Traditionally, temporary dams are made with sand bags. They can be used to circle houses, to block doorways, or to temporarily raise the height of levees.
Presumably, the pumps would be diesel powered since you can’t depend on reliable electricity during a flood.
The basic problems with barrier systems such as this are two:
- It has to be perfect-one soft spot in the the ground and a leak starts.
- You have to have a check valve installed on your sewer line in advance.
Sewer check valves are difficult to maintain over the long term for obvious reasons.
I have seen several of these barrier ideas come and go over the years.
Usually someone floods and builds a levee around their home/apartment building/store/random building. Over the next several years maintenance issues degrade the levee until it is no longer functional, then in a few years they are removed. Another flood, rinse and repeat.
My insurance agent got flooded once too many times (from rain), and contracted with an engineer to build a solid flood wall around his home. Of course a levee or wall is equally good at holding water in vs out, so he had a pump installed. One day rain overwhelmed his pump and flooded his house. He called the engineer and was told to get a second pump. He figured mother nature had more rain than he had money and had the wall removed.
I knew another person who went the flood wall route. Of course he needed to have a mechanism to block off his garage without stopping his car. That was a manually installed barrier he would put in across the door when floodwaters came. One night during a moderate rain at his house he woke up to soggy carpets. It had rained really hard a couple of miles up stream from his house. He sold the house to FEMA and moved away.
Sometimes the barriers will work. Even temporary ones. But you will never sleep easy with a barrier.
The only way to avoid a flood is pilings. Decide what level of flood you want to protect yourself from, add a foot because the next flood will always be higher than the last, and raise your house. THEN you can sleep easy.
I remember the Aquadam from an episode about 6 years ago, at a nuclear power plant in my (approximate) vicinity.
The “rubber berm”, as it’s called in Wikipedia, worked well to hold flood waters out of the primary reactor containment building. Until someone working inside the berm poked a hole in it with the scoop of their Bobcat. :smack:
So, potentially useful, but also fragile.
I just happened to run across the owner of that dam on youtube. It took him and two other guys to set it up. He spent $8300 on it but he said it never leaked and there is a quick shot of it working, you can see flood waters all around and dry land by his house.
Here, the folks Joey p is talking about, sell you on their product.
The problem with these sort of devices is - at their heart, they are water balloons. If water is too high on one side, the pressure is too great. The device will start to roll if not properly “nailed down”. How would you anchor it? (Ever tried to hold a water balloon? It’s pretty squirmy) These things are good for as the OP notes, about 27 inches - so minor flooding or marginal areas. For bigger floods, there’s probably a reason why even a 6-foot model would be impractical and certainly not against a strong water flow. The practical application is in spring thaw floods, where the water crest time and height is predictable and there is time to prepare. The aquadam picture shows a graduated series of 3 progressively larger bladders bracing each other - and they are very short, and appear to be anchored into the banks on each side for stability. Plus, without decent prep - and even with it - these dams are going to leak, so you can’t put them up against the building (for stability) unless you can tolerate a decent amount of water leaking in, and still you need a pump to keep bailing the leakage.
I see a problem, Houston. 30" high dam and 50" rainfall.
So if everyone in town has one and then they are drained simultaneously after the flood, is the result a secondary flood?
Now my twisted mind is imagining a dome like the plastic bubble in the middle of the board over the dice-roller in the board game Trouble, except the die is a house…
I think if you could afford to put a glass-and-aluminum dome structure over your house, you could afford to buy property on higher ground. Besides, a dome like that would probably get sucked away by hurricane winds.
Isn’t that the reason islanders in the Pacific and Carribean regions tend to put their houses on stilts? Then again, it seems like those are more like what we would call “huts” rather than “houses” because they don’t seem to be as lavishly outfitted$ as the stuff people from The Colonies like to live in. On the other hand, once you’ve got your home on stilts, you’ve lost the use of basement/cellar space. And I would then worry about earthquakes rattling the whole platform down.
Well, there’s the rub, right? Proper planning of your infrastructure (storm drainage, access and egress roads and highways, responder staffing, etc.) would certainly mitigate these crises a hell of a lot. But putting those safeguards in place requires money and that money is not available when you’ve promised the businesses you won’t tax them if they move their operations in and bring all their people. And, even if the money was available, planning an infrastructure to handle this kind of a storm would be relying on the models and predictions coming from that ‘Bad Science’ – and nobody* believes that garbage! [/rant]
—G!
$ I’m not criticizing the islanders’ homes, in fact that seems to be the prudent architecture for the conditions. I’m suggesting modern people really don’t need to own so much junk or build fortresses in which to stuff it all. Such fortresses are difficult to put on stilts.
*…in political office…
Modern-built stilt houses are real common on the Keys and a few other areas of Florida. Some are McMansions or even larger. They scale fine.
Usually the area under the house at ground level still has the electrical feed, water heaters, etc. And the car & boat storage. So that stuff gets damaged in a flood, but it’s a pittance compared to the damage from putting the whole house at ground level.
Well there are some VERY nice huts around where I live! 
And basements aren’t a concept in lowland areas. With a raised house, you have choices. Some places leave the underside open and have a huge shaded parking area. Other enclose them and have a great party room. Just make sure the party furniture is easily replaced. Of course in both you need extra fire protection and usually an elevator. With a whole-house generator, things are pretty good in such homes no matter what the weather.
As you pointed out, people who lived in hazardous weather locations for generations didn’t mess around with dikes or “waterproofing”. They took two routes: “camps” which blew away in the storm and were easily replaced, and pilings. We have both in the N.O. area. The only places that are threatened by storms are the cheap post WW II structures. Built by people who didn’t plan to live in them long or at all. And people who moved here because of the air conditioning.
And now ask yourself, what’s the difference between that dome and, well, a house? Why is it unacceptable to have the water lapping up against your walls? Well, because the water will hasten the decay of the materials the walls are made of. And some of the water will seep through the walls, and soak everything inside the house. And both of those statements are true of the dome, too. Or, if you can make a dome that resists both of those problems, why not make the house that same way to begin with?
But of course, such water-resistant materials are going to be more expensive. So it’s best to design the house so that there’s nothing on the other side for the water to seep through to. And make the water-resistant parts as small as possible, to save on costs. And next thing you know, you’ve got a stilt house.
Much of Venice is built on stilts.
Not precisely. The foundations of most Venetian buildings are piles made from the large pine trees found inland. These were pounded into the mud over the centuries as buildings were added to the main islands. It’s not perfect. The floor of St. Mark’s, for example, has a very visible wave as different parts move. Most of the old buildings are reinforced with metal plates on the outside bolted to metal rods running across the buildings to prevent teh block walls from falling down as parts of the wall settle.
But then, the problem is less the floods but just general sinking over the centuries. Similarly they have a problem with wave action from motorboats causing slow but steady erosion of the brick walls lining the canals; so motorboats in town have a strictly enforced speed limit, James Bond movies notwithstanding. Regardless, gradual decrepitation (?) is a long term problem. There are a number of walkways that are “Rio Terra”, i.e. a canal was filled in to become a raod when the maintenance was too much over the centuries.
The problem is that heavy pounding surf can be incredibly destructive. Given that extreme storms like Irma threaten a 10 to 15 foot storm surge, which if bad luck holds, could coincide with a high tide - and then the waves pound at the ground floor itself, not pass under the piles. Depends how high the builders planned for. And of course, if they failed to make everything sufficiently wind-proof, then that just adds to the destruction.
Quite right. The best way to avoid a hazard is to not build where it exists. For a big country the USA is remarkably short of land that has *no *hazard for hurricane, overland flood, tornado, wildfire, earthquake, heavy snow, nor ice storm. Certainly some areas are safer than others, but hazard-free building locations are few and far between. And tend to include the economic “hazard” of being where there is no economic infrastructure like existing cities, jobs, schools, etc.
The second best way, admittedly at extra cost, is to design the structure to handle the target hazard(s). Which, as you say, still carries the much smaller tail risk of a hazard more severe than the design was built for.
But Grestarian seemed to say it was simply impossible to create anything more than a grass hut that could live through storm surge. Which is, of course, abject nonsense.
Today, Monday dawned sunny and calm at my place in Broward. The remaining beach cams with power show little beach erosion, some sand lifted into beachfront parking lots, and a few palm fronds lying around. If only we had the collective willpower to bury our electricity infrastructure once and for all, we’d have near zero power outages.
I have not gotten a damage assessment from the neighbors yet. Living in a condo the largest risk is that anyone in the stack above you did a crappy job of preparing and their unit took in a bunch of water that then flows inevitably downhill to yours.
I hope to fly in to tomorrow to resume work. The airlines are generally talking about gingerly restarting South Florida ops mid Tuesday depending on how the damage assessments beginning now turn out. Probably be late Wed at best before things are up to full speed, and that depends on the airfields not having taken too much damage. The buildings and grounds are real stout. The boarding bridges, not so much.
Late edit: Sorry about that off-topic second half; I thought for a bit this was the Irma thread
“Venice is sinking” is a result of the whole area geologically subsiding over the last half century due to Mestre on the mainland drawing down the underground aquifer to support industrial activities. It has little to do with flooding as a cause, but the lower ground level makes floods in the city more frequent and more acute. In the last few decades, since the problem was identified and the draw-down of the aquifer was stopped, the subsidence has stopped. Venice is not on stilts. The tree trunks were used for piles, and pounded level with the (filled in) ground level to provide a footing for brick and rock walls
Article about a $500M project that was proposed/rejected in 1996 that would have saved $50-100B in flooding today. Problem is it cannot be built today. Had to be done then while the I10 was being built up.
Yeah, but $500M is a lot of local money and if it works, nobody would have known that was what saved Houston and nobody would have been praised. On the contrary, $100B is only a tiny bit of federal money and I mean, who could have forseen this anyway and it’s unseemly to blame anyone in the midst of a national disaster.