That is what I understand, that the CBD is the only area largely unaffected by surge/flooding. The levee system largely held across much of the area, but it wasn't enough to keep the surge from topping it and leading to flood waters rising 3-4' in many parts of the city. At that point, it becomes a matter of elevation. Many homes that I'm seeing (outside of east of town) look like they have the standard slanted driveways & elevation that you see across much of Florida & the US; this is leading to the roads being full of water, but the actual houses themselves being spared most water damage. I imagine this is not the case everywhere, but some people may have been spared by being just a few feet higher than somewhere else.

The CBD is about 3-7' above sea level, from what I understand and from what I can tell using Google Earth; in a city where the average elevation is about 6' below sea level and where flood waters rose, on average, 4-6'...you can see that much of the system did its job and the center of the city was spared the worst. I should qualify the statements made earlier to say that the rises of 8-15' inside the city are generally in the most low-lying areas; to the east of the city, those are true figures, but inside the city those generally apply only to the lowest of elevations (those 10' below sea level and lower).

Obviously, that's no consolation to areas just outside the city, as that is where the water is going to pile up, but hopefully those areas can start to recover as soon as possible as well.