posted
China is undertaking the biggest engineering project in history (with maybe the exception of The Great Wall Of China) by building a damn on the yangtze river. If you don't know how big this dam will be, listen to this. The biggest dam in the US is the Grand Coulee (sic?) Dam with 3 turbines. The yangtze river dam will have 28! All bigger than any at the Grand Coulee Dam.
Now my question is, how will the effect the people of Shanghai (The yangtze river runs right by Shanghai)? Their sewage system was the river. Now that it's stopped, will nearly 30 million people, aren't there going to be sewage problems?
Posts: 43 | Registered: Dec 2004
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posted
I heard about this. I think I heard that it was going to dislocate millions of people upstream. Also, certain organizations are worried about it collapsing, because that would cause the entire river valley downstream to flood. They worry because China isn't known for their amazingly safe building practices.
Posts: 903 | Registered: May 2003
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posted
The dam is pretty much complete, guys. I'm actually a little bummed, because I never did get to see the Three Gorges -- which were on my list of "sites to visit before I die" -- before they were essentially drowned.
Posts: 37449 | Registered: May 1999
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posted
I keep reading this as "The yangtze river darn in China" for some reason. Like someone doesn't want it to be in China, and we should relocate it or something.
Why are they building the dam? For power purposes? And that sewage does sound icky.
Posts: 21182 | Registered: Sep 2004
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posted
Yeah, it's a shame you didn't get to see them. They aren't really drowned by the impounded lake, but they have lost some of their apparent height. I saw the markers where the water would be and it really isn't that big a percentage of the distance up. I wonder if the lesser gorges were affected much. The are, if anything, even more spectacular (or were) than the Yantze river gorges.
Oh, and I believe the dam will serve 2 main purposes. Power and flood control.
Posts: 609 | Registered: Apr 2003
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posted
The lake will extend just under 1000 miles up the river once it has filled (which will take decades). The construction of the dam was the largest construction project ever attempted (per/time) and will be the largest dam in the world by a large gap. The weight of the water in the formed lake will be so great that geophyscists are predicting minor siesmic shifts in the Asian plate as a result.
What are the concerns?
Well first is one that will and has happened, and was mentioned here: the sinking of various historic and natural sights. the valley will be filled with water; moving out the people was one of the largest rellocation project in the history of the world, as several major cities will be under water.
The others are just concerns. With such a major dam, if something goes wrong, in design or construction, the resulting disaster will be un matched in magnitude. China isn't really known for high quality production, but there's no reason why they can't do it right...
There's also a concern with the backup of silt. This is a problem with all dams, and those that were constructed before the problem became apparent are pretty much usless now. Basically, silt that the river carries with it gets stopped at the dam, and builds up behind it. Now the three gorges dam takes that into account with a "slit door", but there's some concern if that'll work, and even if it does, if it will only take care of the problem next to the dam, but allow silt pile-ups miles back from it. If the silt builds up too high it causes flow problems, more stress on the dam, makes it harder to get energy from it, and actually with a river this size, can cause the lower plains to change chemical composition since they're no longer recieving the usual nutrient-rich soil.
The dam does three things, it brings in absolutley massive amounts of power, more than any power plant in the world, and this will be a huge boast to the Chinese economy, now a major portion of the continent is garunteed continual, renewable energy. Second, flood control, one of the major problems building the dam was dealing the raging river, famous for the destructive floods it sheds out. Thridly, and in my opinion, the reason that got it going, it puts China on the map as a serious industrial country.
posted
Arn't they also buuilding big lifts for cargo transports and cruise ships so they can sail in the new lake. i remember seeing that on the show?
Posts: 513 | Registered: Oct 2001
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posted
They are doing two things for ships. A massive system of locks (think the Panama canal) for the very large ships (barges), these are two way, so many ships can be in them at once.
They're also building the largest elevator in the world for some smaller ships, which, for a significant fee, can be put in this water elevator and brough up or down the dam in a much shorter period of time.
posted
From articles I've seen over the last few years, the relocation project is riddled with corruption. Party officials have looted funds that were supposed to help people relocate. It's very sad. Good post, Hobbes, I didn't know silt was such a problem with dams, nor that the lake was so heavy it will cause seismic shifts.
Posts: 6316 | Registered: Jun 2003
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posted
Thanks. Yah, I was pretty surprised by the weight thing, but it makes sense, 1000 miles of water, much of which is many hundreds of feet deep, that's a lot of mass!
Silt is a huge problem, especially with old dams whose artificial lakes have become significantly filled, some of them are 2/3 silt now. There's a big industry in blowing up these dams and letting the rivers clean themselves up.
posted
Thinking about this just makes me want to cry. I understand the economic reasons for it, and appreciate how much power they'll be able to produce.
But it seems to me that the price is just so high.
Posts: 3214 | Registered: Apr 2002
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posted
Silt is also very important to the river downstream in general. There's all sorts of problems in the Grand Canyon because of lack of silt caused by dams.
Posts: 14745 | Registered: Dec 1999
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posted
The problem with siltation is that the solution of the silt door simply won't work unless they can figure out a way to keep water velocities up until the water literally runs into the dam. A river can only carry the material as long as it's moving, as soon as it reaches the pool the material drops out, which is why we see deltas form where rivers flow into the ocean. So most of the material will drop out 1000 miles upstream of the dam, and will only work it's way down as the lake fills in and the flows pick up in the pool. Fortunately it will take a long time, and flood storage doesn't become an issue until the silt actually starts to exceed the normal pool elevation.
I'd also like to point out that there are huge problems with taking dams out and letting the river reclaim itself. It would work but it would cause massive bank failures upstream of the former dam site, among other problems.
Posts: 609 | Registered: Apr 2003
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posted
Good topic. I think that this is a huge problem, for many reasons. As Hobbes pointed out, the lake that will be created by this dam is going to be immense. What that means is that 25% of China's farmland is going to be submerged by water. Completely. As in unusable.
Of those farmers who depend on their land for revenue and food, 40% are not going to be reimbursed for their loss. Also, nearly 1,300 archaeological sites will be lost due to the dam's construction - and though some are being "relocated" to higher ground, there will still be many hundreds lost forever. China is not doing what it must to preserve these sites and to catalogue the sites that cannot be saved - not by a long shot.
This expense is all occuring so that China can enjoy a 10% rise in national power output, which still puts it at only 15% of what the U.S. produces annually. Granted, flood control benefits will (ostensibly) stop the catastrophic floods that have killed over 300,000 people so far, but this is far from a guarantee. As others have noted, China is not a beacon of superior craftsmanship.
Posts: 86 | Registered: Feb 2001
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posted
Cool, I didn't know a lot of that stuff. Here's something that I thought was also interesting.
The amount of electricity the Chinese will get from the damn will give them 1/4 to 1/2 of the amount of energy they have right now! Wow! That's a lot of energy!
2nd, do you know where they're relocating all those people? They're relocating them to Tibet and (I think) to the Xinjiang Uygur region, which is virtually all desert. Also, that sewege isn't going to clean itself up! Well, thanks for responding to this everyone!
Posts: 43 | Registered: Dec 2004
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posted
One hundred new water treatment plants will be installed on along the river to deal with the problem. There's also the fact that a lot of people who were doing the dumping of waste will no longer be in the valley, and thus, wont be dumping it there. One problem that hasn't come up here yet though is fish. Now the dam is designed to let the fish through unhindered (which remains to be seen if it'll work, but it's not the first time this has been done so it should), however durring the extrodinarily long construction, many earthen dams are used to re-route the water, and they certainly don't let fish through. So fisherman are getting hard hit right now.
To picture the immense scale of this, imagine filling a proffesional basketball stadium halfway up with water, and then pulling the plug and watching all that water dissapear in one second. That's the flow of water that it's designed to handle. The power it produces will be equivelant to approximatly 18 nuclear power plants.
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