As we quickly approach the two-year anniversary of Hurricane Katrina making landfall and devastating the city of New Orleans, it seems a good time to reflect on what happened...and what's being done to be sure it never happens again.

New Orleans Flooding following Katrina

You probably know the basics already...monster Hurricane Katrina made landfall in New Orleans on August 29, 2005. The city's levee system failed, and severe flooding brought the city to its knees. What you probably don't know is that some of the major assumptions most people are going off of are wrong. For example, Hurricane Katrina was a monster storm...when it was in the middle of the Gulf of Mexico. By the time it made landfall along the Louisiana coast, its winds were down to around 125mph...and since the storm actually made landfall to the east of New Orleans, the winds in the city peaked at just 100mph. Nothing to sneeze at, but certainly not nearly as bad as it could have been.

So, if Katrina was just a typical hurricane by the time it made landfall - and not the monster that everyone has been led to believe - why did the city get innundated with flooding? What happened?

Two big things - levees and wetlands. The levee system was terribly inadequate for the risks the city faced. New Orleans is very close the Gulf Coast, and faces the constant threat of water and flooding because of the Gulf and the hurricane risk. So the levees were built to prevent flooding in the city. But these levees were designed to withstand a category three hurricane - even though New Orleans could easily be threatened by a category four or five storm. (In reality, the levees couldn't even handle the winds of Katrina - barely a category two storm in New Orleans.) Then there's the problem of the vanishing wetlands. For years the Mississippi River carried tons of sediments (mud, silt, etc.) downstream and then dumped it in the marshy wetlands of coastal Louisiana as the river emptied into the Gulf. That's how the wetlands, and even the land that New Orleans is on, got built up over time. But once we started aggressively managing the Mississippi, trying to prevent its natural floods, that land-building process got interrupted. The river now carries much less sediment than it used to, and so there's less mud and silt being dumped by the river in coastal Lousiana. So the marshes...and the city of New Orleans...are sinking...and disappearing. In fact, 30% of Lousiana's wetlands have vanished, reclaimed by the Gulf of Mexico. This is so important because wetlands are a natural barrier to storm surge and a hurricane's large waves. With less wetlands, there is less protection from a hurricane's watery wrath. This combination...inadequate levees combining with the disapperance of nature's natural hurricane barrier...made New Orleans a sitting duck back in 2005...just sitting there, waiting for Katrina.

Two years later the Army Corps of Engineers is trying to improve New Orleans flailing levee system. They're working on a plan that will strengthen the levees...but even the 'new' levees are still going to be so inadequate, they won't be able to withstand the force of another Katrina. Then there's the managing of the Mississippi issue. This is such a complex problem that it's anyone's guess as far as whether or not it's being addressed. But one thing is certain. Until that issue is resolved...until the Mississippi is allowed to flow more naturally, and can start rebuilding coastal Lousiana again...New Orleans and the surrounding wetlands will continue to sink into the Gulf of Mexico.

Inadequate levees...vanishing wetlands and a sinking New Orleans...seems like not much has changed over the last two years. Unfortunately, hurricanes are not going to wait for New Orleans to get it right. Katrina was just the warmup...

Hurricane Katrina before Landfall

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