Of all the myths surrounding Katrina -and there are thousands of them- the biggest one by far is that New Orleans flooded because it is below sea level. I know you’ve all heard it and I know many of you have repeated it. It’s simply not true. It’s a myth.
Before I explain it, I’m forced by history to give you the following warning. Understanding the reasons behind New Orleans flooding requires you to A) Read the whole post. B) Think. If you are unable or unwilling to do both, then here is something else to spend your time doing.
And one last warning. I KNOW many of you are already composing your rebuttal to this post in your head even before you read it. (Caught ya didn’t I?) If you’ve already decided I am wrong and you are going to set me straight, then please follow the above link. If you don’t live in New Orleans and/or you’ve never studied the area and its topology, having a blogger account does not make you an expert.
It is true, of course, that New Orleans is below sea level, that is not a myth. But that had nothing to do with why New Orleans flooded. In fact if we had magically elevated New Orleans 3 feet above sea level the day before the storm, New Orleans would have gotten the exact same amount of water. In fact, the true elevation of the ground has almost nothing to do with it. As I’ve said repeatedly, the section of the city that was hit the worst is largely above sea level and the lowest spot in the city stayed dry. — That’s why I often council against people who have never even been to New Orleans taking strong opinions on why it flooded. (Hint: It had more to do with longitude than elevation. The further east, the worse the damage.)
The true vulnerability of New Orleans lies not it its elevation but its proximity to the coast. Every coastal city shares this vulnerability; New Orleans is actually more protected than most. Each city deals with it a different way. Louisiana has build levees for example and Galveston built a 17 foot high sea wall. If Rita had topped (or broken) that seawall, Galveston would have looked not unlike New Orleans. They built that seawall because in 1900 they got slammed worse than Katrina slammed New Orleans. – And they were above sea level.
In Katrina however, New Orleans’ defenses broke. Common wisdom in the mainstream media and the blogospehre is that they broke because “Katrina was a Cat 4” and the storm surge was just too high. That’s simply not true. In digging thru the Wizbang archives I found a graphic that illustrates the error of this belief. Ironically when this was posted by Kevin, it meant New Orleans was safe.
This was taken from a gauge just a few yards from the breach at the 17th Street Canal. The red line shows the record high water mark previous to Katrina. We “knew” we could take that much water again. In fact we just hoped it stayed below the 8 foot mark so it would not overtop the floodwalls.
What we did not anticipate -and no one had real cause to- was that the walls would crumble long before the water reached previous levels. Karina sent less of a flood surge in to Lake Pontchartrain than previous hurricanes. (I think that red line is Ivan) This graph makes it easy to understand why I say the hurricane did not flood us, it was a dam break.
It also shows why being 3 feet above sea level would not have made much of difference… The water still would have flowed in. (granted the water would not have been as deep in some places but that’s neither here nor there. If the city were perfectly level at +3′ MSL that would mean that the whole city took water not just 80%.)
Other coastal towns have gone different routes. The Mississippi Gulf Coast is probably about the size of New Orleans, but they are built more like a “strip mall” along the coast and New Orleans is more centralized. They don’t have our levee system; believing that being above sea level was enough. I have not gotten over there but numerous reports indicate that whole towns are simply gone. Looking at the satellite images, I believe it.
Let me repeat for the 10th time… If the levees had held, New Orleans would have come thru Katrina a little battered but largely fine. We still would have been hit by a hurricane but that would have been small potatoes by comparison.
Should we “move New Orleans?” I guess if we want to move every coastal city and every town that lives near a man made dam and every town in an earthquake zone and every town in a tornado zone and every town…. You get the point.
Ironically -and the point people miss- is that New Orleans -even being below sea level- is not that prone to flooding. And you don’t have to take my word for it… 60% of the city did not have flood insurance. And their mortgage companies did not require it. Why? Because they were above the 100 year flood plain.
We have what is arguably the most capable drainage and pumping system in the world. We can handle something like 3 inches of rain in 90 minutes and 1 inch per hour basically indefinitely. Give any other major city 1 inch of rain per hour for 24 hours and see what you get. It won’t be pretty.
And we could have EASILY handled Katrina if not for a hardware failure. If you have a car wreck because your breaks go out while you are going 60mph on the interstate, you don’t blame the interstate.
The levee work announced yesterday by the Whitehouse will put our flood protection back to where it was supposed to be (and we were told it was) before Katrina. If this had been done last year, New Orleans would be fine today.
Considering this has already cost the US Treasury $60 Billion and it likely to cost another $100 Billion more, really understanding the dynamics of the situation might be a good idea for everyone.
Sadly, the MSM has done a horrific job explaining all this. Mostly because (and I’m planning a big post on this later) because the news media today is not about information, they are about drama. They don’t care how or why New Orleans flooded. If they can show black people staving in the Superdome and blame George Bush, they are here with the Satellite trucks. Ask them to explain to the U.S. citizens why a half a million people are homeless and the Treasury is spending 100 billion dollars on something and their eyes glaze over.
So I do my best to explain it in my little corner of the blogosphere.
Two final thoughts.
As for paying for the restoration, the Federal government has not just the traditional obligation to pay for it as they would when they rebuild every other city after a tragedy, now they have an additional burden. Considering the feds flooded the city, they now bear the cost of fixing it.
Lastly, some you all want to whine about the feds sending us money. OK, I have a proposition for you…. Louisiana could pay for every penny of the restoration out of its own pocket if we were given the same cut of the oil taxes that every other state in the union gets. We produce 24% of the oil produced in this nation. We’ll sell OUR oil on the open market and pay for everything ourselves.
You all don’t mind paying 4 bucks a gallon for gas do you?
Speaking on behalf of the entire state of Louisiana, we’ll keep the oil and you guys don’t have to pay for the levees. Deal?
According to FEMA maps dating back as far as 1984, most of New Orleans is within the 100 year flood plain.
You want to see the 100 year flood plain in New Orleans? Drive around. Anywhere you see buildings or cars that got flooded, you’re in it.
I don’t know where you got the odd idea that any of the lower parts of the 9th Ward were outside of the flood plain. They’re not, at least according to the maps that people actually use for this. That’s part of the reason so few people had flood insurance there – nobody could issue it for a reasonable premium.
The problem with all these grand statements that people love to make, is that it is VASTLY more complicated than just “moving people out the low-lying area.”
Not any more. Once a wood-frame house has been flooded for any length of time, it’s just a matter of *when* you tear it down, not “whether.”
If they go by the rules set up before Katrina, the lower 9 will not be considered below the 100 year plain because (short of man made failure) it still has a less than 1% chance of flooding any given year.
Not true. Please look up the flood plain maps (available at FEMA and other places) before you claim this again. You don’t have to had had a flood to consider something a “flood plain.” The fact that much of New Orleans had to be pumped dry after even a moderate storm shows how far off you are on this.
I also think that anyone who lives next to any beach in the Gulf or on the Atlantic should take their own chances, and not expect me to pay for their mistake, just like I don’t expect anyone to pay for the risk I take in living in an active hurricane zone (but a bit farther inland).
Flood plain/tsunami risks are things you can look up, it’s not like anyone kept this stuff a secret.
By the way: between the storms last year and the storms this year, I’m down about $12,000 in lost income, which isn’t going to be made up by *anyone*.
Speaking about geology and oil, how come nobody seems interested in the Bay of Bengal or the Andaman Sea? Or, how about off Rio de la Plata?
Look at what the Russians can’t get at in the Kara Sea, which has taken huge outflows over time. Although they have a nice overlooking field on the Yamal Pen.
I say look forward to the alluvium! Where is Halliburton on this matter?! Or, SEDCO! Where is our platforms for meeting future energy needs?!
Heavy, Heavy sigh
>I don’t know where you got the odd idea that any of the lower parts of the 9th Ward were outside of the flood plain.
Could it freaking be that I have a 4 foot by 5 foot map showing the flood pain of the freaking city on my dining room table? Do you?
>You want to see the 100 year flood plain in New Orleans? Drive around. Anywhere you see buildings or cars that got flooded, you’re in it.
Sigh- Did you ever hear of this thing called google? From the first hit!
For land use planning purposes, the regulatory floodplain is usually viewed as all lands within reach of a 100 year flood.
A “100-year flood” is defined as a flood event that has a one percent chance of occurring in any given year.
Gee that EXACTLY what I said above.
I spent a good 20 minutes typing that comment to explain it to you. It was a waste of my freaking time.
This is a serious issue that involves millions of peoples lives and billions of dollars. PLEASE if you care to be taken seriously learn the terms and use them properly.
You’ve made some good points… but then you piss it all away by babbling. If I wanted that I’d invite Susie back.
The paradoxical situation I outlined above exists. Sorry if its existance offends you.
Please, if you wnat to discuss it, don’t exceed the bounds of knowledge or common sense.
This thread is probably dead and you won’t see this, but I have been wondering ever since I read your post – what is the ‘lowest spot in the city that stayed dry’?
I live in New Orleans in the ‘sliver along the river’ and am curious about this.
Am I the only one that wonders why New Orleans sat there for over 100 years and did nothing about their bowl situation? In 1900 Galveston lost 12000 at 8ft above mean sea level (msl). They scrimped and got a sea wall built and elevated the city to 23 ft msl. New Orleans knew about this yet did not have the sense to apply it to themselves. If Galveston lost 12000 at 8 ft above msl, what did New Orleans think was to happen to them at 10 ft below?