I’ve kind of been thinking/expecting in the back of my mind that the New Orleans flooding will subside and drain away now that he storm’s gone, like it usually does in most locales after the storm is over. However, it just occurred to me (I’m Captain Obvious) that that New Orleans waters not going to go anywhere if NO is sitting in flooded bowl level with, or below, the outside water level, and that NO will stay flooded until the levees are repaired, and the the city will have to be pumped out which is going to take months. NO is going o be under water for quite some time.
They are alredy preparing to actually remove more of the levee where the original breech occurred (once the lake has dropped) to get some of the water out more quickly, then patch up the levees and begin pumping.
The Army Corp of Engineers guy said at a press conference (yesterday?) that once the levee is fixed they have to fix the pumps and then it will be 35 to 90 days to de-water the city.
Really should have keep those levees built up strong.
The water level in lake Ponchartrain was raised by the hurricane. The levees failed, and the water level in the city reached equilibrium with that raised lake level. The lake is draining to its normal pool size. As long as they don’t block the holes in the levees too soon, that will also lower the water level in the city. Since the city is lower than the normal lake level, they can’t get rid of all the water that way, but even a foot or two represents many thousands of acre feet that won’t have to be pumped out.
It has more to do with the point Squink made. Ponchartrain rose above its normal levels with the hurricane rains (and some storm surge) and is slowly returning to its normal levels, out through Lake Borgne to the Caribbean. As it recedes, breeched levees in N.O can let the"top layer" of water out to drain east from the lake into the Caribbean. Once equilibrium has been reached, they need to shore up the levee (to prevent the lake from returning) and begin pumping. The water will be pumped into the (now lower) lake, into the Mississippi River, and into the bayous south and east of the city.
Lake Ponchartrain, the bayous to the south of the city, and (according to Tom’s link) the Mississippi river. Here’s a nice overview of the Geography of New Orleans. Satellite shots show the disconnect between lake Ponchartrain and the gulf and the canal system. Unfortunately, the pumping stations aren’t pinpointed; likely one of those “lessons of 9/11” things.
The pollution will probably just get sucked out with the water. If they had to filter out all the crud, then the de-watering process would take years, not months.
Squink…
thanks for posting that link to N.O. geography. Very enlightening. I was watching CSPAN a couple of days ago and the Army Corps of Engineer General was explaining that when they built this levee system they designed it to handle up to a category 3 hurricane. They did the risk analysis studies and found that there was less than a .05% chance that within 300 years there would be a category 4or5 storm to hit N.O. In other words they felt that they had a 99.5% level of safety to protect against a cat 4 or 5 hurricane.
In light of what I learned about the geology of the area (the irony that the current solution may well be contributing to the failure of the system since the river is no longer depositing silt along the riverbanks) it seems that we really need to rethink the next course of action when the city gets back on it’s feet. Man and his engineering feats are wonderful and amazing but there are times when we need to “fall back” and regroup with a better game plan.
If the toxic water is just drained back into surrounding nature, wouldn’t that be counterproductive–it would seep into the natural water supply and render the area uninhabitable for months anyway… ??
(Unless you’re willing to take a tetanus shot every time you scrape your knee while playing outside & putting a little bleach in everything you drink, that is…)
Remember, the city is at the mouth of the largest river system on the continent. There’s a lot of fresh water that goes through N’Awleans. Anything they dump into the river will quickly be washed out the Gulf, which they wouldn’t be drinking anyway, and more fresh water will be pouring into the city’s supply from everywhere from Pittsburgh to Yellowstone.
Mind you, New Orleans does also get the pollution from everyone upstream of them, which is darn near everyone. But they’ve always gotten that, even at the best of times. I presume that the city’s infrastructure and citizens are already capable of handling that expected level of pollution.
