There's a splendid extended article in today's Chicago Tribune by architectural critic Blair Kamin on the present state and potential future of New Orleans. His first hand report talks about what it's like to be a solitary tourist in a largely abandoned city, and talks about how much more of the city endured than reports have indicated. He makes a strong case for the rebuilding of New Orleans, both its feasibility and its necessity. Kamin talks about how reversing the flow of the Chicago river, to avoid the contamination of the lake and its drinking water, is just one concrete example of how a city triumphed over nature. If you can, pick up a copy of the paper so you can also see Chris Walker's great photos. If you can't, you can reader Kamin's account, free for the next seven days, here.
An even more cogent example, and one which I've yet to hear anyone discuss, is that in its early history Chicago almost drowned in its own muck and filfth, with regular and vicious outbreaks of cholera until the decision was made in 1850's to raise the level of the entire city six to ten feet. You can still see it clearly in the old neighborhood houses where stairs lead down to what used to be the entrance, and especially along the riveredge of the Loop, where you can clearly see how the current level of the streets are over a full story over ground level. Lower Wacker Drive is where Chicago's "natural" level lies.
As New Orleans is rebuilt, why can't we do something similar to raise its lower districts back above sea level?
From what I understand, raising New Orleans won't work the way it did in Chicago. Since every drop of rain that falls in New Orleans has to evaporate or be pumped out, the ground water does not get recharged. As a result the land subsides. As more dirt is put on top that accelerates the process. so things keep sinking. The upshot is that where the city is, was (and still wants to be) a wet marsh. Land such as this new really lends itself to building on easily.
Sure in Chicago we had marshes too, but we also aren't sitting below sea (or lake level) so we can let rain recharge our auquifers.
You've raised some excellent points. (damn!) Pumping out all the ground water was the big idea of 1910 that made all the low-lying areas habitable; the downside was the subsidence. Much of downtown Chicago is now built on caissons that go down to bedrock. Perhaps securing low-lying areas in New Orleans with large superstructures for new construction could begin to wean the city away from pumping out all the groundwater, neighborhood by neighborhood. The cost would be immense, but so would the cost of recreating the crucially important Port of New Orleans further up stream. Could it be any worse than the Big Dig in Boston? By creating the superstructure block by block rather than building by building, it might create innovations in engineering that could keep costs well below the boondoggle level.
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