"Of all the myths surrounding Katrina -and there are thousands of them- the biggest one by far is that New Orleans flooded because it is below sea level. I know you've all heard it and I know many of you have repeated it. It's simply not true. It's a myth.
Before I explain it, I'm forced by history to give you the following warning. Understanding the reasons behind New Orleans flooding requires you to A) Read the whole post. B) Think. If you are unable or unwilling to do both, then here is something else to spend your time doing."