How long is the lifespan of the Three Gorges Dam? )
“If the Three Gorges Dam is built, it will eventually be blown up”
This warning was not issued by Americans or Europeans, but by Mr. Huang Wanli, a famous Chinese water conservancy expert of. At the beginning, the number of people who opposed and abstained from the construction of the Three Gorges Dam was as high as 841, and Professor Huang Wanli was still chanting “the Three Gorges must never be built” before his death.
Why can’t the Three Gorges go up? What are your concerns?
The dream of building a dam on the Yangtze River began as early as the time of Sun Yat-sen. Obviously, everyone can realize the huge economic benefits of building a dam, not only to generate electricity, but also to prevent floods, aquaculture and greatly improve shipping conditions.
Professor Huang Wanli
With such a good prospect, what concerns do you have?
Of course, as a water conservancy expert, what Professor Huang sees is not just economic benefits, but a series of consequences after the completion of the dam:
1. The economic benefits of the Three Gorges Hydropower Station may not necessarily be Can recover its astronomical cost.
2. After the completion of the Three Gorges, the Yangtze River will slow down and even become a quiet lake. River sand will be deposited in Chongqing, and the waterway will be filled up, blocking Chongqing Port. The backwater will submerge towns such as Hechuan and Jiangjin, and tragedies will occur during the summer and autumn flood seasons.
3. Professor Huang believes that the limited water storage capacity of the Three Gorges cannot decisively change the occurrence of flood disasters in the Yangtze River.
These three are the most representative concerns. In addition, there are dam site subsidence, reservoir-type earthquakes in the reservoir area after water storage, and ecological environment impacts after water storage, such as methane emitted from the decomposition of submerged plants in the reservoir area, fish migration after the completion of the dam, etc. .
These issues have been repeatedly mentioned in the book “Yangtze River, Yangtze River: The Three Gorges Project Controversy”. From the 1950s, the earliest discussions of objections followed, and until the completion of the Three Gorges Dam, there were still many different voices.
The question is: Are these concerns happening?
The construction of the Three Gorges Dam began in 1994 and was completed in 2009. It lasted 15 years, with a total dynamic investment of 248.537 billion yuan, a total installed capacity of 22.5 million kilowatts, and an annual power generation of about 100 billion kilowatt-hours. So, have the things Professor Huang worried about happened since it was built 22 years ago?
1. Has the Three Gorges lost money?
“In 20 years, the Three Gorges Hydropower Station will only have labor costs, no electricity revenue, and the country’s financial resources will be unbearable.”
This is one of the arguments in the “Three Gorges Project Debate” that year. There is another saying that the investment per kilowatt of the Three Gorges Project is two or three times more expensive than that of large and medium-sized power stations in mountainous areas. In fact, it is very simple to prove whether to make money or not. Comparison of the total power generation of the Three Gorges Project and the on-grid electricity price:
The Three Gorges Project did not open until 2009Initiate electricity. In 2003, Zuoan Unit 2 was put into operation, which is one of the Three Gorges units. From 2003 to 2020, the total power generation of the Three Gorges has reached 1,399,229 GWh. If calculated on the basis of the on-grid electricity price of 0.26 yuan per kilowatt-hour, the Three Gorges Project has earned almost 363,799,540 yuan from 2003 to now.
It is estimated that many friends are considering whether the electricity in the Three Gorges will be free in the future. Of course, this is a commercial act rather than a public welfare act. What does it matter how much money you make as long as you operate in a market model? If it supplies electricity for free, what about other power stations? But you are also worried, because the maintenance of fixed assets with a total investment of more than 20 million in the Three Gorges and the maintenance of the Three Gorges reservoir area will also require a lot of money.
2. Is the Three Gorges siltation really serious?
One thing is certain, a large amount of floating debris in the Three Gorges Reservoir was washed into the reservoir area, but this does not mean that the siltation is serious. That’s sediment. From August 20, 2017, an observer published a report on the Three Gorges that the subsidence was smaller than originally estimated.
The average volume is 220,000 tons, but after water storage, it is reduced to only 40,000 tons per year. In addition, since the water was impounded in 2010, the sediment deposition in the Three Gorges Reservoir area has reached 1.168 billion tons, about 146 million tons per year, only 1/2 of the estimated amount. In addition, large-scale hydropower stations on the upper reaches of the Jinsha River and major tributaries such as the Yalong River and the Dadu River have been built
It is a joke that siltation affects navigation. However, after the reservoir area was impounded, some rivers did form new obstacles. For example, boulders that were originally above the water surface have become submerged reefs and need to be cleaned up. However, more than 100 shallows were also submerged and disappeared. A 5,000-ton single ship and a 10,000-ton fleet can directly reach Chongqing Port, which has become an important sea outlet in Southwest China.
3. Have floods increased?
Some people may think that the Three Gorges can be built once and for all, but it is not at all. The annual runoff of the Yangtze River is 960 billion cubic meters, and the storage capacity of the Three Gorges is 39.3 billion cubic meters, which can provide 31 billion cubic meters of flood control storage capacity. It seems that the storage capacity is quite large, but in fact there is a big difference between the flood season and the dry season of the Yangtze River. Moreover, the flood time history has the characteristics of large volume and flat peak, and the flood storage capacity can only suppress the peak value.
What do you mean? That is to say, the storage capacity of the Three Gorges is not enough to completely reduce flood storage, but it is mainly the cooperation of the middle and lower reaches of the embankment. In other words, the Three Gorges has no practical significance in fighting floods? It cannot be fully understood in this way. For example, the Jingjiang section is the most dangerous section of the Yangtze River, because after passing the Three Gorges is the Jianghan Plain, where sediment is deposited on the ground to form rivers, and the levee is even 6-10 meters above the ground. Once the embankment breaks, the consequences will be disastrous.
Jingjiang EmbankmentA bird’s-eye view of the Shashi section, not far away is the famous dangerous section in the past, and the current scenic spot – Guanyinyan.
In 1998, the maximum flow of the flood peak was 63,300 cubic meters per second, which occurred once in less than 20 years. The Jingjiang embankment is designed every 40 years. However, in 1998, due to the repeated back-and-forth of the warm and humid air flow in the south and the cold high pressure in the north, repeated precipitation occurred in the Yangtze River Basin, and the continuous flood peaks caused more than 9,000 main embankment dangers.
After the completion of the Three Gorges Dam, the storage capacity will be vacated before the arrival of the flood peak, so as to avoid the direct impact of higher flood peak flow on the downstream Youyou resource network. In the case of reducing the total flow, reduce the larger flow to ensure that it is within the safety range of the downstream embankment. For example, both 2010 and 2012 had a flow of more than 70,000 cubic meters per second, but they passed through safely.
The capacity of the Three Gorges Dam is also explained above. It can be slowed down but cannot be avoided. We cannot expect one Three Gorges Dam to solve all problems. Dam design is a compromise of multiple interests. It is impossible to increase the height of the dam infinitely, and it may exceed the bearing limit of the earth’s crust, and the consequences will be more serious.
As for other hidden dangers, such as water storage earthquakes, methane emissions, green energy such as hydropower, 100 billion kwh a year is equivalent to burning 319 Electricity generated by 10,000 tons of standard coal directly reduces carbon dioxide emissions by 85.8 million tons per year, which is much more meaningful than none.
The last ecological problem we care about does exist. It is difficult to design fish ladders in the Three Gorges Dam, so fish migration does encounter obstacles. For example, the Chinese sturgeon will spawn in the middle and upper reaches of the Yangtze River and the Jinsha River and other tributaries. After the completion of the Three Gorges Dam, a new spawning ground formed below the dam site, but it did not continue to take shape. However, supplementing artificially raised Chinese sturgeon is also an exception, and other fish migration problems will also exist.
The Three Gorges has been completed. How long is its lifespan?
No matter how different opinions are, the Three Gorges was built, and from various perspectives, it has brought a very positive effect. So what is its lifespan? How many years can it last?
1. Is the deformation of the Three Gorges Dam real?
2. Is it true that the life of the Three Gorges Dam is 50 years?
3. Is there a risk of the Three Gorges Dam breaking?
Limited to space, let’s discuss a few core topics that everyone is most concerned about. 1. The problem of primary deformation of the Three Gorges Dam in 2019. At the end of June 2019, the satellite photos of the Three Gorges on Twitter and other social media looked crooked, as if they had begun to deform after 10 years of operation.
The degree of deformation is already very serious, it seems to have been demolished, that is, within a year or two! This issue has been constantly detonated in the media, attracting the attention of the official media. But it is obvious that friends who have traveled in the Three Gorges during the same period have also refuted the rumors, and the Three Gorges Dam has not deformed at all. Is it better to see than to take more accurate satellite images?
On July 9, 2019, Zhongxin.com released a rumor titled “Deformation of the Three Gorges Dam”. Why can’t you stand? What is “elastic deformation”? “According to reports, if the dam has such visible deformation, problems such as cracking and water leakage will follow one after another, and it will collapse in a flood if it is not removed.
In addition, according to the data in April 2019 (the rumor period), the deformation index of the dam is within the allowable range (the dam is not a rigid body, and slight deformation is allowed). Academician Chen Houqun, who participated in the quality inspection of the dam, was interviewed Shi said that the displacement of the Three Gorges Dam is invisible to the naked eye.
So why is there distortion? It’s not a day or two since Google Maps has image processing problems. There are many stories about cars parked on the wall, planes flying to the sky, planes flying to the ground, and an island in the Pacific Ocean Wait. You don’t have to worry about it.
Is it true that the life of the Three Gorges Dam is 50 years?
I don’t know 50 years Where does the life of the dam come from. The design life of residential buildings is 50 years, which is a fact. Of course, this is different from life. But in 2014, the Ministry of Water Resources issued the “Rational Life and Durability Design Code for Water Conservancy and Hydropower Projects” ( SL 654-2014), clearly stipulates that the design life of the first-level backwater structure (dam) is 150 years.
It was completed in 2009 12 years, so the lifespan is still very long! Of course, like civil buildings, design life and service life are two concepts. Just like our Mars rover Zhurong on Mars, the design life is 3 Martian months, which is equivalent to 92 Earths day or so. But the question is really only 92 earth days?
Obviously, it needs maintenance. If it is not maintained, it may be in use It ends within the lifespan. If there is reasonable maintenance, the lifespan can even be doubled, such as the documentary “The World After the Disappearance of Human Beings”. If there is no maintenance, then a little crack may be the beginning of the collapse of the entire building.
The Three Gorges Dam is not a closed dam, but a smart dam, loaded with 5330 monitoring points, including normal vertical lines, inverted vertical lines, and tension lines , extensometer, precision gauge, static level, precision leveling point, bimetal standard, temperature steel pipe standard, multi-point displacement meter, bedrock deformation meter, drilling inclinometer and other monitoring equipment:
In April 2019, the cumulative vertical displacement of the dam foundation was between 1.45mm and 26.69mm, the settlement of the dam body tended to be stable, and there was no significant increase before and after impoundment; the horizontal displacement in the upstream and downstream directions of the dam was between -1.82mm and 28.70mm It is mainly affected by water level and temperature, and it changes periodically. Generally, it moves downstream every winter, moving upstream in summer. The distribution of vertical displacement and horizontal displacement is related to the height of the dam, which is larger in the middle of the riverbed and gradually decreases on both sides, which conforms to the deformation law of gravity dams, and the dam body is in an elastic state.
The total length of the dam is 2335 meters, and this deformation cannot be detected visually, let alone satellite photos!
But the dam always fails. How long can the Three Gorges Dam last?
The Hoover Dam was built in 1935. It has been 86 years so far. Will it crash? Yes, but certainly not now, the United States *** will always maintain. How long will it last? As far as human life goes, it’s pretty much semi-permanent.
The Three Gorges Dam was completed in 1994, and its design, cement, steel and other materials and design technology have greatly improved compared with the 1930s progress. Moreover, Sandouping, the dam site, is also a granite foundation. The Three Gorges is not in the seismic zone, and the geology is relatively stable, so there is no need to worry about the short life span.
May be withdrawn from active service due to military strikes, super earthquakes or floods. The former two are indeed possible, but the latter is unlikely to be swept away by the flood. As long as the dam is properly designed, it is possible that the dam will not collapse even if it overflows the embankment. For example, the Va Ion dam in northeastern Italy collapsed, and sediment rushed into the reservoir, blocking the entire reservoir area. The lake water rushed out and washed away downstream. The dam is actually intact, but it is useless.
What are the consequences of dismantling the Three Gorges Dam?
Whether it is demolished or repaired, it will affect the ecology. A long-term stable water flow will form a new ecology, and if it is demolished, the ecology will disappear, so this is an issue that needs to be discussed.
The other is that the benefits brought by the removal of the dam will disappear, such as new docks, new shipping Lines, new flood protection system, etc. Whether this is a heavy burden must also be considered. With global warming, the probability of heavy rain is increasing, and the Yangtze River without the Three Gorges will face an even harsher environment, so demolition is not considered. Even if there is, it will be rebuilt for purpose.
Why doesn’t China remove so many dams in the United States?
Another focused question, more interesting and poignant. Since the early 2000s, a large number of dams have been removed in the United States. A total of 87,359 dams can be found on the US Army Corps of Engineers’ National Inventory of Dams (NID). By 2015, more than 1,300 dams had been removed in the United States to restore river ecology.
On the other hand, we in China are building dams on a large scale, one after another on the Yangtze River and its tributaries. So, are we really ignoring China’s ecology? If you think so, it’s just someone else’s trap, because the dams that have been demolished in the United States have been built for too long, have been damaged, are difficult to maintain, and have exceeded their service life. If these dams are not removed, more severeheavy dam break.
America has a lot of new dams to build too! The key to not building a dam is not ecology. This is the result of comprehensive consideration. If you have any questions, you can find out whether the Americans plan to dismantle the Hoover Dam. After all, they are 86 years old, should they retire when they are old?