There's a museum in New Orleans that has a Katrina display and it turns out that they did indeed call in Dutch experts to advise them. The Dutch gave them sensible ideas like building low elevation parks that could flood without issue and hold lots of water, instead of concrete spillways and drainage that just moves water fast until it fails catastrophically when inundated. Louisiana being Louisiana, it was all ignored.

The museum convinced me that New Orleans is doomed in so many ways. Everything from the Atchafalaya ORCS to the paving over of wetlands to build the city to the destruction of the Plaquemines marsh lands to the southeast of the city all seem to be maximally unhelpful for preventing storm damage.