You get it once, but the second time, you get enough for another house, and that one is torn down and the land is condemned
Jed, I think you hit the nail on the head. Let the market (insurability of a piece of land) dictate zoning for floods, i.e. if a claim is placed against flood insurance, the land becomes permanently un-insurable against floods. The user could still build on that property, but would have to mitigate against flood damage on his/her own dime (i.e. build on a berm, build a floating house, whatever).
I think search and rescue operations should operate similarly, i.e. you get one free rescue from a dangerous place, after that you are on your own.