On July 18th, the Three Gorges Dam received the largest water inflow since the beginning of this year due to heavy rainfall in Chongqing, Sichuan, and other areas in the upper reaches of the Yangtze River. According to China’s “Regulations on the Numbering of Major Rivers”, this meets the standard for the flood to be assigned a number. The Three Gorges Dam water level has increased by 8.04 meters over the past two days.
After the Chinese official media reported on July 17th that the “Yangtze River Flood No. 2 of 2020” had formed in the upper reaches of the Yangtze River, the Three Gorges Reservoir’s water level rose rapidly, rapidly reaching 61,000 cubic meters per second at 8 a.m. on the 18th. At 6 pm on July 18th, the water level in the Three Gorges reservoir had reached 163.59 meters more than 18.59 meters above the flood limit.
The Three Gorges Dam started discharging water in order to protect the infrastructure, and on July 18th, it opened five more floodgates, making it the largest flood discharge this year. The discharge flow has reached 36,000 cubic meters per second.
According to experts from the Yangtze River Hydrology Bureau, they expect that Flood No.2 will reach Wuhan city in 4-5 days. The water level of the Yangtze River in the Wuhan has risen well above Wuhan city’s ground level, making it a veritable hanging river. While the average elevation of the city of Wuhan is 21 to 27 meters, the water level of the Yangtze River, on July 17th, in Wuhan has already reached 28.38 meters. Currently, Wuhan city is only protected by a large embankment along the river, and a video shows that water was seeping through, and if it collapses, Wuhan residents will be submerged in 3 to 4 stories of floodwater.
According to news circulating on social media, the flooding was caused by the embankment collapse of ching River in Enshu. The ching River is a tributary of the Yangtze River and the water feeds into it from downstream.
Since the Yangtze River increased its flood discharge, water from the Ching River could not flow out, which led to a rise in water levels throughout the basin. Coupled with heavy rainfall and flash floods in the mountains, the basin turned into a severely flooded zone and embankments collapsed.
Due to flood peak No.1, orange level flood warnings were issued for the middle and lower reaches of the Yangtze River such as Dongting Lake area, and Poyang Lake area. Wuhu city’s emergency flood control response was raised to the highest warning level on the same day as well. A video taken by Chinese netizens on July 17th shows that flooding has reached residents in Anching, Anhui province, and citizens have to use zodiac boats to go home.
According to the rainfall forecast released by the Yangtze River Water Information Network, heavy rainfall is still expected in the Yangtze River Basin from the 17th to the 20th.
The 100 or so reservoirs in the Three Gorges Project and the Yangtze River basin, and major hydrological stations in Poyang Lake and Dongting Lake all carry out joint commands.
The official Chinese Vice Minister of Water Resources, Ye Jianchun, had stressed at a State Council policy press conference on July 13th that the Three Gorges Dam is effective in controlling flooding.
However, Reuters reported that David Shankman, a professor of geology at the University of Alabama who studies flooding in China, said that while one of the main reasons for building the Three Gorges Dam was to prevent flooding, in fact, the dam cannot stop floods as severe as this year’s.
Fan Xiao, a Chinese geologist, also noted that the Three Gorges Dam reservoir holds less than 9 percent of the flood’s volume. “The Three Gorges reservoir can only partially and temporarily intercept flooding upstream, but it can do nothing to stop flooding caused by heavy rainfall in the middle and lower reaches of the Yangtze River. ”
He argued that the Three Gorges Dam and other major dam projects could make flooding worse by altering sediment flows in the lower reaches of the Yangtze river. The inherent need for engineered power generation for the dam also affects flood control. “When people only consider using reservoirs to solve flood control problems, they tend to ignore, or even undermine, the natural ability of rivers and lakes to regulate flooding.”
Taiwan’s Sanli Press website reported on July 18th that the flooding was getting more and more intense, and the flow rate at the Three Gorges Dam reached 61,000 cubic meters per second at 8:00 p.m. on that day. The dam is expected to receive a new round of incoming water on the 21st, can the dam really hold?