The dams are colossal engineering works that provide numerous benefits to the surrounding cities, such as energy and flood protection. However, they are often accompanied by national and international controversies. And no dam has acquired both renown (and controversy) and the Chinese dam of the three throats, one of the most titanic construction projects on the planet and the largest hydroelectric dam.
Its connected reservoir is capable of containing a volume of water so large that the rotation of the Earth has changed, extending the duration of the day by 0.06 microseconds.
The three throats. Built along the Yangtze River in the province of Hubei, it was planned in 1919 by the first president of the Republic of China, Sun Yat-sen, as a measure to control the floods of the river and generate energy. But, above all, to become a symbol of China’s power. Although its construction would not begin until December 1994 and would be put into operation in 2009.
It has more than 2 kilometers long and 182 meters high. When it is at its maximum point, it can contain 42,000 million tons of water. Suffice it to say that 510,000 tons of steel were needed to build it, which would be needed to erect 60 Eiffel towers.
What is it for? It has three objectives: flood control, hydroelectric energy production and improve navigation. Keep in mind that the three throats today generates 11 times more energy than the gigantic Hoover dam, the world’s largest power plant with 22,500 MW. And through 34 huge generators, supports a large part of the Chinese nation. In addition, it helps keep the Yangtze River, the third longest in the world, during the flood season protecting adjacent cities such as Wuhan, Nanjing and Shanghai.
It has slowed the rotation of the Earth. However, there is a Price to pay to store so much water. Once the dam reservoir, the weight of the dough, which is more than 39 billion kilos, is enough to slightly change the rotation of the earth. As? The inertia of the earth depends on its mass (water) and the distribution of that mass with respect to the axis of rotation. The axis of the Earth is an imaginary pole that crosses the center of the earth from “above” to “down”. The earth revolves around this pole and performs a complete rotation every day.
But as the dough is redistributed on the planet, this change slightly alters the rotation. And the greater the distance of a mass (relocation of the water from other areas to the Chinese reservoir) to its axis of rotation, the slower it will rotate, therefore it affects the duration of the earth days. To understand the phenomenon, it is only necessary to visualize the turn movement of an ice skater: if its mass is uniformly distributed (for example, collecting their arms towards the body), it will turn better and faster after a few laps. If the dough changes, rotation and turn also change.
The result. That means that raising 39 billion kilograms of water at 175 meters above sea level increases the inertia of the earth and, therefore, slows its rotation. However, according to NASA, the impact is minimal. Its scientists calculated that the change in such mass increases the duration of the day by just 0.06 microseconds and makes the earth just a little more round in the center and flatter in the upper part.
It has passed other times. In fact, hundreds of phenomena that alter that movement are produced every year. He tsunami that hit the Southeast Asia in 2004 or the 2010 Chilean earthquake They also affected the rotation of the planet. NASA then confirmed that the 2004 Indonesian earthquake had decreased the duration of the day by 2.68 microseconds.
What affects us? Nothing. Although it sounds very shocking, the reality is that we will not notice any change. Miguel Sevilla, deputy director of the Institute of Astronomy and Geodesia, He defended years ago in this information article That these phenomena “have no greater significance, apart from the large material and human damage they cause.” Although they serve to warn us of “the effects they have on people, buildings and in nature.”
Other controversies that do matter. In fact, beyond how this Chinese dam affects the rotation of the Earth, the project has been plagued by other controversies that do significantly affect the lives of humans and ecosystems. One of them is the amount of damage that causes the environment. It is estimated that 70% of China’s fresh water is contaminated and the dam could be worsening the situation, since it is based on old waste and mining operations facilities. Every year 265 million gallons of non -treated sewage are deposited in the Yangtze River.
On the other hand, when the project was built, 1.2 million people were forced to relocate in new homes. And currently, the Chinese government is still migrating people out of the area.
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