> Just want to point out this approach won't work for Florida (and I'm not implying you said it would). The land in south Florida is porous limestone, and the w

> Just want to point out this approach won't work for Florida (and I'm not implying you said it would). The land in south Florida is porous limestone, and the water will just pass under any dykes you build. Not a problem. Just drive a sheet pile curtain along the retaining wall to force the flow net through a long enough path that the resistance alone reduces the flow volume. This sort of stuff is covered in civil engineering degrees at graduate or even undergraduate level. Google for sheet pile flow net to get the idea. And by the way, while you claim that Florida is limestone, the Netherlands is just a big old alluvial plain comprised of loose sand.