I'm sorry, but short of building something like they have in the Netherlands, this is doomed to happen again eventually. This is a sinking city. They should save what is on high ground, build a double or triple wall to protect it and then let the remainder go back to wetlands.
I agree that the site should be abandoned. Was describing my idea of how to most quiclky drain it, and not making a judgement regarding the wisdom of re-occupation/