The catastrophe that has unfolded in Nepal since August 26 has left thousands dead or missing in massive mudslides. It was most likely triggered by climate change and the accelerating melt of Himalayan glaciers. But experts are also asking whether human activity associated with China's expanding presence in Tibet intensified the disaster.
The disaster began with a natural event. A massive avalanche of ice and rock sheared away part of a glacier at an altitude of 5,200 meters near the Tibet–Nepal border. It then moved through a mountain landscape increasingly reshaped by human activity, setting off a cascade of destruction.
"The devastating flash floods that tore through Nepal's Trishuli and Koshi river valleys should not be seen as simply another Himalayan tragedy," wrote Brahma Chellaney, a professor of strategic studies at the New Delhi–based Centre for Policy Research and a fellow at the Robert Bosch Academy in Berlin, in an August 28 article for Nikkei Asia.
"The lesson is clear: In the fragile Himalayas, human alterations to rivers and mountain landscapes can dramatically amplify the impact of natural disasters," added Chellaney, author of several works on transboundary water security, including Water: Asia's New Battleground.
Gyirong, a major border crossing between China and Nepal, has become a critical trade bottleneck. Roughly 30 percent of bilateral trade passes through it, and Chinese products accounted for 95 percent of the goods traded there in 2024. Its vulnerability was already evident in July 2025, when floods washed away the bridge linking Gyirong to Rasuwa in Nepal, halting the movement of goods and people until operations resumed on January 1, 2026.
Gyirong consequently emerged as Tibet's principal logistics hub. "And inevitably, urbanization deep in the valley developed organically there," Robbie Barnett, a British Tibetologist and research associate at the School of Oriental and African Studies (SOAS), University of London, told Le Monde.
In 2015, Gyirong replaced the former Zhangmu crossing, 300 kilometers farther east, after an earthquake destroyed it. When the author entered Tibet through Zhangmu in August 1985, it handled 90 percent of the goods moving between China and Nepal.
Why Did the Flood Become So Destructive?
The disaster unfolded with extraordinary speed. Scientists have been trying to determine how such an enormous mass of ice and rock descended into the upper watershed of the Lhende Khola, a river valley along the Nepal–Tibet border. The avalanche became a dense debris flow that temporarily blocked the narrow gorge before the improvised dam collapsed.
Within minutes, a wall of water, mud, and boulders surged downstream. The collapse produced seismic waves so unusual that automated monitoring systems initially registered the event as a magnitude 5.2 earthquake. The deluge then swept through Nepal's steep valleys, destroying villages, bridges, and roads.
Debris destroyed several downstream hydropower plants, causing widespread power and communications outages. The floods also devastated the Tibetan side of the border. In Nepal, the mud and wreckage left an extensive trail of destruction and severely impeded search-and-rescue operations.
How Human Activity May Have Amplified the Disaster
For Chellaney, however, the natural trigger explains only part of what happened.
"The key question is why the floods became so destructive downstream," he wrote. "The answer lies in the cumulative effect of Chinese upstream infrastructure, altered river channels and the absence of meaningful transboundary cooperation. None of these caused the glacier failure, though together they may have amplified its consequences."
One important factor, Chellaney argued, was the transformation of the river corridor near the Tibet–Nepal border. Over the past decade, China has built levees, border facilities, highways, and other infrastructure along the riverbanks, narrowing parts of the upper valley. Under ordinary conditions, these projects facilitate trade and transportation; during extreme floods, they can create new vulnerabilities.
The torrent carried away excavated earth, concrete rubble, construction equipment, and structural debris. These materials turned an already violent flow into what hydrologists compare to liquid concrete, creating a battering ram capable of crushing nearly everything in its path.
A second factor may have been changes to the river's hydrology. Diversion dams, water-intake structures, embankments, and other upstream developments have, according to Chellaney, "created localized bottlenecks in the narrow Himalayan gorges."
When the avalanche-driven surge encountered these bottlenecks, water may have pooled temporarily before overflowing and generating secondary flood pulses. Downstream communities therefore faced not a single wave but several destructive surges in rapid succession.
The Cost of an Information Blackout
The most preventable failure may have been informational rather than physical. China operates hydrological monitoring stations on rivers originating in Tibet and collects real-time data on upstream conditions. Yet despite closer ties with Kathmandu, Beijing has not established comprehensive, year-round mechanisms to share data and issue emergency alerts in real time, either with Nepal or with other downstream countries.
Even without a fully integrated telemetry system transmitting data around the clock to Nepal's Department of Hydrology and Meteorology, an immediate Chinese warning about abrupt changes in water levels, the formation of a debris dam, or other upstream anomalies could have provided valuable time to evacuate settlements and trekking routes and protect vulnerable infrastructure.
As Chellaney put it, the absence of institutionalized hydrological transparency turned a natural hazard into a governance failure. Timely notification might not have prevented the flood, but it could have reduced the death toll.
According to an August 30 Reuters report, Nepal had asked China to share hydrological information three months before the disaster but received no data. At a May 27 meeting in Kathmandu, around 20 Nepalese and Chinese officials discussed closer cooperation on flood monitoring and glacier-related risks. The participants included representatives from the Tibetan region where the disaster occurred.
Two Nepalese officials told Reuters that China had not provided the requested information. "What we really expected from them, and what we still expect, is to be informed a little earlier in the event of early glacial movements and early movements in this region," said Sauhardra Joshi, a hydrologist with Nepal's Flood Forecasting Division.
Censorship Obscures the Disaster
The Chinese Communist Party's tight control of information has further obscured the scale of the disaster. Chinese state media showed little footage of the destruction in Tibet and Nepal beyond selected images of rescue operations, while videos circulating on social media were quickly removed.
Tibet, which the People's Republic of China annexed by force in 1950, remains one of the country's most politically sensitive regions, alongside Xinjiang. Beijing's official narrative emphasizes the benefits of Chinese rule, while foreign journalists may enter Tibet only on tightly controlled visits that leave little scope for independent reporting.
Foreign correspondents in Beijing have therefore found it extremely difficult to assess the destruction and loss of life on the Tibetan side. On August 30, the state-run Xinhua News Agency reported that more than 260 foreign nationals from 23 countries were among hundreds missing in Tibet. The largest groups included 104 Nepalese, 49 Indians, 33 Latvians, 18 Americans, and 15 British nationals.
Xinhua put the total number of missing people in Tibet at 546 and the death toll at 16. In the absence of independent access, however, those official figures cannot be verified.
"On Thursday night, as global headlines led on the devastation in a Himalayan valley, China's state broadcaster opened its main bulletin with the launch of Xi's new book, a selection of his 'most important and fundamental works,'" observed Laura Bicker, the BBC's Beijing correspondent.
Bicker noted that foreign journalists cannot travel to Tibet without government permission and have only a narrow window in which to gather information before online videos disappear and sources are silenced. State media, meanwhile, have concentrated on dramatic rescue efforts. "As a journalist who has covered North Korea, it has often been easier for me to contact interviewees in Pyongyang than it is in the Tibetan capital, Lhasa," she said.
The contrast between China's tightly controlled online space and the images visible elsewhere makes the country's information firewall especially apparent, Bicker argued. Tibet's history of political repression and allegations of serious human-rights abuses make the region particularly susceptible to censorship during a crisis. So does Beijing's characterization of the Dalai Lama as a separatist.
Chinese state media instead emphasized the leadership's response. Premier Li Qiang traveled to the affected region to inspect cleanup operations, while Xi Jinping instructed emergency services to make every effort to assist the victims.
Following a meeting of senior Party officials, Xinhua quoted the leadership as directing that "all available resources" be mobilized to locate and rescue missing people, whether Chinese or foreign.
Bicker argued that the muted coverage reflected the priority Xi places on political stability. The Communist Party fears that a disaster of this scale could provoke public anger over both the official response and the failure to anticipate the risks.
China's Dam-Building Drive in Tibet and their Consequences
Often described as "Asia's water tower," the Tibetan Plateau is one of the continent's most strategically important regions. At an average elevation of 4,000 meters, it is the source of the Indus, Brahmaputra, Yangtze, Yellow, Mekong, and Salween rivers, which together supply fresh water to nearly two billion people.
China has embarked on an enormous dam-building program across the plateau. In December 2024, Beijing approved what is expected to become the world's largest hydropower project on the Yarlung Tsangpo, the Tibetan name for the Brahmaputra. The planned facility would have roughly three times the generating capacity of the Three Gorges Dam on the Yangtze River.
The project has profound ecological and human implications for Tibet and for countries downstream. Designed to generate 60 gigawatts, the Motuo project in southern Tibet, also known as Medog, was included in China's 14th Five-Year Plan in 2020. It is part of a much broader wave of hydropower development across the plateau. India and other downstream countries have repeatedly raised concerns and called on Beijing to consult them.
This expansion has been justified in the name of decarbonization, often with limited regard for affected communities. According to Tenzin Palmo, a researcher and author of a report for the International Campaign for Tibet, 198 hydropower dams have been built or proposed across historic Tibet, including the Tibet Autonomous Region and the Tibetan regions of Kham and Amdo now incorporated into Chinese provinces. Of these, 54 are operational, 26 are under construction, 40 are in the planning stage, and 73 have been proposed.
Chellaney warned that the Nepal disaster may bring renewed scrutiny to the Yarlung Tsangpo megadam at the Great Bend, where the river curves around a mountain peak before flowing south into India. Building a facility with nearly three times the generating capacity of the Three Gorges Dam near a major geological fault would create substantial risks for millions of people downstream in India and Bangladesh.
"The Nepal disaster is more than a national calamity," he wrote. "It is a warning that the boundary between natural disaster and human-made catastrophe is blurring in the Himalayas." As infrastructure expands and glaciers weaken across one of the world's most geologically volatile mountain systems, governments upstream and downstream face growing pressure to cooperate before the next cascading disaster occurs.
Barnett has likewise warned of the risks posed by Beijing's vast construction projects on the "Roof of the World," both to the environment and to downstream populations.
"Ultimately, in all these projects, the desire to extract energy from nature, on the one hand, and to impose its power on its neighbors, on the other, involves gambles with terrifying risks in the face of nature's limits," he said.
This article was originally published in French by Asialyst and has been edited and republished here in English.