Impact of China's Brahmaputra dams on India: Is Assam CM right in discarding Pakistan's water-related scare narrative?

The Brahmaputra and its tributaries carry more than 30% of the country’s total water resources potential, and 41% of the total hydropower potential (Image: PTI)

Assam Chief Minister Himanta Biswa Sarma recently countered Pakistan's latest water-related scare narrative, calling it a 'baseless attempt' to stir fear over a hypothetical scenario involving the Brahmaputra River.

In a post on X, Sarma responded to the claim, "What if China stops the Brahmaputra's water to India?". "Let's dismantle this myth, not with fear, but with facts and national clarity,” Sarma wrote.

The Assam CM said China contributed only approximately 30-35% of the Brahmaputra’s total flow — mostly through glacial melt and limited Tibetan rainfall. “The remaining 65-70% is generated within India, thanks to torrential monsoon rainfall in Arunachal Pradesh, Assam, Nagaland, and Meghalaya; major tributaries like Subansiri, Lohit, Kameng, Manas, Dhansiri, Jia-Bharali, Kopili; and additional inflows from the Khasi, Garo, and Jaintia Hills via rivers such as Krishnai, Digaru, and Kulsi,” he wrote on X.

His remarks come after Rana Ihsaan Afzal, a senior aide to Prime Minister Shehbaz Sharif, recently warned that India’s decision to place the IWT in abeyance could provoke a chain reaction, with China potentially retaliating by blocking the Brahmaputra River’s flow into India.

China’s share in basin discharge

The Brahmaputra originates near the Chemayungdung Glacier in Tibet (river known as Yarlung Tsangpo), enters Arunachal Pradesh and flows through Assam before continuing through Bangladesh as the Jamuna. It ultimately drains into the Bay of Bengal.

According to an article on natstrat.org, China accounts for only 22 to 30 per cent of the total Brahmaputra River Basin’s discharge. The article has been authored by PK Saxena, former Indian Commissioner for Indus Waters and Adviser, Ken Betwa Link Project Authority, Bhopal, and Teerath Singh Mehra, former commissioner, Brahmaputra and Barak, Ministry of Jal Shakti, Government of India.

How China can worry India?

The proposed Medog (or Motuo) Hydropower Project, a massive dam in Medog County near the ‘Great Bend’ remains a concern. According to Indian Express, the planned 60,000-MW Medog project will be the world’s largest hydropower facility, with a generation capacity three times that of the Three Gorges Dam on the Yangtze, currently the world’s largest hydropower station.

There have also been concerns over China’s South-North Water Diversion (SNWD) project, the Western Route of which apparently involves diverting water from the Yarlung Tsangpo (and other rivers) to the country’s dry northern regions. However, no official sources are available on these reported plans, according to Indian Express.

How does India use the Brahmaputra system?

The Brahmaputra and its tributaries carry more than 30% of the country’s total water resources potential, and 41% of the total hydropower potential, as per estimates in the CWC-ISRO Brahmaputra Basin Atlas.

However, hydropower in Arunachal Pradesh is the only significant planned use.

According to reports, the National Water Development Authority has proposed two links to connect the Brahmaputra and its tributaries to the Ganga basin.

These are the Manas-Sankosh-Teesta-Ganga Link, joining the Manas, a tributary of the Brahmaputra, to the Ganga via the Sankosh and Teesta and the Jogighopa-Teesta-Farakka Link, joining the Brahmaputra at the planned Jogighopa Barrage to the Ganga at the Farakka Barrage.

Neither of these projects are likely to be impacted in any significant way by upstream intervention in the Brahmaputra in Tibet.

Should India be worried?

Though China is the upstream state of the Brahmaputra, geographically, most of the Brahmaputra’s volume is generated after it enters India in Arunachal Pradesh. Also, the Brahmaputra is a rain-fed river that swells during the Indian monsoon season. Hence, making any Chinese attempt at manipulating the flow of river water downstream is both hydrologically limited and politically risky.

Nilanjan Ghosh, vice-president of Development Studies and senior director at Observer Research Foundation in Kolkata, told Times of India that China's upstream interventions will have "negligible or almost no effect" on Brahmaputra's overall flow.

According to Indian Direct Selling Association senior fellow Uttam Sinha, even during lean periods Yarlung Tsangpo's annual outflow from China is far lower than Brahmaputra's total discharge in India. "India’s lower riparian position does not necessarily mean acute disadvantage," Sinha told TOI. He, however, said irrespective of whether China eventually builds a super dam or not, India must be prepared by building capacity.