China dam fault raises Bangladesh concerns

Fresh geological findings from China have renewed concerns in Bangladesh over the long-term safety of the world’s largest hydropower project being built on the Yarlung Tsangpo River, which becomes the Brahmaputra in India and the Jamuna in Bangladesh.

While Dhaka’s concerns have largely centred on water availability and environmental impacts, Chinese researchers have now identified an active fault line beneath the project site that could pose additional engineering and geological challenges.

The findings were published last month in the Chinese-language journal Sedimentary Geology and Tethyan Geology, supervised by the state-owned China Geological Survey.

The study was carried out by researchers from Chengdu University of Technology, the Civil-Military Integration Centre of the China Geological Survey, and the Middle Yarlung Zangbo River Natural Resources Observation and Research Station.

According to the researchers, the Paizhen Fault, an active fracture in the
Earth’s crust in the eastern Himalayan region, passes through the reservoir area of the proposed hydropower project and could significantly affect the structural stability of dams, roads, bridges, tunnels and other major infrastructure.

“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 wrote.

They said the fault has fractured surrounding rock formations and altered their mechanical properties, making engineering foundations more vulnerable.

“This makes the foundation bearing capacity and structural stability of nearby engineering projects more susceptible to damage,” the study noted.

The researchers also described the terrain around the reservoir as having a “loose structure and weak cohesion”, warning that prolonged water immersion, combined with fault activity and earthquakes, could increase the risk of slope instability, landslides and rock collapses.

Construction of the mega-dam began last year on the Tibetan Plateau. Once completed, it is expected to generate around 300 billion kilowatt-hours of electricity annually—approximately three times the output of China’s Three Gorges Dam—making it the world’s largest hydropower project.

The Yarlung Tsangpo flows east across Tibet before entering India as the Brahmaputra through Arunachal Pradesh and Assam, eventually reaching Bangladesh as the Jamuna River.

Because of its transboundary nature, the project has attracted close attention from downstream countries concerned about potential implications for river flows, sediment transport, ecology and long-term water security.

The latest geological assessment adds another dimension to those concerns by highlighting seismic risks associated with the project site.

According to the study, the Paizhen area lies within the Himalayan seismic belt, one of the most active earthquake zones in China and neighbouring regions.

The researchers said a strong seismic activity zone has developed along the Yarlung Tsangpo and that geological records from the area provide an important basis for assessing the structural stability of the hydropower project.

The Paizhen Fault forms part of a broader network of tectonic faults created by the ongoing collision between the Indian and Eurasian tectonic plates.

The researchers concluded that the fault has remained active since the Early Pleistocene and continues to exhibit significant activity during the present Holocene epoch.

Analysis of ancient lake sediments suggests the fault was active as recently as 9,500 years ago.

They also cited the magnitude 6.9 earthquake that struck Milin, Tibet, in 2017 near the northern end of the fault as evidence of the area’s continuing seismic potential.

“Under regional seismic action, landslides and collapses can easily be induced, threatening the safety of engineering facilities and personnel,” the researchers wrote.

To reduce those risks, the study recommended strengthening structural safeguards throughout construction and operation.

It urged engineers to reinforce vulnerable slopes, install retaining barriers and adopt other protective measures to minimise the risk of landslides and structural failure.

For Bangladesh, where the Jamuna is a vital source of water, agriculture and livelihoods, the findings underscore the importance of closely monitoring developments on the upstream transboundary river, alongside continued regional dialogue on water management, environmental sustainability and infrastructure safety.