Article by Dr Kanchan Lakshman
The catastrophic floods in Nepal have raised urgent questions about the safety of mega-hydropower projects in the fragile eastern Himalayas, where earthquakes, glaciers, landslides and powerful rivers create an extraordinary combination of hazards.
The Himalayas are often described as Asia’s water towers. After the catastrophe that struck Nepal on August 26, 2026, they must be understood as a landscape of cascading risks. A mountain can collapse, a river can be blocked, a sudden surge can sweep away a settlement, and a hydropower plant can become another casualty of it. The tragedy should force a fundamental reassessment of how infrastructure is planned across these fragile mountains.
The scale of Nepal’s disaster is staggering. By October 10, police figures put the death toll at 1,457, with 4,720 people still reported missing. Floodwaters devastated sections of the Bhote Koshi-Trishuli corridor, destroying homes, bridges, roads and hydropower facilities. Workers were trapped in tunnels; communities lost access to electricity, transport and livelihoods. These losses revealed how interdependent the region’s infrastructure has become.
According to the International Centre for Integrated Mountain Development (ICIMOD), a massive ice-and-rock avalanche broke away near Langtang Lirung in Nepal. Rock, ice, mud and water accelerated into the Lhende Khola and then the Bhote Koshi. Debris may have briefly dammed the channel before water broke through. Researchers are still examining the precise sequence. The available evidence does not establish that a Chinese dam or construction project triggered this event.
Nor should the flood automatically be called a conventional glacial lake outburst flood, or GLOF. Unlike a typical GLOF, the August disaster did not begin with the failure of a pre-existing glacial lake. It was a mountain-slope collapse that developed into a destructive debris-laden flood, possibly involving a temporary landslide dam. Different mechanisms demand different monitoring and warning systems.
Yet the broader warning is unmistakable.
In July 2025, a separate flood in the same border corridor resulted from a lake suddenly draining on the Purepu Glacier in Tibet. In August 2024, a rock avalanche unleashed water from glacial lakes above Nepal’s Thame village. The triggers differ, but the pattern repeats: high-altitude instability can unleash destruction far beyond the place where it begins.
This is the context in which China’s enormous hydropower ambitions on the Yarlung Tsangpo, known downstream as the Siang and Brahmaputra, must be examined. The Nepal flood occurred in a different river basin; it is not evidence that the Medog hydropower complex caused the tragedy. But the geological processes that made Nepal vulnerable are highly relevant to China’s plans in the eastern Himalayan syntaxis, where steep terrain, glaciers and active faults converge.
In July 2025, Beijing formally launched the construction of a five-station hydropower cascade on the lower Yarlung Tsangpo. Its stated investment was about 1.2 trillion yuan, or $167.8 billion. China presents the project as a major clean-energy undertaking. Those benefits matter. So does the question of whether engineering on such an extraordinary scale can adequately anticipate an extraordinary range of natural hazards.
The region is not geologically quiet. The Indian plate continues to press into Eurasia, producing faults, fractures, and frequent seismic activity. In 2026, reporting on research by Chinese geologists highlighted the active Paizhen Fault and warned of implications for nearby dams, tunnels, roads, and bridges. Separately, researchers studying the lower Yarlung Tsangpo have called for careful examination of reservoir-induced seismicity: the possibility that the weight of impounded water and pressure entering rock fractures could affect already stressed faults.
This does not mean that reservoirs inevitably cause earthquakes, or that the Medog project is destined to fail. It means that risk assessment can not end with the reassuring question, “Can the dam withstand a strong earthquake?” It must also ask what an earthquake could do to the slopes above a reservoir, how a landslide might displace water, whether debris could obstruct a tunnel or spillway, and how an emergency release would travel downstream.
History offers a warning. In Italy in 1963, a massive landslide plunged into the Vajont reservoir, generating a wave that overtopped the dam and devastated communities below. The dam largely survived. The disaster demonstrated that the failure of an entire mountain-reservoir system can be catastrophic even without the conventional collapse of a dam wall. Himalayan planners cannot afford to ignore that lesson.
Climate change increases the complexity. Warming temperatures can thin glaciers, thaw frozen ground and alter water movement within steep slopes. Heavy precipitation, earthquakes and landslides can interact with these changes. Scientists caution that any particular collapse requires careful attribution; the August 2026 disaster cannot simply be labelled “caused by climate change”. Nevertheless, designing long-lived infrastructure around yesterday’s mountain conditions would be dangerously complacent.
Construction can introduce additional pressures. Access roads, tunnels, spoil disposal sites and excavated slopes may disturb fragile terrain. Reservoirs can change sediment transport and seasonal flows. The concern is not that every project causes disaster, but that many projects built close together may multiply exposure. A natural event that would once have swept through an unoccupied gorge can now strike villages, work camps, powerhouses and transportation corridors in rapid succession.
The consequences do not stop at national borders. From Tibet, the Yarlung Tsangpo enters India as the Siang and eventually flows through Assam and Bangladesh as the Brahmaputra-Jamuna system. Millions depend on its water, sediment, fisheries and floodplains. Downstream communities therefore have a legitimate interest in knowing how projects may affect river behaviour during droughts, extreme rainfall, earthquakes or operational emergencies.
Beijing maintains that the Yarlung Tsangpo project will meet high safety and environmental standards and will not harm downstream countries. Chinese officials have also rejected speculation linking Chinese infrastructure to the Nepal flood, pointing instead to a glacial collapse in Nepal. These positions do not eliminate the need for independently accessible evidence, transparent modelling and meaningful consultation with those living downstream.
What would responsible development look like? First, basin-wide hazard mapping should consider glaciers, unstable slopes, active faults and the routes along which debris and flood waves could travel.
Second, independent specialists should review not merely dam-wall strength but possible chains of events involving earthquakes, landslides, temporary blockages, reservoirs, and tunnels. Third, construction plans must include realistic evacuation routes, tunnel-rescue provisions, and systems that remain functional when communications and roads fail.
Fourth, China, India, Nepal and Bangladesh should strengthen cross-border access to hydrological, seismic and satellite information, including real-time warnings of abnormal flows and mountain-slope failures. A river does not pause at a frontier while officials debate jurisdiction. Regional scientific cooperation is not an infringement of sovereignty; it is the most practical expression of responsibility in a shared mountain environment.
Finally, public accountability must extend beyond technical assurances. Project developers should disclose environmental assessments, emergency operating protocols and the assumptions behind worst-case scenarios. Downstream governments should commission their own independent modelling, prepare communities for low-probability but high-impact events, and resist answering one mega-project with another before cumulative risks are understood.
Nepal’s August flood does not prove that China’s Brahmaputra project will become a disaster. It proves something more useful: in the Himalayas, hazards do not occur neatly one at a time. Rock, ice, water, earthquakes and infrastructure can combine in ways that overwhelm conventional planning. The choice is not between clean energy and public safety. The real test is whether governments are willing to make safety, scientific openness and downstream accountability prerequisites for development. The Himalayas have delivered their warning. Ignoring it would be the greater man-made risk.
