Dams and Landslides

Three Gorges officials admit they can’t fill reservoir, for now

(November 16, 2009) Because of severe drought conditions in the middle and lower reaches of the Yangtze River, a top official from the Three Gorges Group recently admitted (Chinese) in an article for Outlook Weekly that the plan to fill the reservoir to 175 metres this year is impossible. Zheng Shouren, chief engineer of the Three Gorges Group and member of the China Academy of Engineering (CAE) says the dam operators have no choice but to stop filling the reservoir and release more water to drought-stricken regions downstream.

The 175-metre mark—the maximum height at which the dam can operate and produce the most power—is considered the final step in the completion of the dam.

According to the English language Xinhuanet, officials began raising the reservoir from 145 metres on September 15th, expecting to reach the 175-metre mark by the middle of October at which point they could declare the 15-year-long construction period of the world’s largest and most controversial dam scheme finished. But because millions of citizens downstream are struggling with severe drought conditions, government officials have ordered the dam operator to increase the amount of water flowing through the dam.

Now the Yangtze River Flood Control and Drought Relief Headquarters reports that between October 19 and November 10, the amount of water flowing from the reservoir was 4-billion cubic metres more than the operators had originally planned.

Three Gorges problems may be systemic

The downstream drought isn’t the only factor foiling the Three Gorges dam operator’s plan to fill their massive reservoir. According to Xinhua, lower than average rainfall upstream has meant that water volumes entering the reservoir from the upper reaches of the Yangtze—averaging 8,260 cubic meters per second in early November—are 34 percent lower than last year’s volumes.

The failure to raise the dam’s reservoir to its projected height highlights one of the weaknesses with the project: without reliable water flows, Three Gorges power output will be unpredictable.

Promises from the Chinese government that Three Gorges would be the world’s largest generator of reliable power seem to be evaporating before the project is even declared finished. According to the BBC, at the current water level of 170-171 meters, only 11 of the dam’s 26 hydropower generators are operating.

Nor is the problem of filling the reservoir related only to the vagaries of water flows in the Yangtze.

Last year, the operators tried to bring the Three Gorges reservoir to its maximum height, but were forced to stop filling at the 172.8 metre level after the rising waters caused frequent geological disasters. At that time, government officials were also forced to temporarily suspend all shipping in the Three Gorges area, due to the increased number of landslides. Improved navigation was one of the three pillars justifying construction of the Three Gorges dam, in addition to power generation and flood control.

The inability to raise the reservoir to its maximum height now has some officials questioning how the dam is operated. Zheng says that it would be wiser to raise the reservoir level earlier in the year, or, he predicts, “there will be no way to fill the reservoir to 175 m in most years.”

But doing so, says the Outlook Weekly article, would likely have two consequences: increased chance of upstream flooding, and competition for water among upstream reservoirs. If officials start to store water earlier in the year and during the flood season (May through August) —when they should be passing it downstream—they increase the risk of flooding upstream. And deeming the early-filling of the Three Gorges reservoir a priority might come at the expense of upstream dams, which could be forced to release more water than they had planned or anticipated.

Critics predicted, before Three Gorges was built, that all other uses of the Yangtze would have to bend to make the dam viable. That warning now seems to be coming true.

The failure of the dam’s operators to fill the reservoir to its maximum height and bring the project to completion is causing some officials to call for a new plan. Together with other experts in water, Nie Fangrong, former vice chief engineer of the Water Resources Bureau of Hunan Province, argues that it’s time to rethink the operating mode of Three Gorges, saying a comprehensive plan is needed to properly regulate Three Gorges and other reservoirs, as well as the mainstream of the Yangtze and its tributaries.

The Three Gorges dam may not be officially completed, but dam officials are already facing conflicts over its operation.

One way or the other, Three Gorges officials and government leaders must face the music: by building this dam they now have to trade off upstream and downstream water needs, decide whether to put populations at risk of landslides or reduce power output, and answer to angry taxpayers who are paying for a dam that may operate at partial capacity because of lower-than-expected water flows.

Op Ed, Probe International, November 16, 2009

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