My advice: Do not build a city below sea level in hurricane territory.
No matter how big you build your protective barriers, sooner or later a storm will come along that will either overtop them or breach them. The most rational solution is to import vast quantities of crushed rock and fill the city up to say 20 meters above sea level. Then build on top of THAT. It would mean complete demolition of the existing city, step by step. It will never be done because it is far too expensive.
New Orleans will be rebuilt exactly as it was and the same thing will happen again.