365 Days of Climate Awareness 314 - The Three Gorges Dam

China’s Three Gorges Dam is the world’s largest, in the size of the dam and reservoir, and in generation capacity. It measures 2,335 m/7,661 ft/1.45 mi long, 181 m/594 ft tall, and required 27.2 million cu m/35.6 million cu yd of concrete. The dam traps a reservoir of 39 cu km/9.4 cu mi volume and 1,084 sq km/419 sq mi, about 2/3 the size of Rhode Island. Its generation capacity is 22.5 GW, and increased China’s hydroelectric capacity by nearly 20% when it came on line.

Location of the dam within all of China.

Closer view of the Yangtze river, central China.

The original concept, to build a 30 million horsepower dam east of the Three Gorges stretch of the Yangtze River, was expressed by the statesman Sun Yat-sen in 1919. The project was alternately pursued and shelved until 1944, when a team of Americans surveyed the region and drew up plans. A team of 54 Chinese engineers went to the US for training and began work, but it was interrupted by the Chinese Revolution. Though Mao Zedong approved of the concept he favored other dams over the Yangtze, and only in the 1980’s did debate on it resume. In 1992 the project  was approved and in December 1994 work began. Construction was complete in December 2007 and the station was fully on line by May 2012.

2008 month-by-month power output of the Three Gorges Dam.

China's electricity production by source through the years.

Central China has a monsoonal climate, so the Yangtze’s flow is extremely seasonal, as is the dam’s electricity output, peaking from June to October. The plant consists of 32 700-MW generators which distribute power to nine provinces and two cities, including Shanghai. It began delivering power in 2003, with only three installed generator units, and the total increased until 2012 when, with all 32 running, the dam delivered 98 TWh of power. Since then it has averaged more than 97 TWh per year, nearly 40% of all US hydropower (260 TWh) combined and about 7.5% of China’s annual total of 1,302 TWh.

Side-on view of the dam.

Aerial photo showing the dam and part of the reservoir.

The dam has slowed the river’s upstream flow, leading to increased sedimentation throughout its middle and upper reaches, though there is not consensus on the precise effects. It has led to increased landslides upstream as the dammed water raises the water table, and also serves to control flooding in the river’s lower reaches. Water level in the gorges rose more than 91 m/300 ft, submerging an estimated 1,300 archeological sites, 13 cities and 140 towns and displacing 1.4 million people.

The Yangtze, before and after the dam (reservoir not yet full).

The Qutang Gorge.

The Three Gorges.

Tomorrow: China and rare earths.

Be brave, and be well.