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Water level mark at dam reaches height of success
By Guo Rui (China Daily)
Updated: 2010-10-27 09:33
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The water level at the Three Gorges Dam in Yichang, Hubei province, reaches the design capacity of 175 meters on Tuesday. [Photo/China Daily] |
Capacity of 175 meters hailed as a milestone
YICHANG, Hubei - Water rose to the maximum level at the Three Gorges Dam on Tuesday, driving electricity output to capacity at the world's largest hydropower plant for the first time since it began operating two years ago, its operator said.
The water level in the reservoir hit its peak height of 175 meters at 9:00 am on Tuesday, said Cao Guangjing, chairman of the China Three Gorges Corporation.
That marks the culmination of the mammoth $23 billion project on the upper reaches of China's longest river, the Yangtze. The dam is considered the best way to end centuries of flooding along the river basin and to provide energy to fuel the country's economic boom.
Cao said raising the water level to capacity is "a milestone in the construction of the gigantic reservoir".
He added that it would enable the project to fulfill its functions of flood control, power generation, navigation and water diversion.
The new level does not mean complete success for the project. It does, however, begin to answer concerns raised at the beginning of the project over such issues as the functioning of key equipment, water quality and sediment control, Cao said.
The reservoir began to store water in 2003 and Tuesday marked the third attempt to raise the water level to capacity since 2008.
On the first attempt, in 2008, the water level reached 172.8 meters before geological hazards prevented it being raised further.
On the second attempt, in 2009, the level could only be raised to 171.43 meters because of drought.
In September, the dam started holding more water and discharging less and reached full capacity after 47 days.
Reaching capacity allows experts to observe, research and validate the dam's original design, Cao said.
Monitoring equipment shows that the dam is operating smoothly.
The water level will be maintained at 175 meters for about two months for surveillance purposes before dropping. After that the level will be kept between 145 meters and 175 meters, depending on flood control needs.
But that could carry risks.
Last year, Caijing magazine revealed a government report that warned that rising water levels were increasing landslide risks as the soil around the dam became more saturated and unsettled.
The article cited a pre-flood inspection report by local officials that identified nearly 700 areas vulnerable to geological damage, 587 of them possible landslide spots.
When reservoir officials attempted to raise the water levels last fall, at least one town near Chongqing had to evacuate dozens of residents after a 400-meter hairline crack appeared on the slopes above homes.
But hydrology expert Yan Echuan, part of a team hired by the government to assess geological risks, said on Tuesday he doesn't believe that keeping the water at the maximum level poses an increased danger since water levels have been as high as 172 meters in the past.
"Theoretically, there would be risks of landslides and even collapses," he said.
"But it does not make too much difference if the water level is raised two or three meters from 172 to 175 meters. There's no substantive change in the local geological conditions," said Yan, a professor of hydrogeology at China University of Geosciences in Wuhan.
He said he was only aware of "one or two minor cases of earth-shifting" caused by the raised water level.
The reservoir's water-level fluctuation corresponds to 22.15 billion cubic meters of water, which will ensure water demand in the lower reaches during droughts.
A higher water level expands the navigable course of the reservoir by 150 kilometers. Navigation costs are also cut by at least one third compared to a water level of 156 meters, the previous target before 2008.
The project has generated about 440 billion kWh of electricity since 2003.
Now, the power plant will be able to realize its designed annual power-generation capacity of 84.7 billion kWh.
The Three Gorges Dam Project was launched in 1993 with a budget equivalent to $23 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 will be installed.
The project was constructed in three phases, and storing water at the 175-meter level was a requirement once the last phase of construction was complete.
After nearly 16 years of construction, work on all the main sections of the gigantic project was completed last month.
Some 1.3 million residents in Chongqing municipality and Hubei province were relocated to make way for construction of the dam.
Xinhua and AP contributed to this story.