Left image before flooding
Right image of flooding from a Cat5 Hurricane (not a breech of the lake) - red areas are the lowest areas in the "bowl".
Actually that 2nd image is indeed from a breach, not a Cat 5. The superdome is shown at the edge of the flooding, and it is right about at sea level. In a Cat 5, the storm surge would overtop the levee, 13' at its lowest point, and would fill the bowl until it reached 13' above sea level.