Even though Tarun Gogoi, former Assam chief minister, wrote a letter to the prime minister on 18 September expressing grave concern over China’s declaration to block a tributary of Brahmaputra, experts are now downplaying the fears over the move by stating that the proposed block in the water flow to the Indian territory may not have a serious impact on the river after all.
Soon after Chinese news agency Xinhua declared that Tibet is going to block a tributary of Yarlung Tsangpo, Gogoi wrote the letter to Modi urging him to take up the matter with China as he felt that construction of such a dam over the Brahmaputra would adversely impact the downstream flow, ultimately crippling the economy of the state.
The Congress leader also went on to say that a dam on the upper reaches of Brahmaputra will cause grave concern for Assam as well as other parts of the North East.
But, in spite of Gogoi's concerns over the dam, experts are now presenting a different take on the situation. Dr Bhagwat Pran Dowerah, a geologist who has conducted extensive research on hydro-water projects and dams and was appointed as a member of the expert committee to study the impact of the Subansiri Lower Hydroelectric Project by the government, says that this fear emerges from the notion that Yarlung Tsangpo itself is the Brahmaputra.
“Yarlung Tsangpo is only a tributary of the Brahmaputra. The river Brahmaputra gets its name only after the three major tributaries meet,” Dowerah said.
“China has said that it is going to block a tributary of Yarlung Tsangpo. The river Yarlung Tsangpo, that is known as Siang in Arunachal Pradesh in India, contributes only 30 percent of water the Brahmaputra drains. Even this amount of water is not entirely fed by glaciers in China,” Dowerah said.
He pointed out that the foothills of Himalayas in North East India get much more rainfall than its upper reaches based in China. A major portion of the water in the Siang comes from these rains.
“Though there is no proper scientific study to show exactly what amount of water is generated in China to feed the river and what amount in India, still I do not think that blocking a tributary will bring a substantial difference to the water flow of Brahmaputra. For Brahmaputra drains much more water than we use from it,” Dowerah added.
“The said dam to be built in Tibet is about 42 megawatts of power. The amount of water to be blocked is 295 million cubic metre. We in India are envisaging projects bigger than that on the tributaries of Brahmaputra. For example, the Subansiri Lower Project aims to store 4.5 times more water than the dam in Tibet,” Dowerah said.
He also said that the only matter of concern here is that all the tributaries of the Brahmaputra originate in China. India needs a transparent treaty with China to ensure that the water needed here is not blocked by the neighbouring country.
“China has the right to build dams on the rivers that flow through it. But we need to ensure that we continue to get our due share of water. Only a water treaty can make it possible,” he said.
Environmentalist Chandan Dowerah, who has written extensively on issues related to environmental impacts of dams, questions the validity of protests raised against China’s move to build the dam on the tributary of Brahmaputra.
“We ourselves have made dams on the tributaries of Brahmaputra. But have we raised similar questions about the riparian rights of Bangladesh or even that of Indian states in the downstream of the river?” he questions.