It did not rain. Yet the river swallowed the village.
At around 8:40 a.m. on the 26th in Rasuwa, Bagmati Province, north-central Nepal, a river running along the Himalayan foothills suddenly swelled and swept away a bridge, villages, and a construction site. The area is a border region about 120 kilometers north of Kathmandu.
According to the Ministry of Foreign Affairs, nine Korean workers building the Upper Trishuli-1 hydroelectric power plant in Rasuwa lost contact. They included three from Korea Hydro & Nuclear Power and six from Doosan Enerbility. Another 10 Koreans at the same site were initially isolated but were later confirmed safe. The Nepali government has formed rescue teams of soldiers and police and is using helicopters to reach those stranded.
The South Korean government set up an overseas nationals protection headquarters led by the foreign minister. As President Lee Jae Myung ordered the use of all available resources, a joint rapid response team made up of the Foreign Ministry, the National Fire Agency, and the National Police Agency departed for the site on the 27th. The South Korean Embassy in Nepal requested search and rescue operations from the Nepali government immediately after learning of the incident and sent a consular officer to the scene.
The damage has spread across both sides of the border. According to preliminary Nepali authorities’ figures, the death toll is around 100, with more than 400 missing. Many of the missing are foreign tourists who had gone trekking in the Himalayas or on religious pilgrimages. Fatalities and missing persons have also been reported in the Tibet Autonomous Region of China upstream. Combined, the number of missing across the two regions exceeds 660. Because communications and roads have been cut off, the tally is changing by the hour.
It was not only people who were swept away. The Friendship Bridge linking Nepal and China was washed out, and a border trade checkpoint was buried under debris. The trade route crossing the Himalayas came to a complete halt. Nepal’s power authorities estimate that more than a dozen hydropower plants were damaged, disrupting over 400 MW of generation capacity.
The first question was the cause.
Nepal’s hydrometeorological department confirmed that no rain had fallen in the Rasuwa area sufficient to trigger flooding. In flat terrain, rivers do not swell without rain. In the Himalayas, it is different.
The International Centre for Integrated Mountain Development (ICIMOD) said in an initial analysis that a mass of ice and rocks that broke loose from an upstream glacier had blocked the Rende Khola River and then collapsed all at once. The ice jam across the valley acted like a temporary dam, holding back water until it broke under its own weight, unleashing trapped water and sediment downstream.
Experts call this phenomenon a glacial lake outburst flood. As glaciers melt, lakes form between ice and rock debris; when the water rises and the barrier gives way, millions of tons can spill out at once. It is similar to a dam breaking, but with no warning. Walls made of ice and soil have no spillways or instruments.
It is also difficult to gauge the scale. If a lake the size of a soccer field were filled 10 meters deep, the water alone would weigh more than 70,000 tons. Many Himalayan glacial lakes are dozens of times larger. One can imagine what happens downstream when the trapped water suddenly bursts out.
The floodwaters carry mud, gravel, and boulders. Instead of clear water, a heavy mass of muddy slurry moves through the valley at tens of kilometers per hour like concrete. That is why bridges, roads, and heavy equipment cannot withstand it. It is also why people at the site described it as a wall rushing toward them, not water.
News first reported that a magnitude 4.4 earthquake had been recorded at the time, but this was later corrected to a massive landslide that caused the shaking rather than an earthquake. The impact of the collapsing mountain was strong enough to be picked up by seismographs.
What makes this even more severe is that it was a repeat disaster. In the same Rasuwa area last July, a glacial lake on the Tibetan side burst and caused flooding in the Bhotekoshi River. The border bridge was cut off, hundreds of cargo trucks were swept away, and hydroelectric facilities were damaged. In just over a year, it happened again, in the same way, and on a larger scale.
Nepal is a country that aims to turn water flowing down from the Himalayas into electricity to drive economic growth. Because most of its territory is mountainous, thermal or nuclear power plants are difficult to build, making hydropower virtually its only major source of electricity. It has also pursued plans to export power to India and earn foreign currency. Its strategy of treating water as an asset has been shaken by a disaster caused by water itself.
Upper Trishuli-1, being built by Korean companies, was considered a project that could change Nepal’s power landscape. Once completed at 216 MW, it was expected to supply around 20 percent of Nepal’s total electricity. The total project cost is $647 million, or more than 900 billion won.
Korea Hydro & Nuclear Power and the Korea Finance Corporation co-developed the project, with Doosan Enerbility handling construction, and completion had been expected by the end of this year. Doosan Enerbility formed an emergency response headquarters and planned to send a response team to the site, including CEO Jeong Yeon-in.
The river that began the disaster was not in Nepal. It was in a valley on the Tibetan side of the border. The disaster crossed the border, but the signal warning of danger did not.
Himalayan border rivers straddle two different countries upstream and downstream. Only the upstream country can monitor in real time when ice collapses and water is trapped. For downstream residents and construction sites to have time to evacuate, that information must be transmitted immediately. Once an ice dam bursts, it can take only tens of minutes for the water to reach downstream villages. Even a few minutes’ advance notice can allow people to move to higher ground.
The reality is the opposite. There are only a handful of upstream monitoring installations, and water information sharing across the border is not institutionalized. Even when the same region suffered an accident last year, downstream residents learned of the danger only when the water was already upon them. This time as well, the power plant site was hit by the floodwaters just as workers were preparing for the morning shift.
There are precedents for responding to cross-border disasters in other regions. Countries in the Rhine River basin in Europe have long operated systems that immediately pass upstream water level and pollution information to downstream nations. The Himalayan border rivers do not yet have such a system.
The issue is not the lack of technology. Satellite methods for tracking changes in glacial lake area are already in use, and some valleys in Nepal have automated warning networks combining water gauges, vibration sensors, and sirens. The problem is that these are neither dense enough to cover all high-risk areas nor able to reach upstream territory beyond the border.
There is also a shortage of funding and personnel to install and operate warning networks. Nepal has a small economy. It is difficult to afford the cost of continuously monitoring thousands of glacial lakes and maintaining warning systems in every valley. That is why international organizations and support from developed countries have been discussed.
The signals from the Himalayas are getting stronger. According to a report released by ICIMOD in March this year, the rate at which glaciers in the Hindu Kush Himalaya are thinning has more than doubled, from 34 cm per year before 2000 to 73 cm per year after that. Between 1990 and 2020, glacier area shrank by 12 percent. If global temperatures continue rising 1.5 to 2 degrees Celsius above preindustrial levels, 30 to 50 percent of glacier volume is projected to disappear by 2100.
As glaciers melt, more lakes form to hold the water, and more lakes mean more places that can burst. Thousands of glacial lakes are identified across the Himalayas, and among them, only those at high risk of collapse are separately managed. The 2023 disaster in India’s Sikkim, where a glacial lake burst and caused a downstream hydropower dam to collapse, killing dozens, also stemmed from the same cause.
The water issue does not remain confined to mountain regions. The rivers that begin in the Himalayas flow on to India, Pakistan, Bangladesh, and southern China. Up to 2 billion people depend on glacial meltwater. Right now, the meltwater overflows and becomes a disaster; later, as glaciers disappear, water shortages will follow.
The first solution most often mentioned is a cross-border warning system. The idea is to sign agreements under which upstream countries relay glacial lake water levels and landslide signs to downstream areas in real time, and to create a structure in which sirens sound automatically. If water does not remain within one country, monitoring cannot remain within one country either.
Redrawing hazard maps must follow. If authorities calculate which glacial lakes are most dangerous and how many minutes it would take flooding to reach each valley after a burst, evacuation plans can be prepared. Such data can be produced by combining satellite observation and field surveys.
For hydropower plants and other mountain facilities, experts say design standards must change. If previous standards were based on rainfall and flood frequency, they must now also account for surges of water released almost instantaneously by upstream glacier collapse. Placing dormitories and office buildings on higher ground away from rivers, and setting evacuation routes and assembly points at each site, are also cited as necessary measures.
Communication problems were also exposed this time. Because contact with the site was cut off immediately after the incident, it took time to assess the situation. Equipping sites with satellite communications devices and personal location beacons that still work when terrestrial networks fail would shorten the time needed for rescue teams to decide where to search first.
Korean companies are now faced with the task of reviewing their risk management standards for overseas worksites. Domestic builders and power companies have expanded hydropower and road projects in mountain regions across Southeast Asia, South Asia, and Latin America. Climate disasters have become as significant a business risk as political conditions and exchange rates. It is now necessary to document disaster response responsibilities, insurance, and evacuation standards when signing contracts.
Protecting workers on site must also be addressed. At large overseas construction sites, far more local workers are employed than Korean staff. There are calls to check whether evacuation training and warning instructions are given in local languages and whether they work at night and on weekends.
The government still has its own role to play. The system for protecting nationals abroad should not stop at sending personnel after an accident occurs. Critics say it also needs advance preparation: identifying where Korean citizens and company worksites are located in risky regions and establishing contact networks with local authorities and international organizations.
There is also a strong view that climate action itself is the fundamental remedy. If the pace of greenhouse gas reduction cannot keep up with glacier melt, the number of accidents will continue to rise no matter how many warning systems are installed. What is happening in the Himalayas is not a distant story. A power plant built by a Korean company was swept away, and Korean workers were caught in the flood.
Search and rescue efforts are continuing. Cut-off roads, swollen rivers, and mountainous terrain with nowhere suitable for helicopters to land are hindering operations. Families remain waiting for news.
On a morning with no rain, the river covered the village. How we read the warning sent by the Himalayas will shape the landscape of next summer.