China controls some of the largest rivers in Asia, experiences heavy rain and has vast stores of water locked in glaciers in the west. But despite these abundant resources, China has a water problem. While central and southern regions are quenched by massive rivers like the Yangtze, the northeastern megacities like Beijing and Tianjin have endured serious water scarcity as agriculture, industry and population size rapidly increased.

To address the imbalance, China has undertaken one of the biggest engineering projects in the world: rerouting the flow of one of the world's mightiest rivers and its tributary, and ferrying the water thousands of miles from the center and south of the country to the thirsty north.

Called the South-to-North Water Transfer Project (SNWTP), the vast system of canals, pipes, dams, reservoirs and pumps moves staggering amounts of water via two routes through central and eastern China.

"It binds into a single network four major river basins, six provinces, three megacities, myriad bureaucracies, and more than 700 million people," Michael Webber, a professor emeritus in the School of Geography, Earth and Atmospheric Sciences at the University of Melbourne who specializes in regional economic development in China, wrote in a 2023 journal article.

But even this is not enough to satisfy the water needs in the North: China is currently expanding these routes and is planning a third, western route for the project, which would snake through the Tibetan Plateau before feeding the water-parched north and east. The route is attractive to Chinese officials because the river-and-glacier-threaded plateau, dubbed the Water Tower of Asia, has abundant water resources and is the source of numerous major rivers.

However, experts say the routes could worsen conditions in parts farther south that provide the water. What's more, the Tibetan portion of the project has stoked fears and suspicion in neighbors, as unofficial plans swirl suggesting major transboundary rivers could be diverted away from other countries and further into China.

The huge plan is "unbelievable," Mark Wang, a professor of human geography at the University of Melbourne, told Live Science. "The proposals [have] underestimated the negative impacts — environmental, earthquakes, evaporation and economic cost," as well as the international impacts, Wang added.

Water imbalance

Construction of the SNWTP began in 2002. The eastern route has operated since 2013 and transports water from the mighty Yangtze from Yangzhou, near Shanghai, to the megacity Tianjin, which has a population of 15 million people. The central route, which goes from Danjiangkou to Beijing and Tianjin, began flowing the following year, carrying water from the Han River, or Hanjiang. Together, they have moved 21 cubic miles (88 cubic kilometers) of water more than 1,800 miles (2,900 kilometers) since they began operating, according to the Chinese government — more than double the maximum amount of water held in Lake Mead.

The motivation for this project is obvious: China must support nearly 20% of the world's population with just 6% of its freshwater reserves. And this water is not distributed evenly across the country. Northern China has nearly half of the country's population and more than half of its agriculture but just one-fifth of the country's freshwater reserves.

In some places, the imbalance is even more dramatic. Tibet, in the west, has 4.8 million cubic feet (136,800 cubic meters) of water per person, while Tianjin, in the Northeast, has just 3,990 cubic feet (113 cubic m) per person. The United Nations considers less than 1,000 cubic m (35,000 cubic feet) of fresh water available per person water scarcity and less than 500 cubic meters (18,000 cubic feet) per person as "absolute water scarcity." The average in the U.S. is 314,300 cubic feet (8,900 cubic m).

Water transfer

China has a long history of rerouting water to serve its needs. Parts of the eastern route, for instance, use the Grand Canal, which was first built in the fifth century B.C.

And the broad concept of transferring water from the south to the north was first laid out by Mao Zedong, China's first communist leader, in 1952.

"Control of water has been a key theme in Chinese history and mythology," Tom Harper, a lecturer at the University of East London specializing in Chinese foreign policy and international relations, told Live Science.

Currently, the eastern route, which stretches 715 miles (1,150 km) from the Yangtze River to eventually reach Tianjin, transfers around 4 cubic miles (15 cubic km) of water per year.

This water needs to travel 213 feet (65 m) uphill, meaning pumping stations have to raise the water along the route.

The central route, meanwhile, relies on gravity to channel around 3 cubic miles (13 cubic km) of water 790 miles (1,270 km) from Danjiangkou Reservoir, on the Han River in Hubei province, to eventually reach Tianjin.

The Danjiangkou Reservoir already existed before the commencement of the project, but it was significantly expanded to raise the water level — and required 350,000 people to be relocated as a result.

The routes are now key to providing water to Beijing and Tianjin. For example, around 70% of Beijing's water comes from the route, experts told Live Science.

Fixing the fixes

The Chinese government and many Chinese scientists have boasted that the project has increased the water supply to people in northern China, raised the groundwater table in northern regions, and increased economic activity and agriculture in the region.

A major part of the project also focused on improving water quality: Freshwater supplies in China are heavily polluted, which reduces the amount of drinkable water.

"These were reservoirs, these were rivers, these were groundwater resources that had severe pollution impacts," Darrin Magee, a dam expert at Western Washington University, told Live Science. "So in the south where we had abundant water resources, the quality tended to be very bad in some areas."

To rectify this, the SNWTP installed water-cleaning stations along the route and the government implemented measures to reduce water pollution, including shutting down or relocating hundreds of manufacturing businesses that dumped their waste into waterways along the routes.

Along the eastern route, "pollution was terrible," Wang noted. "The central government put in a lot of effort… and they have control of the pollution again in a short period of time," he noted, adding that the water quality has significantly improved along the routes.

However, experts have said that the massive project has damaged ecosystems, displaced hundreds of thousands of people and fueled saltwater intrusion into underground reserves in water-providing areas, as the Yangtze River's freshwater flow is reduced.

"When the South-North Water Transfer was being proposed, many, many Chinese scientists were also against it because you just create lots and lots of new problems, whatever you fix," Emily Yeh, a professor of geography at the University of Colorado Boulder who specializes in Tibet, told Live Science. "Why not conserve water instead?"

Other experts agreed. "The water problem in China, it's not just physical water scarcity, it's the structural problem," Wang said. The biggest driver of water consumption is farming irrigation, which is water-intensive and leads to significant water loss. Conserving that water would go a long way to alleviating water scarcity, Wang added.

If China's "first priority is conservation, you won't need a large-scale, world's largest mega project," Wang said. Chinese authorities seem to be realizing this. They're also attempting large-scale water conservation policies, Wang said.

But the country is forging ahead with engineering projects.

The SNWTP's sources, particularly along the Han River, have less water per capita than the world's average, so siphoning off large amounts of the river's water could severely strain local areas. This has become such a problem that Chinese authorities are now undertaking even more engineering projects to alleviate the problem caused by the SNWTP. For instance, a new, smaller diversion is being added near the Danjiangkou reservoir, because people downstream are not getting sufficient water, Wang said.

The central route is further being extended to improve Danjiangkou's water levels. The central route relies on gravity, so a high water level is required for the route and the reservoir's dam to function. If water levels dip too low, as happened in 2011 during droughts, the dam stops working. So, engineers are connecting the Danjiangkou reservoir to the Three Gorges Dam, the world's largest dam, on the Yangtze, to increase the water supply.

The project is "a fix to fix the fix to fix the fix," environmental researcher Stevan Harrell wrote in the Made in China Journal — emphasizing the ever-growing number of engineering projects to deal with poor water governance.

Western route

Even though the two existing routes provide vast amounts of water to the North, and other water-conservation measures are being rolled out, Chinese authorities say the supply to the North is still not enough to meet demand, and that more water diversion is necessary.

The SNWTP's planned western route through the Tibetan Plateau won't start operations until at least 2050, but since its earliest planning stages, it has been mired in controversy.

The western route's official path would take 4 cubic miles (17 cubic km) of water per year from the Tongtian, Yalong and Dadu rivers — all tributaries that eventually feed into the Yangtze. The route would cross about 190 miles (300 km) of the Tibetan Plateau to the Yellow River, which then flows to the water-scarce north and east. The government has commissioned more feasibility studies for this route as part of the country's newly announced five-year plan.

The construction of such a massive project is fraught with difficulty. The Tibetan Plateau rises 10,000 to 15,000 feet (3,000 to 4,500 m) above sea level. These high altitudes present several problems, such as challenges in construction and maintenance, and difficulties in preventing water from freezing.

To transfer water across the plateau, the route would require pumping stations, along with a series of 300- to 1,000-foot-tall (100 to 300 m) dams, which would rank among the tallest dams in the world. The project would also require cutting 200 miles (300 km) of tunnels through the mountains, including the Bayan Har Mountains, which separate the upper Yangtze and Yellow River drainage basins.

The Tibetan Plateau is very seismically active, meaning earthquakes could lead to collapses or landslides, potentially damaging the vast infrastructure.

In 2018, Chinese scientists attempted to overcome the difficult terrain by transferring water through the air. But the "Sky River," or Tianhe project, ultimately proved unfeasible and has been effectively cancelled.

But China has not been deterred by these obstacles. The ongoing construction of the Dianzhong Water Diversion Project, in Yunnan province in southwest China, provides a test case for transferring water across mountainous, earthquake-prone landscapes. The damless design relies on a 380-mile-long (610 km) series of 58 tunnels, as well as pumps, to carry water through the mountainous and seismically active terrain. It is the "the world's longest water tunnel that could fit two high speed trains" and is "seen as a pilot demonstration project that will inspire and inform the design for the Western Routes," according to the Hong Kong-based think tank CWR. The first stage of the Dianzhong project is due for completion later this year, with a second phase recently announced.

Red flag

While the official western route has yet to break ground, alternative proposals have caused serious concern in neighboring countries. One unofficial plan developed in the 1990s, which politicians and academics subsequently considered completely unworkable, suggested funneling 48 cubic miles (200 cubic km) of water (four times the flow of the Yellow River) away from the Brahmaputra River, which flows into India and Bangladesh, and diverting the water toward the Yellow River basin, which serves the North and East of China.

A second controversial proposal, known as the Red Flag River project, suggests diverting 14 cubic miles (60 cubic km) of water 3,700 miles (6,000 km) from the Lancang, Nu and Yarlung Tsangpo rivers (called the Mekong, Salween and Brahmaputra rivers when they leave China) across the Tibetan Plateau to the northern Xinjiang region, which has high water stress and is facing desertification. Officials suggested the plan could turn Xinjiang into China's "California." The diverted water could also potentially be rerouted toward Beijing, experts told Live Science.

Some experts have called these "semi-official" proposals, as they have no official government backing but have been discussed openly by researchers with heavy government backing and support in China, which the government wouldn't allow if these people were truly speaking out of turn, Wang said.

Despite no official government backing, the plans have worried neighboring countries, particularly India, due to fears that any water diversions on international rivers could significantly reduce vital downstream supplies. Massive water engineering projects are already being built in Tibet, such as the upcoming Motuo megadam on the Yarlung Tsangpo — close to the proposed starting point for the Red Flag River project.

"There's a lot of concern that there might be water diversion, because China has been talking about this for many, many years," Tenzin Norgay, a researcher at the nonprofit organization International Campaign for Tibet, told Live Science. "If it happens, it's going to be a huge risk to downstream countries."

Researchers have calculated that the Red Flag project would likely siphon around 20% of the rivers' upstream flows, though the overall water loss for the whole of each river is less than that. Regardless of the actual amount of diversion, the lack of international consultations and transparency is exacerbating suspicions, experts told Live Science.

A changing climate

While China is forging ahead with attempts to redistribute China's water and reduce water scarcity via the SNWTP, climate change could scramble those plans. An increased risk of droughts over the coming decades could compromise the SNWTP's ability to move water.

The Tibetan Plateau, which is a source of water for almost 2 billion people, is particularly at risk. The world's "Third Pole" is rapidly warming, leading its numerous glaciers to melt. This could lead to sudden flooding, followed decades later by reduced river flow as the glaciers disappear. Desertification, meanwhile, is also impacting the Tibetan Plateau.

"Short to medium term, [we'll] see an increase in runoff as melting begins earlier each year," Magee said. "But over the long term, decreased snowpack means less secure water resources for most of China."

Taming nature

China's water management approaches include vast dam-building projects, cloud seeding, monumental tree-planting schemes and water-transfer projects, all of which rely on technological and engineering solutions to control the natural world, experts told Live Science.

When it comes to megaprojects, "If there's any country that will do it, it's China," Magee said. "The People's Republic of Engineers."

Other experts agreed. "It is part of this idea that you can engineer your way out of these problems, even if it's with trees rather than with machines," Yeh said. "A large-scale engineering approach to the natural world has been a characteristic of Chinese approaches to perceived or real environmental problems."

This is particularly true for the Tibetan Plateau. "The government is really imagining Tibet as a source of ecological service for the rest of the country," Yeh said.

Other experts agreed that Chinese authorities typically take an engineering approach to attempt to manage nature.

But Wang noted that China faces big pressures, which is why its government is looking for big solutions.

"If you understand China's energy issues, you understand why China is doing this. If you understand the water and food security issues, you understand so many things China has done," Wang said.

In southwest China, Chinese soldiers load and fire rockets toward the sky as aircraft and drones circle overhead, dropping their toxic cargo into the air. The weapons are not trained on an enemy, and the planes aren't dropping bombs. Instead, they are targeting the clouds hovering in the sky.

This footage is just a tiny snapshot of the massive, countrywide effort to seed the clouds with rain at an unprecedented scale.

More than 50 countries around the world use cloud seeding to modify the weather at small scales, including the United States.

But China is the world leader, employing around 50,000 people; using thousands of rocket launchers and dozens of planes; and investing the equivalent of billions of dollars in these initiatives, experts told Live Science.

In 2018, China embarked on its most ambitious cloud seeding plan. The Tianhe ("Sky River") project aimed to create a permanent airborne water "corridor" from one river basin to another on the Tibetan Plateau. The project was intended to be part of the country's much bigger South-North Water Transfer project — a massive effort to transfer water to China's highly populated and water-scarce North and East.

From the start, the Sky River faced scathing criticism from scientists who said the project was unworkable. Yet China forged ahead.

China's pursuit of such a scientifically questionable geoengineering technology shows just how far Chinese authorities are prepared to go to achieve the country's water and climate goals. It also reveals how the Chinese government views the natural world, experts have said.

"There is an impetus to control and to view the environment as a machine or an infrastructure that can be controlled," Emily Yeh, a professor of geography at the University of Colorado Boulder, told Live Science.

The science of cloud seeding

China uses cloud seeding to produce precipitation to build up snowpack, help alleviate droughts, reduce the impact of hailstorms, and create skies clear of clouds and pollution for official events — as it did most famously during the 2008 Beijing Olympics, experts told Live science.

But cloud seeding can't create rain from an empty sky. Instead, it causes existing clouds to generate precipitation more efficiently by injecting particles into a cloud. Water droplets then coalesce around these particles, and the water eventually falls as rain or snow.

"Every single drop in any cloud you have ever seen — there's a particle in it," Rob Rauber, an atmospheric scientist at the University of Illinois Urbana-Champaign, told Live Science. Cloud seeding speeds up the raindrop-forming process by introducing more particles, he explained.

There are two main ways to do this, depending on whether the temperature of the clouds is above or below 32 degrees Fahrenheit (0 degrees Celsius). Warm-cloud seeding is known as hygroscopic seeding, while cold-cloud seeding is called glaciogenic seeding.

"They have the same general goals or approach," Jeff French, head of atmospheric science at the University of Wyoming, told Live Science. "And that is to introduce something into the cloud that would increase the efficiency in which cloud droplets or ice crystals are able to grow to precipitation-size particles and fall out of cloud either as rain or as snow."

A salt such as sodium chloride is typically used for hygroscopic seeding to attract water droplets, French said. Glaciogenic seeding, by contrast, takes advantage of cold clouds' supercooled water — water that is liquid even when temperatures are below freezing — by introducing silver iodide. This substance has a similar structure to ice and collides with supercooled water in a cloud, causing it to freeze and eventually fall from the cloud, French said.

Scientists insert seeding particles into clouds in a number of ways, including by dropping them from planes and drones, firing shells or rockets into the clouds from the ground, or burning materials in chambers that release the combustion byproducts into the air.

Scientists are still learning exactly when and how to use these techniques most effectively. Rauber and French both noted that it's difficult to quantify cloud seeding's impact.

"It becomes kind of a quagmire when you ask that question: 'Does cloud seeding work?'," French said. For his research, he used airplanes, ground sensors and radar across the U.S. Mountain West to measure the effects of seeding from aircraft on the initiation and growth of crystals and eventual snowfall. "From a physical standpoint, I can say very confidently that cloud seeding works," French said.

However, that experiment was in cold, mountainous conditions, and the impact of cloud seeding depends on many conditions, so tracking whether cloud seeding increases precipitation over a longer period and in different conditions can be challenging.

"Not all clouds are created equal," French said. Some are colder or warmer, and the seeding material won't work as well; in others, the size or distribution of droplets makes precipitation less likely. Even within a small region, the snowfall varies tremendously from one point to another. And beyond a small region, all bets are off.

"If you have a very successful cloud seeding program, that is producing, maybe 7% or 9% or even 10% more precipitation over a mountain range, downstream of that mountain range, the impact may be 1%," French said. "But it is a really difficult number to get our arms around."

French added that scientists should be careful to not overpromise what cloud seeding can accomplish.

"If the promise is that cloud seeding is going to eliminate droughts even on a local level, the answer is no, it can't live up to that. There's no scientific evidence," French said. But if targeted properly, it can moderately increase natural precipitation, he said.

Cloud seeding on the Tibetan Plateau

Despite cloud seeding's limitations, China has established weather modification bureaus across the country.

"They have a whole campus of people who are working in the weather modification field," Rauber said. "They have a fleet of aircraft — they're on a whole different scale than anything that goes on anywhere else in the world."

Chinese researchers claim that the country has made huge strides in its weather modification. Reports from state-owned media suggested that weather modification efforts increased precipitation by 168 billion tons between 2020 and 2025, and that in experiments, just one cup of cloud seeding material generated 30 Olympic-size pools' worth of precipitation over an area the size of Yellowstone National Park in the arid Xinjiang region.

These weather modifications have also been conducted on the Tibetan Plateau. The vitally important region, nicknamed Asia's Water Tower, is the source of multiple major rivers that supply water to nearly 2 billion people across Asia. But the plateau is facing increasing desertification and glacier loss due to human-caused climate change and other human activities such as overgrazing animals.

China's cloud-seeding ambitions for the plateau reached a whole new level in 2018, when authorities announced the Sky River project. The controversial project aimed to use cloud seeding to create precipitation across a 620,000-square-mile (1.6 million square kilometers) area in the Tibetan Plateau — about the size of Alaska — to divert Indian monsoon rains above the Yangtze River basin and channel the water to the Yellow River basin. From the Tibetan Plateau, the Yellow River flows north and east into the parched northern regions of China, while the Yangtze flows south and east into less-water-scarce areas. The initial plan claimed the project would transfer up to 7% of the country's total annual water consumption, reports noted.

The atmospheric channel was intended to be part of the country's colossal South-North Water Transfer Project, circumventing the region's challenging terrain by moving the water in the sky instead.

The plan, due to be completed in 2025, called for seeding this atmospheric river using tens of thousands of silver iodide-burning chambers on the ground, linked to a series of meteorological satellites that would analyze the weather conditions. Information from these satellites would automatically trigger the burners when the conditions were suitable for cloud seeding.

However, the plan was immediately met with a barrage of criticism from scientists in China. In a translated statement, Hancheng Lu, a professor at the National University of Defense Technology's School of Meteorology and Oceanography, called the project "an absurd and fantastical project with neither scientific basis nor technological feasibility."

The project was unworkable because it is not possible to convert all atmospheric moisture to rain, or to channel moisture in this way, Yeh said.

As of 2022, researchers were working on a significantly scaled-back version of the project. However, China's official channels have gone dark on the topic.

China's newly announced five-year plan, which sets out the policy direction of the country from 2026 to 2030, references weather modification enhancements but doesn't mention this specific project, according to reports from Chinese media.

This has led experts to speculate that the project was quietly canceled.

"When one goes to China and asks atmospheric scientists not involved in it about it, they just sort of laugh, and it's like this embarrassing incident," Yeh said. "It was never possible."

To see whether the project was still going forward, Live Science reached out to several researchers involved in the project, but they did not reply by the time of publication.

The fears of cloud seeding

The pursuit of the Sky River project — despite the low likelihood that it would ever work —— has caused significant alarm in neighboring countries. India relies on the monsoon rains and rivers such as the Brahmaputra, which starts in the Tibetan Plateau before flowing through India and Bangladesh on a 1,800-mile-long (2,900 km) route to the sea. There are also suspicions about cloud seeding being used to cause flooding across borders.

Many of these fears are overblown, experts told Live Science. Rauber noted that cloud seeding can't influence weather enough to reduce water in a wider weather system.

"This is always a question of, 'Are you robbing Peter to pay Paul?'" Rauber said. But the amount of water in storm clouds "is way greater than anything cloud seeding is going to extract."

Climate geoengineering

China's all-in pursuit of technologies like cloud seeding — even on the internationally important and politically sensitive Tibetan Plateau — has raised concerns that China is prepared to go to extreme lengths to engineer its way out of its problems — even when it involves scientifically dubious geoengineering projects with massive risks.

China's determination to address climate change and investment in megaprojects that attempt to engineer the natural world, such as the upcoming Motuo megadam in Tibet and colossal tree-planting projects in northern China, are also signs that China is moving toward larger climate geoengineering, experts have suggested.

This may even involve attempts to change how much sunlight reaches the planet's surface, experts have speculated.

"Given similarities, weather modification could serve as a means to incrementally build legitimacy for solar radiation management, in China and beyond, which may ultimately make it possible to deploy it," researchers argued in a 2019 study.

However, there's no evidence that China is currently pursuing such climate modifications, and it's unlikely they'd do so without some cooperation or buy-in from other countries, researchers wrote in 2023.

"It is currently unlikely that China would deploy SRM unilaterally. But its weather modification programme does demonstrate the country's willingness and capability to undertake large-scale atmospheric intervention projects," the study authors wrote.

Solar radiation modification aims to release particles such as sulfur high into the atmosphere to reflect sunlight back into space in an effort to limit global heating. It is being increasingly investigated by researchers and governments. The controversial concept has never been demonstrated on a large scale, and studies suggest it has many potential risks, such as the potential to shut down monsoon rains.

Scientists have already seen some of the negative impacts of natural solar radiation modification, for instance in the aftermath of large volcanic eruptions, such as Tambora in 1815. "It led to the suppression of the monsoon, because the monsoon is driven by heating from the sun, Rauber said. "And that cuts back on rain in tropical areas, and that causes droughts, which causes all sorts of diseases and can lead to mass starvation," he added.

"The evidence from nature is don't mess with Mother Nature," he said.

Towering 14,800 feet (4,500 meters) above sea level, the Tibetan Plateau, with its frigid temperatures and glacier-covered mountains, is the source of most of Asia's major rivers — the Yellow, Yangtze, Yarlung Tsangpo (Brahmaputra) and Lancang (Mekong) — which supply almost 2 billion people downstream, including the two most populous countries on Earth: China and India.

For that reason, the Tibetan Plateau is often called the roof of the world, the third pole and Asia's water tower.

But in recent years, the region has also earned a new moniker: Asia's power tower, thanks to its huge, untapped potential for generating hydropower.

Faced with water scarcity in densely populated, industrialized and irrigated regions of China; an insatiable need for energy; and a drive to eliminate fossil fuel use, Chinese authorities are pursuing a number of hydropower projects in the region. Together, they will not only tap the region's vast power potential but also attain unprecedented levels of control over vital water sources its neighbors rely on.

The government's flagship project is the Motuo (also called Medog) megadam project on the Yarlung Tsangpo River. The project officially started construction in July 2025, and its costs are staggering — estimated at up to $168 billion.

The megadam is slated to be completed in less than a decade and will dwarf all other hydroelectric projects in the world with its estimated 300 terawatts of annual power output — three times the output of the Three Gorges Dam on the Yangtze, the world's current largest dam, and more than the entire U.S. produced in net hydropower in 2024.

The dam is just part of a bigger Chinese initiative to transform its environment.

"You have a modern, powerful China who is in a way very, very confident of taming nature," said Tenzin Norgay, a researcher at the International Campaign for Tibet (ICT), a nongovernmental organization that works to promote human rights and democratic freedoms for the people of Tibet. The ICT is closely monitoring dam building in the region. "That's literally what they are trying to do, right?" Norgay told Live Science. "They are trying to tame nature."

But the massive project comes with huge risks for both people in Tibet and the hundreds of millions of people in countries downstream, including those in India and Bangladesh, experts told Live Science.

"Controlling [the] nature of the water or the river itself is a danger for the entire Himalayan belt particularly for countries like India, Bangladesh and to some extent also Nepal," said Jagannath Panda, head of the Stockholm Center for South Asian and Indo-Pacific Affairs at the Institute for Security and Development Policy, told Live Science.

Project of the century

China is the world leader in dam building. The government has constructed around 98,000 dams and reservoirs across China, including 40% of the world's largest dams, and numerous dams outside the country as part of its Belt and Road Initiative. But this new project is different.

"There's nothing on this scale, and nothing close to it," Brian Eyler, director of the Southeast Asia and energy, water and sustainability programs at the Stimson Center think tank in Washington, D.C., told Live Science.

The project will utilize Tibet's unique geography to full effect. In the project area, the Yarlung Tsangpo River (known as the Brahmaputra in India and Jamuna in Bangladesh) flows through the world's deepest canyon, called the Yarlung Tsangpo Grand Canyon, and rapidly drops around the horseshoe-shaped "Great Bend," before continuing to flow down and into India and, eventually, Bangladesh.

The project will dam the upper section of the river and divert the water through a series of tunnels that will be cut through the 25,500-foot-tall (7,800 m) Mount Namcha Barwa, before returning the water to a lower section of the river, circumventing the Great Bend. The project will likely have five dams in total, with hydropower stations inside the tunnels. The water will drop 6,500 feet (2,000 m) within 30 miles (50 kilometers) of tunnels, thereby generating a huge amount of hydroelectric power.

"It's really incredible that this type of project can be built," Eyler added.

The cascading dam system will require huge amounts of water to run effectively, meaning there will likely be a reservoir at the beginning, and so during the dry season the Great Bend will effectively run dry, Eyler said.

Mega project, mega challenges

Building such a large project in this region is fraught with risk, experts noted.

The Tibetan Plateau is one of the most seismically active regions in the world, driven by the ongoing collision between the Indian and Eurasian plates. The region has recently been rocked by several major earthquakes, including the 7.1 magnitude Dingri quake in January 2025, which damaged five dams in the region, and the 7.8 magnitude Nepal earthquake in 2015 that damaged a fifth of the country's hydropower capacity.

Parts of the Himalayas are unsuitable for dam construction due to the high risk of seismicity and its effects, researchers have warned, noting that dams are particularly vulnerable to earthquake-induced landslides.

In addition to naturally caused earthquakes, large-scale projects involving land excavation, tunneling and water redirection have the potential to trigger seismic activity, while the creation of reservoirs has been strongly linked with earthquakes in China.

Other natural disasters could endanger people beyond Tibet.

Glacial lakes — bodies of water created by melting glaciers and permafrost — can pose a problem to people downstream if they suddenly release their water and overwhelm dams. This scenario happened in northeastern India in 2023, causing a large, newly built dam to catastrophically fail, killing at least 46 people and impacting 88,000 more.

Climate change is accelerating glacial melt, meaning the threat will only increase as the region's glaciers are further destabilized, experts have warned.

Climate change could also render the dam obsolete sooner than anticipated. Dams typically function for around 70 to 100 years, experts told Live Science. Water levels in the Yarlung Tsangpo are expected to peak in 2060, so when water levels start to fall after that, the whole dam could become useless during dry periods because the water level will be too low to produce hydropower — a status known as minimum pool elevation. Water levels could even drop so low that they can't pass through a dam. This situation, known as "dead pool," is already an issue for some dams on the Colorado River.

The project will also affect Tibetans. "From our viewpoint, displacement of people around that and submergence of cultural sites" are the biggest issues, Norgay told Live Science.

However, the area is sparsely populated, and the reservoirs needed will almost certainly not be as big or as deep as reservoirs of other megadams. So although there will be an impact, it won't be on the scale of the 1.3 million people displaced by the Three Gorges Dam, Eyler noted.

Downstream impacts

Even without a climate-driven reduction in water, the river's flow will be transformed. To ensure a continuous, controlled flow of water through the dam, authorities typically fill reservoirs during the wet season and release water during the dry season. While this ensures that the hydroelectric dam can function, it inevitably impacts the river's natural flow and has knock-on effects for communities downstream. The filling-and-releasing process also raises the possibility of the upstream country — namely, China — "turning off the taps" to benefit the dam at the expense of other downstream water users.

"If a dam operator has an opportunity to take water during a time of drought, they're going to take at the expense of downstream users," Eyler said. "We've seen this happen in the Mekong, where the downstream was suffering drought, but China still filled its reservoirs," worsening drought in 2019 in Thailand, Cambodia and Vietnam.

In the case of the Motuo megadam, any change in water flow will affect India and Bangladesh. The Brahmaputra flows for about 1,800 miles (2,900 km), eventually joining with the massive Ganges River, and is a vital source of water and natural fertilizer for more than 130 million people. It provides India with 30% of its freshwater reserves, while Bangladesh is heavily dependent on the river to support its irrigated agriculture.

"The greatest ecological and environmental impact will be related to sediment flow. The Great Bend itself is a rich provider of sediment to the downstream [countries]," Eyler said. "Sediment is important for agricultural production. It's a very inexpensive natural fertilizer."

Sediment from the Brahmaputra is integral to building up the Ganges-Brahmaputra delta, helping the low-lying region stay above rapidly rising sea levels. The delta is home to nearly 200 million people — including in the megacity of Kolkata — and is considered one of the places most at risk from sea level rise. The Yarlung Tsangpo in Chinese-controlled territory provides up to 50% of the river's downstream sediment flow.

"River deltas are built by sediment flows pushing land out into the ocean year after year," Eyler said. "And either the dams themselves or the lack of flow within the Great Bend will cause a great reduction in the amount of sediment coming down."

The potential reduction in sediment could threaten food security in the downstream countries.

"Millions of people's lives are dependent on this river," Norgay noted.

India also plans to build major dams on the waterway, Norgay added, which could itself have negative impacts downstream.

Not true "green power"

The Motuo megaproject is just one of several new dams planned or under construction in Tibet; the ICT counts at least 193 dams in the region that have been planned or built since 2000, when China embarked on a policy of expanding infrastructure projects in the region.

The surge in hydropower projects is intended to help China move away from fossil fuels, experts told Live Science.

"It is part of a more widespread strategic vision where China is trying to become more sustainable," said Tom Harper, a lecturer in international relations at the University of East London who specializes in China.

One key to China's strategic vision is phasing out coal.

"This dam has been described as the coal killer. There are numerous coal plants that can be taken offline as a result of this and retired permanently," Eyler said. "When you bring in China's carbon emissions reduction goals, through 2050, the dam makes a lot of sense."

However, hydropower is not as sustainable as it's often portrayed, and it has environmental impacts. Large dams can cause severe environmental damage to river ecosystems. The creation of reservoirs can also release greenhouse gases as trees and plants are covered with water and subsequently rot, though this is less of an issue in cold places like the Tibetan Plateau, Darrin Magee, a hydropower expert at Western Washington University, told Live Science.

Though the authorities claim there will be no significant environmental impact from the dam, that's hard to believe, Eyler said. "Typically, the larger the project, the greater the impacts, and this is the largest dam system ever created."

Scientists also question the necessity of using hydropower to meet sustainability goals, when the Tibetan Plateau has huge, untapped wind and solar power potential.

Experts had different theories of what China would do with such a vast amount of energy generated in such a remote and sparsely populated area.

"There's certainly no need for it, right now or in the foreseeable future in the area where Motuo Dam is sited," Magee said. "But China solves that problem by building ultra-high voltage DC transmission lines at, at a rate that no one in the world is matching." These high-voltage lines transport energy from the west to east, bypassing local grid networks, he added.

Norgay and Panda both think Tibetans are unlikely to benefit.

The power will likely be moved east to power Chinese industry, they said, and it could also align with the political goal of further integrating Tibet into China, Panda added.

Eyler, meanwhile, thinks it will be used to power data centers in Tibet, "which can be built around the super dam, in a naturally cool and cold environment."

Better cooperation needed

There is little official information about the megadam for Chinese authorities, Eyler noted, and the lack of transparency is fueling fears. For example, Indian politicians have expressed concern that the megadam will give China full control of the river, and that China could potentially weaponize ‬the river by deliberately reducing the flow of water or by releasing large amounts of water in one go, thereby devastating downstream communities. Some researchers have called this possibility a "water bomb."

Eyler, however, said that this risk is low, and that the dam system's design means it cannot hold back enough water to cut off supplies downstream.

"I don't think that there's some type of nefarious plot out there from Beijing to bring these countries to heel by controlling the upstream of the rivers," he said. "China's top priority is to develop its economy, bring stability to the country, and building large dams on rivers is one way to do that."

The expansion of hydropower is a key aim for China in the next few years, as the country embarks on the 15th five-year plan from 2026. With shared water resources in short supply, better cooperation among neighboring countries is vital, experts said. Yet China and India share only limited data, Panda noted.

Some of the concerns from neighbors could be mitigated by better communication between stakeholders, Magee said. "Be more transparent with the data, bring more voices into the conversation, have some realistic assessment of both need for the project and the impacts."

But even with better communication, the megadam and other upcoming dams means China will still largely control the region's water resources due to its upstream position.

"This is a dam project which actually gives China the upper hand," Panda said.