The Paizhen Fault, active since the Pleistocene epoch, has fractured surrounding rock formations and weakened the foundations of an area that includes the project’s reservoir and associated infrastructure. The findings have intensified concerns about earthquakes, landslides and structural instability close to the border with Arunachal Pradesh.
Construction of the project began in July 2025 near the Great Bend of the Yarlung Tsangpo in Nyingchi, after Beijing approved the scheme in December 2024. The river enters Arunachal Pradesh as the Siang, becomes the Brahmaputra in Assam and later flows into Bangladesh as the Jamuna.
Researchers from the Chengdu University of Technology, the Civil-Military Integration Centre of the China Geological Survey and a Yarlung Tsangpo research station studied tectonic activity around Paizhen, also known as Pai township. Their work was published in a journal overseen by the China Geological Survey.
They found that sustained movements along the fault had produced rock masses with loose structures and weak cohesion. Prolonged immersion after reservoir filling, combined with earthquakes and continuing fault activity, could easily destabilise slopes on both sides of the reservoir.
The study urged engineers to introduce extensive slope reinforcement and retaining structures to reduce the risk of collapses. It also warned that dams, tunnels, bridges and roads in the construction zone could be affected by the weakened geology.
The fault’s northern section was associated with a magnitude 6.9 earthquake near Mainling in 2017. The wider region lies within one of the world’s most seismically active belts, shaped by the continuing collision of the Indian and Eurasian tectonic plates.
The project is expected to cost about 1.2 trillion yuan, or $167 billion, and comprise five cascade hydropower stations. It is designed to exploit a fall of roughly 2,000 metres along a short section of the river as it turns sharply through the Yarlung Tsangpo Grand Canyon.
China expects the complex to generate about 300 billion kilowatt-hours of electricity annually, almost three times the output attributed to the Three Gorges Dam. Much of the power will be transmitted to eastern regions, although Beijing says the project will also support Tibet’s electricity requirements and its national carbon-neutrality goals.
The geological disclosure presents a significant challenge to assurances that the development will be safe and will not harm downstream countries. Reservoir-induced slope failures could block the river temporarily, creating natural dams that may later burst and release destructive volumes of water.
An earthquake-triggered landslide or infrastructure failure would carry particular risks because the project lies upstream from densely inhabited valleys in Arunachal Pradesh and Assam. The Brahmaputra system supports farming, fisheries, drinking-water supplies, navigation and power generation across the Northeast, while its seasonal floods replenish agricultural land.
Concerns also centre on China’s ability to regulate water flows during dam filling, electricity generation and emergencies. Beijing says the scheme is intended mainly for hydropower and will not consume large quantities of water. It has promised to maintain communication with downstream countries and argued that controlled reservoir operations could improve flood management.
Hydrological modelling by China-based scientists has suggested that carefully managed releases could reduce flood peaks and support dry-season irrigation and navigation. Such projections, however, depend on transparent operating rules, reliable data exchanges and coordination across borders.
New Delhi has formally raised the project with Beijing and said it will monitor developments and take measures to protect downstream interests. Officials have stressed that China, as an upstream country, must ensure that activities on the Yarlung Tsangpo do not damage communities farther south.
