Suggestion is that flood protection be provided by water, large structured bags could be tethered to the ground in an area to be protected and filled with water to produce flood defenses.

As long as the height of the bags is greater than the depth of the water, they are unlikely to be lifted by it. If the water level is greater than the bag height the tethering will help.

The bags would be shaped like a traditional levee or dike, wider at the bottom than at the top. The bags would seal well against each other due to the flexibility of the bags, and would not let water through (unless they were letting the water out).

The material would need a degree of puncture resistance and may be more reinforced on the side that is controlling the water to control punctures from floating objects.

A more sophisticated system would leave the flood bags partially full, around 1 foot high. As flood water laps at the base of them, pumps could automatically start to use the flood water to continue the inflation to the desired height.
-- PiledHigherandDeeper, Jun 04 2003

Spragg Bag http://www.waterbag...economi/economi.htm
Used for transport of water [thumbwax, Oct 04 2004, last modified Oct 21 2004]

Bags of water http://www.waterweights.com/fnf.htm
Something like this [PiledHigherandDeeper, Oct 04 2004, last modified Oct 21 2004]

Air filled version http://www.noaq.com/
[PiledHigherandDeeper, Oct 04 2004, last modified Oct 21 2004]

RapiDam http://www.rapidam.com/datasheets.asp
Self-supporting flood dam [OnionBread, Oct 04 2004, last modified Oct 21 2004]

What about water pressure?
-- thumbwax, Jun 05 2003


Water pressure is equal to the height of the water, as long as the height of the water bag is greater than the height of water against it, it should be able to support the water behind it.
-- PiledHigherandDeeper, Jun 05 2003


Except the pressure on the other side of the levee (the side you're trying to keep dry)would be significantly less than that water pressure (pressure = density * gravity * height). The water would tend to push between the bags. Sandbags only work because they're much more dense than water, so they keep that from happening.
-- mandy, Jun 05 2003


The bags are supposed to be levee shaped in one piece, the only joins would between bags side to side.
-- PiledHigherandDeeper, Jun 05 2003


In that case, what you might look into is Spragg Bags.
-- thumbwax, Jun 05 2003


Spragg Bags would do it (b4 any one says it) they float on the website because they are filled with clean water and are being floated in salt water.
-- PiledHigherandDeeper, Jun 05 2003


Sandbags work because they are heavier than water (and won't drift/ float away) and because they bind well together. This idea doesn't do either. Also, it's probably too late and too dangerous to fill a sandbag with flood water.

Nevertheless your idea has two fundamental merits: the use of water to add (1) bulk and (2) weight to an easily transportable flood protection system.

I suggest the following enhancement(s):

Put a high density gel substrate in sackcloth. This will absorb water and set like a sandbag in the presence of water. The addition of heavy particles in the gel will add weight to help hold the bags in place.

Alternatively, consider the use of quick setting spray foams to build a massive dyke on the ultra quick-time.

<slorrrch> <slorrrch> <slorrrch> and Bingo! The village is protected by a giant meringue.... hmm, this diversion's maybe worth a separate idea.
-- FloridaManatee, Jun 05 2003


This [link] is a flood defence system that is held in place by the weight of water that is being held back. It's a single skin, so doesn't need to be filled with water, and It's much faster to deploy than sandbags. There are free-standing and fixed versions shown on the site.
-- OnionBread, Jun 06 2003


I just wrote and then deleted the same idea as this (with the same name, but in a different category).

My subdivision flooded a month or two back and I was about to get out the inflatible pool and fill it up in front of the door. It was the only thing I could think to do. Luckily it stopped raining right about that time. That's the 2nd time in my life that the rain stopped right before I was about to be flooded, but the first time in this house. Long time residents say that it has never flooded like that in the entire 30 years they have lived there. Hopefully that was a once in a lifetime event and I won't have to try the swimming pool dam any time soon.
-- Zimmy, Jun 05 2009


er, big flaw, water density. sand bags are denser and thus dont float away with the tide.if you have bags of water submerged in water they are almost weightless.
-- Arcanus, Jun 05 2009


also really hard to stack. some heavier than water hybrid material is going to be needed.
-- WcW, Jun 05 2009



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