How does the world’s largest dam subtly alter time on Earth?
Nearly 20 years after construction was completed, the Three Gorges Dam, the world’s most powerful dam located in China, continues to fascinate scientists and engineers, not only with its crazy figures, but also with its more surprising impacts on the planet. A recent NASA study reveals that this gigantic structure could even influence the Earth’s rotation.
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The grandeur and colossal impact of the Three Gorges Dam
The Three Gorges Dam, an engineering feat located in China, stands 185 metres high and stretches 2,335 metres in length. Its retention capacity is staggering, capable of storing up to 40 km³ of water (a mass of 40 billion tonnes of water). It is this immense quantity of stored water that scientists believe has a measurable effect on our planet’s rotation.
Scientific discovery: an influence on the Earth’s rotation
Benjamin Fong Chao, a geophysicist at NASA’s Goddard Space Flight Center, has conducted research showing that the dam has a tangible effect on the Earth. Similar to the consequences of major events such as earthquakes, the colossal weight of the water held back by the dam alters the Earth’s mass distribution and, consequently, its moment of inertia, slightly affecting its rotation.
The principle of inertia explained
The phenomenon observed at the Three Gorges Dam can be compared to an ice skater accelerating his rotation by bringing his arms towards his body. In 2004, the displacement of tectonic plates following a major earthquake had already measurably altered the Earth’s rotation. By holding back a considerable mass of water, the dam has a similar, albeit more modest, effect.
Measured impact: minimal but significant displacement
According to Chao’s calculations, the displacement of this mass of water shifts the Earth’s poles by around 2 centimetres and extends the length of a day by 0.06 microseconds. This change is tiny, but it adds to other global factors such as global warming and melting ice, which concentrate more mass around the equator.
Future implications for time measurement
Scientists predict that the accumulation of such changes could necessitate a periodic adjustment of the duration of minutes and seconds in our clocks. The proposal under discussion is to remove one second from the minute every four years, thus more accurately reflecting the real duration of a terrestrial rotation.
The 3 Gorges Dam in figures :
Location: On the Yangtze River in China’s Hubei province
Type: Concrete gravity dam
Dimensions:
- Length: 2,309 metres
- Height: 185 meters
Reservoir :
Capacity: 39.3 billion cubic metres (i.e. 40 km³)
Surface area: 1,084 km²
Length: 660 km
Hydroelectric power station :
- Installed capacity: 22,500 MW
- 32 turbines of 700 MW each
Annual production: 84.7 billion kWh
Locks :
- 5 successive locks for ships up to 10,000 tonnes
- 1 boat elevator for ships up to 3,000 tonnes
Construction :
- Start of construction: 1994
- Commissioning: 2003-2008
- Cost: Over 17 billion euros
Objectives :
- Power generation
- Flood control
- Navigation improvement
Impacts :
- Displacement of around 1.5 million people
- Modification of the river ecosystem
- Submergence of numerous archaeological sites
This article explores the surprising impact of the Three Gorges Dam on the Earth’s rotation, highlighting how a human construction can interfere with our planet’s natural rhythm. Despite its minimal effect, this discovery raises important questions about the long-term implications of large-scale construction and its management in an era of climate change.
Source: Wearewater.org
