[volguus zildrohar]

I don't know if we'll see them in the near future under current conditions. They're incomprehensibly expensive, would use an ungodly amount of resources and would take a massive outpouring of ingenuity and manpower...they're kind of impractical.

That being said, the regions you mentioned are about the only places I could see something like this being built short of some kind of ecological disaster that would all but necessitate them in other parts of the world.