We had a big one a while back, in Detroit. We have Hines Drive, which is an amazingly good idea. It is an area that is a long park that follows the Rouge River. Normally it is one road and parkland on each side. During a flood, the whole thing becomes part of the Rouge River, and the road is closed. Then when the river recedes it is used as a park again. No buildings, but bathrooms, that are flood resistant.