Chinese study flags active fault risk beneath China's $147-billion Brahmaputra dam

China’s ambitious plan to construct the world’s largest hydropower project on the Yarlung Tsangpo River in Tibet has come under renewed scrutiny after Chinese geologists warned that the proposed dam site is located on an active fault line that could pose significant risks to the project’s long-term safety and stability.

According to a New18 report, the warning comes from a study published in the Chinese-language journal ‘Sedimentary Geology and Tethyan Geology’ by researchers affiliated with the China Geological Survey.

The findings are notable because they originate from a Chinese government-linked scientific institution, adding fresh weight to concerns that India has repeatedly raised about the project’s location in one of the world’s most seismically active regions.

According to the study, the hydropower project is being built on the Paizhen Fault, an active tectonic fault zone near the Great Bend of the Yarlung Tsangpo River in southeastern Tibet.

Researchers found that the fault has remained geologically active for millions of years and continues to experience tectonic movement.

“The Paizhen Fault, which has been highly active since the Pleistocene, will have a major impact on the structural stability and construction of nearby structures, including dams, roads, bridges and tunnels, as well as the reservoir area,” the researchers were quoted as saying.

The study warned that repeated movement along the fault could destabilise surrounding rock formations and mountain slopes, increasing the risk of landslides, rockfalls and ground deformation in and around the project area.

Researchers said such geological activity could directly affect critical infrastructure planned as part of the hydropower complex, including underground tunnels, powerhouse caverns and other large engineering structures. To mitigate these risks, the study recommended continuous geological monitoring, reinforcement of vulnerable slopes and the incorporation of fault activity assessments into every phase of the project’s design and construction.

China formally launched the massive hydropower project in 2025 in Medog County, close to the dramatic Great Bend of the Yarlung Tsangpo River. At this point, the river makes a sharp U-turn before flowing into India as the Siang River in Arunachal Pradesh and later becoming the Brahmaputra.

With a planned generating capacity of around 60 gigawatts, the project is expected to surpass the Three Gorges Dam and become the largest hydropower station in the world. The project is estimated to cost about $147 billion.

India’s concerns

The latest findings are expected to intensify concerns in India, which has consistently highlighted the geological vulnerabilities of the Himalayan region where the dam is being constructed.

New Delhi has repeatedly argued that the area is highly prone to earthquakes, landslides and glacial hazards, raising questions about the safety of such a large infrastructure project. India has also expressed concerns over the potential downstream consequences of any structural failure, sudden water discharge or changes in river flow patterns.

The Brahmaputra river system is a critical water source for millions of people living in Arunachal Pradesh and Assam, making any upstream intervention a matter of strategic and environmental significance for India.

Apart from safety concerns, India has also sought greater transparency from China regarding the design, operation and hydrological implications of the project. New Delhi has maintained that activities on transboundary rivers should take into account the interests and concerns of downstream countries.

China, however, has consistently defended the project, describing it as a run-of-the-river hydropower scheme intended primarily for electricity generation. Beijing has maintained that the project will not significantly affect downstream water flows.

Although the Chinese study does not recommend halting construction, it highlights the active Paizhen Fault as a major engineering challenge that must be addressed throughout the project’s lifecycle.

The findings add a new scientific dimension to an issue that has already attracted environmental, geological and geopolitical attention across the Himalayan region, with experts closely watching the development of what is set to become the world’s largest hydropower project.

With inputs from agencies