August 25, 2025
NEW DELHI – Mr Tabeng Siram has farmed in the fertile valley of the Siang river in India’s hilly north-eastern state of Arunachal Pradesh for decades, cultivating crops such as rice, orange, cardamom and ginger. It is something his ancestors also did.
But this centuries-old agrarian lifestyle is at risk from plans to build India’s biggest dam – the US$13.2 billion (S$17 billion) Upper Siang Multipurpose Project (USMP) that could flood his land.
The threat for Mr Siram and others in this region, however, is not just from India’s dam – further upstream, China has just started building the even larger Medog Hydropower Station. Combined, both dams could greatly affect one of South Asia’s most important rivers, the Brahmaputra, which is the lifeblood for millions of people.
Experts say the race to build these mega dams reflects the intense geopolitical rivalry between India and China, as well as both countries’ need for energy. But such large dams will inevitably affect water flow along the river and flood control – and both are being built in an earthquake-prone region.
The 11.2-gigawatt (GW) USMP has been billed by the Indian government as a “strategic necessity”, one that will not just generate electricity, but also counter possible threats posed by the 60GW Medog Hydropower Station. That dam is being built on the Yarlung Tsangpo river in Tibet.
The river is known as the Siang in Arunachal Pradesh and the Brahmaputra farther downstream, where it becomes a vital waterway for transport and source of rich alluvial sediment for growing rice, tea and other crops.
The Brahmaputra river basin covers 580,000 sq km across Tibet, Bhutan, north-east India and Bangladesh, where it joins the Padma or Ganges river.
India’s officials have described the Medog dam as a “water bomb” and an existential threat to locals in Arunachal Pradesh. The USMP, with its estimated reservoir capacity of nine billion cubic m of water, they add, could help absorb sudden water releases from China’s dam and protect locals downstream from flooding, or even replenish the Siang’s flow in case China holds back water during a drought.
But thousands of locals such as Mr Siram, who risk being permanently displaced because of the dam, refuse to budge. This is complicating India’s response to the perceived risks from the Medog dam.
“I won’t move at any cost,” he told The Straits Times on the phone on his way back home in Parong village after a protest meeting on July 20 against the dam in Upper Siang district. “Our home, farmland and ancestral land – all will be submerged, which is why I oppose this dam,” added Mr Siram, who is in his 60s.
Experts say building dams in this ecologically fragile and seismically active zone could have devastating consequences for the Himalayan ecosystem and its people.
The USMP, first proposed in 2017, gained priority after the Chinese authorities approved the construction of the Medog Hydropower Station in December 2024 and began building it in July 2025.
Officials in India have launched feasibility surveys for the USMP. But these efforts have been met with stiff resistance from locals, which has stalled progress and prompted the Bharatiya Janata Party-led state government to deploy paramilitary forces to prevent unrest.
It has been estimated that 27 villages in the Upper Siang and Siang districts risk being submerged and thousands of people could be uprooted. While the state government has claimed the support of a growing number of villages for its “pre-feasibility report” surveys, opposition from locals has been mounting.
On July 20, the Siang Indigenous Farmers’ Forum (SIFF), a prominent local community-based group, organised a protest meeting in Geku that Mr Siram attended. It was one of the largest such meetings so far, attended by several thousand people from Upper Siang, and even beyond.
The meeting ended with a call for the USMP to be scrapped and central paramilitary personnel deployed in the region to be withdrawn. Locals also adopted a resolution officially describing the Siang as a “sacred” river, whose flow must not be obstructed.
The Siang’s water is vital for farming, and people in the area refer to the river as “Ane”, meaning “mother” in the language of the Adi indigenous community.
“People of the Siang valley are totally dependent on the gift of the Siang river,” said Mr Likeng Libang, SIFF’s general secretary, explaining their opposition to the dam. “Our daily domestic lives, economic life, cultural values – everything depends on this valley.”
Concerns are, however, not just limited to displacement or loss of livelihoods. The environmental impact from such a large dam in one of India’s most biodiverse regions could be consequential too.
An expedition into the mountainous Siang valley between 2022 and 2024 discovered more than 1,500 different species of plants, insects, birds and other wildlife, some new to science.
The area, in the eastern Himalayas, is also seismically active, raising fears about a man-made deluge if another big quake strikes there. In 1950, the Assam-Tibet earthquake – with a magnitude of 8.7 – struck this region, killing around 4,800 people.
The NHPC Limited, which is implementing the USMP, did not respond to questions from ST.
In recent years, the vast Brahmaputra river basin has become a geostrategic battlefield for water and security between India and China, a contest that has further intensified with these two big dams.
A bilateral agreement to share hydrological data of the Brahmaputra river remains suspended since June 2023. Moreover, their longstanding land boundary dispute has led the Brahmaputra river basin to be viewed more through a lens of rivalry rather than one of cooperation.
Multiple smaller dams are either being constructed or have been planned in this basin in India and China, prompting fears of irreversible threats to the region’s biodiversity and millions of people.
Dr Mirza Zulfiqur Rahman, a visiting associate fellow at the Institute of Chinese Studies in Delhi, told ST that he worries India and China are engaged in a race to build these dams more as “strategic sovereignty markers” in remote borderlands than for electricity generation or to achieve their respective net-zero emission goals.
“And it is the Himalayas that will ultimately suffer, along with the many Himalayan communities who do not have the political heft in India’s democracy or the voice in China’s authoritarian regime to influence how this race builds up,” he said.
Dr Rahman noted that India and China treat the Brahmaputra river basin as their “sovereign territorial containers”, with little thought about the consequences of their actions downstream.
He argued: “A democracy and a middle riparian state like India should be taking the leadership in creating a bio-regional and eco-regional understanding of this space, but it has not even expressed interest in understanding it in such a manner.”
India is referred to as a middle riparian state in the transboundary Brahmaputra basin, as the river originates in Tibet and then passes through north-east India before flowing into Bangladesh, where it eventually empties into the Bay of Bengal.
India has not even allocated adequate resources to understand the river systems in its territory, which is an area where China has done far better. Because of this, it is “able to build quicker and build bigger, and more efficient dams upstream”, noted Dr Rahman.
“Unfortunately, India is in a position today where it has not done any research and is just scrambling to provide a response to what China is doing upstream,” said Dr Rahman.
Mr Himanshu Thakkar, coordinator of the South Asia Network on Dams, Rivers and People, said that there is very little credible information in the public domain in India about the Medog Hydropower Station, something that is necessary for the country to formulate its appropriate response.
“Until and unless you know the basic and salient features of the (Medog) project, you can’t even start speculating on its capacity to cause harm downstream, whether it is to create floods or dry up the river,” he said.
Questions linger about the extent of the impact of the Chinese dam downstream in India. The Yarlung Tsangpo river, as it enters India, contributes only between 14 per cent and 15 per cent of the total flow of the Brahmaputra, with the rest made up of other sources downstream, including tributaries and monsoon rains.
Mr Thakkar suggested that India should publicly demand details of the Medog dam from Beijing, something China is obligated to provide under international law as an upper riparian state.
“And India should use all its monitoring capacity to understand what China is up to so that we can decide whether we need this large dam in Upper Siang in the first place,” he added.
But there are fears that the Upper Siang dam will be pushed through in the name of national security, despite widespread opposition and ecological concerns.
“Pushing the dam through in a hurry as a strategic weapon or response would be a mistake,” Mr Thakkar said. “We will only end up creating a monster without fully understanding the impacts and implications of what we are doing.”