Brahma Chellaney, OPEN magazine

China’s own scientists are warning the world about the serious risks posed by the colossal Chinese super-dam rising just miles from India’s border on the upper reaches of the Brahmaputra. Why has India been loath to leverage those scientific warnings?

For more than five years since China’s rubber-stamp parliament approved the project in March 2021, India has responded to the threat the super-dam poses to downstream Indian communities with quiet diplomacy: confidential demarches, requests for transparency and cautious official statements. That strategy has produced virtually nothing.

Construction continues at full speed on what will become the world’s largest hydroelectric dam, rising in Medog county in Tibet’s Nyingchi prefecture.

The behemoth dam could singlehandedly reshape the course of the Yarlung Tsangpo, as the Brahmaputra is known in Tibet. While the intense rains across Arunachal Pradesh, Assam and Meghalaya contribute immensely to the Brahmaputra’s flows during the fourth-month monsoon season, the river’s lean-season or dry-season flows depend for almost eight months on perennial sources such as glacier melt, mountain springs, snowmelt and other base flows originating mainly in Tibet.

The perennial flows carry nutrient-rich Himalayan silt. Trapping this sediment behind the mother of all mega-dams would starve downstream floodplains of vital nutrients, while releasing sediment-stripped water would incrementally erode riverbeds in India and Bangladesh regardless of the season. The super-dam’s flow regulation would thus represent a major geopolitical and ecological vulnerability downstream.

The Medog project itself poses a geological and humanitarian challenge whose consequences could reach millions of people across Arunachal Pradesh, Assam, Meghalaya and Bangladesh. Ironically, the strongest case against the project is coming from China’s own state-linked scientists.

Instead of a single dam with a reservoir, the unprecedented Medog project appears to be a vast, tunnel-linked hydropower and water-diversion complex deep in the Himalayas. It reportedly dams the Brahmaputra at more than one point around the Great Bend, where the river makes a dramatic U-turn around the towering Namcha Barwa peak before gushing south into India.

The project remains shrouded in secrecy. Yet some state-linked Chinese analysts claim it includes a tunnel dozens of kilometres long bored through Namcha Barwa, linking the northern and southern reaches of the river across its Great Bend. Taken together, this sprawling infrastructure is best described as a super-dam.

For Tibetans, the mega-project represents another assault on their land, culture and way of life. It is being built in one of Tibetan Buddhism’s most sacred landscapes. The tunnelling, damming and large-scale excavation are widely viewed as a desecration of territory long revered by Tibetans, who for centuries have served as environmental guardians by respecting nature as both their teacher and protector.

Against this backdrop, India should abandon its largely silent approach and highlight at multilateral forums the warnings published by Chinese geologists. New Delhi should spotlight Chinese scientific evidence that the dam is being constructed atop an active fault system with unusually fragile geological conditions. When China’s own experts describe the project as vulnerable to seismic instability, India possesses a powerful diplomatic opportunity that it has yet to seize.

The dam is staggering in scale. Planned with a generating capacity of 60,000 megawatts—nearly three times larger than the Three Gorges Dam—it is designed to exploit the dramatic 2,000-metre descent of the Yarlung Tsangpo as the river bends around the Namcha Barwa massif before entering India. The project, approved in China’s Five-Year Plan in 2021 and estimated to cost about $127 billion, embodies the Chinese Communist Party’s longstanding ambition to build the world’s biggest engineering marvels.

But the super-dam’s location is precisely what makes it extraordinarily dangerous. The dam sits within one of the world’s most seismically active regions, where the Indian and Eurasian tectonic plates collide.

This Himalayan collision zone has produced some of Asia’s most destructive earthquakes, including the 1950 Assam-Tibet earthquake that was so powerful that it cut off India’s northeast from the rest of the country. It also caused significant changes to the Brahmaputra, including the blocking of tributaries by landslides and alterations to the river’s course and riverine morphology.

A more recent example of Himalayan seismic instability was the devastating earthquake that struck Myanmar in 2025, with tremors extending almost 1,000 kilometres to Bangkok. Meanwhile, the catastrophic flash flooding along the Tibet-Nepal border has served as a vivid demonstration of how tightly linked glacial, hydrological and geological systems are in the Himalayas.

Unlike conventional hydroelectric projects built on relatively stable terrain, the super-dam is being carved into mountains already fractured by persistent tectonic movement. The Himalayas continue to undergo active crustal deformation.

Geography magnifies the risk for millions living downstream in India. Any catastrophic failure of the super-dam would occur along the international boundary, directly affecting densely populated river valleys in northeastern India. While Bangladesh may not escape death and destruction, India would likely bear the overwhelming human cost.

The super-dam debate changed fundamentally in June 2026, when a team of Chinese geologists published a landmark study in Sedimentary Geology and Tethyan Geology, a journal overseen by the state-run China Geological Survey. The research was conducted by scientists affiliated with three state-backed Chinese institutions: the Middle Yarlung Tsangpo River Natural Resources Observation and Research Station; the Chengdu University of Technology; and the Civil-Military Integration Centre of the China Geological Survey.

The study’s conclusions are surprisingly direct. The researchers confirmed that the active Paizhen geological fault runs directly beneath the reservoir and key infrastructure zone of the Medog super-dam complex. They warned that repeated tectonic activity has fractured the surrounding bedrock, weakening the foundation upon which the dam, diversion tunnels and transport infrastructure will depend.

More strikingly, they concluded that the rock and soil surrounding the reservoir zone possess a “loose structure and weak cohesion,” making them highly susceptible to landslides and instability once the dam’s enormous reservoir is filled. Even moderate seismic activity or fault movement, they cautioned, could “very easily trigger” widespread slope failures, mass landslides and rock collapses into the river channel.

To illustrate the immediate threat, the study highlighted the magnitude-6.9 earthquake that struck the India-bordering Nyingchi prefecture, where the super-dam is being built. The earthquake occurred along the northern edge of the same Paizhen Fault network, demonstrating that the very fault system underlying the dam remains capable of generating powerful earthquakes.

The study’s warning extended to operational hazards affecting supporting infrastructure. The authors emphasized that seismic deformation along the fault threatens the structural integrity of the super-dam complex’s multi-kilometre subterranean diversion tunnels cut through the towering 7,782-metre-high Namcha Barwa mountain, as well as the bridges and logistics corridors located downstream from the dam.

If Beijing’s own scientific establishment acknowledges these grave geological hazards, why is India not making them central to the international conversation?

There is another reason these findings deserve global attention: China has an inglorious history of dismissing internal scientific warnings about dams.

Before the catastrophic 2008 Wenchuan earthquake on the eastern rim of the Tibetan Plateau, chief engineer Fan Xiao of the Sichuan Geology and Mineral Bureau repeatedly warned that the nearby Zipingpu Dam could induce seismic stresses by impounding massive quantities of water above an active geological fault. After nearly 90,000 people died in the earthquake, numerous international and domestic geologists later linked the rapid filling of Zipingpu Dam’s reservoir to the catastrophic magnitude-7.9 earthquake.

Impounding millions of cubic meters of water in high-pressure mountain valleys increases pore-fluid pressure along local faults, which can trigger earthquakes—a phenomenon known scientifically as “reservoir-induced seismicity,” or RIS.

This is not the only grim precedent to haunt China. Another prominent example was the catastrophic 1975 Banqiao Dam collapse, which occurred despite scientific warnings. Prominent Chinese hydrologist Chen Xing had repeatedly warned that excessive construction of dam reservoirs along rivers in Henan province, while ignoring geological limits and flood-discharge capacities, would lead to structural collapse. His warning was dismissed.

Yet despite the obvious lesson that ignoring credible geological warnings can carry catastrophic consequences, Chinese President Xi Jinping’s regime is persisting with the super-dam’s construction.

India’s restrained approach may be understandable. Beijing rejects binding water-sharing treaties, embraces an absolute territorial sovereignty doctrine over upstream rivers, and routinely resists transparency on projects that can significantly affect transboundary river flows. Without legal mechanisms to halt construction, New Delhi has concentrated on satellite monitoring, downstream infrastructure and disaster preparedness while raising concerns confidentially through bilateral channels.

But in stark contrast to China’s unilateralist approach to projects in border regions, including on shared rivers, India still hews to quiet diplomacy, although this approach has yielded little. China’s construction footprint has expanded continuously along the Himalayan frontier despite years of Indian objections.

Just imagine the reverse scenario. Had India begun constructing a 60,000-megawatt dam immediately upstream of Chinese territory near a contested frontier, Beijing would almost certainly have mobilized international opinion, emphasized environmental risks, highlighted scientific concerns, and portrayed the project as reckless and a direct strategic threat. China excels at shaping global narratives when its interests are involved.

India has essentially chosen silence where China would choose amplification.

The greatest irony is that India already possesses the evidence needed to reshape the international debate on the super-dam. It does not have to speculate about hidden faults or invent worst-case scenarios. Chinese scientists have documented the active Paizhen Fault, fractured bedrock, weakened foundation capacity, unstable reservoir slopes and seismic history in painstaking technical detail. Those findings deserve global scrutiny precisely because they originate within China’s own state-linked scientific system.

Quiet diplomacy has not slowed construction, increased transparency or secured binding safeguards. Continuing the same approach while the world’s largest and riskiest dam rises beside the Line of Actual Control (LAC) is less a strategy than an admission of helplessness.

When the potential danger from the super-dam is measured not only in megawatts but also in millions of downstream lives, New Delhi ought to demand evidence-based accountability by placing the Chinese scientific system’s own geological warnings at the centre of the global conversation.

China’s Dam Frenzy Spawns Dam Collapses

For more than seven decades, China has pursued the most ambitious dam-building program in human history. Since Mao Zedong declared that China must “tame the rivers,” dams have become symbols of national power, technological modernity and the Communist Party’s ideological triumph.

The country has transformed its landscape by damming every significant river, diverting waters across distant river basins, and exporting its dam-building model to Asian, African and Latin American countries.

Yet beneath this show of engineering prowess lies a sordid record Beijing has long sought to cloak: China has experienced more dam failures than any other nation. Thousands of dam reservoirs have collapsed because of substandard construction, political interference and geological miscalculation.

The world’s deadliest dam disaster occurred not in a colonial state but in modern China during the Mao era. Even today, aging infrastructure and extreme weather events continue to expose vulnerabilities within the country’s vast dam network, raising the risks of catastrophic dam collapses.

When the People’s Republic of China was founded in 1949, the country possessed just 22 dams of significant size. Today, it has more than 85,000 dams, including over half of the world’s approximately 50,000 large dams. In effect, China has completed, on average, at least one large dam every day since its so-called Communist revolution.

This extraordinary expansion of dams has been rooted in the Communist Party’s longstanding conviction that rivers should be reengineered to serve political and economic objectives. During Mao’s infamous “Great Leap Forward,” local authorities were encouraged to construct reservoirs at breakneck speed, often prioritizing production targets over engineering standards. Scientific caution frequently yielded to ideological goals, while experienced hydrologists who questioned ambitious projects faced political scorn or even persecution.

The consequences of such a dam-building frenzy have extended to the social domain. By 2007, Chinese authorities acknowledged that 22.9 million people had been uprooted by dam and other water projects since 1949, in one of the largest occurrences of development-induced resettlement in world history.

It is against this backdrop that China’s extraordinary dam-building record is matched by an equally staggering dam failure record. Official statistics released by the Chinese government acknowledge that at least 3,500 dams failed just between 1951 and 2008. Earlier government figures showed 2,796 collapses by 1980 and roughly 3,200 by 1981—equivalent to nearly 4% of all dams then in existence.

The true number may never be known. Information surrounding dam failures has long been treated as a state secret, and China has generally been reluctant to share failure data internationally. At a 1991 international conference on dam safety in Vienna, participating countries reported their historical dam collapses. China alone stated that it had none to report, despite its own published domestic statistics documenting thousands of failures.

This opacity has obscured an uncomfortable reality: many failures were not acts of nature alone, but products of systemic human error impelled by an authoritarian political system.

The defining catastrophe occurred in August 1975 in Henan province. Following unprecedented rainfall from Super Typhoon Nina, the Banqiao Dam overtopped and breached. Its collapse unleashed a chain reaction that destroyed the nearby Shimantan Dam and approximately 60 additional reservoirs in a cascading hydraulic failure.

The immediate deluge killed an estimated 26,000 people. Subsequent famine, disease and social collapse raised the total death toll to between 170,000 and 230,000, making Banqiao the deadliest structural dam failure ever recorded.

The catastrophe could have been averted had authorities heeded the warnings of Chinese hydrologists, especially as Chen Xing had repeatedly warned that over-building reservoirs would likely trigger structural collapse. Rather than revising the project, authorities denounced Chen’s criticisms as politically incorrect.

Details of the disaster, in fact, remained classified for three decades before being partially declassified in 2005.

More than an engineering failure, Banqiao was a failure of governance, where ideology overruled scientific expertise.

Although Banqiao remains unparalleled, later disasters have shown that the underlying problems did not end with Mao.

In 1993, the Gouhou Dam in Qinghai province collapsed, killing more than 300 people. Investigators attributed the failure to serious design defects, inadequate quality control and poor compaction during construction. Qinghai, the birthplace of the present Dalai Lama, has historically been part of the traditional Tibetan region of Amdo, a major cultural and spiritual homeland for Tibetans.

In 2000, a massive landslide created a natural dam on the Yiong Tsangpo, which is a tributary of the Yarlung Tsangpo. It joins the main river just upstream of where the Yarlung Tsangpo makes its great bend around the Namcha Barwa mountain and enters Arunachal Pradesh as the Siang/Dihang, which then becomes the Brahmaputra.

Despite clear warning signs, the temporary dam on the Yiong Tsangpo eventually burst, sending destructive floodwaters through Tibet and into Arunachal Pradesh, destroying bridges and vital infrastructure downstream. The event illustrated how Himalayan geology can transform localized instability into an international disaster.

More recently, the connected Yongan and Xinfeng dams in Inner Mongolia failed in rapid succession in 2020 after heavy rainfall. Although evacuations prevented mass casualties, the dual failure inundated farmland, destroyed roads and renewed concerns about thousands of aging reservoirs constructed in pursuit of political quotas without modern safety standards.

These failures together underline continuity rather than exception. The recurring causes of failure reflect an infrastructure network built rapidly, expanded relentlessly and maintained unevenly. Thousands of older dams now lack modern monitoring systems, early-warning sensors and upgraded flood-control capacity.

China’s most famous dam, the Three Gorges Dam, has never suffered a major structural failure. Yet it has carried profound environmental impacts and significant geological risks.

The project officially displaced 1.4 million people, submerged cities and villages, altered aquatic ecosystems, intensified pollution within its mammoth reservoir and trapped enormous volumes of sediment. Geologists have also documented thousands of micro-earthquakes and widespread landslides associated with the immense weight and fluctuating levels of its reservoir, which holds 39.3 billion cubic meters of water.

Today, the principal concern over this giant dam is less an abrupt collapse than cascading risk. The Three Gorges Dam, on the Yangtze River, sits within a broader network of upstream reservoirs, meaning extreme rainfall could compound hydraulic pressures across multiple dams simultaneously, unleashing a sudden surge of water. Such a scenario, eerily reminiscent of Banqiao’s domino effect, could threaten downstream industrial hubs and mega-cities along the Yangtze.

This background is especially relevant as China erects its unprecedented super-dam on the upper reaches of the Brahmaputra, within one of the world’s most seismically active mountain belts. China’s own hydraulic history offers a cautionary lesson: the greatest danger is often not the river but the belief that it can be bent to the Chinese will.

Beijing is again smothering inconvenient scientific warnings. In earlier decades, engineers, hydrologists and geologists who questioned excessive dam construction or inadequate flood-discharge capacity were frequently mocked and marginalized, allowing flawed projects to proceed without meaningful scrutiny. Now Beijing is persisting with the construction of what it calls “the project of the century” even as its own scientists warn of serious geological risks at the site.

‘Dam-For-A-Dam’ Strategy?

The fact that no country has built more dams than Beijing and that no country has witnessed more dam failures than China should shape how the world evaluates the Himalayan super-dam and how India responds. As the record shows, Chinese engineers are capable of building monumental structures. The deeper question is whether any government can safely impose permanent hydraulic control over a dynamic, earthquake-prone river system whose behaviour continually exceeds human prediction.

The greatest threat posed by the Medog mega-project is the possibility that the world’s largest hydroelectric dam could become the world’s greatest transboundary flood hazard. India’s response should prioritize resilience, surveillance and diplomacy.

For India, the project is a strategic and humanitarian challenge whose consequences threaten millions living downstream. Much attention has focused on whether the super-dam will allow China to manipulate cross-border river flows. That concern is legitimate. The Brahmaputra is the lifeline of northeastern India, irrigating farmland, sustaining fisheries, replenishing wetlands and supporting livelihoods before flowing into Bangladesh, where it becomes the country’s single largest source of freshwater.

Yet the more immediate danger may be one that receives far less discussion: the catastrophic risk of structural failure in one of the world’s most earthquake-prone landscapes. An unparalleled dam built inside the Eastern Himalayan Syntaxis creates not only Chinese geopolitical leverage but also systemic disaster risk for downstream communities.

India thus faces a defining policy choice. Should it respond by constructing its own giant counter-dam immediately downstream as a “water buffer” strategy? If China abruptly impounds water, creating a drought in the lean season, or suddenly releases massive volumes of water, unleashing an artificial flood, could India’s downstream counter-dam regulate river levels, absorb a surge and mitigate the “water bomb” risk? Or should India pursue a fundamentally different strategy centred on technology and flood resilience?

New Delhi’s proposed Upper Siang Multipurpose Project (USMP) is an 11,000-megawatt hydroelectric and flood-control dam in Arunachal Pradesh estimated to cost roughly $13 billion. Officially, the project serves two purposes: generating clean electricity and creating sufficient storage capacity to absorb sudden surges originating from China’s super-dam. On paper, the logic appears compelling. If China controls the river upstream, India should possess a hydraulic buffer downstream.

The problem is that rivers do not obey human logic. They follow gravity and geology. Human logic seeks control; nature embraces chaos.

A downstream mega-dam cannot reliably neutralize the catastrophic failure of a much larger upstream structure located only a relatively short distance away. Instead, it risks creating a cascading disaster in which one dam’s collapse triggers another.

The geography makes this risk particularly disquieting. China’s Medog project sits just upstream of the Line of Actual Control (LAC), while the proposed Upper Siang dam would be constructed shortly after the river enters India. Between them lies the steep, narrow Yarlung Tsangpo Grand Canyon, the world’s deepest and longest canyon. Rather than dissipating the energy of moving or falling water, this terrain accelerates it, channelling enormous volumes of water through confined valleys at extraordinary velocity.

Should China’s super-dam ever experience a catastrophic breach—whether from a powerful earthquake, a massive landslide from the Namcha Barwa massif or some other extreme geological event—the resulting flood wave would not resemble an ordinary river flood. It would be a high-energy torrent carrying sediment, boulders, liquefied mud and shattered concrete capable of destroying infrastructure across its path.

The downstream Indian reservoir would then become part of the hazard rather than the solution.

The central weakness of the counter-dam concept lies in an operational contradiction. A flood-control reservoir is effective only when it is substantially empty. A hydroelectric reservoir is economically productive, especially as a power generator, only when it remains relatively full.

The Upper Siang project cannot maximize both objectives simultaneously. If operators maintain high water levels to generate 11,000 megawatts of electricity, the available flood cushion shrinks dramatically. If they keep a large empty buffer for emergency protection, electricity generation and project economics suffer correspondingly.

A second constraint is time. Because of the close proximity between China’s super-dam and India’s planned Upper Siang dam, downstream authorities might receive little more than several tens of minutes of warning following an upstream structural failure. Even with perfect communications, safely releasing billions of cubic meters of water from the Upper Siang structure through spillways within such a narrow window would be virtually impossible.

The third, and perhaps most important, problem is seismic. The Eastern Himalayan Syntaxis is among the world’s most active tectonic regions, with the devastating 1950 Assam–Tibet earthquake demonstrating the enormous geological forces capable of reshaping entire river systems.

Any future earthquake of similar magnitude or impact could damage both the Chinese and Indian dams during the same seismic event, transforming two strategic assets into a cascading infrastructure catastrophe.

It is a classic case of correlated risk: when two or more critical systems occupy the same hazard zone, their failures become mutually reinforcing rather than independent.

Given that downstream engineering cannot effectively mitigate the risks posed by the Medog super-dam, India must leverage its rapidly expanding space and remote-sensing capabilities to eliminate strategic blindness over the Tibetan Plateau.

Just as China does not have a water-sharing treaty with any downstream country, it also lacks comprehensive, year-round, real-time, automated hydrological data-sharing and emergency-notification mechanisms with any neighbour.

During crises, India, therefore, cannot assume that Beijing will provide timely information about reservoir conditions or geological emergencies. The obvious solution is autonomous observation. Rather than depending upon Chinese disclosures, India can build an independent picture of upstream risk.

India’s NISAR and RISAT series satellites, together with Cartosat imaging satellites, offer precisely the technological foundation required for continuous monitoring of the Medog project, including detecting subtle structural movement, reservoir expansion, unstable mountain slopes and landslide precursors.

Jointly launched by ISRO and NASA, the NISAR satellite, with its dual-frequency radar technology, measures millimetre-scale ground deformation and monitors natural hazards like Himalayan landslides and glacier dynamics. The Cartosat satellites provide high-resolution sub-meter stereo imagery for building 3D models of steep Himalayan slopes, while the RISAT series gives round-the-clock synthetic aperture radar (SAR) coverage during heavy monsoon downpours when optical cameras are blinded by clouds.

Equally important is what happens on the ground. A dense network of automated acoustic and radar water-level sensors positioned near the LAC along the Siang River would transmit instantaneous water-level anomalies into India’s disaster management architecture. Sudden upstream impoundment, abnormal discharge or unusual flow acceleration would automatically trigger downstream alerts without requiring human interpretation.

In an age of satellite intelligence, early warning is becoming as strategically valuable as physical infrastructure.

Furthermore, India should invest in distributed flood-management systems along the Siang and Brahmaputra floodplains. Controlled flood-bypass channels, diversion tunnels and dry floodways could redirect extreme surge waters away from densely populated settlements into designated unpopulated, low-lying areas.

Restoring Assam’s historical wetlands, beels and oxbow lakes would recreate natural sponge basins that absorb flood peaks while simultaneously enhancing biodiversity and groundwater recharge. Embankment setbacks (moving traditional levees further back from the riverbank) would provide the Brahmaputra greater room to expand during exceptional floods instead of forcing enormous hydraulic energy into narrow corridors.

Transparency itself can become a strategic instrument of pressure on Beijing. India should routinely publish open-source satellite analyses, seismic assessments and independently verified geological reports concerning conditions around Medog. The message to Beijing should be that establishing infrastructure capable of endangering millions of people across the international boundary carries corresponding responsibilities of disclosure and accountability.

A first step toward compelling Beijing to lift its opacity should be a formal diplomatic request demanding full technical disclosure of the Medog project, including design specifications, geological assessments, reservoir safety studies, seismic modelling and emergency response protocols. India should simultaneously request permission for an independent international scientific inspection involving experts from multiple countries.

Beijing will probably refuse. But refusal itself carries diplomatic value. A government genuinely confident in the safety of its engineering should welcome independent scrutiny, particularly when millions of downstream lives are potentially affected. Opacity reinforces suspicion.

India should also elevate the issue in international scientific and environmental forums rather than treating it solely as a bilateral matter. The central question is universal: Should the world’s largest dam be constructed directly across an active geological fault in one of Earth’s most seismically unstable mountain systems without independent international oversight?

At the same time, India must prepare for China’s unparalleled super-dam ultimately becoming an enduring reality. The more durable Indian response should centre on layered resilience: autonomous satellite surveillance, AI-assisted flood forecasting, automated river sensors, restored wetlands, engineered floodways, evacuation infrastructure and sustained diplomatic pressure for transboundary transparency. Together, these measures could contribute to reducing both uncertainty and human vulnerability.

But India must also reshape the international narrative by placing China’s own scientific warnings, dam-failure record and refusal to allow independent scrutiny at the centre of the global debate. The super-dam may well stand as a monument to China’s ambition; it should not become a tombstone for downstream millions.

The latest evidence suggests that the Chinese scientific establishment understands the dangers of the under-construction Himalayan dam—the world’s largest—more clearly than its political leadership is willing to acknowledge. With the livelihoods of two billion people at stake, the international community needs to weigh in.

By Brahma Chellaney, Project Syndicate

The world’s largest dam is rising in one of the world’s most geopolitically treacherous and seismically unstable regions. Just a few kilometers from the heavily militarized border with India, China is constructing an unprecedented hydropower project in Tibet on the Yarlung Tsangpo, the world’s highest-altitude major river, better known internationally as the Brahmaputra.

The super-dam will dwarf China’s Three Gorges Dam, currently the world’s largest, in power-generating capacity. Its reservoir will impound a gargantuan volume of water above millions of people downstream in India’s northeast and deltaic Bangladesh, much of which lies barely above sea level.

Now the most troubling warning is coming not from foreign critics but from China’s own scientists. A recent paper published in the state-linked, Mandarin-language journal Sedimentary Geology and Tethyan Geology identifies serious geological hazards at the construction site. The geologists conclude that the terrain has a “loose structure and weak cohesion” and warn that fault movement or an earthquake could easily trigger large-scale instability, threatening both the reservoir and surrounding infrastructure. The authors recommend reinforcing the reservoir slopes, installing retaining structures, and redesigning key elements to reduce the risk of catastrophe.

When scientists working under a communist regime issue such warnings, the international community must pay attention.

The new dam is rising at the Great Bend of the Brahmaputra, where the river plunges steeply through the world’s deepest and longest canyon before entering India. It also sits squarely within the Himalayan seismic belt, created by the slow-motion collision of the Indian and Eurasian tectonic plates. This is among Earth’s most earthquake-prone regions, with a record of producing devastating temblors.

The danger is not simply that an earthquake might damage a dam. A gigantic reservoir could itself trigger a quake by intensifying geological stresses. Reservoir-triggered seismicity, or RTS, has been documented for decades.

One likely example occurred in China. In one of the deadliest natural disasters in modern Chinese history, an earthquake on the Tibetan Plateau’s eastern rim in 2008 killed nearly 90,000 people, mainly in Sichuan province. While scientists continue debating the precise relationship, influential research concluded that the immense weight of water stored in the reservoir of the new Zipingpu Dam may have increased pressure along an underlying fault, potentially advancing the earthquake by decades or even centuries.

Instead of facing up to that scientific possibility, China has embarked on a vastly larger dam project in an even more fragile geological setting. But the Himalayan fault system does not respect national borders; nor would the consequences of a major dam failure. The powerful 2025 Myanmar earthquake demonstrated how interconnected this seismic zone is, with tremors traveling far enough to trigger the collapse of a high-rise building in Bangkok, some 1,000 kilometers away.

The Brahmaputra is the lifeline of northeastern India, irrigating farms, sustaining fisheries, replenishing wetlands, and supporting millions of livelihoods before flowing into Bangladesh, where it is the single largest source of freshwater. Like China’s giant dams on the Mekong, the super-dam threatens to alter cross-border river flows and reduce the downstream transport of nutrient-rich sediment essential to the river’s ecology and riparian countries’ agriculture.

Worse, a catastrophic structural failure—or even an emergency release of impounded water following seismic damage—could unleash devastating floods across densely populated downstream plains with little warning. What begins as an engineering failure in Tibet could become a humanitarian catastrophe extending all the way to Bangladesh, the world’s most densely populated country outside microstates and mini-states.

The geological danger is only part of the story. China is increasingly transforming its control of the Tibetan Plateau—the source of most of Asia’s major rivers—into strategic leverage. It has built cascades of dams on transboundary rivers, withheld hydrological data during periods of tension, and resisted entering any water-sharing treaty with downstream states. Water has become another instrument of coercive statecraft.

The sheer scale of what China calls “the project of the century” will inevitably give it unprecedented control over river flows. Even routine reservoir operations can affect downstream ecosystems, agriculture, sediment transport, and flood patterns.

Yet the project remains shrouded in secrecy, with the Chinese government releasing remarkably little technical information despite the enormous transboundary implications. There has been no meaningful environmental transparency, no independent geological review, and no credible consultation with the countries facing the greatest downstream risks.

International law has long recognized that states sharing transboundary rivers bear responsibilities toward one another, including preventing significant cross-border harm, exchanging relevant information, and consulting on projects that could materially affect downstream neighbors. Adherence to these principles is essential to safeguard shared resources. China’s continuing opacity undermines them.

The Himalayan watershed is often called Asia’s water tower because its rivers sustain nearly two billion people across multiple countries. When the largest dam ever attempted is introduced into this fragile ecosystem, secrecy becomes a regional security risk.

Given the extraordinary stakes, China should immediately invite an independent panel of international seismologists, geologists, and dam-safety experts to inspect the site, review the project’s geological assumptions, and assess whether the recommended design modifications are sufficient. China should also institutionalize year-round, real-time hydrological data-sharing and emergency notification mechanisms with India and Bangladesh, and commit to ongoing transboundary consultation on major design changes.

Ironically, the latest evidence suggests that the Chinese scientific establishment understands the dangers more clearly than its political leadership appears willing to acknowledge. Now that China’s own geologists have raised the alarm, policymakers must embrace transparency and accept transboundary responsibilities before a potential water bomb is fully assembled upstream.

Brahma Chellaney, Professor of Strategic Studies at the New Delhi-based Center for Policy Research and Fellow at the Robert Bosch Academy in Berlin, is the author of nine books, including Water: Asia’s New Battleground (Georgetown University Press, 2011), for which he won the 2012 Asia Society Bernard Schwartz Book Award.

© Project Syndicate, 2026.