Estimating from a Google map, it looks like the dam is about 1000 km from the Mediterranean sea, give or take. Put these two numbers together with Mr. Kobayashi’s 157 km[sup]3[/sup] of water in the lake. Assume the river valley is flat-bottomed with vertical walls 10 km apart (being generous here), then there’s enough water there to fill the entire river valley, from dam to sea, up to a depth of 15.7 meters (52 feet). That’ll pretty much wipe out everyone who doesn’t get out of the way.
The best available info indicates that wasn’t a dam break, it was more of a strong ebb tide and flood.
Other info suggests it was an issue of heavy combat vehicles sinking into deep mud, obstructing operations to the point where the opposing irregular light infantry could execute a full withdrawal. (Compare with the battle of Agincourt, where heavy infantry in deep mud became sitting ducks for opposing long-range ordnance.)
I think the long term effects would be the real issue. For instance, out west, the Hoover Dam and the other dams with it, make Southern California, Las Vegas and Phoenix possible. LA should be able to support around four million people, but the dams on the Colorado river provide enough water to support the nearly twenty million people in the Southern California area and much of the winter farming of the USA. Similarly Phoenix and Las Vegas should support around 100,000 each, both are huge cities now because of the dams.
If you breach the dams, fine, but could you get them rebuilt today? It would be politically hard to do with the environmental issues today and not to mention Mexico. Can you imagine Mexico saying, “Sure take all the water from the Colorado River, we don’t want any” today?
Who are the potential rulers of Egypt who have stated an inclination to “wipe Israel off the map”?
The Aswan High Dam is a clay-and-rock filled embankment dam; that is, it is a massive pile of rock-reinforced clay that is compacted by the pressure of water behind it. At nearly a kilometer base width and a height of only 110 meters, it is a massive earthen work that could not be significantly damaged by any single conventional explosive device; a large series of engineered sapping charges would be required to damage the structure of the dam such that it would give way. It would take a ground penetrating nuclear weapon to do any kind of catastrophic damage to the dam or its footings from a single attack.
Stranger
Yes, but isnt that the kind of dam design that once there is a breach where water is flowing where it shouldn’t the breach quickly enlarges and keeps doing so at an ever increasing rate unless you repair it post haste?
I aint no dam bombing expert, but I’d suspect if the Iraelis bombed the crap out of it and kept bombing the guys as they were trying to fix it they could cause the dam to fail.
There would be some ideal means of breaching the dam by weakening the embankment and starting a narrow flow of water. But that would take time, decreasing immediate casualties downstream. As soon as the bombing started Egypt would open all the sluices to decrease the water level as rapidly as possible. Once water starts to flow through the channel bombed out of the dam it will take some time to enlarge and erode more of the dam. The material blown out of the channel will mostly end of on top of the dam nearby, slowing the erosion process somewhat. Altogether the flow of water through the dam will be reduced, and the extent of flooding would be greatly reduce.
An alternative is to concentrate on weakening a large portion of the dam until it gives way under the pressure of the water much more rapidly.
A much simpler approach is to rely on Soviet engineering and Egyptian governmental competence, and wait. It will fail eventually.
Kind of sidebar here, but there’s an interesting novel regarding the breaching of the Glen Canyon Dam, called Wet Desert. It deals with some of the issues brought up in this thread. The book was written by a hydrologist / dam expert of the Bureau of Reclamation.
J.
I doubt they could drain the down the lake fast enough to make enough of a difference to keep a small breach from becoming a big breach. And if they can drain that thing fast, thats going to a bunch of flooding anyhow.
The videos I recall (and my childhood civil engineering experiments in the local creek) seem to indicate that a once an earthen dam is breached, its gets outa control fast.
Breaching the Aswan High Dam would be the equivalent of literally demolishing a small mountain. Surface contact blasts tend to remove a shallow crater of material (essentially spallation), and the material from which the Aswan Dam is constructed tends to resist deep penetration bombing, plus the configuration of the dam is such that any cavity deep within the dam will be compressed and filled by surrounding material due to the pressure on the dam, making it robust against incidental damage. Breaching such a dam doesn’t just require weakening the lower structure or footings as with a gravity arch dam; you literally have to remove enough material to allow water to flow through a breach before it will start to fail.
Any breach in a dam will result in erosion, but an embankment dam of the proportions of the Aswan High Dam can’t fail catastrophically in the way that you envision, nor is it subject to significant damage from any conventional bombing campaign. A substantial ground penetrating explosive impulse in the ten kiloton equivalent TNT yield range would be required to open a large breach in that structure.
The Glen Canyon Dam is an arch dam, which is not like the Aswan High Dam in construction or behavior.
Stranger
I never said a word about weakening the structure or the footings. I AM talking about water flowing through a breach making it worse. Why do you think I meant something else? Breaching an earthen dam doesnt require you to do anything to the lower structure or footings.
Its really not a top breach if there ain’t no water flowing through there is it?
You think its nearly impossible baring ground penetrating nukes to remove enough material to cause that. I don’t think its impossible even without nukes. It really boils down to just how hard is it doesnt it?
I respectfully disagree with you. Have you not heard of the Grand Teton dam failure? Once the water starts flowing through the breach, material is eroded out at a increasingly rapid rate.
Lets say it turns out the Iraelis (barring a nuke) really can’t breach the dam in any practical manner.
They could still bomb it uselesslly to their advantage. I suspect most Egytians have seen some sorta of documentary/disaster porn show about how bad it would be if the dam did burst.
Now, lets say relations go south and things get ugly between the two nations. Israel announces war is on and they are going to bust the dam (though they know it won’t work). And they start bombing hard to put on a show. Even if it does nothing, I suspect it would cause one hell of a panic for most people downstream (at least in the short term).
The Grand Teton dam was smaller and of different proportions, constructed out of different materials (basically a sandy loam matrix with the fissured local rock), and was not sufficiently compactified by hydrostatic pressure before failure, i.e. it failed when they filled it. Of course, when a dam is breached, the failure will erode the adjacent walls and the downflow will be destructive. But large earthen work dams like the Aswan High Dam don’t fail catastrophically (complete collapse of structure or footings) the way an arch or arch gravity dam does as envisioned by people who’ve seen The Dam Busters. And the sheer size of the Aswan High Dam makes it impossible for a single attack with conventional explosives to remove enough material to breach the structure. To physically move enough material to cause a breach simply requires more energy than can be provided by a transportable amount of conventional explosives in gravity bomb delivery.
Stranger
I think he’s talking about my post on weakening the dam. You wouldn’t need nukes, just accuracy. You have to blast material off the dry face of the dam working your way back. Bombs or explosions in the middle of the dam will just redistribute the material.
The harder the material the better I think. The clay will absorb a lot of the shock from explosives, and seperations could close themselves up under weight. The harder material will fracture. Hit enough spots on a concrete dam and water will start forcing its way through factures and take the whole thing apart quickly. The clay has to be physically moved to get a flow of water going or to narrow it enough to fail under pressure.
The water level behind the dam is important. The lower the water, the less pressure on the dam, and the material has to be removed to a greater depth, which will allow more time for water to be drained from the lake. But it looks like the maximum release rate is 21000 m3/sec. That’s probably the rate when the reservoir is full, so at that rate, which would decline as it drained, it would take months to drain 111 km3. Still, if you want to breach it, do it when the reservoir is full, and you need to move the least dam material.
The Aswan High Dam is 40 m wide at the crest, 980 m at the base, and 110 m high. To breach a section that is about 25% of the height from the top and 20 m wide would require the removal of over a hundred thousand tons of material from one specific place on the dam. That is how hard it is.
Could you do this with conventional explosives? Well, yes, if you could repeatedly drill the face with blasting holes, pack explosive within the material, and blast away the same way we blast passes and caves through rock. But bombs are not that efficient at material removal, and the concept of precision bombing a 20 m by 30 m patch over and over again the hundreds of times is beyond conception. There is no practical way to breach the Aswan High Dam by the use of conventional explosive bombs.
Stranger
You aren’t digging a ditch in flat ground. You’re cutting a channel through the top of a dirt ridge. The difficulties are the depth to the water level and the accuracy of the bombs. You don’t need to open a 20m wide channel, a 1 inch wide channel will do the job. You just have to hit the dam starting on the dry side of the dam so that the explosion drives a large amount of material horizonatally out where it will fall away from the channeling area. You have to hit same spot enough times to get down to the depth you need. 30 meters down might take a few hits in the same spot. 10 meters might be possible with one hit. As you work your way back towards the water, some of the material you blow out fills the channel that you cleared, so it may need an extra pass, but even at 25% of the dam height, the run is less than less than 300 meters. Once water starts to flow through that channel, even if its partially blocked with loose clay and rock, the dam will erode rapidly. The idea is to get the water to remove all the material.
You can start the channel from the reservoir side also.Because theres no water pressure compacting the material above the water line the waste can be blown out over the water. Once you get down to the water level, the breaching water will help dig the channel and clear the material that ends up back over the channel as you move towards the face.
I’m not contending that many bombs can be placed with that accuracy easily. It would be easier to land a few C130’s on the dam carrying a couple of excavators and explosives. Timing the explosives in sequence could make them much more efficient at creating a channel. If you only have to go 10 meters down, a bunch of excavators and bulldozers might do the whole job faster.
ISTR during Gulf War I the Air Force came up with deep penetrating bombs, and I see from Wikipedia Israel has picked up a few dozen since 2005. No reason why Israel couldn’t create their own tailored to the dam’s design, and with GPS guidance kits for bombs you can place bombs exactly where they need to go. You won’t do it with a single plane, but I’m betting Israel could get it done.
Now surviving the international backlash from such an act, that’s something else entirely.
I don’t disagree with you that there are physical differences between the two dams. I don’t follow what you are saying about being compactified (?) by hydrostatic pressure. Embankment material isn’t appreciably compacted by the weight of the reservoir behind it.
They can and will fail catastrophically though. I’m not under the delusion that an arch gravity dam behaves the same as an earthen dam. I’ve not seen The Dam Busters, whatever that is. I do have occasion to model dam breaches, however.
Since I’m no expert on explosives, I’ve no idea if conventional explosives could do this or not. I should have mentioned that I’m not taking any sides on that question.
Probably going to take a lot more than that, actually. The US is starting production of the first “earthquake bomb” since WWII, the Massive Ordnance Penetrator (MOP). This article claims it contains “about the same amount of explosives” as Barnes Wallis’ Tallboy bombs.
It’s not designed for excavating, but instead to destroy deep bunkers. That said, the Tallboy created craters “80 feet deep x 100 feet across” so we can use that as a starting point. A 30 meter deep channel 30 meters wide through that dam is a 153,000 cubic meter channel. Assuming each Tallboy created a crater with a volume of 5,930.667 cubic meters and that whatever medium those results were obtained in is comparable to the Aswan Dam (both highly questionable assumptions, but to go with it just for the moment), that’s a channel that requires 26 precisely-placed MOP’s. From what I can tell from that Defense Industry Daily article, the USAF has ordered either 16 or 32 MOP’s. These can only be carried on B-2’s or B-52’s, so we would actually have to do the bombing for Israel, and use up nearly the entire stock (or possibly, not even have enough).
And that’s based on a bomb that’s somewhat suitable for the operation. No amount of 500-lb GP bombs are going to do more than scuff the surface a bit.