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The Day the Earth Began to Slow Down: Three Gorges Dam Effect

Clean energy is provided, but at what cost?


The remarkable (and somewhat contentious) Three Gorges Dam deserves more than simply the word "powerful." Chinese leaders have been under fire from scientists and environmental groups alike since the $30 billion project was disclosed. Many people believe that the dam will eventually fail and cause disaster. The dam is being criticized for trapping pollution, causing earthquakes and landslides, uprooting citizens (about 1.3 million people have already been displaced), and ruining historical sites as well as endangered wildlife habitats.

After years of labeling the dam one of the most outstanding achievements of engineering in Chinese history, the government ultimately admitted that the project was ill-conceived, but the harm had already been done. The dam, on the other hand, isn't all bad. Its final 32 generators (each capable of generating 50 MW of power) began operating at the end of July last year, and the gushing water produced has enough energy to generate about 22.5 million kilowatts (22,500 megawatts) of energy (estimates vary), which is roughly equivalent to 15 nuclear reactors.

It also doesn't cause concerns about radioactive materials being released, which is a good thing, especially after the Chernobyl and Fukushima nuclear disasters, so the negative effects of its construction can be overlooked by most, owing to the fact that it's a clean, efficient way of providing energy to a growing population.

However, the dam's consequences go far beyond its environmental impact and its potential to produce much-needed energy. It's also affecting the Earth's rotation.


Do you have any idea how a dam could affect the Earth's rotation? Here's a great resource that breaks it down even more:

In China's Hubei province, the Three Gorges Dam spans the Yangtze River. It will be the world's largest hydroelectric power station when completed, with a total capacity of 22,500 MW. When the water level reaches its peak, it will flood a total area of 632 km2. A total of 39.3 cubic kilometers (9.43 cubic miles) of water will be stored in the reservoir. More than 39 trillion kilograms of water will be produced (42 billion tons).

Due to a phenomenon known as "the moment of inertia," which is the inertia of a rigid rotating body with regard to its rotation, a movement in that mass will affect the Earth's rotation. An object's moment of inertia about a given axis expresses how difficult it is to change its angular motion about that axis. The greater the distance between a mass and its rotation axis, the slower it will spin. You may not realize it, yet examples of this may be found in everyday life. When a figure skater tries to spin faster, she will draw her arms tighter to her torso, reducing her moment of inertia. Similarly, a diver seeking to perform a faster somersault may tuck his body.

Raising 39 trillion pounds of water 175 meters above sea level will slow the Earth's rotation by increasing its moment of inertia. However, the effect will be negligible. NASA scientists determined that shifting such a mass would only add 0.06 microseconds to the length of the day and make the Earth only slightly more round in the middle and flat on top. It will also cause a two-centimeter movement in the pole position (0.8 inches). It's worth noting that a change in any object's mass on the Earth relative to its axis of rotation would affect its moment of inertia, albeit most shifts are too slight to notice (but they can be calculated).

But don't be concerned. The rotation of the Earth varies a lot, and there are a lot of variables involved. First, the Moon is progressively receding from the Earth, somewhat altering the Earth's rotation. Earthquakes, such as the 2011 mega quake in Japan, aid in the process (the same event shifted Earth's rotation by 2.68 microseconds). Furthermore, the duration of the day changes by around a millisecond every five years or so, which is about 550 times larger than the change caused by the Japanese earthquake.

Nonetheless, this knowledge raises a slew of intriguing issues. To put it another way, how far is too far? Individually, none of these factors make much of a difference, but when taken together, who knows? So, what are your thoughts on the subject?


About the Writers:

Maina Zaina, Writer and a Virtual Assistant at AVCreativity Studio. She enjoys media entertainment and is an avid fan of "K-Wave". She loves her job because she is exposed to different types of entertainment. She also believes in the saying "If you want to be successful, don't seek success - seek competence, empowerment; do nothing short of the best that you can do" by Jaggi Vasudev

Pamela Elizabeth, Editor-in-Chief at AVCreativity Studio. Earned a Bachelor’s Degree of Secondary Education Major in English. She loves going on little adventures alongside reading good books. She is enthusiastic about her work and ensures that her clients receive the finest service possible.

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