New Delhi, July 23 -- India is keeping a close watch on China's construction of what is set to be the world's largest hydropower dam on the upper reaches of the Brahmaputra river and could fast-track a multipurpose dam in Arunachal Pradesh to act as a buffer against sudden changes in water flows, people familiar with the matter said on Monday. Chinese Premier Li Qiang presided over a ceremony on Saturday marking the start of construction on the $167-billion dam on Yarlung Tsangpo river in Tibet, according to reports in China's state-run media. The Motuo hydropower station is set to overtake the Three Gorges dam as the world's largest. There was no reaction from Indian officials to the development, though people familiar with the matter said on condition of anonymity that New Delhi had conveyed its concerns over the project to Beijing through diplomatic channels. The project has drawn criticism for its potential impact on the environment of Tibet and on millions of people in India and Bangladesh. Concerns about the dam could spur India to fast-track a multipurpose dam in Arunachal Pradesh, known as the Siang Upper multipurpose storage project, to act as a buffer against sudden changes in the flows of the Siang and Brahmaputra rivers, the people said. The Chinese dam is located around a "great bend" on the Yarlung Tsangpo river, which is known in India as the Brahmaputra. The Siang, which flows through Arunachal Pradesh, is the Brahmaputra's main tributary that connects it to the Yarlung Tsangpo. In June 2022, the government entrusted the National Hydroelectric Power Corporation Ltd, India's largest state-backed power firm, with preparing a preliminary feasibility report and a detailed project report for the proposed Upper Siang dam. "The Centre has been in discussions with the Arunachal Pradesh government on the issue of the Upper Siang project. The initial surveys have not yet begun. It will be better to speed up these works because the dam will need to be built for not just power but to protect against any future changes in the flow of Indian rivers," an official from the river basin management wing of the water ministry said. While there was no official reaction to the start of construction of the dam in Tibet, the people pointed to the position taken by the external affairs ministry on the matter during a media briefing on January 3. "As a lower riparian state with established user rights to the waters of the river, we have consistently expressed, through expert-level as well as diplomatic channels, our views and concerns to the Chinese side over mega projects on rivers in their territory," external affairs ministry spokesperson Randhir Jaiswal said....