the levees only method of flood 'management' has proven to be an unmitigated disaster
here's a decent description of how we got here, guess we just keep building higher and higher levees? talk about chasing your tail
pbs.org
Interview with John M. Barry, author of Rising Tide, for "A Tale of Two Rivers"
Note: This transcript is from a videotaped interview for the "A Tale of Two Rivers" segment of "Great Projects." It has been edited lightly for readability.
John Barry (JB): Well, there was a flood in 1850 and, to give you a sense of comparison, a levee a few miles upriver from New Orleans was 1.8 feet high. By 1922, the same levee, to hold a lesser flood, had to be 20 feet high. In Morganza, Louisiana, there was a levee that held the flood of 1850 seven-and-half feet high. In 1922, again, a lesser flood, the same levee had to be 38 feet high. And the same increase in the levee heights was true up and down the river. Obviously, if a river can't spread out, it's going to rise up. That's exactly what it did and that, of course, completely contradicted the levees-only theory in policy, but the Corps of Engineers was not listening.
Interviewer (INT): Be more specific in how it contradicted the policy.
JB: Well, according the levees-only theory which was based on a 17th century Italian engineer named Gugiel Menee's observations and hypotheses, you wanted actually to increase the water in the river, because the more water in the river, the higher the slope and, therefore, the faster the current is going to move, which is true. And the faster the current was going to move, then the more it was going to scour out the bottom of the river, which is also true. The problem is, it's not going to increase the scour enough to accommodate the extraordinary enormous increase in water, really a geometric progression between low water and a great flood. So, you know, the Corps of Engineers kept sticking to this hypothesis despite the fact that every scientific observation contradicted it. So you had a disaster that was waiting to happen.
INT: What kind of a guy was Edgar Jadwin?
JB: Jadwin was arrogant, very military, which is hardly surprising, considering he was a general, didn't like to be contradicted, and thought he knew all the answers. By the same token, he knew almost nothing about the Mississippi River, which is odd, because I believe he spent some time in New Orleans as district engineer. And in testimony to Congress, the material that the Corps of Engineers handed out actually stated that in a natural state without any levees whatsoever, the Mississippi River did not flood the Yazoo Mississippi Delta. Now this was land that the river had actually made by depositing sediment. And when a congressman from the delta asked Jadwin about that, Jadwin deferred to the information he had handed to him. I mean it was really extraordinary.
And he also was responsive. As you know, he was in the military hierarchy. He had directives from the White House to keep the cost down. And he was insistent upon that. I think that affected estimates -- this is speculation on my part, but I believe it affected estimates on how much water was in the river during the '27 flood, 'cause, obviously, the more water, the more expensive it is to take care of it. And the Corps of Engineers came up with a very low estimate, much lower than civilian engineers who measured the same things. And I think that was all part of that military hierarchy. When the Mississippi River Commission wanted to propose its own plan to Congress, they actually reported to him. And he refused to forward their plan to Congress because it was different from his plan; Congress did get it through the back door, you know, handed to them unofficially, and after they demanded it, then Jadwin agreed to hand over that plan as well.
INT: What was Jadwin's position on levees-only?
JB: You know, he was not an expert on the Mississippi River. He inherited the levees-only policy. Even after the dynamiting of the levee below New Orleans, which, to all intensive purposes, exploded the levees-only theory as well, but even after that, for a few weeks he still insisted the levees-only theory was valid. But, you know, that was basically an institutional thing. I don't personally think that that was a deeply held belief that he had.
INT: Was he toeing the party line or ...
JB: Well, the Corps of Engineers had been for the levees-only policy for 40 years, if not longer, and he was the head of the Corps of Engineers. So he was not about to change that policy.
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INT: Jadwin did seem to come up with a plan that worked to some degree.
JB: Yeah. The flood control plan that the Corps of Engineers put in after the '27 flood is basically what's in place today, with some adjustments. And, of course, Jadwin didn't write the plan. In fact, he had a very sharp engineer who had been in the Corps, but actually was then a civilian -- he had a physical disability that forced him to retire from the Army -- who wrote the plan. And it was a good plan, you know, once they gave up the hypothesis of levees-only. You know, there were a couple of gaps in it and there were some political problems with it -- chiefly, in effect, the plan would have allowed the flooding of the State of Arkansas and Louisiana, essentially using that as a natural reservoir. Originally the levees in Arkansas were going to be lower than the levees on the Mississippi side, so the river would naturally flood in Arkansas. That was ultimately taken care of by what was then a very controversial policy called cut-offs. The river moves like a dollar sign, in S's. And a cut-off is like the straight line through a dollar sign. It straightens the river and, therefore, it carries more water faster. But there were a lot of people who thought cut-offs were not going to work. And, in fact, they've worked pretty well, not perfectly. They shorten the river by 150 miles in total, and that lowered the flood plain in Greenville, Mississippi, for example, by 15 feet, which is an enormous lowering. That was initially. Now since the cut-offs have been put in, the river has regained probably one-third of that length and some of the lowering of the flood plains -- some of those benefits have been lost. And ultimately the river will probably regain all the length. And then you make more cut-offs, I guess.
INT: What's the biggest flaw with the Jadwin plan?
JB: I don't think the Jadwin plan--and let's talk about Project Flood, which is not the same thing as the Jadwin plan -- the Corps currently calls it Project Flood. I don't think the plan itself is flawed. I think the question is how much water can it accommodate. And the figure that Army engineers used for the 1927 Flood is lower than the figure that most civilian engineers used for the 1927 Flood, in fact, a lot lower, more than 500,000 cubic feet a second. And, to give you a sense of how much water that is in a flood, Niagara Falls is 200,000 cubic feet a second. So you're talking about a difference, not total amount to water in the river, just a difference between the two estimates of two-and-half the amount of water going over Niagara Falls. And the Project Flood has a margin of error over the lower figure for the '27 flood. But even with the margin of error, if it works as designed, it's not going to handle as much water as the civilians said was in the river in 1927. This was up at the mouth of the Arkansas. So even if it works perfectly, if you get that much water again at that spot, you're going to have an extraordinary disaster that might be bigger than '27. On the other hand, the Army might have been right. It might have been the lower figure, and that might have been a 10,000-year flood or a 20,000-year flood. We don't know.
INT: What about the Achapalaya, trying to capture that?
JB: Well, the Achapalaya is obviously a major problem, and the Army is doing, I think, as well as anybody could do there. It's an extraordinary complex issue, handling the sediment load whether or not you're going to silt up the entire swamp, whether or not the Mississippi River is going to continue to flow past Baton Rouge and New Orleans or shift down the Achapalaya. There are a lot of people who think that the river is ultimately going to go where it wants to go. There are others who think that they can hold it in place, or even if it shifts down there in some major flood, during the next low water they may be able to recapture it and send it down the present channel.
INT: Describe the power of the Mississippi River in a flood mode.
JB: There's really nothing like the rising Mississippi. It's just an extraordinary force. I mean you can look out on the surface and even on the surface it won't look the same in two different spots. You can see sometimes it's almost as if a whirlpool is trying to form. You'll see the level of the water at one spot, you know, six inches, maybe a foot, sometimes more than that, higher than the water level not far away. And there's not one current in the river. There's a current on the surface, many currents on the surface. There's different current ten feet down, 20 feet down, 30 feet down, friction with the riverbank, friction with the river bottom. The last several hundred miles the bottom of the river's actually below sea level. So it's got no reason to flow at all. It's only the force of the water pushing behind it and the force of the water on top that's sort of rolling over it like an ever- breaking wave that keeps the river moving. And when the currents are -- I mean in flood -- you can get a sustained current of 13 feet per second -- that's almost nine miles an hour. So you've got a force that can be well over a mile wide, hundred, hundred and fifty feet deep, and close to 200 feet in New Orleans, moving at nine miles an hour. I mean if you can imagine that, it's -- it's you know, literally an awful thing to look at in the in the literal sense, full of awe.
INT: What's the force comparable to?
JB: Well, it can attack a buzz saw and rip right through it. And less true today because of various protections on the riverbank and so forth but in its natural state it would just take acres of the river bank in one shot -- the trees, you would hear them crack. It would sound like cannons firing one after another as a tree snapped. And, of course, the river actually made all the land from Cape Girardo, Missouri to the Gulf of Mexico. It owns that land. It created that land by depositing sediment upon it. So that natural flood plain in the Mississippi is 34,000 square miles. The river has -- the mouth of the river has been as far east as the State of Mississippi and as far west almost to Texas. It just goes back and forth.
It owns that land. Going back to the levees-only theory, the idea that man could contain that force within a couple of mounds of earthis just ludicrous.
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