China builds mega-dam system in the harshest place on the planet

China is building its largest dam system ever along its longest river, part of a series of hydroelectric projects being built in one of the most remote and inhospitable regions on the planet.

The rivers targeted for the dam project have their source high in the mountains of Tibet, supplying water to one-fifth of the world's population. Among them is the Yangtze River , which is vital to China's economic goals . The Chinese government is pushing ahead with plans to build more than 10 dams along this stretch of the river.

" Major projects are being undertaken in one of the most earthquake-prone places on Earth," says Ruth Gamble, an environmental historian of Asia from La Trobe University, of construction activity in the area .

The construction of the Baihetan Dam alone required more than 10,000 workers, about 8 million cubic meters ^of concrete, and cost $31 billion. The dam has a maximum height of 289 meters and an arc length of 709 meters, generating 16,000 megawatts of electricity, twice the amount generated by the largest dam in the United States, the Grand Coulee Dam. However, it is only one of several dams built along the Yangtze River.

Bach Hac Than Dam.

China estimates that the upper reaches of the Yangtze River, known as Jinsha , which straddles the Tibet Autonomous Region and Sichuan Province, have the potential to generate 112 gigawatts of electricity. That is a quarter of the country's current hydropower capacity.

'People often say that China is the hydropower capital of the world and the southwest is the hydropower capital of China,' said Gamble . 'The country is trying to achieve net zero emissions and building hydropower projects will help them get there faster. It is the region with the largest concentration of hydropower potential in the world .'

The rivers that originate in Tibet 'fall' into the lowlands in a very short period of time. The kinetic energy from this can be harnessed for hydroelectric power. However, Gamble points out that the area has a lot of hydroelectric potential, but it is also very unstable geologically. Therefore, construction also involves many risks.

A section of the Jinsha River in Sichuan Province.

Dams on the Jinsha River are particularly vulnerable to severe impacts because of the highly mobile tectonic plates that intersect there, and the many fault lines that surround them. The largest dam on the river will be 239 meters high and the world's tallest rockfill dam, part of the Lawa Hydropower Plant project and is expected to cost $4.6 billion.

This will be a difficult project to complete because it is being built on the riverbed. To build it, the crew will need to stabilize the terrain by pouring rocks and concrete mixture into the 'jelly-like' bottom of the river. Meanwhile, giant concrete cliffs will be placed along the edge of the mountain to withstand landslides and avalanches.

Lawa Hydropower Plant Construction Site on Google Earth.

The 239-metre-high dam, Ms Gamble explained, would be made up of multiple concrete floors, each the size of a skyscraper, and would sit next to concrete cliffs. Furthermore, the dams are being built on unstable ground, surrounded by steep mountainsides in one of Asia's most earthquake-prone regions.

In 2007 alone, there were more than 100 earthquakes between the Sichuan Basin and the Jinsha River. And then in 2008, a major earthquake occurred in Wenchuan, in the Sichuan Basin. It was one of the largest earthquakes China has ever seen, killing more than 87,000 people. So if an earthquake were to strike a fault line along the Jinsha River, all the dams on the river could be destroyed.

If a major earthquake caused one of these dams to fail, it would be like a domino effect, Gamble explained . If they couldn't hold two dams together, each time one collapsed, the disaster would be worse .