Among their findings: Katrina was not a superstorm, and the levee walls were built properly.  

According to the National Hurricane Center in Miami, the Atlantic is in a cycle of heightened hurricane activity due to higher sea-surface temperatures and other factors. The cycle could last 40 years, during which time the United States can expect to be hit by dozens of Katrina-size storms. Policymakers--and coastal residents--need to start seeing hurricanes as routine weather events, not once-in-a-lifetime anomalies.