What was so (terribly) special about Hurricane Katrina?

Hurricane Katrina was terribly devastating. But from the scientific point of view was Katrina somehow unique, are they any lessons we have learned related specifically to Katrina? Read few comments.

Dmitry DukhovskoyAssociate Research Scientist, Center for Ocean-Atmospheric Prediction Studies, Florida State University

I can say that Hurricane Katrina was a category 5 hurricane (according to Saffir-Simpson hurricane wind scale), which is the strongest hurricane category. However it had weakened by the time it made a landfall at Louisiana coast. The strength of the hurricane does not make it unique, though. I would say that Katrina was a classic tropical storm. It was very unfortunate that this strong hurricane made a landfall on a highly-populated area. It is a very unfortunate combination of factors added together that caused this disaster (hurricane strength and, landfall location). Although it is important to note that it was not the winds that caused such devastating consequences but failure of the surge protection levees that caused flooding of New Orleans. The city lays mostly below the mean sea level, protected by the levees, and it doesn’t take much to flood the area in case of levee failure. What this dramatic story has shown is that this kind of natural phenomena has to be taken into account at the design stage of coastal structures and protection levees.

John Nielsen-Gammon, Professor of Meteorology, Texas A&M University

Katrina was unusually large and powerful, though not exceptionally so. The most unusual aspect of Katrina was that its combination of strength and track allowed the storm surge to overwhelm the protective system that New Orleans had in place. New Orleans is the only major American city with a large portion of its population living below the level of the surrounding water. This was the truly unique aspect of the combination of events.

New Orleans has learned from Katrina, with strengthened defenses against storm surge. There’s little in the particular circumstances of New Orleans and Katrina that is generalizable, except for the broader issue of how people respond to displacement due to natural disasters. Here is a good discussion.

William DrennanProfessor, Department of Ocean Sciences, University of Miami

The factors that made Katrina especially devastating were indeed somewhat unique. By the time Katrina made landfall, it had reduced in intensity somewhat, from a category 5 storm to a 3. While there was some wind damage, most of the Katrina damage was from water.  Here, it is important to distinguish between the very significant damage to two distinct  neighbouring areas, Mississippi and New Orleans. Much of the damage to Mississippi, and to
other coastal regions of the Gulf of Mexico, was from storm surge, that is sea water pushed onto  land by the hurricane winds. This frequently happens when hurricanes make landfall, and happened previously in the region with Hurricane Camille in 1969.

The unique aspect of Hurricane Katrina was the damage to New Orleans. Much of New Orleans lies below sea level, and so is susceptible to flooding either from the Mississippi River or Lake  Ponchartrain. To prevent such flooding, a series of levees, sea walls, canals and pumps has been constructed around the city. During the Hurricane Katrina, the levee system failed at numerous  locations, either by overtopping or by undercutting of the foundations. It is this failure of the civil infrastructure (either through inadequate design or in some cases, poor maintenance) that was unique here. The magnitude of the disaster was compounded by poor civil planning/organization that resulted in the city not being evacuated before the storm, as well as the very poor response following the disaster.

In terms of lessons learned, I am hopeful that we are now much more aware of the need for
i) properly maintenance of civil infrastructure (here related to flood control) designed to prevent disasters and
ii) adequate investment in the agencies related to disaster management and prevention.

hile we can not prevent natural disasters from happening, with proper investment and preparation we can minimize the risk to lives and infrastructure.

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