Posted on 05/22/2007 9:30:23 AM PDT by TigerLikesRooster
Three Gorges dam causes downstream erosion--study
21 May 2007 08:48:29 GMT
Source: Reuters
HONG KONG, May 21 (Reuters) - China's Three Gorges Dam, the world's largest hydropower project, is retaining huge amounts of sediment and nutrients and causing significant erosion in the downstream reaches of the Yangtze River, researchers have found.
In a paper published in the latest volume of the Geophysical Research Letters, Chinese scientists said the dam had retained 151 million tonnes of sediment each year since 2003.
The researchers from the East China Normal University in Shanghai calculated supplies of water and sediment at places along the river which had previously not been monitored and combined them with the regular gauging stations.
"The Three Gorges Dam, which has regulated the waters of the Yangtze River since 2003, retains two-thirds of the upstream sediment each year," they wrote.
"In response to this retention, significant erosion occurs in the riverbed downstream of the dam ... Sediment flux to the Yangtze River mouth has decreased by 31 percent per year. The Yangtze delta is shrinking.
"Continued sediment retention at these rates, combined with more dams planned for the watershed, will severely affect people and the ecosystems on the Yangtze delta," they added.
The paper gave no details nor estimates of how many people would suffer.
Official Chinese press reports say the build-up of silt in the Three Gorges Reservoir is under control.
Huge sluice gates at the bottom of the 185-metre-high dam wall are opened between June and September to lower water levels and flush away sediment collected in the reservoir during floods.
In the past, large damming projects elsewhere have resulted in silt and nutrients being trapped behind the dams, damaging fish stocks and the fertility of downstream farmland.
Many environmentalists say creation of the Three Gorges Dam will have unforeseen ecological effects apart from becoming a cesspool of sewage and industrial pollutants.
The reservoir created by the dam has inundated two cities, 11 counties and 116 towns in Hubei province and neighbouring Chongqing municipality. More than 1 million people have been relocated and 1,600 factories submerged.
Ping!
That didn’t take long...........
Hard to believe they didn’t know this would happen.
Still a cool project...
The Discovery Channel has a good "Engineering Marvels" segment on it.
Anybody surprised by this, stand on your head.
TGD is an ecological disaster and has destroyed too many villages and historical sites to even count.
ALL YOUR SEDIMENT ARE BELONG TO US!
Hehehe, of COURSE they do...
They better hope their dams are better than the rest of the junk they build. They do know its supposed to hold back water, right?
They knew, they just didn’t care.
All which were ecological disasters in their own right at one time or another.
Like the Soviet built Aswan Dam on the Niles. The thing is an eco-time bomb. But we never hear about it from Greenpeace, etc., since it can't be blamed on the U.S. And besides, like the Chinese, "their intentions were good."
B/c it was a socialist show piece first, and an engineering project second.
With that news, Beijing will breath a sigh of relief and continue as planned.
The question has always been how much sediment would it trap.
Apparently the authors of this article haven't figured out that answer either since in one place they say the dam traps 2/3 of the sediment and in another they say the sediment leaving the mouth of the river has been decreased by 31% (as opposed to being decreased by 2/3.
There are a lot of environmentalists that are opposed to any kind of man made dam, or interfering with those made by beavers which are ok because they were not made by people.
Putting in the dam destroyed huge amounts of one type of habitat, and created huge amounts of other types of habitats.
However all you will hear from these people are bad things.
If a beaver builds a dam and floods someone's property they will fight to protect these new wetlands and to protect the beavers new habitat, but when mankind changes their environment to better suit their needs all they have to say are bad things.
They are simply anti-human.
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