China’s Mega Brahmaputra Dam Faces Flood Risk Concerns, Researchers Warn

Chinese Researchers Predict Rising River Runoff and Increased Flood Risks This Century; Project Estimated to Cost 168 Billion

Chinese researchers have warned that the Brahmaputra River in Tibet, where China is constructing what is planned to be the world’s largest hydropower project, could experience increased river runoff and heightened flood risks over the course of this century. The project is estimated to cost 168 billion.

Researchers from the Chinese Academy of Sciences and Yunnan University reconstructed the river’s runoff history from 1325 to 2020 using tree-ring width records from the southeastern Tibetan Plateau.

By combining the reconstruction with climate data, the researchers developed a model projecting that river runoff could increase under future climate scenarios, potentially leading to a rise in high-flow events, including floods.

According to a report by Hong Kong-based South China Morning Post on Monday, the findings were published in the journal China Science Bulletin on October 8.

The research team said the findings provide a long-term understanding of changes in the Yarlung Tsangpo River’s hydrological patterns and a scientific basis for assessing future water-resource risks.

Yarlung Tsangpo is the name given to the Brahmaputra River in Tibet before it flows into India.

The researchers stressed that projected changes in river runoff should be considered when planning water-resource development and storage infrastructure, as well as when assessing transboundary water risks in the region.

According to the researchers, the Tibetan Plateau has been warming at approximately twice the global average rate, affecting its ice cover and hydrological cycle.

They noted that changes in the river reflect not only the hydrological conditions of the plateau but also have implications for drought and flood patterns across South Asia.

“In recent years, with the ongoing warming of the climate, the hydrological regime of the Yarlung Tsangpo River basin has been undergoing significant changes,” the researchers said.

The proposed project has also raised geological concerns. In July, Chinese geologists warned that an active fault line directly beneath the planned dam could threaten its structural stability.

In a paper published in the journal Sedimentary Geology and Tethyan Geology, the researchers urged engineers to strengthen slope stability and introduce protective measures to reduce the risk of landslides and structural collapses, the South China Morning Post reported.

The concerns come amid growing attention to mountain hazards in the Himalayan region. Flash floods along the China-Nepal border on August 26, triggered by an ice-and-rock avalanche and the subsequent collapse of a temporary river blockage, highlighted the region’s vulnerability to such disasters.

According to the report, the disaster killed nearly 1,500 people and left more than 5,500 missing in Nepal and China.

The Brahmaputra originates in Tibet and flows south into India. It is known as the Siang in Arunachal Pradesh before being called the Brahmaputra further downstream.

China is constructing the massive hydropower project in Medog, also known as Motuo, in southeastern Tibet near the disputed border with India.

Upon completion, the project is expected to have an installed capacity exceeding 60,000 megawatts—nearly three times the capacity of China’s Three Gorges Dam, currently the world’s largest operating hydropower plant by installed capacity.

The dam is being built in a deep Himalayan gorge where the Brahmaputra makes a sharp U-turn before flowing into Arunachal Pradesh and subsequently Bangladesh.

Despite significant engineering challenges, China has proceeded with the project. The construction site lies along a tectonic plate boundary in an area prone to earthquakes.

China’s Foreign Ministry has previously defended the project, stating that it would not affect downstream countries. Beijing has also maintained that potential safety concerns have been addressed through decades of studies and the implementation of safety measures.

However, the latest research highlights the need to assess future changes in river flow, climate-related risks and geological hazards when evaluating the long-term implications of the massive project for the wider Himalayan region and downstream areas.