Framework

I think the donut shape is an excellent idea. However, I think the best way to make it is with large prefabricated pipes. For example 8-20 ft diameter corrugated drainage pipes. If one took 5-10 or more and made a donut shape. Cutting and welding bolting the ends together. Then use stiff smaller pipes for spokes like a crude overly strong wagon wheel. The final wheel shape is built flat on the ground maybe 1/4 to 1/2 under ground with extra dirt piled on each side to help deflect flying objects. It should be made strong enough so it can still slide around without tarring apart if hit by an extreme jolt. High Winds would be unlikely to tip it over. Buying and transportation of the pipes to the site should not raises any big issues - for it looks like you just have a big drainage problem. Learning how to weld is not that hard.

Offered by Mike.

Using drainage pipes would seem impossible for most people. Welding requires lots of power, especially if you're going to try to weld something that large. This is why I'm going for a more primitive approach--I want something that can be made without power, rather like a indian teepee but covered in dirt, and/or junk. I'm really wanting to get away from concrete as an answer too, because of the large amount needed and high expense. It's not hard to get now, but later it might be. Making a torus from culverts is cool though, since the heavier and more redundant it is the better. What about using 4 concrete elbows? Where would you get those and the corrugated drain pipes from?

Another option with the torus is to design it to float, like an innertube. The culvert torus would probably float without a base; a concrete one might not. A sphere will float, and can be kept upright a number of ways. The idea is that if (when?) a flood came, you might be better above the water then below it. So a large, sturdy, land based torus building that will magically float if immersed might be a good thing to work on also. Would be very hard to test in real life, unfortunately, requiring accurate models to be built and tested. (and hope for the best)

Offered by Joe.

Local concrete supply places or possibly your Department of Transportation would be a good place to start asking questions about where to get them.

Offered by Clipper.