| Submit your comments on this article | ||
| China-Japan-Koreas | ||
| China's 15-year lesson in how not to build a dam | ||
| 2006-05-20 | ||
But the completion of the Three Gorges dam has been anything but harmonious. It is now being cited as a textbook example of how not to build a dam. Before it even starts operating, the giant hydro-electric scheme is threatened by silt - the solution to which is to pour yet more concrete into the Yangtse river.
As the waters behind the dam rise, increased pressure will allow it to generate more power and recoup the $22bn (£11bn) investment more quickly. But the output is not as significant as had been originally imagined. At first, it was envisaged the dam would supply at least a 10th of the country's energy, but electricity supply has grown rapidly along with the economy, and by the end of this year, it will provide less than a 30th. And the dam's environmental record is, at best, mixed. Several species of freshwater fish are no longer able to reach their spawning grounds. Scientists warn that the upstream water quality has deteriorated because the flow is too slow to allow the river to clean itself. More than half of the sewage from Chongqing is pumped into the river untreated. New water treatment plants have been built, but this has failed to stop a slow stagnation. To minimise the loss of fertile land, farmers have been encouraged to dig up soil under the flood line and re-lay it on the tops of hills, but much biodiversity has already been lost under the reservoir. Green activists urged the government to learn the lessons of the Three Gorges by allowing greater public participation in future projects. Consultation was absent from the approval debate for the dam. Even the National People's Congress was so enraged by the plan that a third of delegates either voted against or abstained - the closest to a rebellion that China's rubber stamp parliament has ever seen. | ||
| Posted by:Steve White |
| #35 stupid chinks, I once watched as a group of 5 grown men attempted to jack a truck out of a small muddy stream in western china, they tried over and over to jack the truck up in the mud and of course only succeeded in sinking the jack, not deterred though they kept repeating this process for hours, after many hours they finally realized they could use the winch in the stuck vehical to get it out of the tiny but muddy stream it was stuck in. Independent Logical thinking patterns just arent there in the Middle Kingdom, too many years towing the party line I suspect. |
| Posted by: bk 2006-05-20 09:52 |
| #34 Ummmm, OK I'll bite Just exactly how do you figure that increased water in any region is contributing to the intensifying desertification of large tracts of surrounding lands. Seems to me that at the absolute minimum the extra humidity caused by evaporation of the lake surface would INCREASE humdity, hence MORE rainfall in any region downwind from the lake. Upwind would not be affected in any way, so the net effect in the area is more rainfall, not less, so NO "Desertification" effect. |
| Posted by: Redneck Jim 2006-05-20 23:59 |
| #33 China long ago qualified the archaeo sites as "bourgeois", thus their destruction was of little to no importance to the CCP other than being a footnote. However, the dam is contributing to the intensifying desertification of large tracts of surrounding lands, which in turn is contributing to a massive outflow of Chinese citiznry and ethnic groups from these areas. CAN ANYONE SAY "ASIA-WIDE WAR(S) FOR WATER", or "MONGOL INVASION(S) PART DEUX", etc. |
| Posted by: JosephMendiola 2006-05-20 22:50 |
| #32 you assume storage - they don't store electricity... |
| Posted by: Frank G 2006-05-20 22:45 |
| #31 On the other hand, the power generated by the dam represents a lot of oil that China will NOT need to buy. Oil being a fungible resource - reduced demand should translate into reduced prices. |
| Posted by: DMFD 2006-05-20 22:19 |
| #30 Not quite right Zenster, the "Head" from turbine to surface would not change, so flow would be the same, thus output power would remain the same regardless of silt. The problem with silt is that it reduces Pondage (capacity) Not a problem here where the reservoir is so vast, and silt will also erode the turbines , depending on how much flows through them, it may be only a few years before they erode and need replacement. It's not a major, or even insurmountable problem. |
| Posted by: Redneck Jim 2006-05-20 20:27 |
| #29 Low pressure, due to decreased water depth in silted up reservoirs, equals low-kilowatts. Sorry Zenster, but you are wrong. Hydroelectric generation depends on the vertical distance between the top of the water and the point where the electricity is generated. The actual depth of the water is immaterial. Go visit the hydro plant at Niagra Falls if you don't believe me, |
| Posted by: phil_b 2006-05-20 20:21 |
| #28 I don't see how silt would affect a Hydro project. Unless the dam uses top-flow runoff to power its turbines, sedimentation makes a huge difference. Turbine spin rates are directly related to the water pressure impingeing upon their impellers. Low pressure, due to decreased water depth in silted up reservoirs, equals low-kilowatts. If the dam's reservoir is reduced in volume by excessive silt deposits on the reservoir bed, the turbines will see substantially less cumulative water pressure and deliver far less power, or at least maintain shorter periods of power generation before depeleting available water acreage. Yes, silt can affect hydro projects. |
| Posted by: Zenster 2006-05-20 19:36 |
| #27 Zhang, you forgot the Russian Far East ceded in the treaties of Aigun and Peking circa 1850. |
| Posted by: phil_b 2006-05-20 17:28 |
| #26 they oughtta - China has a |
| Posted by: Frank G 2006-05-20 17:17 |
| #25 All of those areas are ones that China has had trouble conquering and keeping multiple times in their history. It remains to be seen whether modern technologies have changed the natural limits of China to any great degree, although Indian friends of mine are quite worried about the Maoist incursions and threat from China via Nepal. |
| Posted by: lotp 2006-05-20 17:14 |
| #24 Mao: a million? Ha! I killed that many before breakfast... China has remained a large country despite large and perennially restive populations because its rulers and various contenders for power have never hesitated to kill as many people as they have to, in order to consolidate their rule. The Chinese have believed, in principle, that any number of deaths is permissible to preserve China's territorial integrity. In practice, they ceded Burma, Canton, Formosa, Hong Kong, Korea, Kyrgyzstan, Mongolia, Shanghai, the Ryukyus, Tsingtao and Vietnam. However, this was before China acquired modern weaponry and nukes. |
| Posted by: Zhang Fei 2006-05-20 17:01 |
| #23 a million? Ha! I killed that many before breakfast... |
| Posted by: Mao Tse Tung 2006-05-20 16:31 |
| #22 AP: On the subject of taking out a dam of this scale? Well confined explosion of some sort, 100 meters+ below the water surface on the upstream face of the dam. See Operation Chastise for the general idea. Think Taiwan retaliation for Chicom invasion or attack from the mainland for a cause. I think any Taiwanese leadership would have to think long and hard about this. If the destruction of the dam kills a million people, China could flatten Taiwan with nukes. I don't think it makes any sense for Taiwan to intentionally inflict civilian casualties on China. During WWII, the Allies collectively had many more people than the Germans or the Japanese. It was conceivable that we could kill enough of them to demoralize them. China has over a billion people. Taiwan has no nukes. Any mass casualty Taiwanese attack on Chinese civilians would kill just enough Chinese to get them very, very angry. Maybe angry enough to go nuclear. Let me put it this way - in the immediate aftermath of 9/11, when people thought as many people had been killed as on Hiroshima or Nagasaki, the nuclear option was brought up but eventually dismissed. The Chinese are likely to be less restrained if a million of their civilians are drowned. |
| Posted by: Zhang Fei 2006-05-20 16:26 |
| #21 phil_b: Greenie sky-is-falling nonsense. I'm more and more inclined to this point of view. I suspect this dam will work fine. They spent so much money ($30b) on it that if it fails, the people involved might be executed on live TV. They've also spent some money on foreign contractors to make sure it gets done right: A group of experts from the Harza Company of the United States were invited today to inspect the Three Gorges Project at the middle reaches of the Yangtze River [Chang Jiang] for a second time. These experts may be hired to supervise the construction of the world's largest water control project, the Three Gorges Project, which combines hydroelectric power generation and navigation functions, will cost 203.9bn yuan and will take 17 years to complete. |
| Posted by: Zhang Fei 2006-05-20 16:06 |
| #20 Article: The state has gone into overdrive to proclaim the achievements of the 1.4 mile-long dam This is a pretty impressive-sized dam. Hoover Dam is just under a quarter-mile long. |
| Posted by: Zhang Fei 2006-05-20 16:01 |
| #19 i love your 'unhealthy obsession' AP. Plus i love how engineers are rantburgers because i learn. Nice to know our next big enemy has an achilles heel. mind you if china goes down our economies get dragged too: we are interconnected |
| Posted by: anon1 2006-05-20 12:27 |
| #18 Thanks for bringing your expertise to the discussion, AP. |
| Posted by: lotp 2006-05-20 12:03 |
| #17 Water is periodically released through passages at the base of the dam to clear silt. The river carries huge amounts of silt. When the water velocity slows entering the reservoir, the silt settles out, creating an alluvial fan. This can be a problem with navigation of ships at the upper end of the reservoir. Supposedly, this situation has been extensively modeled, but with the Chicoms, who knows? The impacts of this dam are tremendous. Hundreds if not thousands of archaeological sites are permanently lost without examination. A relatively few were examined before the water rose. Rising water saturates hillsides, causing landslides. Pollution and runoff generated is not cleansed by the river, but rather sits in still water, becoming a serious health hazard. Millios of people have been displaced from many generations-old towns and villages to get them away from the rising waters. The Chicoms are planning more big dams. Their central planning feature minimizes examination of environmental impacts. And it all runs on big loans, which can be shaky for a multitude of reasons. On the subject of taking out a dam of this scale? Well confined explosion of some sort, 100 meters+ below the water surface on the upstream face of the dam. See Operation Chastise for the general idea. Think Taiwan retaliation for Chicom invasion or attack from the mainland for a cause. |
| Posted by: Alaska Paul 2006-05-20 11:44 |
| #16 I predict 100 yr flood will do the trick! /and yes I'll still be alive to say i toldyaso! |
| Posted by: Fidel C 2006-05-20 10:59 |
| #15 yep. ooops! |
| Posted by: Frank G 2006-05-20 10:06 |
| #14 www. ThreeGorgesProbe.org The social and environmental impacts of China's big dams and water projects. |
| Posted by: 3dc 2006-05-20 10:05 |
| #13 Actually a recent 3Gorges article mentioned that an error in the computer program actually placed the dam in a higher earthquake probability area. Oops! |
| Posted by: 3dc 2006-05-20 10:00 |
| #12 We bidn our time, waiting for the big one. |
| Posted by: Fly Ash Liberation Army 2006-05-20 09:59 |
#11
| |
| Posted by: bk 2006-05-20 09:52 |
| #10 If you build a dam with intakes at the top, you only get water through when full...Intakes have to be at variable height or permanently low for efficiency - the pressure head provides velocity and helps drive the turbines = higher power output. Alaska Paul has built an unhealthy obsession for this flyash-ridden POS and could tell more. The concrete used is like 4 times the amount of flyash limits we allow in California for regular concrete...cheaper but NOT stronger. I see big things in the dam's future...like a quake |
| Posted by: Frank G 2006-05-20 09:40 |
| #9 It's not my area of expertise, but IIUC the heavier silts fall out when they enter the lake. It's the really fine stuff that accumulates by the dams - and floats into the turbines. But we have several mechanical/civil engineers on this list ... maybe they could comment ... |
| Posted by: lotp 2006-05-20 09:10 |
| #8 lotp, I'm not trying to justify my position, but silt is relatively large grained stuff 0.05mm and silt by definition settles out of still water such as in a dam. I don't see how silt in a large dam would be a problem since the water drawn off for power is at the top and hence has the least amount of silt. |
| Posted by: phil_b 2006-05-20 08:31 |
| #7 Silt can block turbines, rendering the dam inefficient or unable to generate electricity. It's a serious issue, especially if the silt deposition rates are higher than planned for in the dam's design. Large amounts of silt are also a sign of heavy erosion upstream. As soils are washed away, the land is less able to absorb rainfall, increasing the possibility of massive flooding that can overwhelm the dam. |
| Posted by: lotp 2006-05-20 08:15 |
| #6 Before it even starts operating, the giant hydro-electric scheme is threatened by silt I don't see how silt would affect a Hydro project. What matters is flow and head. Silt wouldn't affect these things. BTW, I see how silt would be a problem for a dam whose purpose is water storage, but that's not the purpose of this dam. Greenie sky-is-falling nonsense. |
| Posted by: phil_b 2006-05-20 07:38 |
| #5 What would it take to blow up a damn of this scale? Time. |
| Posted by: Nimble Spemble 2006-05-20 07:10 |
| #4 |
| Posted by: RD 2006-05-20 02:56 |
| #3 What would it take to blow up a damn of this scale? |
| Posted by: Classical_Liberal 2006-05-20 02:10 |
| #2 Oh, I forgot. It now replaces the Aswan Dam as the best target for the buck on the planet. |
| Posted by: 3dc 2006-05-20 01:23 |
| #1 No mention made of the landslide that closed off a tributary river and killed hundreds with a massive wave. These steep gorges are being saturated with water as never before in history. They are now experiencing liquidification. |
| Posted by: 3dc 2006-05-20 01:22 |