What does 390 million tonnes of silt look like?

July 8, 2012 7:04 AM

Bystanders are dwarfed as they stand watching a tremendous rush of water gushing through gaps in a dam in China, part of a carefully-choreographed operation to remove silt from the Yellow River
posted by Renoroc (31 comments total)

Managing the Yellow River has been a critical preoccupation of Chinese governments throughout their history. Largely because, when it's not well-managed, the river tends to flood and/or change course every century or so, generally drowning millions.

I wonder what effect the deepening of the Chanel will have, though. The US's experience with the Mississippi suggests to me that every "river control solution" tends to directly produce new "river control problems."
posted by GenjiandProust at 7:24 AM on July 8, 2012 [3 favorites]

Still, I can say that those are the most impressive photos I've seen taken by a dam site.
posted by GenjiandProust at 7:25 AM on July 8, 2012 [10 favorites]

You should feel bad for that pun.
posted by sonic meat machine at 7:28 AM on July 8, 2012 [3 favorites]

Thassa a hella lotta silt.
posted by flapjax at midnite at 7:32 AM on July 8, 2012

Just to nit-pick, that's (allegedly, god knows how you calculate it) 30 million tonnes of silt. The 390 figure is the 13 year total.

To me, it's counter intuitive - I would have thought that the silt being fragged out of the damn would have laid down just as much new silt downstream as the water there was washing away in the first place. Except it was more likely to dump it in the corners, making the channel deper but narrower...
posted by sodium lights the horizon at 7:38 AM on July 8, 2012

I don't think the silt coming out of the dam is what they're talking about. It sounds like they release a large amount of water and the 'high velocity' water then going down the river scours away the bottom of the river. That silt on the bottom of the river is what they're talking about.
posted by TheJoven at 7:44 AM on July 8, 2012 [1 favorite]

I can't imagine what that does to the fishery (is there a fishery in the Yellow River?).
posted by HuronBob at 8:14 AM on July 8, 2012

She'll let you play for a while and shares well. But, if you take to much, Mother Nature always wins. Always.
posted by I'm Doing the Dishes at 8:23 AM on July 8, 2012 [1 favorite]

Nature bats last. More on this later.
posted by Danf at 8:37 AM on July 8, 2012

When I toured the Three Gorges Dam a couple of years ago, one of the guides made the comment that the dam was constructed without any sort of thought about fish spawning. So, now the chinese government initially had to use dumptrucks to physically transport fish upstream. Apparently, since then they've installed fish ladders to help upstream spawning.

When we watched the video about the construction of Three Gorges Dam, the soundtrack for Jurassic Park was the background music. I thought to myself, "I wonder if they licensed this."
posted by absalom at 8:45 AM on July 8, 2012 [2 favorites]

It's good that that guard is standing at attention over that rushing torrent or else it might try to escape its banks.
posted by Burhanistan at 8:52 AM on July 8, 2012 [3 favorites]

They've been doing that on the Colorado, I think.

As to the fish, it's not like massive floods are anything new. If that were a problem for fish, they'd have all died out thousands of years ago.
posted by Chocolate Pickle at 8:56 AM on July 8, 2012

I don't know if this is true about the Yellow River, but high spring flow is a normal and natural part of a river and understand that damming of rivers has contributed to problems downstream by moderating the level of high water (the Colorado River being one example).
posted by jamincan at 9:07 AM on July 8, 2012 [1 favorite]

When we watched the video about the construction of Three Gorges Dam, the soundtrack for Jurassic Park was the background music. I thought to myself, "I wonder if they licensed this."

And, if so, did they do so ironically?

That said, China has been doing hydraulic engineering for 2500 years. And guess what Hu Jintao did before he got serious about politics?

It would be interesting to learn more about how the history of Chinese hydraulic engineering projects is reflected in these modern megaprojects.
posted by b1tr0t at 9:08 AM on July 8, 2012

I admire Alone Soldier for his standing so guardly.
posted by srboisvert at 9:27 AM on July 8, 2012 [2 favorites]

Huang He gonna Huang.

Seriously though, the Yellow River's silt content has been both a blessing and a curse basically since humans settled it's basin. While the loess provides incredibly fertile soil, it also leads to frequent and often violently flooding river has probably been one of the deadliest natural features known to humanity.
posted by Panjandrum at 9:28 AM on July 8, 2012 [1 favorite]

Oh god, I have nightmares that look exactly like those photos.
posted by Blue Jello Elf at 9:41 AM on July 8, 2012

For anyone else who was curious after reading this, here's a NASA page on the Yellow River Delta. Great photos and informative.
posted by maryr at 9:52 AM on July 8, 2012 [2 favorites]

I kind of hate it when the Daily Fail has actual neato/interesting things like this, to fool people into thinking they are a quality source of legitimately useful information.
posted by elizardbits at 10:15 AM on July 8, 2012 [5 favorites]

Isn't the purpose to wash the build up of silt from the Dam itself? The silt builds up upstream from the dam lowering the actual capacity of the dam. The holes seemed to be lower down specifically to draw the silt off the bottom of the dam. It then washes away down stream where it performs its usual role of replenishing minerals in and around the river.

I think they mean it deepens the dammed section of the river by 2m each year. (presumably the same 2 m each year.)
posted by mary8nne at 10:29 AM on July 8, 2012

I imagine it helps both up and downstream. It helps restore the natural flow of the river.
posted by maryr at 10:42 AM on July 8, 2012

I hope they had plenty of porta-potties set up for this event. The fact that it's called the Yellow River doesn't help.
posted by orme at 10:45 AM on July 8, 2012

I.P. Freely’s copyright attorneys will be in touch.
posted by Burhanistan at 10:52 AM on July 8, 2012

Ugh, really? Pee jokes? You're so dammed immature.
posted by maryr at 11:17 AM on July 8, 2012

Lighten up, Francis.
posted by Burhanistan at 11:19 AM on July 8, 2012

Yeah I could bladder on all day about this subject.
posted by Jofus at 11:23 AM on July 8, 2012 [1 favorite]

So, having done some pretty shallow research on the subject in the past, would this be a deep, meaningful solution for the lack of silt flowing downstream or are they just pissing into the wind on this one?
posted by Slackermagee at 11:31 AM on July 8, 2012

When I toured the Three Gorges Dam a couple of years ago, one of the guides made the comment that the dam was constructed without any sort of thought about fish spawning. So, now the chinese government initially had to use dumptrucks to physically transport fish upstream. Apparently, since then they've installed fish ladders to help upstream spawning.

Fish Screens are a technology that extracts water from silty, steep rivers without damming the river or hampering endangered salmonids.

In the US, the Army Corps, burdened by Congress, the CEQ, and EPA with an environmental mission, its ear ever-open to the shallow-water Navigation industry, uses barges to ship fish up the Missouri, past all the unnecessary dams. This also happens on the Columbia.

It ensures that some barges are actually using the navigation routes that the US pays the Corps of Engineers to maintain.

Meanwhile, in Deltaic Louisiana, we are begging the Corps to send the sediment behind the dams on the Missouri this way.
posted by eustatic at 11:47 AM on July 8, 2012

THE TIME OF THE AUTUMN FLOODS came and the hundred streams poured into the Yellow River. Its racing current swelled to such proportions that, looking from bank to bank or island to island, it was impossible to distinguish a horse from a cow. Then the Lord of the River was beside himself with joy, believing that all the beauty in the world belonged to him alone. Following the current, he journeyed east until at last he reached the North Sea. Looking east, he could see no end to the water.
posted by Huplescat at 2:54 PM on July 8, 2012

A teensy dam (by comparison) in WA state (Condit) was recently removed. This neat time-lapse dynamite-the-dam video shows clearly how much silt can pile up behind a dam in a century.
posted by Twang at 5:56 PM on July 8, 2012 [3 favorites]

Managing the Yellow River has been a critical preoccupation of Chinese governments throughout their history. Largely because, when it's not well-managed, the river tends to flood and/or change course every century or so, generally drowning millions.

Viz the Hydraulic empire hypothesis.

To me, it's counter intuitive - I would have thought that the silt being fragged out of the damn would have laid down just as much new silt downstream as the water there was washing away in the first place.

OK, this article explains the silt situation. The geography is such that the Yalu has hundreds of miles to travel across a loess plain, and the velocity of the water being slowed by the circuitous path of a mature river (like the Mississippi's bayous) means tremendous silt buildup, meaning the channel actually sits within a silt deposit that rises above the plain, as if held in by levees. Thus the dam opening washes away silt from the existing channel and prevents it from running out of capacity, which would break these natural levees and flood the loess plain.

And speaking to the prior point:
A Minister of Works was appointed to take preventive measures after a disastrous flood in 2297 BC, but to little avail, because there was another great flood a few years later. The Minister was banished, and another was appointed, and it has been a feature of Chinese administration that for over 4000 years there has almost always been a major official charged with flood control.
posted by dhartung at 6:01 PM on July 8, 2012