If terrorists were to destroy Hoover Dam, what would be in danger by the flooding alone?
If terrorists were to destroy Hoover Dam, what would be in danger by the flooding alone?
The initial damn gone tusami would likely destroy everything down river as far as the Gulf of California. It wall also cause major water supply problems to southern Nevada, Souther California, and parts of Arizona.
The major urban areas affected by the water surge would be Laughlin, Bullhead City, Fort Hohave, Needles, Topock, Lake Havasu City then probably take out Parker Dam and continue to damage urban areas down to Yuma.
Simple, just follow the river it empties into, anything within a mile will probably get flooded out.
I actually recall there being a documentary on how the hoover damn was targeted by nazi saboteurs during the time of WWII
Simple, just follow the river it empties into, anything within a mile will probably get flooded out.
I suspect the damage would be a lot further down stream than you state, although a lot will depend on the amount of damage. When the St Francis Dam failed the flood wave caused major damage for several miles down stream and debris was found up to 54 miles. There are several other serious dam failures where the flood wave caused severe damage for many miles down stream of the dam, however, it's not easy getting exact distances the wave went other than listing some of the urban areas that were miles away from the dam and got wiped out or severely damaged. The Teton Dam flood wave travelled several miles despite the slow failure of the dam keeping the flood wave lower than if it had all gone at once. The Buffalo Creek flood wave destroyed 16 towns along the creek, so it clearly went a long way - from Google maps I estimate it at about 30 miles.
I suspect the damage would be a lot further down stream than you state
I suspect @blackjack2145309 meant all the way down the river, but with a mile wide floodplain.
AJ
I suspect @blackjack2145309 meant all the way down the river, but with a mile wide floodplain.
maybe they did, but for a lot of it the canyon is not that wide.
However, the damage done in the Buffalo Creek Dam failure and the St Francis Dam Failure would give a very good idea of what it would be like.
If terrorists were to destroy Hoover Dam
Without a nuclear device sitting RIGHT on the damned dam, that's just not going to happen. You could destroy the electric generators and powerhouses, but the physical dam itself just ain't going anywhere.
They dug all the way down to bedrock for the base to sit on, and to virgin rock for the wings of the gravity arch. It's just like the arch you see under a trestle, meaning as it gets pressed on, it transfers all the energy to the supports, so it's not holding it back simply by itself.
For comparison, the Great Pyramid of Giza weighs about 5.75 million tons. The Hoover Dam weighs about 6.5 million tons.
Without a nuclear device sitting RIGHT on the damned dam,
Don't need a nuclear device, just a decent load of explosive against the dam wall on the water side to blow a good sized hole in the wall and the pressure of the water would do the rest. The Hoover Dam is a a precisely calculated structure designed to take a certain level of pressure while maintaining structural integrity. Damage that structural integrity and it will give way.
Damage that structural integrity and it will give way.
Which is the point of requiring a nuclear device. No conventional explosive is going to be enough.
No conventional explosive is going to be enough.
depends on the amount of damage you want to do and where you place. Conventional explosives have been enough to destroy large dams in the past, and mother nature has been very good and destroying dams as well.
We will have to agree to disagree then.
Ayep. If you want to totally destroy everything with a bomb at the base you probably would need a nuke. But a lot can be done without going that far.
However, the bombs in Operation Chastise (the Dam Buster Raid) they used bombs of 7,500 pounds that exploded about 30 feet below the surface. The immediate damage done to the dam was only about a third to a half of the eventual damage done as once the dam was breeched the water flowing through scoured out a lot more of the dam and greatly increased the hole. This is a problem that's been seen with every dam failure that's been observed. Today explosives are a lot more powerful than they were back in WW2. Thus you get a lot more bang per pound.
Thus, normal explosives set only 50 or 100 feet below the surface right up against the dam wall on the water side will do very considerable damage, how much that hole later expands due to scouring is another issue.
Another aspect to do with placement would be if the explosives blew a hole into the interior of the dam where the generators and other interior spaces are it may or may not blow through the down stream face of the dam, but the water in flow would create havoc with the interior spaces.
The results will be dependent on the amount of explosives, their placement, and the type of explosives. How you decide those factors would be based on your intended results.
Need a lot more detailed plans etc to do a full analysis, and I've not got the time or interest to do so.
............
One aspect not mentioned so far would be to use conventional explosives to blow away the rock around one or both of the anchor points to cause it to collapse. However, I seriously expect you'd be noticed putting them all in place, especially drilling into the rock to do the job properly.
Another aspect to do with placement would be if the explosives blew a hole into the interior of the dam where the generators and other interior spaces are
Hoover Dam is different. The dam itself is completely solid, no interior spaces. They cut 4 tunnels around the damn that carry the water to the power plant and the downstream river.
https://en.wikipedia.org/wiki/Arch-gravity_dam#/media/File:Hoover-dam-contour-map.jpg
The dam itself is completely solid, no interior spaces.
Not according to a paper by the Missouri University of Science and Technology on page 15 of their report (Fig. 16 Distribution of internal galleries of Hoover Dam) the main dam wall has 2 elevator shafts and numerous galleries listed as Abutment galleries, Grouting Galleries, Drainage galleries, Radial Galleries, Pump Chamber, and and adit tunnel with a plug in it. There are 9 gallery levels and several shafts shown.
Years ago I saw a PR video of the dam where they did an inspection of the internal galleries, which is why I knew there are spaces inside the dam wall. They aren't huge as most are only five or six feet wide and high, but they are there.
Years ago I saw a PR video of the dam where they did an inspection of the internal galleries, which is why I knew there are spaces inside the dam wall. They aren't huge as most are only five or six feet wide and high, but they are there.
https://mechanicalc.com/reference/fracture-mechanics
Those galleries you speak of have a secondary purpose. They are effectively crack stops. If, and that's a big if, something caused a fracture, when that fracture tip hit the rounded edge of it, it would stop the fracture from progressing.
The placement and shape of those areas was deliberately engineered.
Lit of years ago, saw a documentary of WW2 Allies planning air bombing of a Nazi dam. The barrel shaped bomb had to hit the water a certain way, roll forward as it sank a certain way to end down at the bottom water side of the dam. Not saying it would work in this idea, but hey, it's a fiction story idea?
That's known as 'The Dam Busters Raid' and was a real life attack on the dams of the Ruhr Valley in Germany. It was successful and it did cause a major disruption o the German war production, but it was not as effective as they hoped. However, the dams involved were not as deep as Hoover dam is, and the deeper down the higher the pressure, but also the thicker the dam wall is.
IIRC Hoover Dam was massively over-designed, over-engineered and overbuilt. It was constructed to withstand a designed pressure of 45,000 psi at bedrock (bottom of dam). It is 660 ft thick at that point, gradually reducing to 45 ft at the roadbed across the dam.
However, assuming a full Lake Mead (water depth of about 720 ft), the water pressure at bedrock is less than 400 psi.
I very much doubt a Ruhr-type attack would work with anything less than a nuke.
Also, due to the interlocking block construction, type of concrete and aggregate used and cure cooling practiced, the dam is continuing to cure and get stronger - as shown by some 1995 core samples taken. There is a reason that Hoover Dam was mentioned in those "after mankind falls" articles as one of the few structures expected to still be standing after 10,000 years.
A lot depends on what you want to do as you do not have to set the explosives at the bottom of the wall. A good explosion and damage near the top would be sufficient as the water flowing through the hole with expand the damaged area a lot, as has been proven in the photos of past damaged dams.
That's known as 'The Dam Busters Raid' and was a real life attack on the dams of the Ruhr Valley in Germany. It was successful and it did cause a major disruption o the German war production, but it was not as effective as they hoped.
The first dam they hit (Mohne) was in the Ruhr valley, it caused some damage to the war effort.
The second dam they hit was the Eder. There was little in the way of military production in the area, there *was* a P.O.W. camp for Soviets along with a few villages downstream of the dam and you can imagine what happened there.
I think the third dam (Sorpe) was hardly damaged at all.
However, the dams involved were not as deep as Hoover dam is, and the deeper down the higher the pressure, but also the thicker the dam wall is.
the Sorpe's embankment dam with its concrete core covered in soil withstood the attacks with only minor damage.
There's been enough silt build up at the bottom of Lake Mead that you're looking at a similar situation. And the water level there is now so low you really could blow a fifty foot deep chunk out of the top and not have it affect anything.
Compare the Lancaster's bomb run in the Dambusters movie to the X-Wing down the Deathstar trench in Star Wars. Its a straight rip off.
I feel like the bigger problem would be the effects measured years later in the loss of available water for such a huge area of the southwestern US.
That would truly suck for a lot of people.
In other words... yes, I'm interested in reading a story dealing with these problems. Preferably written by someone other than myself, I wouldn't want to wait so long to read it.
Tee Hee.
--Shinerdrinker
You don't need to blow the dam for that.
This link goes into the situation in August 2021, comparing it to levels a year earlier.
This Documents the level now, along with the levels in 2020 and 2021. You can see that the fall in water levels is accelerating, as one would expect in V-shaped valleys.
You can activate the lines in the graph for 2017-2019, they show a similar pattern to 2020.
Not only have explosives improved, but also the delivery. No need for bouncing bombs today with guided missiles doing exactly that (self guidance).
Whilst the apex's of damns are their strongest points, the sides aren't and rely on a straight, equal transference of load from middle to the two sides. You can mimic this with a flat surface, a piece of paper and two heavy books. Bend the piece of paper between the two books and you can load a load of weight on to the top of the arch. Apply that same weight to the side and the arch will crumple because there is only one anchor for the transference of weight.
Or an other, quicker example, is an egg. Place an egg lengthways between your two hands (or prosthetic) and push against the two ends and it will resist quite robustly, try the same experiment against the sides and you will most likely end up with egg on your f...
A damn may be solid, but that also could work against it with relation to transference of blast wave. Several strikes to the inside of one side of the curve would fracture the concrete and the transference of shock through the concrete would most likely blow the outside face opposite the strike(s) completely off the dam. Then it's really up to the professionalism of the steel erectors and how well they tied the rebar together...
If terrorists were to destroy Hoover Dam, what would be in danger by the flooding alone?
Destroying Hoover Dam is a common fiction trope, particularly crime dramas. I wonder whether the authors did thorough research or whether they resorted to dramatic licence.
AJ
Most likely dramatic license, as to the public "a dam is a dam is a dam" ...
Using just the three mentioned by Ernest - St. Francis, Teton and Buffalo Creek.
St Francis was a concrete gravity dam, which was a successful design for a number of dams, but it failed because it had defective soil foundation that eventually gave way.
Teton was an earthen dam - a design which basically counts on a massive pile of earth and stone to hold back a man-made lake, but the site chosen was a fractured rhyolite location, and permeable loass (basically compacted dust) was used to build the 300 foot dam. It started leaking when it was initially being filled and gave way within 24 hours ... probably a good thing it wasn't completely full.
At Buffalo Creek, there weren't any dams, it was three coal slurry impoundments that had been created by miners without any engineering advice. In wet weather, they started fulling up with water, and once the upper one gave, it took the lower two with it, pretty much wiping 16 coal mining towns, 125 deaths and over 4000 left homeless. The aftermath was a scriptwriters dream - corrupt politicians bought off by the mine owners, competing investigations pointing fingers at the Feds, WV Governor, Mine Owner, the Land owners, the UMW and the victims ...
My deepest apologies for my rudeness in behavior ... I must place the blame on being raised by a pastor, and having not been taught how to be a proper wild child and social rebel in my youth ...
Using just the three mentioned by Ernest - St. Francis, Teton and Buffalo Creek.
While they aren't the same construction as Hoover, the havoc caused after they failed is a good indicator of what would happen if Hoover was seriously damaged, which is what the original poster was asking about. How you go about causing that breakdown is another question.
I was wondering if the kind of flood mentioned by EB was realistic or if the water would spread out too thin before it got that far. So I looked at the numbers.
The capacity of lake Mead is 28.9 million acre-feet.
An acre-foot is the amount of water it would take to cover one acre of land to a depth of 1 foot.
28.9 million acres is around 45,227 square miles.
The entire Colorado River is only around 1,450 miles.
If the Hover damn failed, a miles wide floodplain (excluding areas where the river flows through canyons) stretching from Hover Dam to the Gulf of California is certainly plausible.
I think you have some invalid data in your figures.
First, your numbers assume a complete failure of all 720+ ft of Hoover Dam, which is highly unlikely. A partial collapse might be possible, but still unlikely.
Also, I believe your numbers are with Lake Mead at full capacity, however at present, the Lake Mead water level is over 170 ft below "capacity" so the actual reduction in max numbers could be as high as a 50% reduction.
Additionally, while the top of the dam is only 45 ft thick, the dam thickness at the current water surface level is probably closer to 200 ft thick, and thus a much stronger barrier ..
First, your numbers assume a complete failure of all 720+ ft of Hoover Dam
No, I'm not assuming anything.
so the actual reduction in max numbers could be as high as a 50% reduction
Even if only half the water in lake Mead were released, that's still enough water to cover more than 20 thousand square miles to a depth of 1 foot.
More than enough water for the level of disaster EB was talking about.
ETA: Even 25% of the volume of Lake Mead would cover 11,300 square miles at a depth of 1 foot.
I couldn't find anything giving the distance along the Colorado from Hover Dam to the Gulf of California. So for the sake of discussion I will use 700 miles (slightly less than half the total length of the river).
Even 25% of Lake Mead at a length of 700 miles and an average flood depth of 1 foot gives a flood zone slightly more than 16 miles wide.
I couldn't find anything giving the distance along the Colorado from Hover Dam to the Gulf of California. So for the sake of discussion I will use 700 miles (slightly less than half the total length of the river).
Apparently you didn't try very hard. Just go to Google maps and click distance. Straight line is 298 miles. It's 292 by road from Yuma, so figure 350 or so, half your guess.
More than enough water for the level of disaster EB was talking about.
If it was going out into flat land, and dumped all at once, possibly. It's not. Where does the Colorado River flow? Down the Colorado River CANYON. It would probably start overflowing when it got down to Willow Beach, Arizona, and THEN where's it going to go? Into the desert.
Obviously, Ernest looked at a map, but it doesn't look like he looked at a topographical map. Willow Beach Campground, Willow Beach Road, and Jumbo Wash Road are all natural drains for the Colorado, from when it DOES flood. It's going to be very difficult for much other than slightly elevated river levels to reach beyond that - and that assumes an instantaneous disappearance of the Hoover Dam.
Keep in mind the concrete in there is STILL curing, and is even stronger now than it was when it opened.
Keep in mind the concrete in there is STILL curing, and is even stronger now than it was when it opened.
The St Francis Dam failure is a good example of why that doesn't matter.
As strong as the dam itself might be, if water were to make it's way past the abutments with the dam at it's full supply level, it wouldn't take much time at all for the flow to increase sufficiently to scour out the abutments and scour into the bedrock & start undermining the base of the dam.
Even if such scouring isn't enough to cause parts of the edges of the dam to break away, the effects down stream would still be disastrous.
While more people would have time to evacuate than if the dam itself were to fail over a few minutes, even so a huge amount of damage and loss of life would occur downstream.
As strong as the dam itself might be, if water were to make it's way past the abutments with the dam at it's full supply level, it wouldn't take much time at all for the flow to increase sufficiently to scour out the abutments and scour into the bedrock & start undermining the base of the dam.
The abutments for Hoover Dam ARE on bedrock. They specifically went there with them so it COULDN'T leak around the wings.
The abutments for Hoover Dam ARE on bedrock. They specifically went there with them so it COULDN'T leak around the wings.
This discussion isn't about whether the dam could fail in the manner that the St Francis Dam did due to problems with the geology. but whether it could be destroyed by Terrorists.
Explosives at the abutments could cause fractures & leaks, and once started would result in scouring that would lead to the dam no longer holding the water back- even if the dam remained standing.
Even so, the effect of that much water going around the abutments would most likely lead to undercutting of the base of the dam (as deep as it is), leading to cracking throughout the area that was undercut- if the under cutting went in far enough.
The dam's strength is in it's ability to resist compression. Without the load of the water behind it, and the lack of support underneath it would adversely affect the dam, even if it was undamaged by the explosions or the water draining past it.
Apparently you didn't try very hard. Just go to Google maps and click distance. Straight line is 298 miles. It's 292 by road from Yuma, so figure 350 or so, half your guess.
I wasn't looking for straight line or road distance. I was looking for the distance along the river course itself. Not the same thing.
I wasn't looking for straight line or road distance.
You also weren't looking at the map, either, or you'd have seen that the river doesn't meander that much. Meaning the road distance from Yuma to the Hoover Dam pretty much MATCHES the river distance.
Suddenly you're all a bunch of dam engineers?
Just write the dam story - it's fiction, after all.
Suddenly you're all a bunch of dam engineers?
Just write the dam story - it's fiction, after all.
And fiction that ignores reality (that isn't actually meant to be fantasy) tends not to do well at all.
Sure, some things can be used as a plot device (and often an author will have a preface stating that to avoid all the complaints later on), but a story that is full of factual errors isn't something i waste my time on.
And not many others do either.
If factual errors bother you, you must not read stories on SOL, but many others apparently do, and often enjoy them.
If factual errors bother you, you must not read stories on SOL, but many others apparently do, and sometimes enjoy them.
It's a shame you weren't able to comprehend what i wrote.
In this case, I only give real points for 'it's fiction, after all' to alternate universe stories, where the Hoover Dam was constructed on the cheap, or with substandard materials, or an incompetent chief engineer (or maybe all of those). If we're talking this universe, with this Hoover Dam, do the dam research and make it plausible.
The dam was also designed to be so heavy that the full pressure of the lake wouldn't move it even if it was detached from the walls of the canyon.
The dam was also designed to be so heavy that the full pressure of the lake wouldn't move it even if it was detached from the walls of the canyon.
I think it'd move. Even half full, that's 18.2 BILLION tons of water, and Hoover Dam only weighs 6.5 million tons. Now, I'll grant you that's actual weight of the water, and not the force it's putting on the dam, which is different. (The pressure from the water at the bottom of the lake pushing on the dam is at 310 psi, in case anyone cares.)
Just a point of trivia the first and last men killed in the construction of the dam were father and son. a truly multi-genertional project
The easiest way to destroy Hoover Dam is to rename it. Hoover was a Republican and "responsible" for the great depression from 1929 to world war two. Maybe the Democrats would prefer Franklin Delano Roosevelt Dam. Lots of Republicans in that era would like to Damn FDR.
Lots of tavern owners are publicans. A pub is a kind of tavern. If you own two or more you are a re-publican.
The easiest way to destroy Hoover Dam
Pardon me for being cynical, but how many here have ever destroyed a Hoover Dam?
AJ
Pardon me for being cynical, but how many here have ever destroyed a Hoover Dam?
If you include calling a jam of stuff in the hose of my Hoover vacuum cleaner a Hoover Dam, I used to destroy a Hoover Dam on a regular basis back in the 1970s until I replaced the Hoover with an Electrolux.
The easiest way to destroy Hoover Dam is to rename it.
Hoover Dam was at one time was called Boulder Dam.
Boulder Dam
"Hoover Dam is named for Mr. Herbert Hoover, the Nation's 31st president. When construction of the dam was initiated, on September 30, 1930, Secretary of the Interior Ray Lyman Wilbur ordered that the dam to be built in the Black Canyon of the Colorado as part of the Boulder Canyon Project Act be called "Hoover Dam". By a Congressional Act of February 14, 1931, this name was made official.
After Mr. Hoover left office, the names "Boulder Canyon Dam" and "Boulder Dam" were frequently used when referring to the dam, allegedly because the new Secretary of the Interior did not like Mr. Hoover. However, the name of the dam was never officially changed from "Hoover." In the 80th Congress (1947), a number of bills were introduced to "officially" restore the name of Hoover Dam. On March 4, 1947, House Resolution 140 was introduced for this purpose.
Source: http://www.usbr.gov/lc/hooverdam/History/articles/naming.html"
If terrorists were to destroy Hoover Dam, what would be in danger by the flooding alone?
Nothing.
Hoover Dam is an instruction to the cleaners, destroying it would only result in an accumulation of dirt.