India is concerned that a planned Chinese mega-dam in Tibet could reduce water flow on a major river by as much as 85% during dry months. This development has prompted Delhi to accelerate its own dam projects to counteract potential impacts. India has been exploring upstream water control measures since the early 2000s, aiming to manage flows from Tibet’s Angsi Glacier, which feeds over 100 million people downstream in China, India, and Bangladesh. However, these plans face strong opposition from local residents of Arunachal Pradesh, who fear their lands and livelihoods will be destroyed.
In December, China announced the construction of the world’s largest hydropower dam near the border, just before the Yarlung Zangbo river crosses into India. This move raised concerns in New Delhi that China could leverage control of the river, which originates from the Angsi Glacier and is known as the Siang and Brahmaputra downstream, as a strategic tool.
India’s top hydropower company has been conducting surveys near potential dam sites, protected by armed police, while government officials discuss fast-tracking projects, including the ambitious Upper Siang Multipurpose Storage Dam—set to become India’s largest if completed. An internal government analysis, obtained by Reuters and shared here for the first time, highlights Delhi’s worries about the Chinese dam’s impact. It estimates that Beijing could divert up to 40 billion cubic meters of water annually—over a third of the typical flow—especially affecting the non-monsoon season when dry lands are vulnerable.
The Indian project aims to mitigate this risk with its own storage capacity of about 14 billion cubic meters, allowing controlled water release during dry periods. This could reduce water shortages in key regions like Guwahati by roughly 11%, compared to 25% if India does not build the dam. Additionally, the Indian dam would act as a buffer, absorbing excess flows from potential Chinese infrastructure breaches, with a proposed plan to keep 30% of its reservoir empty to handle unexpected surges.
China’s Foreign Ministry spokesperson responded to Reuters’ inquiries by asserting that the dam’s design and construction are based on thorough safety and environmental assessments and that it would not harm downstream countries’ water resources, ecology, or geology. China maintains it is committed to responsible management and ongoing communication with neighboring countries like India and Bangladesh.
In India, authorities and local communities are actively resisting the dam’s construction. When NHPC workers attempted survey activities in May, locals intruded, damaging equipment, burning a bridge, and looting police tents. Many belong to Arunachal Pradesh’s Adi community, who rely on farming and produce like paddy, oranges, and pears, all crucial to their livelihoods. Villagers have established checkpoints to prevent access, forcing security personnel to trek long distances under cover of darkness.
Approximately 16 Adi villages, with around 10,000 residents, face submersion due to the dam’s reservoir. Overall, over 100,000 people could be affected. Community leaders state their land, rich in crops and fruits, sustains their families and education, and vow to oppose the project vigorously. The local government’s support, including plans for compensation and developmental aid, aims to placate residents, with some villages agreeing to allow work to proceed.
Despite official assurances, construction delays are inevitable, possibly spanning a decade, meaning India’s project may lag behind China’s, which anticipates operation by the mid-2030s. This timing gap could leave the Indian infrastructure vulnerable to Chinese water releases during monsoons, risking flood surges against the dam.
Experts warn that building large dams in seismically active Tibet and Arunachal Pradesh introduces additional risks. The region’s high seismicity and extreme weather conditions—triggering landslides, mudslides, and glacial lake bursts—pose threats to dam safety. Advancing such projects necessitates closer cooperation between India and China to mitigate these dangers.
