One of humanity’s largest ever projects is slowing down the spin of the Earth, making our days slightly longer.
Work on China’s Three Gorges Dam, the largest power station in the world, wrapped up in 2006. Located on the Yangtze River, just west of the city of Yichang in Hubei province, the project took 17 years and cost $37 billion to construct.
The purpose of the Three Gorges Dam
The hydro dam now generates around 0.54 Twh of electricity a day, enough to power 5.4 million households for one month.
Not only does it power communities, but the Chinese government said Three Gorges was essential to stop continuous devastating floods across lower lying lands.
However, some 1.5 million locals were forced to leave their homes as 13 cities and 140 towns in the country were flooded for the project to become a reality. And now, the country has proposed an even larger hydro dam across the Yarlung Zangbo River which could be three times as powerful as the Three Gorges.
This has worried environment experts; especially when you consider the impact Three Gorges has already had on our planet…
NASA’s worry over Three Gorges Dam
The US space agency was concerned about a number of factors, including disease, pollution, landslides and seismic activity issues.
NASA explained on its Earth Observatory website: “The epic scale of the dam project is matched by the level of controversy it continues to generate.
“Concerns about major environmental impacts, the relocation of 1.2 million people, and the flooding of 13 cities, more than 1300 villages, archeological locations, and hazardous waste dumps were raised throughout the planning and implementation.
“Environmental concerns include increased seismicity from the loading of the water, landslides, changed ecosystems, accumulated pollution, increased chances for waterborne diseases, and salinity changes in the Yangtze estuary.”
As if that wasn’t enough, the dam has also impacted the rotation of the Earth as it travels through the universe.
NASA explained that major changes to where mass lies on Earth can have small influences how our planet spins – known as its inertia.
How the dam slowed the Earth’s spin
Dr Benjamin Fong Chao, a geophysicist at NASA’s Goddard Space Flight Center, explained that the giant dam has a capacity of 40 cubic kilometres.
That’s the equivalent of 10 trillion gallons of water – similar to the amount of mass that was shifted in the 2004 Indian Ocean earthquake and tsunami, which registered at 9.1 on the Richter scale.
NASA said that that earthquake decreased the length of day by 2.68 microseconds.
In contrast to that, the space agency states that when the Three Gorges Dam is at its fullest point, it actually creates a really small resistance to Earth’s spin – making the day longer.
Dr Chao’s own calculations say it would increase the length of a day by 0.06 microseconds as well as move the pole position of Earth by roughly two centimetres.
While these changes might be marginal – and can be triggered by natural disasters – surely it serves as a warning to be careful what we do on our planet…
