The World’s Largest Hydropower Project and the Fate of Brahmaputra
Author: PPD Team Date: August 20, 2025
The Brahmaputra is not only one of Asia’s mightiest rivers but also a lifeline for millions across India and Bangladesh. Its scale and transboundary nature make it a source of both sustenance and tension.
The river is an important source of irrigation in the states of Assam, Arunachal Pradesh, Bihar, and West Bengal. It originates in the Mansarovar Lake region in the Kailash ranges of the Himalayas in Tibet (China). The river flows for approximately 2,900 kilometres, eventually merging with the Ganga before emptying into the Bay of Bengal. It is among the highest and deepest rivers in the world. In Tibet, it is known as the Yarlung Tsangpo. The river travels eastward for nearly 1,625 kilometres across the Tibetan Plateau, at an average altitude of 4,500 metres. It flows through dry, flat terrain and is fed by tributaries such as the Raga Tsangpo and the Lhasa River.
After entering India through Arunachal Pradesh, it is called the Siang. It then flows south and southeast into Assam, where it becomes the Brahmaputra. In this region, it is joined by several major tributaries from both sides, including the Lohit, Subansiri, Burhi Dihing, Kopili, Jia Bhareli, Manas, and Gangadhar. The river widens into a large valley, marked by heavy erosion and sedimentation. Majuli, the world’s largest river island, lies within the Brahmaputra in Assam.
Majuli island on the Brahmaputra in Assam. Credit: The Itinerant Analyst.
In Bangladesh, the river takes the name Jamuna. It is joined by the Teesta River before meeting the Ganges (Padma River) and eventually flows into the Bay of Bengal.
But beyond its cultural and ecological significance, the Brahmaputra is also central to regional geopolitics. There is growing concern over a cascade of dams that China is planning to build on the Brahmaputra in Tibet. China currently has 11 proposed hydropower projects on the river and many more across the Tibet Autonomous Region.
The Brahmaputra became a pressing issue after China officially began construction of the Medog Hydropower Station on July 19, 2025. This will be the world’s largest hydropower project.
The Medog hydropower station: site, structure, and strategic weight
The Medog hydropower project is planned in Tibet, near the Great Bend of the Yarlung Tsangpo River, close to Namcha Barwa. Here, the river makes a violent U-turn and plunges more than 2,000 metres in elevation within a short distance, one of the steepest river descents in the world.
The Great Bend of the Yarlung Tsangpo River near Namcha Barwa in Tibet, where the river dramatically changes course before entering India as the Brahmaputra. Credit: ThePrint.
The project is expected to generate up to 60 gigawatts (GW) of electricity, nearly triple the capacity of China’s Three Gorges Dam (22.5 GW), which itself slowed the Earth’s rotation by 0.06 microseconds, according to NASA researchers. The scale of Medog is staggering. Bloomberg reported that the project would use more steel than 116 Empire State Buildings and enough concrete to build a two-lane highway around the Earth five times. Engineers plan to drill tunnels from the top of the canyon down to its base, channelling water through turbines before returning it to the river’s course. While marketed as a low-impact design, the plan risks draining one of the Brahmaputra’s most ecologically rich stretches. It also means introducing heavy construction into a highly sensitive seismic zone, just 153 miles from the epicentre of the devastating 1950 Assam-Tibet earthquake.
The idea was first floated in China’s 2021 five-year plan. It was quietly approved in December 2024, with no public debate and little transparency. Environmental reviews and relocation plans, if any, have remained behind closed doors. Yet rumours of damming the Great Bend long predate Xi Jinping. For decades, China has eyed this remote location for its immense hydropower potential.
The material demands of the Medog project are extreme. It will consume an estimated 50 million tons of cement, 6 million tons of steel, 250 million tons of sand and aggregate, and 500,000 tons of copper. Hundreds of thousands of tons of explosives will be required. Harsh high-altitude weather will accelerate wear on equipment like drill bits, adding to construction costs and complexity.
Despite the terrain and risk, the project is expected to drive 3 trillion yuan in investment over the next 10 to 15 years. It will be developed by the Power Construction Corporation of China (PowerChina), a state-owned enterprise. According to the Chongyi Water Resources Bureau, the final cost could reach 1 trillion yuan, or USD 127 billion.
The risks downstream
The dam site lies in one of the deepest and most remote gorges in the world, within a highly seismic zone marked by frequent landslides, intense rainfall, and rapid erosion. The strongest earthquake ever recorded on land struck just 300 miles from the proposed construction area. Building the Medog dam will require extensive infrastructure, including high-capacity access roads, long tunnels, and complex slope reinforcement systems, in a region that remained inaccessible by road until 2013.
The Brahmaputra River’s route from Tibet through northeast India into Bangladesh, where it joins the Ganges before flowing into the Bay of Bengal. Credit: Map data © OpenStreetMap contributors, ODbL; map tiles © CC BY-SA 2.0.
The area is also an ecological hotspot. Medog lies within the Eastern Himalayan biodiversity zone, home to dense forests and rare species. According to Article 32 of China’s Regulations on Nature Reserves, no production facilities are allowed in core or buffer zones. Yet, the dam is set to be built within protected areas, disregarding both domestic environmental laws and international commitments.
The International Campaign for Tibet (ICT), an NGO, reports that the project will forcibly displace over 24,217 people living within a 50-kilometre radius of the site. These communities, mostly Tibetan, have lived in harmony with the river for generations. Downstream, the impact could be even more severe, more than 130 million people in India and Bangladesh rely on the Brahmaputra for their livelihoods and water security.
A United Nations report on the project states, “Today, many rivers in the Tibet Autonomous Region (TAR), China, along with the livelihood of Tibetan communities, remain under constant threat due to rapid expansion of hydropower projects. Under the argument of promoting energy transition in the face of climate change, the Chinese government, with its large hydropower industry, is promoting a new wave of large hydropower dams in the Tibet Autonomous Region. Despite the existence of less impactful renewable energy options, China’s relentless pursuit of large-scale hydropower disregards the ecological, social, and human costs.”
While China is known for its engineering feats in some of the world’s most difficult terrain, the risks cannot be ignored. The 1975 Banqiao Dam collapse killed more than 26,000 people, a reminder that even the most advanced infrastructure can fail, with catastrophic consequences.
China’s case for the Medog dam
China’s continued push for dams on Tibetan rivers is driven by rising demand for water and electricity amid shrinking natural resources. About 80 per cent of China’s water is located in the southern and eastern regions, supporting 64 per cent of the population. In contrast, the more arid northern and western regions, though vast in size and home to 36 per cent of the population, have far less water per capita (2020; Ministry of Water Resources, China).
Eastern China enjoys roughly 6,147 cubic metres of renewable water per capita. Western and northern provinces often have less than 5,049 cubic metres per capita, contributing to chronic water scarcity. More broadly, China must support 20 per cent of the world’s population with less than 8 per cent of global freshwater. Water has become both a strategic asset and a point of vulnerability.
Northern megacities like Beijing and Tianjin, along with major agricultural zones, face intense water stress and recurring droughts. China’s South-North Water Transfer Project, designed to move water from the Yangtze basin to drier northern regions, reflects the scale of its resource imbalance. The planned hydropower dam on the Yarlung Tsangpo fits into this broader strategy, aiming to secure water and energy for water-stressed provinces.
With a planned capacity of over 60,000 megawatts, the Medog project would become the world’s largest hydropower plant. It supports China’s climate goals by expanding zero-emission electricity and providing power to Tibet and underdeveloped areas in western China (Guruswamy & Singh, India-China Relations).
The dam would also expand water storage capacity, regulating seasonal flows and helping mitigate shortages intensified by climate change. Through the downstream infrastructure, it is expected to support water delivery to northern and western provinces.
India’s concerns and counterplans
The Chief Minister of Arunachal Pradesh, Pema Khandu, and several indigenous groups have warned that the Medog dam could act as a “water bomb,” where sudden or deliberate releases upstream in Tibet could devastate villages, farmland, and lives downstream. While Arunachal Pradesh and Assam have early warning systems, they are not designed to withstand large-scale dam failures from across the border.
In response, the Indian government has revived twelve long-stalled hydropower projects in Arunachal Pradesh. In August 2023, it signed agreements with NEEPCO, SJVN, and NHPC to execute these projects.
The centrepiece of India’s strategy is the proposed 11,000 MW Upper Siang project in Arunachal Pradesh, which would be India’s largest hydropower dam. Framed as a counter to China’s project, it faces delays due to strong local opposition over environmental and livelihood concerns.
Despite being proposed years ago, the Upper Siang project remains without a final dam site. Tensions escalated in May when villagers at Parong, one of three proposed locations, forced NHPC officials to withdraw and damaged survey equipment. NHPC, tasked with preparing pre-feasibility and detailed project reports, is now assessing three potential sites: Parong, Dite Dime, and Ugeng.
The Himalayan ecosystem is already under pressure from climate change. A dam-building race could tip the balance, causing irreversible damage. Bangladesh, which relies on the Brahmaputra for over 65 per cent of its annual water supply despite having only 8 per cent of the basin within its borders, may face the harshest downstream impacts.
Local communities are caught between national energy ambitions and transboundary water tensions. Sacred ecological zones are under threat. Democratic consultation processes are being bypassed. International law allows downstream countries to demand a joint Environmental Impact Assessment (EIA) when upstream projects affect their territory. India could use this provision to push for greater transparency and accountability from China.
An analysis by the United States Institute of Peace notes that while military clashes have occurred within the Brahmaputra basin, the risk of water conflict remains low. One reason is that China contributes less to the river’s overall flow than is commonly assumed. Most of the Brahmaputra’s volume is generated within India, not Tibet.
Estimates vary. The Government of India places China’s contribution at 7 per cent, while the Food and Agriculture Organisation (FAO) puts it closer to 30 per cent. Both figures are flawed. India’s estimate includes only the mainstem flow, while the FAO’s one includes both the mainstem and tributaries entering from Tibet. Assam Chief Minister Himanta Biswa Sarma recently stated that the project will have little impact on India. China contributes about 30–35 per cent of the flow, while the remaining 60–65 per cent is generated in India. China’s share comes mainly from glacial melt and rainfall in Tibet. India’s contribution includes torrential monsoon rainfall in Arunachal Pradesh, Assam, Nagaland, and Meghalaya, and major tributaries like the Subansiri, Lohit, Kameng, Manas, Dhansiri, Jia Bhareli, and Kopili. Inflows from the Khasi, Garo, and Jaintia Hills via the Krishnai, Digaru, and Kulsi rivers also add volume.
Another emerging factor is China’s growing outreach to Bangladesh. Any perceived weaponisation of the river could backfire diplomatically, strengthening India’s hand in Dhaka.
India, for its part, does not rely heavily on the Brahmaputra for agriculture due to the region’s high rainfall. Even proposed inter-basin water transfers would have a limited effect given the river’s size. Climate models suggest that while glacial contributions may decline, overall basin flow could increase due to intensified monsoon patterns.
Diplomatic exchanges over the Brahmaputra
China’s decision to build the Medog Dam on the Yarlung Tsangpo without consulting downstream countries has heightened regional tensions. China has taken a similar approach on the Mekong, where it built several dams without consulting Myanmar, Laos, Thailand, Cambodia, or Vietnam, through which that river also flows.
India and China signed two agreements in 2008 and 2010 under which China provides India with hydrological data, specifically water levels and rainfall, twice a day between June 1 and October 15 at three monitoring stations in Tibet. In 2013, both countries signed another memorandum of understanding (MoU), expanding the data-sharing window to May 15 through October 15 each year.
While China shares this river flow data with Bangladesh free of cost, it charges India an annual fee of USD 125,000. These arrangements help India prepare for monsoon-season flooding but remain limited in scope.
There is still no formal treaty or agreement on the broader issue of water sharing between the two countries. The absence of such a framework leaves downstream countries exposed to unilateral decisions made upstream.
Conclusion
China’s Medog hydropower project marks a turning point. Its scale, secrecy, and location in a sensitive zone raise serious concerns for downstream countries. India’s counterplans in Arunachal Pradesh remain stalled, highlighting the difficulty of balancing national security, environmental responsibility, and local consent. Bangladesh stands to face the harshest consequences, despite its limited voice in the debate.
The future of the Brahmaputra will depend on whether the region’s governments choose unilateral infrastructure or cooperative governance. Without transparency, environmental safeguards, and regional dialogue, the river’s role as a source of life may be undermined by the very projects meant to harness its power.