Why China’s New Mega-Dam Is Raising Alarm Among Neighbours

China has begun work on what it claims will be the world’s largest hydropower project—a \$170 billion development that dwarfs the Three Gorges Dam. The announcement, made by Premier Li Qiang over the weekend, sent Chinese construction and engineering stocks soaring. For Beijing, the project offers clean energy, job creation, and an economic boost amid slowing growth. But for downstream neighbours like India and Bangladesh, it revives longstanding fears over water security, as the Yarlung Zangbo River—known downstream as the Brahmaputra—is a critical water source for millions.

The project envisions five dams along a 50-kilometre stretch where the river drops 2,000 metres from the Tibetan Plateau. The first phase is expected to generate power by the early-to-mid 2030s, but beyond the cost and timeline, China has released little detail on construction or environmental safeguards.

This opacity has heightened alarm in India and Bangladesh, which rely on the Brahmaputra for agriculture, drinking water, and hydropower. Officials in Arunachal Pradesh warn the dam could drastically reduce water flow through the Indian state and pose flood risks to Assam. Experts like Columbia University’s Michael Steckler also note the dam may reduce nutrient-rich sediment that sustains farming in downstream floodplains.

Historical tensions add to the unease. India and China fought a war in this region in the 1960s, and analysts like Sayanangshu Modak of the University of Arizona say the lack of transparency fuels fears Beijing could weaponise water in future conflicts. China’s foreign ministry has defended the project as a domestic matter providing clean energy and flood control, adding that it has shared some hydrological data with neighbours.

India has not officially responded, but experts argue the threat may be overstated. Most Brahmaputra water comes from monsoon rains south of the Himalayas, not from the Chinese segment of the river. China’s project is reportedly “run-of-the-river,” meaning it won't store or divert significant water. India itself has proposed large dams on the Siang (its name for the Yarlung Zangbo), partly to strengthen its claim to shared waters.

Disputes over dams are nothing new. Pakistan has accused India of manipulating water flow in Kashmir, and Ethiopia’s Nile dam has sparked threats from Egypt. China’s mega-dam also raises safety concerns, given the region’s vulnerability to earthquakes, landslides, and extreme weather. A recent quake in Tibet has amplified these fears, especially as even smaller nearby projects face major engineering hurdles due to altitude and harsh climate.