This summer, Sichuan Province, Chongqing City, and surrounding areas suffered from extreme weather, such as continuous high temperatures and drought. And the role played by the massive Three Gorges Dam attracted attention again.
At a press conference in late August, the Ministry of Water Resources of China stated that since July, most of the Yangtze River Basin, the longest river in China, has continued to have high temperatures and little rainfall. Therefore, the surface area of Dongting Lake and Poyang Lake decreased by 3/4 compared with June.
Poyang Lake is the largest freshwater lake in China, located in Jiangxi province. The lake connects to the Yangtze River through a channel that shrunk dramatically.
Dongting Lake is in northeastern Hunan Province, a flood basin of the Yangtze River. The lake on July 14 had plenty of water, and only a month later, it was completely dry.
On the Internet, users on social media took various underwater photos, as well as photos of dry riverbeds and ancient cultural relics that had once been submerged, which were shocking.
This drought increased people’s concerns about the Three Gorges Project on the mainstream of the Yangtze River.
Supporters of the project argue that the dam reduces the potential for floods downstream and supplies water when drought occurs. Can The Three Gorges Dam do that? We will study it right now.[End intro]
The multiplied water surface evaporation and bottom seepage of the upstream tributaries and the Three Gorges reservoir area are fundamental causes of the almost cut-off of the Yangtze River this summer.
Dr. Huang Guanhong, the eldest son of Huang Wanli, a professor at Tsinghua University, said that after the Three Gorges Dam was capped in 2003, the water level behind the dam rose from 135 meters (443 feet) above sea level to 175 meters (574 feet).
Since then, the waterway, which is more than 600 kilometers(373 miles) long and has an average width of one kilometer from the Sandouping Three Gorges Dam near Yichang to Chongqing, has been called the Three Gorges Reservoir. Therefore, it significantly increased the water surface area of the original Three Gorges, and the water flow was slow, so it significantly increased the evaporation from the river surface.
Upstream of the Three Gorges Reservoir is the group Jinsha Hydropower Station. It is to make up for the insufficient water storage capacity of the Three Gorges Reservoir during the flood season.
Not only did the CCP construct the Three Gorges, but they also constructed a massive reservoir in the upper reaches of the Yangtze River known as the “Jinsha River Tertiary Reservoir Complex.”
The group Jinsha Hydropower Station has 27 hydropower units with a total length of 2,308 kilometers (1400 miles). These dams planned and under construction on this big river divides the Jinsha River into sections of still water, and these reservoirs have formed a vast evaporative water surface.
Downstream, the tributaries’ water surface area flowing into the Yangtze River’s mainstream has also increased, thus significantly increasing the evaporation.
Besides, the entire Yangtze River Basin, which accounts for nearly one-fifth of China’s land area, has at least tens of thousands of reservoirs. Their water surface area together evaporates a lot of water vapor. For example, the 34-kilometer-long Xiaoshui River in Shimian County, Sichuan, has as many as 17 hydropower stations built or under construction, which means that there is an average of one hydropower station every two kilometers on the Xiaoshui River.
In addition, there are also small reservoirs in the tributaries. Therefore, little water is coming into the small lake, and the small reservoirs also seep, leading to water loss.
Another Tsinghua University professor’s findings show more clearly the impact of the Three Gorges Dam on the Yangtze river’s water flow.
As Radio Free Asia reported, Professor Zhou Jianjun found that before the Dam was built in 2003, the average annual water flow at Yichang on the Yangtze river stood at 450 billion cubic meters. But it had shrunk to just 400 billion cubic meters by 2016, a 50 billion cubic meters loss in 13 years.
Not only that, the matter is made worse when rainfall tends to decrease in places near reservoirs once rivers are overdeveloped.
The Dam has caused water loss and evaporation, contributing to the consequences of this year’s drought season. What about flood control functions? Experts say the historically high water levels in 2020 on the Yangtze and its significant lakes prove the Three Gorges Dam isn’t doing what it was designed to do.
The late famous water conservancy expert and professor of Tsinghua University Huang Wanli pointed out that the Dam’s construction cuts off the sand flow, increasing the upstream flood and causing frequent flooding.
After The Three Gorges Dam completion, the gravel and part of the sediment from the river channel of the Jinsha River and the Sichuan Basin will be deposited in Chongqing to form an underwater rockfill dam, blocking the Chongqing Port. The backwater will submerge Hechuan, Jiangjin, and other towns.
In this drought, we can see stones deposited at the bottom of the Jialing River in Chongqing.
Chongqing suffered heavily in the 2020 flood. The flooding consumed Ciqikou, an ancient riverside trading port near the Jialing River in Chongqing province.
The three Gorges Dam couldn’t control the flood then, contrary to what the state-run newspapers reported.
Flooding on the Yangtze River peaked in the middle of August in Chongqing and Sichuan Province. Meanwhile, the Three Gorges Dam, 280 miles downstream, reached its highest level since it began holding water in 2003.
Chen Guiya, the deputy chief engineer of the Changjiang Water Resources Commission, said, “Since the water level of the Three Gorges Reservoir is allowed to be kept between 145 meters and 175 meters, it has 22.15 billion cubic meters of storage capacity for flood control, which can have a direct influence on the flood control in the Jingjiang section and the Chenglingji section of the Yangtze River.”
Besides, stormwater pours into the Three Gorges Dam reservoir in the Yangtze’s middle reaches at more than 60,000 cubic meters per second.
Therefore, it must drain 38,000 cubic meters of water per second for the reservoir to be partially empty.
People in cities along the Yangtze River were already submerged and receiving more water from the Three Gorges Dam.
Therefore, floods had already caused at least $26 billion in economic losses as of August 2020. The New York Times reported that at least 63 million people had been affected, 54,000 homes were destroyed, and over 200 people had died or disappeared.
Reuters cited David Shankman, a geographer with the University of Alabama who studies Chinese floods, saying, “One of the major justifications for the Three Gorges Dam was flood control, but less than 20 years after its completion we have the highest flood water in recorded history.The fact is that it cannot prevent these severe events.”
Chinese geologist Fan Xiao has persistently voiced criticism of the dam. Fan said the storage capacity at Three Gorges amounts to less than 9% of average floodwater. Three Gorges and other major dam projects could worsen flooding by altering sedimentation flow down the Yangtze.
He added, “When people only consider using reservoirs to solve flood-control problems, they often overlook or even weaken the natural ability of rivers and their lakes to regulate floods.”
Due to limited storage capacity, the Three Gorges Dam only helps control flooding during normal years. To save itself when there is a heavy flood, it must discharge water, and the downstream area will suffer more damage.