Three Gorges Dam Pros and Cons

Three Gorges Dam is an extremely grand project in China, which has drawn both supporters and opponents. There are some advantages as well as disadvantages of this great dam, and the argument about Three Gorges Dam pros and cons has lasted for years. Here are the main concerns.
 

Among all the Three Gorges Dam pros and cons, its flood control capacity is the most controversial. It is true that Three Gorges Dam has a great ability to adjust and restore flood with the reservoir capacity of 39.3 billion cubic meters, which could reduce the damage of Yangtze River flood, especially for the section in Hubei.

However, a large amount of cobblestones are brought from the upstream and accumulate in the bottom of Three Gorges Reservoir, which are difficult to remove. As time goes by, more and more cobbles will accumulate, resulting in less water capacity and weaker flood control capacity. Meanwhile, sand and mud are blocked upstream so that the clearer flowing water in downstream erodes banks more easily, which can lead to bank collapses and causes floods.

 See also: How does the Three Gorges Dam work in Yangtze River flood control?
 

After Three Gorges Dam was constructed, the upstream river becomes deeper and wider, thus the navigation condition is greatly improved, the annual navigation time is prolonged and the navigable ships become larger. It was once reported that ten-thousand-ton ships could easily get to Chongqing from Shanghai when the water level of Three Gorges Project reached 175 meters (192 yards).

But there are numerous bridges over Yangtze River. The distance between bridges and water surface does not allow large ships to pass at all. Moreover, the traffic demand for passing the ship lock of Three Gorges Dam has already exceeded the annual design of 100 million tons as early as in 2011. So, there is usually a long queue of ships that are waiting to pass the ship lock. It is normal for ships to wait for one or two days. If in a hurry or don’t want to wait, people have to unload the ship and transfer the goods by vehicles over dam expressway, which consumes time, man power and money.

 See also: Yangtze River Bridge: How many bridges are there over Yangtze?
 

This is one of the key causes of Three Gorges Dam pros and cons. Three Gorges Dam is a concrete gravity dam, and each dam block ensures its stability on its own gravity. Also, the entire dam was constructed with 27 million tons concretes, 290,000 tons reinforcing bars and 255,000 tons steels, which is like an impregnable fortress. It is said that only nuclear weapons could damage it.

Nonetheless, as a man-made architecture, Three Gorges Dam must have its structural weaknesses. As long as the most critical points of its mechanical structure were found, several hundreds kilograms of explosives could blow up the whole dam on purpose, needless to use any atomic bomb. In addition, Three Gorges Dam must be protected against war or terrorist attacks.
 

Three Gorges Dam has a long lifetime of over 500 years depending on its good quality. That’s to say, the dam would not be broken with five centuries. In this way, Three Gorges Dam is extremely great.

But in the aspect of making profits, Three Gorges Dam’s economic service life is only 50 years, even worse, 40 years estimated by a Canadian organization. After that, it will not be money-making to run Three Gorges Dam.
 

The construction of Three Gorges Dam changes the ecological environment of Yangtze River Basin. The down cutting effect of river water becomes more and more serious, making the water deeper so that the water level of the Yangtze and the lakes in middle and lower reaches drops down. Some lakes have shrunk, even lakebeds are exposed in dry season.

Because the ecological system has been changed, some water creatures suffer a danger of extinction, such as Yangtze hilsa herring, Chinese sturgeon, white sturgeon and Chinese alligator.

Except for the Three Gorges Dam pros and cons above, the construction submerged a large area and caused geographical differences from before as well, which leads to more frequent geological disasters such as landslides, mudslides and even earthquakes.
 

Three Gorges Dam can produce hydroelectric power of 100 billion kWh each year, which has been transmitted to almost 1/3 provinces of China. Hydropower is a clean energy. The operation of the Three Gorges hydropower station can reduce the emissions of hundred million tons of carbon dioxide, one to two million tons of sulfur dioxide, 300,000 to 400,000 tons of oxynitride, 10,000 tons of carbon monoxide and 150,000 tons of dust every year. From these data, the huge contribution of this hydropower station to the environmental protection is also definitely affirmed.
 

Before being flooded for the construction of Three Gorges Dam, the experts had tried their best to save the cultural relics as much as possible. They moved some to the new sites, transferred some to museums or took photos as a reference to later reproduction. But some sights were still partly flooded, such as White Emperor City, Shibaozhai (Precious Stone Fortress), Daning River Ancient Plank Road, and so on. Typically, White Emperor City on the hill became an island in the water. Other more sites were totally flooded. For example, inscriptions of White Crane Ridge, the most precious relics in Three Gorges, sank into water forever. It is a great pity that so many scenic sights have disappeared.

See also: Scenery Change after Three Gorges Dam Completed
 

Three Gorges Dam plays a role in irrigating using water stored in the reservoir. When the drought occurs, the water can be discharged to the downstream, thus people can draw water to irrigate their farmlands to ensure a harvest. On usual days, the water in Three Gorges reservoir can also be transferred to other places for irrigation and drinking through South-North Water Transfer Project, as long as water is needed.
 

Migration of 1.2 million people in Chongqing and Hubei is the biggest difficulty as well as the con of the Three Gorges Dam Project. The fund for migration covers 45% of the total investment. The migrants had to leave and watch their homeland being flooded. Some of them were relocated nearby outside the dam area, more were relocated far from their hometown in Shandong, Shanghai, Jiangsu, Guangdong, Zhejiang, Jiangxi, etc.

Further Reading
Three Gorges Dam Benefits: 5 Major Advantages

Problems Caused by Three Gorges Dam