On Wednesday, torrents of floodwater and mud surged through Himalayan river valleys, engulfing villages and sparking a cross‑border emergency spanning Nepal and the Chinese region of Tibet, leaving an untold number of people swept away or buried.
Thousands reside in riverside communities downstream of the deluge, with hundreds reported dead or missing — among them foreign visitors. Nepal’s prime minister said at least 19 road bridges and 40 kilometres of highway have been washed away.
Key facts about the flash flood.
Which areas were affected by the floods?
The floodwaters tore through the Trishuli River valley, a narrow gorge lined by steep peaks that marks the boundary between Tibet and Nepal’s Rasuwa district.
Nepalese authorities counted 157 fatalities, while Xinhua said a mudslide in China claimed at least three lives and left 265 people unaccounted for. The agency described “significant” casualties at Gyirong Port, where state‑media video showed water and mud inundating structures, toppling trees and cutting off road access.
Footage from Nepal depicted the river, choked with debris, sweeping away bridges and burying parts of towns under mud.
Gyirong Port, a modest settlement hosting a border crossing into Nepal, lies inside the Tibetan Autonomous Region — a zone Beijing tightly administers to suppress opposition to its rule over Tibet. The port, situated roughly 65 kilometres north of Kathmandu, was developed by Chinese officials to integrate Tibet into the Belt and Road Initiative via trade links with Nepal and India.
Beyond the port, the Trishuli continues its course southwest across Nepal.
What triggers a flash flood when there is no heavy rain?
Officials said they were taken by surprise when the flood struck on Wednesday, noting that no rain had fallen, according to Narendra Pariyar, Rasuwa’s chief district officer.
Nepal’s foreign minister, Shisir Khanal, said authorities had received early indications of a Wednesday‑morning avalanche in the zone. The US Geological Survey noted that shaking from associated landslides registered initially as a magnitude 5.2 tremor.
Preliminary analysis by geologists and glaciologists suggests the event was triggered, at least in part, by a massive ice block breaking free from a glacier and plummeting thousands of feet into the valley — a process termed an ice avalanche.
The researchers explained that the impact liberated enormous energy, shattering the ice into a large volume of floodwater.
According to the U.S. National Weather Service, flash floods most often stem from intense thunderstorm rainfall, yet they can also arise from landslides or any event that displaces substantial water.
Wednesday’s ice avalanche resembles a 2021 incident in India, when a Himalayan glacier collapsed and unleashed severe flooding across Uttarakhand, claiming over a hundred lives.
Which tourists are reported missing?
Nepal’s tourism board said that hundreds of travellers, including 391 foreign nationals, are unaccounted for. The missing comprise more than 100 Indians, about a dozen Britons and at least three Americans, plus visitors from Australia, the Netherlands, Malaysia and South Africa.
Among the missing Indians is a contingent of pilgrims from southern India; Mount Kailash in Tibet, revered by several faiths including Hinduism, lies nearby.
Sadhguru, the prominent Indian spiritual leader and founder of the Isha Foundation — which arranges pilgrimages to Mount Kailash — said that 77 participants in its tours were present at the Nepal‑Tibet immigration checkpoint when the floodwaters arrived.
“There has been no official word on the fate of anyone who was at the immigration office,” he said. “We are coordinating with authorities to reach the site and stand ready to join the rescue operation.”
How frequent are landslides in this area?
Although nationwide monsoon rainfall has been below average this season, local outlets reported intense downpours in several hilly zones that triggered lethal landslides and flash floods earlier this month.
In 2024, heavy rains sparked floods and landslides that claimed hundreds of lives across Nepal, notably in the densely populated Kathmandu valley.
Nepal’s rugged terrain makes it susceptible to landslides and floods when intense monsoon rains meet the towering heights of peaks such as Mount Everest.
A warming climate has heightened the danger and lethality of weather events, driving more frequent floods from glacial melt. Climate change has also amplified rainfall intensity, while rapid, poorly planned development further raises the likelihood of loss of life in natural disasters.
Reporting contributions came from Lily Kuo, Suhasini Raj, Hari Kumar, Leo Sands and Pranav Baskar.
