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September 21, 2005

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The Spin Cycle IV

By Greyhawk

(A brief pause in an ongoing series for a sidebar discussion.) The Washington Post reports that Katrina may not have been as powerful as many were led to believe:

The Army Corps of Engineers has said that Katrina was just too massive for a system that was not intended to protect the city from a storm greater than a Category 3 hurricane, and that the floodwall failures near Lake Pontchartrain were caused by extraordinary surges that overtopped the walls.

But with the help of complex computer models and stark visual evidence, scientists and engineers at Louisiana State University's Hurricane Center have concluded that Katrina's surges did not come close to overtopping those barriers. That would make faulty design, inadequate construction or some combination of the two the likely cause of the breaching of the floodwalls along the 17th Street and London Avenue canals -- and the flooding of most of New Orleans.

"We are absolutely convinced that those floodwalls were never overtopped," said van Heerden, who also runs LSU's Center for the Study of Public Health Impacts of Hurricanes.
<...>
The center has also completed a computerized "hindcast" of Katrina, which has confirmed the evidence before their eyes. Their model indicates that most of the surge around the lake and its nearby canals was less than 11 feet above sea level, and that none of it should have been greater than 13 feet. The Army Corps's flood-protection system for New Orleans was designed to handle surges of more than 14 feet above sea level.

It should be noted here that modeling and simulation of complex systems is not perfect, even after the fact. If such behaviors could be modeled with great precision then the decisions to evacuate large cities would not be difficult. But beyond the numbers there's additional evidence supporting the result of this study:
On a tour Tuesday, researchers showed numerous indications that Katrina's surge was not as tall as the lakefront's protections. They showed a "debris line" that indicates the top height of Katrina's waves was at least four feet below the crest of Lake Pontchartrain's levees. They also pointed out how the breached floodwalls near the lake showed no signs of overtopping -- no splattering of mud, no drip lines and no erosion at their bases. They contended that the pattern of destruction behind the breaches was consistent with a localized "pressure burst," rather than widespread overtopping.
Those results are consistent with what we noted back on 10 September regarding the strength of Hurricane Katrina as it passed close to New Orleans on it's way to Mississippi. It's good to see evidence supporting that hypothesis. (And seeing it very rapidly - a few short years ago this sort of result would take months to achieve, and longer to become "public knowledge" - if it ever did so at all.) Expect controversy to be one of the main results of the release of this information, but the first step in avoiding a "repeat of Hurricane Katrina" is to identify what Hurricane Katrina was - something that is still not completely clear (in spite of the endless media coverage to the contrary).

More to come.


Posted by Greyhawk / September 21, 2005 5:35 PM | Permalink

1 TrackBack

Levees not up to spec? from Professor Froward's Slough of Despond on September 22, 2005 1:06 AM

That's a hell of a way to find out the contractor stiffed you. Read More

9 Comments

I've been puzzled by the focus on whether the waters "overtopped" the Levy's. I don't know much engineering, but I lived in Sacramento for many years, of which a large part is protected by a levy system.

In times of serious flooding, the Levy's that were considered a problem by city government agencies were not so much the ones that might overflow, but rather those that shows signs of breech. Engineers from the city were always looking for "wells" alongside the levy rather than at the levy and the height of the water itself. These "wells" look like artesian springs, and can show up many yards from the actual levy itself. They look like pressurized water bubbling up through a hole in the ground.

With the storms, its not just the amount of water that is the problem, it's the extra weight it brings, along with the speed. The extra weight increases the pressure on the water at the bottom of the river to find new outlets. This with the speed makes the river (or canal) become undercut and grow deeper as well as faster. So what happens is that the water can actually force its way underneath the levy to bubble up on the other side. If left unchecked the well can widen and basically destroy the levy from the bottom up rather than the top down. They city engineers always seemed to be more worried about that happening rather than the water overflowing the top. After all, even if water overflows the levy, so long as it remains intact you are probably going to be in decent shape.

Whether this scenario can happen depends more on how deep the levy is, not how much higher it is than the level of the river water. And on what the composition and weight is of the foundation material that the levy is based on.

This is great!
Both positions have merit and it is worthwhile to understand what happened here for a number of reasons.

The main problem is "below sea level".

Dump stones and dredge into the city until it is 20 feet above sea level. We are in the position if opposing irresistable force here. If the city continues to subside it will be at the bottom of a 50 foot well.

Or the city can be moved.

25 years after it is done no one will remember and it will be politically irrelevant anyway

There is yet another set of factors, that none of these reports have addressed yet. Maintenance and nearby construction. A good friend of mine who aside from being an infantry platoon sergeant is a civil engineer. His firm does flood control projects almost exclusively for the Army Corps of Engineers. He pointed out that the money spent on levee maintenance in New Orleans has been below Corps recommendations for some time. And on top of that, the city has long allowed construction along the levees much closer than Corps engineers, or most competent engineers advise. Lack of maintenance and nearby construction certainly weakened the levees.

Somewhere in the first few days after Katrina, I thought I read that the breach was caused by a loose barge. I never saw anything about it again, and can't help to wonder if I actually _did_ see it - or heard it, perhaps, and if so, if it was known or theorized. Are there barges in Lake Ponchetraine? or just in the Mississippi?

I also saw the story about the barge. It seems quite likely.

Re: Lake Ponchetraine & debris. Why do we need the "big lake"? Drain it into the gulf and use the hole as a landfill in which to put all the destroyed houses, school busses,cars, etc. What else can you do with thousands of refrigerators? No more levy problems, no cars sold to unsuspecting buyers, many problems solved.

I have posted correspondence between Dr. Kemp of LSU and myself on the levee break issue. Dr. Kemp reports no evidence of scouring that would indicate the levees were overtopped. It is now up to the Corps of Engineers to prove otherwise:

On the Levees of New Orleans, Update 12

Latest update, w/news & analysis by guest G.B.:

On the Levees of New Orleans, Update 17

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November 26, 2010


America@war
[Greyhawk]
I think anyone who's ever pondered the "comment" option - once only available on blogs and bulletin boards, now ubiquitous on almost any web site - will appreciate this:
The so-called faculty of writing is not so much a faculty of writing as it is a faculty of thinking. When a man says, "I have an idea but I can't express it"; that man hasn't an idea but merely a vague feeling. If a man has a feeling of that kind, and will sit down for a half an hour and persistently try to put into writing what he feels, the probabilities are at least 90 percent that he will either be able to record it, or else realize that he has no idea at all. In either case, he will do himself a benefit.

That's wisdom from the past, captured for posterity at the US Naval Institute, shared via the web on the institute's 137th anniversary.

From their about page:

The Naval Institute shall remain

INDEPENDENT - A non-profit member association, with no government support, that does not lobby for special interests;

NON-PARTISAN - An independent, professional military association with a mission, goals and objectives that transcend political affiliations; and shall encourage

IDEAS - Through its respected journals Proceedings and Naval History, its conferences, its books and its online content, in support of those who serve.

"The Naval Institute has three core activities," among them, History and Preservation:

The Naval Institute also has recently introduced Americans at War, a living history of Americans at war in their own words and from their own experiences. These 90-second vignettes convey powerful stories of inspiration, pride, and patriotism.

Take a look at the collection, and you'll see it's not limited to accounts from those who served on ships at sea, members of the other branches are well-represented.

I'm fortunate to have met USNI's Mary Ripley, she's responsible for the institute's oral history program (and she's the daughter of the late John Ripley, whose story is told here). She also deserves much credit for their blog. ("We're not the Navy nor any government agency. Blog and comment freely.") We met at a milblog conference - Mary knew (and I would come to realize) that milbloggers are the 21st-century version of exactly what the US Naval Institute is all about. Once that light bulb came on in my head, I mentioned a vague idea for a project to her - milblogs as the 21st century oral history that they are.

"Put that in writing," she said (of course - see first paragraph above!) - and here's part of the result.

Shortly after the first tent was pitched by the American military in Iraq a wire was connected to a computer therein, and the internet was available to a generation of Americans at war - many of whom had grown up online. From that point on, at any given moment, somewhere in Iraq a Soldier, Sailor, Airman or Marine was at a keyboard sharing the events of his or her day with the folks back home. While most would simply fire off an email, others took advantage of the (then) relatively new online blogging platforms to post their thoughts and experiences for the entire world to see. The milblog was born - and from that moment to this stories detailing everything from the most mundane aspects of camp life to intense combat action (often described within hours of the event) have been available on the web...

And et cetera - but since you're reading this on a milblog, you probably knew that. And you know that milblogs aren't just blogs written by troops at war, that many friends, family members, and supporters likewise documented their story of America at war online in near-real time, as those stories developed.

The diversity in membership of that group is broad, the one thing we all have in common is the impulse to make sense of the seemingly senseless, and communicate the tale - for each of us that impulse was strong enough to overcome whatever barriers prevent the vast majority of people from doing the same. Everyone at some point has some vague idea they believe should be shared - we were the people who, from some combination of internal and external urging, found and spent those many half hours persistently trying to write it down.

*****

But where will all that be in another 137 years? Or five or ten, for that matter. That's something I've asked myself since at least 2004 - when I wrote this:

Closing Blogs is nothing new. So many site's owners just give up on their own. They come and go, you know, these MilBloggers do. Like any other sort of blogger. Many post in the lonely down hours far from home, spill their guts for the world, then abandon their spots when the tour of duty is up. They have lives again somewhere in the world, and no need to share the details. So it goes.

Many are truly gone - no site left at all. "The page cannot be found." Other blogs remain, like abandoned defensive positions in shifting desert sands.

Membership in the ghost battalion has grown in the years since, and an ever growing majority of those abandoned-but-still-standing sites are vanishing. Have you checked out Lt Smash's site lately? How about Sgt Hook's? If you're a long-time milblog reader you know the first widely-read milblog from Operation Iraq Freedom and the first widely-read milblog from Afghanistan are both gone from the web. If you're a relative newcomer to this world you may never even have heard of them - or the dozens upon dozens of others who carried forth the standard they set down.

If you have a vague notion that something should be done about that, (a notion I've heard expressed more than once...) then you and I and the good folks at the US Naval Institute are in agreement. Preserving the history documented by the milbloggers is just one of the goals of the milblog project, the once-vague idea that we're now making real.

And it's a big idea, if I say so myself - too big to explain in one simple blog post, so stand by for more. Likewise, it's too big a task to be accomplished by just one person. So if you're a milblogger (and exactly what is a milblogger? is a topic for much further discussion on its own) I'm asking for your help. All I'll really need is just a little bit (maybe just one or two of those half hours...) of your time, and your willingness to tell the tale.

We've already made history, it's time to save it.

(More to follow...)




Posted 4:02 PM | Permalink | Comments (0) |

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The Mudville Gazette is the on-line voice of an American warrior and his wife who stands by him. They prefer to see peaceful change render force of arms unnecessary. Until that day they stand fast with those who struggle for freedom, strike for reason, and pray for a better tomorrow.
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  • Solomon2: Latest update, w/news & analysis by guest G.B.: On the read more
  • Solomon2: I have posted correspondence between Dr. Kemp of LSU and read more
  • Lucille: Re: Lake Ponchetraine & debris. Why do we need the read more
  • Don Cox: I also saw the story about the barge. It seems read more
  • suek: Somewhere in the first few days after Katrina, I thought read more
  • John Byrnes: There is yet another set of factors, that none of read more
  • Solomon2: Same data, different interpretation: On the Levees of New Orleans read more
  • Mike Johnson: This is great! Both positions have merit and it is read more
  • Patrick (Gryph): I've been puzzled by the focus on whether the waters read more

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The Mudville Gazette is written and produced by Greyhawk, who recently retired from 24 years of active duty in the US military, but will maintain this disclaimer: Unless otherwise credited, the opinions expressed are those of the author, and nothing here is to be taken as representing the official position of or endorsement by the United States Department of Defense or any of its subordinate components.

Furthermore, I will occasionally use satire or parody herein. The bottom line: it's my house.

I like having visitors to my house. I hope you are entertained. I fight for your right to free speech, and am thrilled when you exercise said rights here. Comments and e-mails are welcome, but all such communication is to be assumed to be 1)the original work of any who initiate said communication and 2)the property of the Mudville Gazette, with free use granted thereto for publication in electronic or written form. If you do NOT wish to have your message posted, write "CONFIDENTIAL" in the subject line of your email.

Original content copyright © 2003 - 2011 by Greyhawk. Fair, not-for-profit use of said material by others is encouraged, as long as acknowledgement and credit is given, to include the url of the original source post. Other arrangements can be made as needed.

Contact: greyhawk at mudvillegazette dot com

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*****

Tending Distant
Fires


Far from hearth and home, watching
Cold alone but not alone
On distant shore and only wanting
Safe return and little more

What tales we'll tell
When that time comes
When tales can be told

When things grim
Seem far away
When other fires go cold

Some distant sunset, vision fading
Memories remain
And tired eyes gaze 'pon folded flags
While distant drums beat their refrain

Saluting fallen friends whose names
And youth will never fade
Here's to those on other shores,
for them live well, the price is paid

- Greyhawk,
Baghdad,
December 2004