trade, Economics and Environment, notes Rasuwagadhi is one of Nepal's two main trading points with China, alongside Tatopani, and accounts for concerning a third of Nepal's $2.95bn trade with its northern neighbour.

Around 60 to 70 trucks passed through the gorge each day, carrying electronics, machinery, vehicles, fruit, clothing and other goods towards Kathmandu. Pandey notes the route additionally handled regarding 80% of Nepal's electric-vehicle imports from China.

In short, how catastrophic flash flood unfolded at remote Nepal is the central thread here, and readers can expect follow-up reporting as the picture becomes clearer.