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A bigger problem than ISIS: The Mosul Dam is failing

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Re: A bigger problem than ISIS: The Mosul Dam is failing

#111

Post by PietdeVries »

abduhl wrote: post #105
Someone wrote: post #68

Earlier quoted context omitted.

Wouldn't that be to crack in compression ? Also, I don't see concrete piles being abandoned at all. Part of the reason may be that, where I live, many poles now are drilled, pressed or vibrated into the ground to decrease noise and potential impact on surrounding buildings. Thats is possible because there is no bedrock to build on where I live, so poles often go down easily for the first meters; I have seen wooden po…

No, tension is what I meant. Imagine the pile hammer hitting the top of the pile. This impulse is transmitted down the length of the pile at the speed of sound as a wave. There exists a point where the wave gets to the end of the pile (this is at the pile tip) and the compression front attempts to continue which results in tension (eg - the pile tip is dragging itself forward with the energy). This is mostly seen wit…

Not sure about your statement...

In the Netherlands this is still done quite often because the soil is too unstable. Concrete piles are driven into the weak soil until it hits the sand. Houses are typically built on top. The pole can be protected with a wooden block that due to the friction can set fire.

Amsterdam is known to be built on wooden piles that remain intact as long as they stand under water: pumping away the water will cause the piles to rot and the houses to sink away.

Re: A bigger problem than ISIS: The Mosul Dam is failing

#112

Post by yalogin »

berntb wrote: post #87
yalogin wrote: post #85

The saddest part of the article is the US tried to blow the dam up during the gulf war. Why? That is as brutal as dropping the nukes on Japan.

Uh, what article are you reading? Or do you think bombing a generator is to "blow up the dam"? The quote is: "the dam had been built to survive an aerial bombardment. (In fact, during the Gulf War, American jets bombed its generator, but the dam remained intact.)" (A dam with bad air defense ought to be an easy target, considering all the emphasis the Americans puts into getting through lots of cement -- and that dam…

Yep. That is what I thought. I realize now that its strategically just to blow out the generator :)

Re: A bigger problem than ISIS: The Mosul Dam is failing

#113

Post by Someone »

Hondor wrote: post #101

Way down the bottom, we see the problem is solved for at least the next year: "Early in 2016, under American prodding, the Iraqis reopened negotiations with Trevi S.p.A., the Italian firm. In September, a team of engineers, hired at a cost of three hundred million dollars, arrived at the dam to perform a crash repair job. Their main task is to install updated equipment, designed to fill the voids beneath the dam more…

The sentence folllowing that starts with But. 'Crash repair job' also doesn't instill confidence that it is a given this will work.

Also, this dam still is close to a war zone, if not in a war zone. That updated equipment may not make it there, can get destroyed in an attack, or the personnel doing the work can be 'persuaded' not to work or may outright be killed.

What surprises me most about this story is that they kept delivering power to the enemy, while they also could have let all or most of the water out. It wouldn't surprise me if money or backstabbing ("we'll keep delivering electricity if you focus on attacking your other enemies instead of on getting back the dam from us") was involved there.

Re: A bigger problem than ISIS: The Mosul Dam is failing

#114

Post by PietdeVries »

cesarb wrote: post #97
chris_7 wrote: post #79

Earlier quoted context omitted.

My vague understanding of a turbine was that it was a spinning magnet, so if you killed the circuit it would just... spin, I guess. If this is a concern, why isn't there a worry that ISIS or just a stray bomb would kill the power lines when retreating from Mosul? Though I suppose they could just target the dam itself...

> My vague understanding of a turbine was that it was a spinning magnet, so if you killed the circuit it would just... spin, I guess. The load in the circuit acts as a brake. If you kill the circuit, the turbine spins faster and faster until it breaks into pieces. To prevent that, the control systems stop the water from flowing into the turbine, but stopping the water from draining is the opposite of what they want.

The story suggests there is a 300 foot wide canal that can be used to let water go in casse of an emergency. Well, how about doing so now? Rather than using the turbines, use the canal to let the water out, but without it generating electricity...

Re: A bigger problem than ISIS: The Mosul Dam is failing

#115

Post by avar »

Filligree wrote: post #80
hvidgaard wrote: post #57

Earlier quoted context omitted.

You could use it to boil some of the water away? A win/win if you're not a civilian relying on the power that is.

Well, on the assumption that it'd work... Now you've got a dam full of boiling water. And as you'll know from cleaning dishes, boiling water is far better at dissolving minerals than is cold water.

How are you calculating that entire reservoir would boil? It's filled with 8B m^3 of water.

I couldn't find the formulas to calculate this myself, but given Tuna-Fish's comment above that it's enough to boil a kiloton of water (1000 m^3) ever hour that's 1K/8B =~ 0.00001%.

So it's going to be more on the order of dropping a single drop of boiling water into a backyard pool every hour, is it not? I.e. something that wouldn't change the overall temperature of the reservoir to any significant degree.

This is all assuming that you'd have to use the energy to heat the reservoir itself, you could just as easily use it to pump out some water and boil it until it evaporates, not impacting the temperature of the reservoir at all, just emitting a lot of steam into the air.

Re: A bigger problem than ISIS: The Mosul Dam is failing

#116

Post by madenine »

madaxe_again wrote: post #107
reactor4 wrote: post #94

Earlier quoted context omitted.

You've got to be kidding me. I started reading "The Forever War" (the space war book) based on some comments I read on here and I assure you that there wasn't any warning about the space war book.

If you want a good space war book, Cixin Liu, Three Body Problem and sequels. The Forever War (not the space war book) is excellent however.

The Forever War (the space war book) is also excellent

Re: A bigger problem than ISIS: The Mosul Dam is failing

#117

Post by germinalphrase »

Someone wrote: post #113
Hondor wrote: post #101

Way down the bottom, we see the problem is solved for at least the next year: "Early in 2016, under American prodding, the Iraqis reopened negotiations with Trevi S.p.A., the Italian firm. In September, a team of engineers, hired at a cost of three hundred million dollars, arrived at the dam to perform a crash repair job. Their main task is to install updated equipment, designed to fill the voids beneath the dam more…

The sentence folllowing that starts with But . 'Crash repair job' also doesn't instill confidence that it is a given this will work. Also, this dam still is close to a war zone, if not in a war zone. That updated equipment may not make it there, can get destroyed in an attack, or the personnel doing the work can be 'persuaded' not to work or may outright be killed. What surprises me most about this story is that they…

Or, the existence of a functioning dam is of benefit to ISIS so they are less likely to destroy it (causing a catastrophe) than they would be if electrical supplies were cut off (?).

Re: A bigger problem than ISIS: The Mosul Dam is failing

#118

Post by exabrial »

I'm curious to what ratio an abusive regime is affected by general sanctions vs the populace under its authoritarian control. Sad to see so many people living in poverty from a dictator, then sanctions, then an invasion, now ISIS (And a dam apparently).

I don't know what the solution is, but that area of the world just cannot find peace.

Re: A bigger problem than ISIS: The Mosul Dam is failing

#119

Post by xg15 »

snowwindwaves wrote: post #62
viraptor wrote: post #54

Earlier quoted context omitted.

Honestly - no, I don't know what happens. Can you tell me? I mean without any modifications that would specifically covert that power into heat, what would happen with the lines cut? Something like the turbines melting, or welding themselves to the structure?

The turbines are Francis type which means they keep spinning until the water flow is stopped. When a generator is disconnected from the power system without first removing the power from the shaft then power in is greater than power out and the result is an acceleration of the generator. Generators are built to be able to withstand a certain maximum rotational speed without flying apart for a certain duration of time…

Thank you very much for the expert information. but that still doesn't make sense to me. The article states they have two control gates and a spillway. (one gate previously defunct but now repaired) So, shouldn't it be possible to block off the turbines and open the control gates instead, so that the total flow stays (roughly) the same?

Moreover, if the dam is indeed that easy to destabilize, letting ISIS control the load seems equivalent to handing them a big red "trigger flood" button for use at their discretion. Sure, right now it's in their interest to keep the dam intact - because they still control many parts of Mossul and need the electricity. But "scorched earth" is not exactly a new concept and if the operation in Mossul continues as planned and ISIS is driven out, they could decide to cut the lines on their end to deliberately cause mechanical failures.

Re: A bigger problem than ISIS: The Mosul Dam is failing

#120

Post by StavrosK »

ChrisGranger wrote: post #38
StavrosK wrote: post #29

Earlier quoted context omitted.

Actually closer to two, 1m3 = 74ft3.

One cubic meter is 35 cubic feet, not 74.

Yes, but it's 74 Google+ likes, or at least that's what an online converter would have me believe: http://i.imgur.com/9xIW1wr.png
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