How did places, like New Orleans, get settled if they are below sea level? Shouldn’t the city have been like Atlantis until pumps were invented? Did New Orleans have windmills at some point in time to pump the water out, like Amsterdam?
Well, according to the Encyclopedia Britannica waterwheels for pumping water date back to the ancient Persians and Romans; the “Archimedes screw” also dates back to ancient times. Suction pumps were invented in the Middle Ages.
The Dutch have been busy draining swamps and reclaiming land since at least the Middle Ages. Actually, land reclamation dates back to ancient times. There is a story that in the 6th century B.C.E. the inhabitants of the Greek colony of Camarina in Sicily drained the nearby marshes in an attempt to reduce disease, but wound up removing their city’s natural defense against invasion, and the city was subsequently destroyed by the neighboring city of Syracuse.
As for New Orleans, the site was first settled beginning in 1717, and “mosquito-infested swamps” were one of the problems faced in building a city there.
New Orleans is above sea level but only slightly so, about 30 feet according to once cite I found. It faces flooding from storm surges from the gulf but flooding is not an issue during normal tides.
Just because land is below sea level doesn’t necessarily mean its under water. I’m not saying the same is true for New Orleans, but look at death valley in California.
In New Orleans, there is a public ferry that you can ride for free. You walk down to get on the ferry and up when you get off. Since water seeks its own level the river must be very, very close to the level of the sea or sea level in New Orleans. Therefore, saying New Orleans is below sea level is somewhat of a UL. :eek:
Don’t forget that New Orleans sits in the Mississippi Delta, a huge allevial fan of muck.
The Delta is slowing sinking because it’s just muck. Prior to human intervention, the Mississippi overflowed it banks every year, depositing silt and nutient-laden soil across the delta. So even as the delta sunk under its own weight, it was replenished on top every year through Spring flooding.
Jump ahead a couple of hundred years plus from when New Orleans was founded. The Mississippi no longer overflows it banks every year depositing new soil. The Army Corps of Engineers constructed levees to prevent the yearly flooding. That in turn means 1) the soil is not replenished but the delta continues to sink, and 2) with the river redirected it moves faster carrying the silt further into the Gulf and extending the delta.
Now add just the sheer numbers of people and their roads, buildings, etc. Not just the weight contributing to the sinking delta, but water runoff from rains is redirected into the river and Lake Pontchartrain.
Crap! Having said all this, I just found this online - Atlantis On The Bayou - New Orleans Is Sinking
On average, New Oleans is eight feet below sea level. The artcle says in some areas, 11 feet below sea level.
New Orleans is below the level of the Mississippi because the river has been constrained by dikes to flow in a more restricted channel than would otherwise be the case.
According to Britannica some parts of the city are as much as 1.5 m (5 ft.) below sea level.
There is a continual struggle to keep the Mississippi flowing past Baton Rouge and New Orleans. Above Baton Rouge there is a short river (Old River) that connects the Mississippi with the Red River and out of this river another one, the Atchafalaya, flows south the the Gulf of Mexico. About 25% of the Mississippi is diverted into this system in order to prevent it from switching course to take a shorter route to the Gulf than is presently the case.
The Britannica says: "The Atchafalaya, via the Old River, threatens to capture the major flow of the Mississippi; since the mid-20th century, however, a navigable system of dams, locks, and levees has kept the waters in check. Normally, some 25 percent of the Mississippi’s flow is diverted into the Atchafalaya and the Atchafalaya Basin Floodway through the Old River Complex (Old River Control Structures), … "
half of our country is still way below sea level.
we build some very strong dikes and sluices tho.
There are parts of England that are below sea level.
An important point to understand is that “sea level” should actually be read as “mean sea level”. Most of the land is drained simply by letting the water out at low tide and resricting the inflow when the tide rises. This requires dikes and drainage canals. I would imagine that pumping water out is an optional extra - perhaps to make the land less watelogged and more fertile.
I would not imagine that there are many places lower than “minimum sea level” - although I would have to say that “sea” would mean the nearest sea - the Dead Sea for example. I guess there might be some desert salt pans that are very low.
Yes, thanks for pointing this out, but consider: If Death Valley bordered the Gulf of Mexico, for example, it’d be called “Drowned Valley”! Yes, land-locked land can be below sea level, but I’m talking about coastal lands… - Jinx
For more info, check out The Control of Nature by John McPhee – an excellent book (one of McPhee’s best, IMHO).
I think that there was a magazine article in a magazine called something like the History of Technology. In it they described how New Orleans is threatened by the naturally high water level, the naturally low land level, and the man made high banks of the Missippi and lakes. They have to pump out water continuously just to keep things from getting any worse.
Wow, now I understand the song.