China is moving ahead with plans to build what is expected to become the world’s most powerful hydropower system in the Himalayas, a massive infrastructure project that has triggered concern across South Asia over its environmental, hydrological and geopolitical consequences. The project is located on the Yarlung Tsangpo River in Tibet, which flows downstream into India as the Brahmaputra and onward to Bangladesh. Chinese authorities describe the initiative as a major step toward clean energy expansion and reduced dependence on fossil fuels. Once completed, the hydropower system is projected to generate significantly more electricity than the Three Gorges Dam, currently the world’s largest hydroelectric facility.

However, limited public disclosure about the project’s design, scale and environmental assessments has fuelled anxiety among downstream nations that depend on the river for agriculture, drinking water and livelihoods. Experts warn that large upstream interventions could alter natural river flows, sediment movement and seasonal water availability. In India, policymakers have expressed apprehension over the potential for upstream control of water during monsoon and dry seasons, which could affect flood patterns and irrigation cycles in northeastern states such as Arunachal Pradesh and Assam. Bangladesh has also voiced concern that changes in sediment flow could damage its delta ecosystem, with serious consequences for farming and fisheries.

Environmentalists have highlighted the fragile nature of the Himalayan ecosystem and the risks of constructing large dams in a seismically active region. Scientists caution that such projects increase the likelihood of landslides, habitat loss and long-term ecological disruption, particularly in an area already vulnerable to climate change. China has defended the project as a sovereign clean-energy initiative, insisting it will not adversely affect downstream water flows. Beijing maintains that existing mechanisms for hydrological data sharing and flood management are sufficient, though critics argue these measures lack transparency and binding commitments.

The project’s proximity to sensitive border regions has added a strategic dimension to the debate. Analysts note that control over a major transboundary river could become a source of leverage during future diplomatic or security tensions. As construction progresses, the Himalayan mega-dam is emerging as a focal point in broader discussions on water security, environmental sustainability and regional stability, with downstream countries continuing to seek greater transparency and cooperation from Beijing.