A Final Test for the Big Dam

By LI LI

A Final Test for the Big Dam

By LI LI

At full capacity, the world’s largest hydropower station w ill tap the potential of flood prevention and power generation

T he water level at the Three Gorges Dam, the world’s largest water control and utilization project, reached its designed highest mark on October 26, which w ill enable the project to fulfill its functions of flood control, power generation,navigation and water diversion.

The water level hit 175 meters at 9 a.m.that day, said Cao Guangjing, Chairman of the China Three Gorges Project Corp.,the developer of the project, calling it “a milestone in the construction of the gigantic reservoir.”

The 185-meter-deep reservoir, built on the upper m iddle reaches of the Yangtze River, China’s longest river, began to store water in 2003.

The Three Gorges Project was ratified by the National People’s Congress in 1992 and started construction in 1994, w ith an estimated budget of 203.9 billion yuan ($30.4 billion). It is a multi-functional water control system consisting of a dam, a five-tier ship lock and 26 hydropower turbo-generators.By 2012, six more hydropower turbo-generators w ill be installed.

The project, located in central China’s Hubei Province, was constructed in three phases and storing water at the 175-meter level was a requirement once the last phase of construction was complete.

The last time the enormous dam was put under a similar test was in 2008, when the reservoir’s water level was lifted to 172.8 meters. According to a report on the website ofPeople’s Daily, during that trial to elevate the water level to the dam’s full capacity, geological calamities and earthquakes were triggered in the upper reaches of the Yangtze River.The water level elevation was halted at 172.8 meters due to the public’s prevalent fear about earthquakes in the wake of the catastrophic Wenchuan Earthquake in May 2008.

Another test was planned in 2009 and eventually given up due to drought spells in the lower reaches of the Yangtze River,which forced the dam to increase its water discharge.

This new round of water level elevation started on September 10 from a level of 160.2 meters. Construction, reservoir sediment, water quality and geological changes can only be put under full tests after the water level reaches 175 meters, said Cao. He said he is less concerned about the normal operation of the dam’s control equipment,generator units, dam gates and ship locks than about the stability of mountains along the reservoir.

According to a report onPeople’s Dailyon October 27, the water level elevation had exerted no impact on the quality of drinking water sources around the reservoir, navigation on the Yangtze River or local residents’daily life.

The w ater level w ill be kept at 175 meters for about two months and then be allowed to drop. In the future, the water level w ill be kept between 145 meters and 175 meters, depending on flood control needs.

That water-level fluctuation corresponds to 22.15 billion cubic meters of water.

The embankment on the Jingjiang section, the most flood-prone section of the Yangtze River, which previously could w ithstand only a once-a-decade flood, w ill now be able to w ithstand a once-a-century flood.

A higher water level expands the navigable course of the reservoir 150 km and increases ship-passing efficiency by four times, cutting navigation costs by at least one third.

Starting from next year, the power plant w ill be able to realize the designed annual power-generation capacity of 84.7 billion kwh.

The electricity generated by the Three Gorges Dam is transferred to eight provinces and municipalities in central, east and south China. Xinhua News Agency said after the water elevation, the hydropower project w ill be able to generate 10 billion kwh more power than when the water level was 156 meters annually.

“A ll Chinese should be proud of the dam,” Cui Bangjian, a villager living close to the dam, told Xinhua.

“The whole scene is becom ing more beautiful, and more ships come and go as the navigation area expands,” the 60-year-old man said.

Some 1.4 m illion residents in Chongqing Municipality and Hubei Province have been relocated to make way for construction of the dam during the last 18 years.