India is intensifying efforts to build its own massive dam in Arunachal Pradesh in response to China’s construction of what is expected to be the world’s largest hydropower dam in Tibet. According to a government analysis and sources familiar with the matter, Delhi fears the Chinese project could reduce water flows on the Brahmaputra River by up to 85% during the dry season. This has prompted urgent action to mitigate potential disruptions, including fast-tracking the Upper Siang Multipurpose Storage Dam, which would be India’s largest if completed.
Plans to harness water from the Angsi Glacier—source of the Brahmaputra—have existed since the early 2000s, but faced resistance from local communities in Arunachal Pradesh. Residents fear displacement and destruction of their way of life due to submergence caused by dam construction. However, China’s December announcement of its mega-dam near the border has reignited strategic concerns in New Delhi, especially given Beijing’s territorial claims in the region and the potential to control water flow into India.
Indian officials, including those from Prime Minister Narendra Modi’s office, have held high-level meetings to accelerate the dam’s development. In May, survey equipment was moved to the proposed site under armed protection, signaling the seriousness of India’s response. The government analysis, corroborated by multiple sources, estimates that China’s dam could divert up to 40 billion cubic meters of water annually, with the most severe impact expected during non-monsoon months when water scarcity is already a challenge.
To counter this, India’s Upper Siang project is designed with a 14 BCM storage capacity, enabling controlled water release during dry periods. This could reduce water shortages in key areas like Guwahati from 25% to 11%. Additionally, the dam could serve as a buffer against sudden water surges from China, with plans to keep 30% of its capacity empty to absorb unexpected releases. While Beijing has not disclosed detailed construction plans, the geopolitical and environmental stakes continue to rise.
