China's Water Threat to India

In a sharply worded message that underscores rising regional tensions, China has warned that it will “not sit idle” if India takes measures to restrict water flows to Pakistan. The statement, invoking the principle “Do not do unto others what you do not want done to you,” signaled Beijing’s willingness to retaliate by leveraging its upstream position on transboundary rivers—most notably the Brahmaputra.

Yet hydrological data and ecological constraints suggest that China’s leverage may be more rhetorical than real. Though the Brahmaputra originates in Tibet—where it is known as the Yarlung Tsangpo—only 30 to 35 percent of the river’s total flow is generated in Chinese territory, largely from glacial melt and limited rainfall. The remaining 65 to 70 percent is contributed within India, fueled by intense monsoon rains across Arunachal Pradesh, Assam, Meghalaya, and Nagaland, as well as a web of tributaries including the Subansiri, Lohit, Kameng, and Manas rivers.

At the point where the river crosses the Indo-China border near Tuting, the flow is estimated at roughly 2,000 to 3,000 cubic meters per second. By the time it reaches the Assam plains—during the monsoon—it expands dramatically, reaching 15,000 to 20,000 cubic meters per second. Far from being dependent on upstream sources, the Brahmaputra is largely a rain-fed river system, with its strength and volume amplified deep within Indian territory.

Chinese engineers are currently developing a $137 billion hydropower project near the border, raising concerns over its potential use as a geopolitical tool. In theory, China could attempt to suppress the river’s flow and release it suddenly to trigger downstream flooding. However, analysts point out that any such maneuver would likely result in limited consequences for India while posing significant ecological and strategic risks for China itself.

The Himalayan Plateau, where the dam is located, is among the world’s most seismically active and environmentally fragile zones. Sudden manipulation of river flows could destabilize the region, heightening the risk of floods, landslides, and long-term hydrological disruption—not just for India, but for China’s own territories downstream.

As both countries navigate an increasingly complex geopolitical landscape, experts caution against the weaponization of water. “In the Himalayas,” one Indian analyst remarked, “you don’t play games with nature—it tends to have the last word.”

While China’s statement reflects broader strategic anxieties in South Asia, the Brahmaputra’s geography and India’s hydrological advantage leave little room for coercive diplomacy. The Brahmaputra is not a lever China can pull without cost, and the Himalayas are no place for strategic gambles. For now, science, topography, and ecological risk appear to hold the upper hand over rhetoric.