Beijing has approved construction of the world’s largest hydropower dam on the Yarlung Tsangpo river in Tibet just north of Arunachal Pradesh. The project, with a planned capacity of 60,000 MW, will surpass the Three Gorges Dam in scale and is coming up in an ecologically fragile earthquake-prone stretch of the eastern Himalayas known as the Great Bend.
The river from China is called Siang upon entering Arunachal, and becomes the Brahmaputra in Assam. It is a lifeline for tens of millions downstream. India has voiced concern that the dam located at a sharp U-bend before the river crosses into Indian territory could be used by China to manipulate flow, trigger flash floods or restrict water, making it, in effect, a “ticking water bomb”.
A project three times the scale of Three Gorges
The Great Bend Dam as it's informally referred to is part of China’s broader push for clean energy under its 14th Five-Year Plan. The USD 137 billion project is expected to take years to complete and will be powered entirely by the transboundary Yarlung Tsangpo.
Located in Medog County, the dam is designed to tap the sharp gradient and high volume of the river where it curves around Namcha Barwa peak. But this section of the Himalayas lies directly on a tectonic fault line prone to major earthquakes and frequent landslides. The project involves deep tunnelling estimated at over 400 km through unstable mountain terrain which could alter the region’s hydrology and trigger unforeseen ecological changes.
Why India sees a ‘water bomb’ ticking
The central worry in Delhi is not just environmental fallout but strategic leverage. China is not a party to any international water-sharing agreement, which means it is not legally obligated to notify or consult downstream nations like India before altering river flows.
India's Ministry of External Affairs reiterated its concern in December 2024, following a Chinese state media report confirming approval of the project.
"As a lower riparian state with established user rights, we have consistently expressed our concerns regarding such projects," MEA spokesperson Randhir Jaiswal said, calling for transparency, prior consultation, and safeguarding downstream interests.
India has no access to real-time data on Yarlung Tsangpo’s flow and no assurance that the river’s seasonal variations won’t be disrupted either unintentionally through mismanagement or deliberately in times of conflict.
Arunachal CM Pema Khandu’s warning
Arunachal Pradesh Chief Minister Pema Khandu has been vocal in sounding the alarm. In an interview with PTI, he called the dam a “ticking water bomb”, warning that entire riverine communities could be wiped out if China decides to weaponise water.
“This is going to cause an existential threat to our tribes and our livelihoods,” Khandu said. “If they suddenly release water, the Siang belt in Arunachal will be devastated.”
Khandu flagged the lack of legal guardrails. “Had China been part of a water treaty, this project could have helped prevent annual floods. But now it becomes a strategic vulnerability.”
He also expressed concern that the dam could reduce the Brahmaputra’s natural flow during non-monsoon months, impacting irrigation, agriculture, drinking water supply and ecology across the North-east.
India’s strategic response: Siang Upper Multipurpose Project
In response to the perceived threat, the Arunachal Pradesh government has proposed a 10,000 MW dam on the Siang river upstream of Pasighat to act as both a hydropower project and flood buffer.
“The Siang Upper Multipurpose Project will help regulate water flow and protect against Chinese water surges,” said Khandu, adding that consultations have been held with the Centre and preliminary planning is underway.
The proposed Indian dam is aimed at mitigating flood risk, storing water during surplus periods and preserving downstream river health even if flow from upstream is reduced. Crucially, the project includes community engagement with tribal groups such as the Adi people whose lives and land lie directly in the river’s path.
Khandu said outreach efforts are already ongoing. “I’m arranging meetings with local communities to build awareness and ensure they are part of the response plan.”
Seismic and ecological faultlines
China’s chosen site for the dam lies in a Grade-V seismic zone where the Eurasian and Indian tectonic plates collide. The area sees regular earthquakes, landslides and glacial lake outbursts, all of which could destabilise such a massive structure. Beijing has insisted the dam will follow “high safety standards”. But India remains unconvinced particularly given the precedent of the Three Gorges Dam, where post-construction data revealed increased landslide activity and reservoir-induced seismicity.
With no joint environmental impact assessment, India has no clarity on how the project may affect downstream sediment flow, fish migration, or monsoon-dependent farming in Assam and Bangladesh.
For India, the risk is not just water scarcity or flooding but the precedent it sets. If one country can unilaterally alter a transboundary river of this scale, the entire water security architecture in Asia could be upended.
