Opinion>Opinions - International

The views expressed by contributors are their own and not the view of The Hill

The mother of all mega-dams is China’s hidden weapon in the Himalayas

by Brahma Chellaney, opinion contributor - 01/22/26 8:00 AM ET

AP Photo/Anupam Nath

A fisherman sits next to his boat along the river Brahmaputra in Guwahati, India.

New disclosures reveal that China’s planned super-dam on the Yarlung Tsangpo — the world’s highest-altitude major river, better known as the Brahmaputra — is not a single structure. Rather, it is a a vast, tunnel-linked hydropower and water-diversion complex, spanning roughly 150 kilometers through the Himalayas.

The project would transform an internationally shared river, originating in water-rich Tibet, into a strategic instrument of state power.

For years, China’s super-dam was discussed as a single, if colossal, piece of infrastructure. That description is now obsolete. What Beijing is constructing on the so-called “Everest of Rivers,” near Tibet’s border with India, is not just the largest dam ever attempted. It is an extensive subterranean network designed to give China effective command over the river before it reaches any downstream country.

A cascade of barrages, reservoirs and power stations — linked by giant tunnels bored through the world’s highest mountain range — will together form a titanic, integrated hydropower system.

It remains unclear whether some of the impounded water will be diverted into what Beijing calls the Great South-North Water Diversion Project. While the eastern and central routes — already operational — transfer water from China’s southern rivers to its arid north, including Beijing, the controversial western line aims to reroute waters from Tibet-originating international rivers that sustain hundreds of millions of people across South and Southeast Asia.

The new project is centered near the Great Bend of the Brahmaputra, where the river makes a dramatic U-turn around a Himalayan peak before plunging toward India. Over a stretch of just 30 miles, the river drops some 6,500 feet — one of the steepest descents of any major river on Earth.

China plans to exploit this extraordinary gradient not with a single concrete wall, but by diverting the river through multiple tunnels, some extending more than 12 miles, to feed a cascade of five power stations. Their combined generating capacity is estimated at over 60 gigawatts — almost three times that of the Three Gorges Dam, currently the world’s largest.

This design fundamentally alters the risk calculus for downstream states. Beijing has described the project as “run-of-the-river,” a term meant to reassure neighboring countries that water storage — and therefore Chinese control — will be limited. But the scale of tunneling and the interlinked reservoirs undermines that claim. Even without massive surface reservoirs, the ability to divert, withhold or abruptly release enormous volumes of water through subterranean channels gives China de facto control over the river’s flow just before it leaves Tibet, which Beijing annexed in 1951.

By occupying Tibet, China effectively redrew the water map of much of Asia. The Tibetan Plateau is the source of ten major river systems that together sustain nearly one-fifth of the world’s population. China’s intensive dam-building and resource extraction across the plateau since the 1990s thus poses a growing risk to Asian water security, ecological stability and regional peace. Control over the headwaters of key transboundary rivers confers immense leverage, turning water into a potential geopolitical tool and raising the specter of environmental disaster and conflict.

Nothing illustrates these dangers more starkly than the current gargantuan project, which officially began in 2025, although evidence suggests preparatory work started much earlier. What is taking shape is, in strategic terms, a hydrological weapon system. It is capable of degrading fragile ecosystems while giving China unprecedented coercive leverage over South Asia — especially India.

There is also a profound seismic gamble. The project lies in one of the world’s most active earthquake zones, where the Indian and Eurasian tectonic plates collide.

Geologists warn of reservoir-triggered seismicity, in which the immense weight of stored water increases stress along fault lines, even if the statistical probability of a major quake remains uncertain. A partial failure, caused by an earthquake or a massive landslide into a reservoir, could unleash a cascading flood racing toward India’s densely populated Assam Valley, with catastrophic consequences for downstream communities, cities and infrastructure.

What makes this project uniquely destabilizing is not only its scale but its opacity. China has released no meaningful technical details, including information on design parameters or water-storage capacity. The project has proceeded without environmental impact assessments open to international scrutiny and without consultation with downstream states that stand to bear the greatest risks.

This is a textbook case of hydrological hegemony: unilateral control over a shared lifeline exercised by an upstream power.

The international response has been strikingly muted. Governments that rightly scrutinize Chinese ports, telecommunications networks and supply chains have largely treated this mega-project as a regional matter rather than a global concern. That is a mistake. Water insecurity is a well-documented accelerator of conflict, forced migration and state fragility. A project capable of degrading ecosystems and affecting tens of millions of people downstream implicates not only Asian stability but the international order itself.

China’s Brahmaputra mega-system should therefore be understood for what it is: an unprecedented experiment in high-altitude engineering, ecological transformation and geopolitical leverage rolled into one. It is a strategic instrument whose consequences will flow far beyond the Himalayas.

Brahma Chellaney is the author of nine books, including the award-winning “Water: Asia’s New Battleground.”