The Three Gorges Dam, built on the Yangtze River in Hubei province, was first proposed in 1919 by Sun Yat-sen, the first provisional president of the Republic of China, as a way to control flooding on the Yangtze River and symbolize Chinese power. The dam took decades to build, and many media outlets claim that it will affect the Earth’s rotation.
Does it really change the Earth’s rotation? Reports say that the dam holds water 175 meters above sea level and weighs more than 39 trillion kilograms. This enormous weight will affect the Earth’s rotation due to its moment of inertia.
Simply put, the further the mass is from the axis, the higher the moment of inertia and the slower it will rotate.
What is “moment of inertia”? It is “a quantity that expresses the tendency of an object to resist angular acceleration, and is the sum of the products of the mass of each particle in the object and the square of its distance from the axis of rotation.”
Moderate The huge mass of water above ocean level increases the Earth’s moment of inertia, but the change in its rotation is reported to be only 0.06 microseconds, meaning that a day is now only 0.06 microseconds longer.
The dam has had some positive effects, such as controlling floods and generating large amounts of electricity. However, its construction has forced the relocation of 1.2 million people. The erosion of the reservoir has affected thousands of insects and fish species that live in its waters. Furthermore, the cost of building the dam has been estimated at $25 billion, with some estimates putting it at $37 billion.
In conclusion, NASA scientists have noticed that the Earth’s rotation fluctuates from time to time due to natural disasters, lunar influences, etc. Therefore, the changes caused by the dam are relatively insignificant in the grand scheme of things. However, we cannot overlook the fact that the Three Gorges Dam is the only man-made object to date that has the ability to singlehandedly affect the Earth’s rotation.
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