Bhotekoshi Flood | The Himalayan Tragedy

Ramesh Kumar, a journalist based in Kathmandu, posted a photo on Thursday (27 August 2026) of the clock tower whose hands had stopped at 09:29.

“A clock that never tells time again,” he wrote on X, formerly Twitter. “Betrawati.”

Mr Kumar arrived at Betrawati in Nuwakot district, a town devastated by the previous day’s flood in the Bhotekoshi River in neighboring Rasuwa district, which borders Tibet. After touring Betrawati, where he was born and raised, he made a grim assessment: “Will Betrawati ever revive as a bazaar? Almost impossible.”

The extraordinary speed and scale of the Bhotekoshi River flash flood on Wednesday (August 26, 2026) around 8:40 am left over 600 dead and nearly 2,500 missing, including foreign nationals, mostly from India.

The Government of Nepal immediately swung into action and mobilized personnel from the Nepal Army, Nepal Police and Armed Police Forces as they launched a massive search and rescue operation.

Meanwhile, scientists have been trying to piece together the chain of events and determine the origin of the deluge as they wonder about the massive disaster, with some describing it as the worst since the 2015 earthquake.

Regarding the origin, the Nepalese and Chinese sides concluded that the source was in the Langtang Lirung area. Determining the exact point where the initial collapse occurred and on which side of the border it was can be difficult.

According to an official of Nepal’s Ministry of Hydrology and Meteorology, satellite images shared by the Chinese side showed a combination of ice avalanche, permafrost movement and rock slide along the Nepal-China border, with the slide occurring on the Chinese side and its impact extending into Nepal.

“The avalanche originated on the Nepalese side of the territory but very close to the border and triggered floods that crossed the Nepal-China border, causing widespread damage on both sides,” said Binod Parajuli, senior divisional hydrologist in the ministry’s flood forecasting division.

The site the researchers point to is in the Lhende Khola, a transboundary high-altitude river that originates in Gyirong District, Tibet and flows south into Nepal, where it is a tributary of the Bhotekoshi and Trishuli river systems.

Flooding in the Bhotekoshi River is not uncommon. Last July, a flood – caused by no rainfall – caused damage and destruction in Bhotekoshi. Scientists later concluded that the disaster was linked to a Glacial Lake Flood (GLOF).

Another angle

While scientists initially considered whether this year’s flood could also be linked to the GLOF, its speed and fury, which washed away villages downstream in three districts – Rasuwa, Nuwakot and Dhading – prompted experts to look at it from a different angle.

Dr. Ranjan Kumar Dahal, an associate professor at the Himalayan Geodisaster Research Center at the Central Department of Geology, Tribhuvan University, described the mass movement that triggered the flood as a storm surge.

“Sturzstrom is a massive rock avalanche in which a large volume of rock suddenly collapses and moves at extremely high speed over a long distance,” Mr Dahal told The Hindu from Trishuli, another area badly hit by Wednesday’s (August 26, 2026) floods. “In a high mountain environment, where rock mixes with ice, snow, firn and frozen ground, this can be understood as a rock-ice avalanche.”

Rasuwagadhi in Rasuwa is the border crossing through which most of Nepal’s trade with China takes place. From May to September, hundreds of pilgrims use this border point to cross into Tibet for the Kailash Mansarovar pilgrimage. Indians make up the largest proportion of pilgrims.

It could take weeks, if not months, to assess the full extent of the damage, officials said, adding that the toll could continue to rise.

The International Federation of the Red Cross said the remoteness of the affected areas, combined with damaged infrastructure, made it difficult both to assess the full scale of the disaster and to provide aid to people in need.

“Current estimates suggest that around 93,000 people may have been affected,” it said. “Many homes were severely damaged, cutting off some of the worst affected communities.”

Two other major questions also emerged after the disaster – whether early warning systems were activated and whether climate change played a role in the disaster. Experts say early warning systems worked as they should, but were ineffective given the staggering speed of the floods.

Kamal Kishore, head of the United Nations Office for Disaster Risk Reduction, said the floods showed once again how fragile mountain ecosystems are and how challenging it is to establish early warning systems in mountain environments.

Scientists have not ruled out the impact of climate change, saying rising temperatures are causing the Himalayas to warm and glaciers to melt faster, but stopped short of directly linking the disaster to global warming.

“We haven’t seen a disaster like this in Nepal that involved a sturzstrom. But there was a similar event in India in 2021,” Mr. Dahal said, referring to the Chamoli disaster in Uttarakhand, where a breach in bedrock under a glacier triggered a massive rock-ice avalanche that turned into a debris flow and flood.

The 2021 Chamoli event has been scientifically described as a rock and ice avalanche, and in some literature specifically as a sturzstrom. Research has found that more than 25 million cubic meters of rock and ice broke loose high in the Uttarakhand Himalayas before moving rapidly downstream.

Catastrophic sturzstrom

“Sturzstrom starts when an unstable rock ice slope suddenly collapses. The collapsing mass rapidly accelerates, shatters and mixes with ice and snow,” explained Mr Dahal.

“Pressure and friction can create meltwater that can increase lubrication in and along the moving mass, reducing drag and contributing to exceptionally long throws,” he added.

According to him, this process can unfold in a matter of minutes.

“As it moves downslope, it can contain more ice, snow, rock, soil and water, potentially turning into a massive debris flow before finally depositing its material,” he said.

Meanwhile, rescue operations continued for a fourth day, with Prime Minister Balendra Shah saying more than 15,000 people had been deployed.

For communities along the Bhotekoshi-Trishuli corridor, the immediate priorities are to find the missing, restore access and assess whether any of the flood-ravaged sites can be rebuilt at all.

It’s a race against time.