For decades, the Three Gorges Dam has stood as a monument to China’s engineering scale and ambition. Its mass is so immense that scientists have calculated it slightly altered Earth’s rotation, lengthening each day by a fraction of a microsecond. It remains the most powerful hydropower station ever built, producing enough electricity to supply more than 70 million homes every year.
Yet far from the Yangtze, on the edge of the Himalayas, an even larger vision is taking shape on a river largely unknown beyond the region. This undertaking is being described as the project of the century—the most ambitious hydropower system ever imagined, comparable in scale and complexity to an interplanetary mission. To realise it, engineers must carve tunnels through mountains that are still rising, in one of the most seismically active zones on Earth. What unfolds here carries consequences far beyond China’s borders, with the potential to affect hundreds of millions of lives downstream in India and Bangladesh. The technical challenge is unprecedented, and the stakes are immense.
The Tibetan Plateau, often called the “roof of the world,” is a landscape of stark, austere beauty. From its glaciers, the Yarlung Tsangpo River flows eastward for more than a thousand kilometres along the plateau’s edge. Then, at a place known as the Great Bend—where the plateau collides with the Himalayas—the river performs a dramatic geological reversal. It swings almost 180 degrees, plunging roughly 2,000 meters in elevation over just 50 kilometres. After this descent, the river exits China, enters India as the Brahmaputra, and eventually empties into the Bay of Bengal.
It is at this Great Bend that construction of the Yaxia, or Lower Yarlung Hydropower Project, officially began in July 2025. The region is extraordinarily remote; road access only reached it a little over a decade ago. The gorge here is the largest canyon on Earth, more than three times deeper and slightly longer than the Grand Canyon. This extreme natural drop—the steepest and deepest on the planet—also represents the greatest untapped hydropower potential on the plateau. Observers note that the objective is not merely to harness this power, but to command it at a scale never attempted before.
The projected output is record-shattering. With an installed capacity of around 60 gigawatts, the project is expected to become the world’s largest single source of electricity. Annual generation is estimated at about 300 billion kilowatt-hours—more than the total electricity consumption of the United Kingdom and roughly three times the output of the Three Gorges Dam.
Official details remain limited, forcing analysts outside China to piece together the design using satellite imagery, state media, and academic research. Studies published in leading scientific journals suggest the project will function as a massive diversion system rather than a single towering dam. Instead of one wall holding back the river, the design is believed to involve a sequence of hydropower stations. One large upstream reservoir would regulate flow, followed by a smaller structure at the top of the gorge. From there, water would be diverted through extensive underground tunnels, passing through turbines embedded deep within the mountains, before being stabilized again downstream and released toward India.
Such a configuration would effectively reconstruct a major river underground. The volume of water diverted is expected to rival the flow of a medium-sized European river. While similar diversion concepts have been tested in other Chinese projects, the scale and remoteness of this undertaking push engineering into uncharted territory. Many once considered such a project impossible in a location so isolated and geologically complex.
The financial commitment reflects that ambition. The projected cost stands at 1.2 trillion yuan, or roughly 167 billion US dollars—four to five times the final cost of the Three Gorges Dam. This investment aligns closely with China’s broader economic strategy. Large-scale infrastructure has long been a cornerstone of national development, serving as a tool to stimulate growth during periods of economic slowdown. At a time when domestic consumption and private investment have weakened, the project promises a powerful boost to industries such as construction, cement, and steel. Market reactions following the announcement underscored this impact, with major state-linked engineering and materials firms seeing sharp gains.
Beyond economics, the project plays a central role in China’s energy and climate goals. As the country targets net-zero emissions by 2060, the dam is expected to replace vast amounts of fossil-fuel power, potentially cutting carbon emissions by hundreds of millions of tons annually. It also strengthens energy security by expanding domestic renewable generation to meet the demands of data centers, electric vehicles, and advanced manufacturing.
However, building a structure of this magnitude in one of the most unstable regions on the planet tests the limits of modern engineering. The site sits at the convergence of multiple tectonic plates, making it highly prone to earthquakes. A historic magnitude 8.6 quake struck the region in 1950, one of the strongest ever recorded. Even without a major seismic event, slow-moving risks remain—landslides, material degradation, and long-term environmental changes that can unfold quietly over decades.
Large dam projects also carry significant social and ecological consequences. Past experience shows that they can displace communities, flood ancestral lands, and disrupt fragile ecosystems. The Three Gorges project alone required the relocation of more than a million people and submerged vast habitats. Similar transformations have already occurred along the Mekong River, where a series of upstream dams has altered seasonal flood patterns that sustain fisheries and agriculture across Southeast Asia. Reduced flood peaks and sudden dry-season releases have destabilized ecosystems, damaged livelihoods, and left downstream communities struggling to adapt.
These precedents have heightened concern in India and Bangladesh, where the Brahmaputra supports agriculture, fisheries, and dense populations. A substantial portion of the river’s fertile sediment originates from the Yarlung Tsangpo gorge. Changes in flow or sediment transport could ripple across the region. Both countries have sought greater transparency, requesting data on design, operations, and long-term downstream impacts. Fears persist that control over the river could become a strategic lever amid unresolved border disputes.
China has stated that downstream flows will remain consistent once the project is complete and that no massive retention reservoirs will be used to withhold water. Even so, uncertainty continues to fuel mistrust. In response, India has advanced plans for its own large dam downstream, adding another layer of environmental and political complexity.
The future of the river now hinges on cooperation, transparency, and shared data. Without open information, fear and speculation thrive. With it, decisions could be guided by measurable impacts and inclusive dialogue that considers both national priorities and the livelihoods tied to the river basin.
If successfully completed, the Lower Yarlung Hydropower Project will stand as a defining statement of the 21st century: a demonstration of reshaping rivers at planetary scale, generating unprecedented volumes of clean energy, and powering an economy built around infrastructure, technology, and renewable strength. Whether it becomes a model for sustainable progress or a source of enduring tension will depend on how its power is managed—both electrically and geopolitically.
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