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Nepal’s deadly flash floods have renewed scrutiny of China’s 60,000-MW Medog dam on the Yarlung Tsangpo. Here’s why experts warn of seismic and downstream risks.
Damaged houses stand precariously near the swollen, debris-choked banks of the Trishuli River after flash floods in Nepal’s Nuwakot district (Photo: AP)
The catastrophic flash floods that swept through Nepal’s border region with China have renewed scrutiny of China’s massive hydropower project being built on the Yarlung Tsangpo River in Tibet, with experts describing the planned dam as a “water bomb in the making”.
The warning has gained fresh attention because the disaster in Nepal demonstrated how quickly a sudden event in the fragile Himalayan terrain can trigger a devastating cascade of water, ice, rock and debris, although the US Geological Survey later determined that the seismic signal initially reported as a magnitude 4.4 earthquake was actually caused by a glacial collapse.
What Happened In Nepal
At least 165 people were killed in the flash floods along the Nepal-China border, while hundreds of others remained missing after a sudden torrent swept through communities, destroyed roads and bridges and buried buildings in mud and debris.
The Nepalese police reported at least 157 deaths, while China’s state broadcaster CCTV reported three deaths and 265 people missing in Tibet’s Gyirong County near the border.
The US Geological Survey initially recorded what appeared to be a magnitude 4.4 earthquake near the Nepal-China border, but subsequently revised its assessment and identified the event as a magnitude 5.2 glacial collapse, based on seismic data, long-period seismic waves and satellite imagery.
Climate experts cited by the AP said an avalanche from a glacier likely caused the flash flood, with the International Centre for Integrated Mountain Development reporting that water levels in the Trishuli River rose by as much as nine metres within half an hour.
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The AP also reported that the same region had experienced a similar flash-flood disaster in August last year, when a glacial lake in Tibet overflowed amid high temperatures, killing nine people and damaging critical infrastructure, including a bridge connecting Nepal and China.
Why The Nepal Disaster Matters For The China Dam
Strategic affairs expert Brahma Chellaney argued on X that the Nepal disaster illustrated how even a moderate seismic event in the Himalayas could produce “massive cascading effects”, before turning his warning towards China’s Yarlung Tsangpo mega-dam.
“The project, located next to the Indo-Tibetan border, is a water bomb in the making, which could drown India’s northeast and wreak havoc farther downstream in Bangladesh,” Chellaney wrote on X.
Chellaney’s warning is specifically about the combination of the dam’s extraordinary scale and the geological setting in which it is being built, while the Nepal disaster has provided a stark example of how rapidly Himalayan hazards can escalate downstream.
Importantly, however, the Nepal floods were not caused by a failure or release from China’s planned dam, and the AP reported that the immediate trigger was a glacial collapse rather than an earthquake.
How Big Is China’s Mega Dam?
South China Morning Post reported that the project is being constructed in Medog, also known as Motuo, in southeastern Tibet, where the Yarlung Tsangpo makes a dramatic horseshoe-shaped turn and drops roughly 2,000 metres over a 50-kilometre stretch.
According to the International Hydropower Association figures mentioned by the report, the project is expected to have an installed capacity of about 60 gigawatts and annual generation capability of roughly 300 billion kilowatt-hours, making it approximately three times the power-generation capacity of China’s Three Gorges Dam.
Reuters reported in 2025 that China had begun construction of the roughly $170-billion project, describing it as a five-dam cascade on a section of the Yarlung Zangbo where the river drops about 2,000 metres over 50 kilometres.
The Yarlung Tsangpo becomes the Brahmaputra after entering India and subsequently flows through Bangladesh, meaning that the project is located upstream of two countries that depend on the river system.
The Seismic Risk
The concern over the dam is not based solely on its size, with the South China Morning Post reporting in July 2026 that Chinese geologists had identified an active fault line beneath the world’s largest hydropower project.
According to the SCMP report, researchers from the Chengdu University of Technology, the Civil-Military Integration Centre of the China Geological Survey and the Middle Yarlung Zangbo River Natural Resources Observation and Research Station studied the geological conditions around the project.
The researchers reportedly found that the Paizhen Fault, described as having been highly active since the Pleistocene, could significantly affect the stability of nearby dams, roads, bridges, tunnels and the reservoir area.
The researchers therefore urged engineers to strengthen slope stability and introduce retaining protections to reduce the risk of landslides and collapses, according to SCMP.
An IANS report citing the Institute for Security and Development Policy’s 2026 report, ‘The Medog Imperative’, also said the project sits in a region marked by the collision of the Indian and Eurasian tectonic plates and warned about seismic volatility.
The same report said studies had raised concerns over landslides and mudflows following earthquakes, noting that even if a dam itself were engineered to withstand an earthquake, secondary geological events could pose serious dangers.
Why India And Bangladesh Are Watching Closely
Reuters reported that India and Bangladesh have expressed concerns because the Yarlung Zangbo becomes the Brahmaputra downstream, while India has also raised questions about the possible effects on water and sediment flows.
Reuters also reported that experts have cautioned against overstating the dam’s ability to control the entire Brahmaputra because a substantial share of the river’s eventual volume comes from monsoon rainfall and tributaries south of the Himalayas.
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China has said the project is designed as a run-of-the-river hydropower system and has rejected concerns that it will divert the river away from downstream countries, according to Reuters.
Nevertheless, Reuters reported that concerns remain over the project’s seismic setting, extreme weather risks, transparency and the possible downstream effects of changes in water and sediment flows.
A Himalayan Risk Multiplier
The Nepal disaster has therefore brought renewed attention to the question of how extremely large infrastructure projects should be assessed when they are located in a landscape exposed simultaneously to earthquakes, landslides, glacial hazards, extreme rainfall and rapidly changing climatic conditions.
The AP reported that experts have linked the increasing vulnerability of the Himalayas to warming, noting that glaciers are melting faster and that steep slopes and river valleys remain particularly exposed to floods and landslides.
Against that backdrop, Chellaney’s “water bomb in the making” description has become a prominent warning about the potential consequences of placing an enormous hydropower project in a seismically active Himalayan region, although it remains a warning about a potential future disaster rather than evidence that the dam itself poses an imminent failure risk.
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Quick Answers
Ask News18China’s mega-dam on the Brahmaputra River could impact India and Bangladesh by potentially reducing water flow during reservoir filling, increasing flood risks from sudden releases, and posing structural integrity threats due to an active fault line beneath the construction site. Landslides induced by earthquakes could also obstruct rivers, forming temporary dams that may break and cause downstream floods.
Ask News18About the Author
Vani Mehrotra is the Deputy News Editor at News18.com. She has more than 10 years of experience in national and international news and has previously worked on multiple desks.
August 27, 2026, 08:30 IST
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