in general, there are a few different types of "foundations" used for housing. you have a raised foundation, where there are concrete posts with wood panels built on top of them. this type of foundation creates the "crawlspace" which can be used to access below the floor. this is a cheap method of building houses, and might be suitable for areas with flooding.

the other type of foundation is a solid concrete slab. this is just as it sounds, and costs more (because concrete expensive) and can be prone to flooding if the water level rises above the slab. but is more sturdy.