Those dams could not only affect water flows but also remove nutrient-rich silt that helps nourish agriculture downstream, he said.
The nightmare scenario for India is that China would one day have the engineering expertise to divert the river at its Great Bend, where it makes a hairpin turn through a gorge many times as deep as the Grand Canyon before rushing into India.
Such an idea has circulated in China for some time, but it is a practical impossibility even for the Chinese, said Mohan Guruswamy of the Center for Policy Alternatives in New Delhi. He said such a project would potentially require nuclear explosions to blow up mountains and the construction of a string of nuclear power plants to haul the water over the higher reaches of the Tibetan plateau.
Guruswamy said many of India’s popular concerns are born of ignorance and a strong dose of jingoism. The Brahmaputra picks up the vast majority of its water a long way downstream from the proposed dams, he said, and India uses only 5 percent of the waters as the river, six miles wide in some places, glides by on its way to Bangladesh.
New Delhi is monitoring the river’s flow as it enters Indian territory but is not overly concerned, said a government official who spoke on the condition of anonymity to discuss the sensitive subject.
As a rising global power, China has shrinking incentive to unilaterally dam rivers to its neighbors’ disadvantage, the official said.
“This sort of thing wouldn’t behoove a country that aspires to be a major player,” he said.
Arvind Subramanian of the Peterson Institute for International Economics in Washington said tensions could rise as climate change melts the Himalayan glaciers and changes the patterns of water distribution in Asia. The risk is that China then takes a larger share of diminished rivers, magnifying the effects of climate change on downstream nations such as India.
And because the upstream power also has military, strategic and economic advantages, many observers say India has minimal bargaining power.
“India has very little leverage over China, and this is just one more lever that China is acquiring,” said Harsh Pant of the defense studies department at King’s College London.
Zhang Jie in Beijing contributed to this report.