Three Gorges Dam: Grand project along the Yangtze

The Streaming Down the Yangtze team has arrived in Yichang, Hubei Province and visited the Three Gorges Dam, the world's largest hydropower station.

Three Gorges Dam.[Photo: IC]

The dam also helps to prevent floods and boost river navigation.

The team's passenger ship went through the dam on a vessel lift, as the dam separates the river with over 100 meter difference in water levels.

For more on this, we are now on the line with Yang Guang, CRI's reporter covering the trip. 

Tell us more about the Three Gorges Dam and its power producing capacity.

“A large dam across the Yangtze River was originally envisioned by Sun Yat-sen as early as in 1919, but it’s not until 1994 the construction of such huge dam was initiated and in 2012 the project was completed and became fully operational. Made of concrete and steel, the Three Gorges dam is over 2,300 meters long and the top of the dam is 185 meters above sea level. The project used some 460,000 tonnes of steel, which is enough to build 63 Eiffel Towers. The Three Gorges Dam is currently the largest power station in the world in terms of electric generating capacity, which is 22,500 megawatts. The electric it produces are transmitted to nine provinces and two municipal cities , most of  which on the east coast of China. For one year it produces around one trillion kilowatts of electricity, that’s nearly 5 percent of the electricity used nationwide annually. It is said the value of electric the dam produces is generated even more quickly than cash printing machine. The hydropower project also means it will limit greenhouse gas emissions. Hydropower saves the energy needed to mine, wash, and transport the coal from northern China. At full power, Three Gorges reduces coal consumption by 31 million tonnes per year, avoiding 100 million tonnes of greenhouse gas emissions.”

How does the dam function in flood control and water navigation?

“Flood has been a major problem for the seasonal river of the Yangtze. Millions of people live downstream of the dam, with many large, important cities like Wuhan, Nanjing, and Shanghai situated adjacent to the river. Plenty of farm land and China's most important industrial area are built beside the river. With the Three Gorges Dam being able to hold up the water flowing from upstream Yangtze, the water volume that could’ve been very big in flood seasons going into downstream can be controlled. The reservoir's flood storage capacity is 22 cubic kilometres. This capacity will reduce the frequency of major downstream flooding from once every ten years to once every 100 years. As well as major flood prevention, the dam is also intended to increase the Yangtze River's shipping capacity. With the dam , the water level of upstream Yangtze had been going up. In winter the water level would reach 175 meters above sea and in summer it keeps around 145 meters above sea. So the water depth of upstream Yangtze has increased, which means more heavy and big ships can navigate on the river. In this way the shipping capacity can be raised.”

How did your ship go through the dam with the vessel lift?

“First there are two ways for ships to bypass the Three Gorges Dam. One is through ship locks and the other, which we took yesterday was through ship lift. Ship docks use two water gates to change the water level within the dock to send ships from upstream to downstream or the other way around. The shiplift however is a kind of elevator; it can lift vessels of up to 3,000 tonnes. Its design uses a helical gear system, to climb or descend a toothed rack with the ship. The ship lift at the Three Gorges Dam was completed in 2015 and went through several trials before official operation. The vertical distance traveled for our ship to pass the dam is 113 meters. It took us roughly 30 minutes to transit from upstream to downstream Yangtze. The time would be increased to three or four hours if we went through the locks. We were told that now only ten or so ships went through the dam with the ship lift every dat at present. It’s expected the design will be more mature in the future and more ships can pass the dam this way.”

That was CRI's Yang Guang with the Streaming down the Yangtze journey.