I remember Scientific American had an article about what would happen to New Orleans if a hurricane hit several years before Katrina [1]. I recall having a bit of a hard time believing it could really be as bad as they said: surely people would have planned for something like this given its inevitability? Obviously I was wrong.

Also, Katerina wasn't even the direct hit that they had modeled so it could have been much, much worse. I still wonder, even in the wake of Katrina, if New Orleans is truly prepared for the storm that is inevitably going to come.

[1] paywalled, but this is the link from 2001: https://www.scientificamerican.com/article/drowning-new-orle...