New research from Chinese academics warns of significant increases in runoff and heightened flood risks along the Brahmaputra River throughout the 21st century. These projections emerge as China advances its colossal hydropower project in Tibet, estimated to cost $168 billion, making it the world's largest planned dam.
Climate Change and Dam Construction Drive Flood Concerns
Researchers from the Chinese Academy of Sciences and Yunnan University reconstructed the Brahmaputra's runoff history dating back to 1325 using tree-ring width data from the southeastern Tibetan Plateau. Combining this historical data with climate models, their projections indicate a future with increased runoff and a higher frequency of major flood events.
The findings, published in the journal China Science Bulletin, emphasize the need to consider these hydrological changes in future water-resource planning, infrastructure development, and the assessment of transboundary water risks. The Yarlung Tsangpo, as the river is known in Tibet, flows into India as the Brahmaputra.
Mega-Dam Project Raises Regional Anxieties
The warning comes amidst ongoing concerns surrounding China's mega-dam project in Medog (Motuo) in southeastern Tibet, near the disputed border with India. This ambitious project is designed to have an installed capacity exceeding 60,000 megawatts, nearly triple that of China’s Three Gorges Dam.
The Tibetan Plateau, warming at roughly twice the global average rate, is experiencing significant impacts on its ice cover and hydrological cycle. Changes in the Brahmaputra river system could drastically influence drought and flood patterns across South Asia, affecting millions downstream.
Seismic Risks and Structural Stability
Beyond climate-induced flood risks, the dam project faces geological challenges. In July, Chinese geologists issued warnings about an active fault line directly beneath the proposed dam site, raising questions about its structural stability. They urged engineers to implement robust measures to strengthen slope stability and protect against landslides and collapses.
The vulnerability of the Himalayan region to mountain hazards was starkly highlighted by the August 26 flash floods near the China-Nepal border. Triggered by an ice-and-rock avalanche and subsequent river blockage, that disaster resulted in nearly 1,500 fatalities and thousands missing in Nepal and China.
China's Stance on Downstream Impact
Despite these concerns, China has consistently defended its dam projects. The Foreign Ministry has previously stated that the project would not adversely affect downstream countries and asserted that safety concerns have been thoroughly addressed through decades of studies and protective measures.