China’s decision to build the massive hydropower project on the Yarlung Tsangpo is significant because this river does not stay in China. It enters India through Arunachal Pradesh as the Siang, becomes the Brahmaputra River in Assam, and eventually flows into Arunachal Pradesh. Construction of the project officially began in 2025 and is expected to become the world’s largest hydropower development, generating roughly three times the electricity of the Three Gorges Dam.
Why India is worried
- Upstream control creates strategic leverage
China sits upstream, giving it physical control over infrastructure that can influence river flows. Even if Beijing does not intend to cut off water, the ability to regulate releases gives it a strategic advantage during crises or periods of tension. Indian analysts worry that water could become another factor in the broader India-China rivalry.
- Flood risks could increase
A major concern is not only reduced water flow but also sudden releases of water. If large volumes are discharged during heavy rainfall or emergencies, downstream regions in Arunachal Pradesh and Assam could face heightened flood risks. The Brahmaputra basin is already among the most flood-prone regions in the world.
- Dry-season water availability
Although China says the project is primarily hydropower-oriented rather than a diversion scheme, Indian policymakers worry that dam operations could alter seasonal flows. Reduced water during dry months could affect agriculture, fisheries, river ecosystems, and local communities dependent on the river.
- Ecological and seismic concerns
The dam is being built in a geologically active part of the eastern Himalayas, an area prone to earthquakes, landslides, and fragile ecosystems. Environmental groups have warned that a project of this scale could affect biodiversity and sediment transport throughout the river basin.
Probably not in the simplistic sense often portrayed on social media.
The Brahmaputra receives enormous amounts of water from rainfall and tributaries inside India, especially in Arunachal Pradesh, Assam, and Bhutan. By the time the river reaches Assam, much of its flow comes from sources beyond Tibet. This limits China’s ability to completely control the river. Some experts therefore argue that fears of China shutting off the Brahmaputra are exaggerated.
However, even partial control over timing, storage, and release of water can have important consequences for flood management, drought conditions, and regional security. That is where India’s concern is concentrated.
How this could change Brahmaputra geopolitics
Water security becomes a national-security issue
Traditionally, border disputes and military deployments dominated India-China tensions. The dam adds a new dimension: control of critical natural resources. Water security may increasingly be discussed alongside territorial security.
India is accelerating its own dam projects
India has explored large storage and hydropower projects in Arunachal Pradesh, including the proposed Upper Siang project, partly to create a buffer against any upstream manipulation and improve flood control.
Bangladesh becomes an important stakeholder
Because the Brahmaputra ultimately flows into Bangladesh, Dhaka also has an interest in any changes to river management. This could lead to greater regional diplomacy involving China, India, and Bangladesh over shared water resources.
More pressure for data sharing and agreements
Unlike some international rivers, the Brahmaputra lacks a comprehensive basin-wide water-sharing treaty among all riparian states. The mega dam may increase demands for transparency, hydrological data sharing, and formal mechanisms to manage disputes.
Bottom line
India’s concern is less about China literally stopping the Brahmaputra and more about China’s ability to influence the river’s timing, storage, and flow from an upstream position. The project introduces environmental, flood-management, and strategic uncertainties into an already sensitive border region. Whether it becomes a source of cooperation or tension will depend largely on transparency, data sharing, and how the dam is ultimately operated once it comes online in the 2030s.