Brahmaputra is no Indus. Tough luck, Pakistan!

In recent discussions about water as a tool of geopolitical leverage, some political commentators have speculated whether China might attempt to retaliate against India for its hardening stance on the Indus Waters Treaty (IWT) by disrupting the Brahmaputra’s flow. The underlying assumption is that, just as India sits upstream of Pakistan on the Indus, China sits upstream of India on the Brahmaputra and could mimic India’s tactics.

However, this analogy collapses under scrutiny — geographically, hydrologically and politically.

Volume doesn’t add up

First and foremost, the ability of India's northern neighbour to control the Brahmaputra’s water is limited by geography and rainfall. The Yarlung Zangbo, as the river is known in Tibet, contributes at most 30.7% of the total water that flows into the Brahmaputra. Some estimates suggest the figure is closer to 14%. The rest of the river’s volume is contributed by Indian and Bhutanese tributaries, with India alone accounting for the bulk of the downstream flow due to the monsoon-fed rivers in Arunachal Pradesh and Assam.

This means that any attempt by China to curtail or divert water would affect less than a third of the Brahmaputra’s total discharge — insufficient to inflict the economic or agricultural shock that a full-scale water stoppage on the Indus could cause to Pakistan.

Hydrology favours India

Unlike the Indus, which flows predominantly through Pakistan after entering from India, the Brahmaputra gathers strength as it travels across India. It is joined by the Siang (originating in Tibet), the Dibang and the Luhit in Assam — all major tributaries based in Indian territory. It is then further fed by the Subansiri, Manas and other rivers that originate in the high-rainfall regions of Arunachal Pradesh, Assam and Bhutan.

The numbers bear this out starkly. At Nuxia, a monitoring point in Tibet, the river’s annual discharge is approximately 31 billion cubic metres. By the time it reaches Bahadurabad in Bangladesh, the annual flow has swollen to around 606 billion cubic metres — proof that China’s segment of the river is a relatively minor contributor.

Contrast this with the Indus system, where the five key rivers of the former Punjab — Beas, Ravi, Sutlej, Chenab and Jhelum — flow largely through Pakistan, though most of their headwaters lie in India. India’s control over these headwaters gives it far more strategic power, which it ceded in 1960 when it agreed to allow Pakistan 80% of the Indus basin’s waters. That leverage, currently under review by India, was real and voluntarily given up. China never had such leverage in the Brahmaputra’s case to begin with.

Terrain limits Chinese ambitions

The topography of the Tibetan Plateau presents an additional constraint. Tibet is a high-altitude cold desert with scant rainfall, averaging just 300–400 mm per year and it depends primarily on glacial melt. This restricts the volume of water that China can marshal for any large-scale diversion project.

Even the much-discussed Motuo dam, should it ever be completed, could influence seasonal flows but would not offer Beijing the ability to starve India of water.

In contrast, India’s side of the Brahmaputra basin, particularly Assam and Arunachal Pradesh, receives torrential rainfall during the monsoon, with up to 85% of annual precipitation occurring from May to September. This not only dwarfs China’s contribution but also makes Indian tributaries far more variable and potent.

Bhutan’s silent strength

An underappreciated aspect of the Brahmaputra system is Bhutan’s contribution. Although it comprises only about 6.7% of the basin’s area, Bhutan contributes around 21% of the total discharge, thanks to its steep terrain and high rainfall. Any analysis that places China and India as the only actors in the Brahmaputra’s drama misses this critical piece of the puzzle.

The implication is clear: even if China were to attempt coercive water politics, it would face not only the limits of its own geography but also the counterbalancing contributions of Bhutan and India’s own rich tributary network.

Geopolitical and hydrological mismatch

The Indus Waters Treaty allowed India to build infrastructure on the eastern rivers and even utilise the western ones for non-consumptive use. Despite these allowances, India has felt constrained by the treaty’s rigid allocation, particularly given growing domestic water needs and Pakistan’s objections to India’s hydroelectric projects.

India’s grievances are not just emotional or political; they stem from real, practical limitations imposed by a treaty many Indians felt was overly generous. Criticism of the Jawaharlal Nehru government’s decision to cede 80% of the Indus basin’s waters to Pakistan has persisted since 1960.

China, however, is not operating under a formal treaty with India over the Brahmaputra. Nor does it possess the geographical advantage India enjoys over Pakistan. It is thus implausible for Beijing to replicate New Delhi’s position vis-à-vis Islamabad. Any attempt by China to use the river as a bargaining chip would likely invite international scrutiny while yielding limited actual impact.

False equivalence

Trying to create a parallel between India’s control over the Indus and China’s position on the Brahmaputra is analytically flawed. The hydrology, terrain and riverine contributions are fundamentally different. India sits atop a river system where it has meaningful upstream control over water that is crucial to Pakistan’s survival. China does not.

Therefore, even if geopolitical tensions escalate, China cannot "settle scores" on India's eastern front through the Brahmaputra in the way some imagine. The river’s geography simply doesn’t allow it.