In the aftermath of Hurricane Katrina, the question remains. What will become of the sodden city that is 80 percent below sea level after the pumps finish removing the flood waters? Is the damage beyond repair, or should we go ahead and restore the city to a condition resembling its former status?
The real answer to the question of rebuilding is yes, and no. This city will never be totally demolished no matter what happens to it. It has been inhabited continually since the 1700s and will continue to be inhabited for the forseeable future. But the hard questions have to do with the large areas of the city, as well as surrounding communities, that are mostly below sea level.
First of all, how is it that a city came to exist below the level of the sea? In its native condition, it wasn’t really that way to begin with. The land that existed before the city did consisted of the Mississippi River and its riverbanks that had built up over time from river sediment. Apart from a few areas, much of the rest of the land the city now occupies was native swamp. Not necessarily below sea level. That process started as eager land developers started looking toward the swamps as a way of developing land into sellable real estate, as the prosperity generated from the port city created a demand for close-in homes. Swamps were drained and then filled in, the land divided into streets and lots and houses. But putting the weight of civilization upon such a muddy base while continuing to pump out water from the land results in a settling effect over time, one that is still occurring.
There have been major efforts to tame the swamps dating back to the 1800s, but the 20th century with its improved technology made the undoable possible. It was obvious from way back that the area was flood prone, and as a response massive levees were built in a process that is still ongoing also. The Mississippi River was always the major worry due to its history of massive flooding. Levees and diversionary channels have allowed the city to even exist at all.
Examining the elevation map (click on thumbnail map) of the city and surrounding suburbs, one can see the obvious problem. Many residential areas are at to noticeably below sea level, here referring to the mean sea level of the Gulf of Mexico which lies 70 miles to the south. The levels of the Mississippi River and Lake Pontchartrain are actually above sea level as they border the city. In other words, the elevation difference is actually worse than it sounds because the main sources of potential flooding exist at a level up to 10 to 20 feet above sea level in New Orleans. That means that land that is at sea level or slightly above is actually in grave danger of flooding as well.
The more historic parts such as the French Quarter tend to fare better than much of the rest of the city because they were built more or less on sensible land, land known to already be safely above the surrounding areas of swamp. These areas bordering the river are the easiest to protect and preserve. A lot of the Central Business District is saveable as well, but only small areas of the residential city tend not to be flood prone in a disaster scenario such as this one.
So what do we do with New Orleans? Build higher and stronger levees, such as the Netherlands did to protect its low-lying areas? The problem the Dutch will always have is that sacrificing their land to the sea would leave a significant portion of their population nowhere to go other than outside of their own country and culture. So as a nation they have made huge if not painful investments in massive sea projects to help protect against cataclysmic flooding, even though common sense might dictate that this is a battle that Nature could ultimately win some day.
In the case of New Orleans, with 480,000 residents within the city limits and many thousands more in the suburbs in flood-prone areas, the United States offers a wide variety of places to resettle. What the returning residents will find when they try to reclaim homes that had been invaded with the murky floodwaters is that the extended submergence will have made things unlivable. Floors and walls will be damaged beyond repair, electrical circuits ruined. Once the water begins to warp and rot the frame of the house, you may as well get the bulldozer. But for those that persist, the final obstacle will be the mold that takes over an inundated structure. Some homes that had minor flood damage will be salvageable, at a cost. The majority of homes within New Orleans will likely have to be demolished, and the surviving ones will face hefty repair bills.
What would it take to guarantee the safety of all below sea level neighborhoods in and around New Orleans? An incredible amount of investment in building larger, sturdier levees. The existing levees, which have been under development for decades and are still far from completed, will now be considered inadequate in the face of what did occur during Hurricane Katrina. They would have to be enlarged considerably, a task so large that it would take decades more to complete. Is it worth it? You’re likely to hear more about this question in times to come.
The easiest solution to this massive and expensive headache is to simply abandon the worst areas in favor of higher ground. The lowest-lying areas could be filled in and rebuilt, but the same disaster potential remains. Eventually the filled-in land would settle just as the existing areas continue to sink gradually lower. It’s a known fact that sea levels are gradually rising, and the phenomenom of global warming is resulting in more frequent and more intense hurricanes driven by rising sea temperatures. It’s time to give up the struggle against the inevitable. The lowest areas should be slated for near total abandonment by not permitting new construction in these zones. In Hilo, Hawaii after tsunamis wrecked the lower areas of the city, parklands have replaced residential areas that were wiped out by the waves. It’s time to do the same for New Orleans. The city and its thriving port and history will go on, but not the waiting-for-the-next-disaster game if sensible measures are taken now.