A transistor radio, flashlights and plenty of batteries is essential. On one of the talking head shows, it was said that because of power outages, if you did not have a radio you could not have been aware of the levee failures until your house became inundated. The water rose so fast, there was little time to make a logical plan of escape.
The plans should have been in place for decades. The city knew the levees were designed to withstand only a cat 3 hurricane. What happened to the city's disaster plan? What happened to each family having their own plan? They knew the threat was there yet the proper actions were not taken by the families that chose to stay, by the city that failed to evacuate those that could not get out themselves, and by the state that failed to coordinate and supervise the execution of the plans.
The plans were inadequate and the execution was hampered by inept leadership. Who does the media want to blame?
It's an urban area - Don't they have the equivalent of tornado sirens? If we have a tornado threat, it's pretty hard to miss the dozens of extremely loud sirens located all over the city.
I find it hard to believe that a city located below sea level wasn't similarly equipped.