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September 10, 2005

The Spin Cycle

Greyhawk

There's been much discussion on the New Orleans levies - to the effect that they weren't built to withstand a Cat 4 or 5 hurricane - and that they should have been rebuilt stronger sooner, but {insert name of your least favorite politician here} spent the money elsewhere, etc etc.

Mostly a worthwhile discussion, indeed. It will certainly cost more to rebuild the city now. But before diving too deeply into the troubled waters of this issue, a few additional facts should be brought to the table.

Here's your trivia question of the day: What category storm was Katrina at landfall? If it's too hard, I'll give you multiple choice: 1, 2, 3, 4, or 5.

Time's up. According to the National Hurricane Center, Katrina was Cat 3 at landfall. I've highlighted the key points in their advisory below:

ZCZC MIATCPAT2 ALL
TTAA00 KNHC DDHHMM
BULLETIN
HURRICANE KATRINA ADVISORY NUMBER 27
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
10 AM CDT MON AUG 29 2005

...CENTER OF POWERFUL HURRICANE KATRINA AGAIN MOVING ASHORE...NEAR THE LOUISIANA-MISSISSIPPI BORDER...CONTINUES POUNDING SOUTHEASTERN LOUISIANA AND SOUTHERN MISSISSIPPI...

A HURRICANE WARNING IS IN EFFECT FOR THE NORTH CENTRAL GULF COAST FROM MORGAN CITY LOUISIANA EASTWARD TO THE ALABAMA/FLORIDA BORDER...INCLUDING THE CITY OF NEW ORLEANS AND LAKE PONTCHARTRAIN.

AT 10 AM CDT...1500Z..ALL HURRICANE WATCHES ARE DISCONTINUED. A TROPICAL STORM WARNING REMAINS IN EFFECT FROM EAST OF THE ALABAMA/FLORIDA BORDER TO INDIAN PASS FLORIDA...AND FROM WEST OF MORGAN CITY TO CAMERON LOUISIANA.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...PLEASE MONITOR PRODUCTS ISSUED BY YOUR LOCAL WEATHER OFFICE.

AT 10 AM CDT...1500Z...THE CENTER OF HURRICANE KATRINA WAS LOCATED NEAR LATITUDE 30.2 NORTH... LONGITUDE 89.6 WEST. THIS POSITION IS NEAR THE MOUTH OF THE PEARL RIVER...ABOUT 35 MILES EAST-NORTHEAST OF NEW ORLEANS LOUISIANA AND ABOUT 45 MILES WEST-SOUTHWEST OF BILOXI MISSISSIPPI.

KATRINA IS MOVING TOWARD THE NORTH NEAR 16 MPH...AND THIS GENERAL MOTION IS EXPECTED TO CONTINUE TODAY AND TONIGHT. ON THIS TRACK THE CENTER WILL MOVE OVER SOUTHERN MISSISSIPPI TODAY AND INTO CENTRAL MISSISSIPPI THIS EVENING.

MAXIMUM SUSTAINED WINDS ARE NEAR 125 MPH...WITH HIGHER GUSTS. KATRINA IS NOW A CATEGORY THREE HURRICANE ON THE SAFFIR-SIMPSON SCALE. WINDS AFFECTING THE UPPER FLOORS OF HIGH RISE BUILDINGS WILL BE SIGNIFICANTLY STRONGER THAN THOSE NEAR GROUND LEVEL. WEAKENING IS FORECAST DURING THE NEXT 24 HOURS AS THE CENTER MOVES OVER LAND. HOWEVER...HURRICANE FORCE WINDS ARE EXPECTED TO SPREAD AS FAR AS 150 MILES INLAND ALONG THE PATH OF KATRINA. SEE INLAND HURRICANE AND TROPICAL STORM WARNINGS FROM NATIONAL WEATHER SERVICE FORECAST OFFICES.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 125 MILES FROM THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 230 MILES.

THE MINIMUM CENTRAL PRESSURE ESTIMATED FROM AIR FORCE HURRICANE HUNTER AIRCRAFT IS 927 MB...27.37 INCHES.

COASTAL STORM SURGE FLOODING OF 15 TO 20 FEET ABOVE NORMAL TIDE LEVELS...ALONG WITH LARGE AND DANGEROUS BATTERING WAVES...CAN BE EXPECTED NEAR AND TO THE EAST OF THE CENTER. STORM SURGE FLOODING OF 10 TO 15 FEET...NEAR THE TOPS OF THE LEVEES...IS STILL POSSIBLE IN THE GREATER NEW ORLEANS AREA. SIGNIFICANT STORM SURGE FLOODING IS OCCURRING ELSEWHERE ALONG THE CENTRAL AND NORTHEASTERN GULF OF MEXICO COAST.

RAINFALL TOTALS OF 5 TO 10 INCHES...WITH ISOLATED MAXIMUM AMOUNTS OF 15 INCHES...ARE POSSIBLE ALONG THE PATH OF KATRINA ACROSS THE GULF COAST AND THE TENNESSEE VALLEY. RAINFALL TOTALS OF 4 TO 8 INCHES ARE POSSIBLE ACROSS THE OHIO VALLEY INTO THE EASTERN GREAT LAKES REGION TUESDAY AND WEDNESDAY.

A FEW TORNADOES ARE POSSIBLE OVER PORTIONS OF SOUTHERN AND EASTERN MISSISSIPPI...SOUTHERN AND CENTRAL ALABAMA...AND THE WESTERN FLORIDA PANHANDLE TODAY.

REPEATING THE 10 AM CDT POSITION...30.2 N... 89.6 W. MOVEMENT TOWARD...NORTH NEAR 16 MPH. MAXIMUM SUSTAINED WINDS...125 MPH. MINIMUM CENTRAL PRESSURE... 927 MB.

More discussion on this later, for now just wanted to clarify this point.

Update 1: Heather, via the comments points us to the National Climatic Data Center - that notes that the storm was cat 4 just prior to landfall - but also adds this crucial data point: winds gusted to over 100 mph in New Orleans - in other words, New Orleans may only have experienced cat 2 winds. (Odd note: in support of this statement NCDC provides a map showing the highest winds anywhere in the track of Katrina to be just 114 mph in extreme southeast La, or perhaps just off shore.)

Update 2: Maha asks a valid question in comments: why does it matter now when it was the response that was bad? Actually, the response wasn't the point of this post - we're talking about whether the claim that the New Orleans levies could handle a cat 2 or 3 hurricane is a valid one. In fact, it appears it was not, as New Orleans didn't experience a cat 4 hurricane - in fact, not even cat 3. And lest we forget, the levy didn't fail until well after landfall anyway - a crucial point that adds to the complexity of the situation, and one that I hadn't forgotten when I began this discussion.

The Washington Post reports here on the key figures to remember, along with a claim that doesn't hold water:

In Katrina's wake, Louisiana politicians and other critics have complained about paltry funding for the Army Corps in general and Louisiana projects in particular. But over the five years of President Bush's administration, Louisiana has received far more money for Corps civil works projects than any other state, about $1.9 billion; California was a distant second with less than $1.4 billion, even though its population is more than seven times as large.
<...>
Despite a series of independent investigations criticizing Army Corps construction projects as wasteful pork-barrel spending, Louisiana's representatives have kept bringing home the bacon.

For example, after a $194 million deepening project for the Port of Iberia flunked a Corps cost-benefit analysis, Sen. Mary Landrieu (D-La.) tucked language into an emergency Iraq spending bill ordering the agency to redo its calculations.
<...>
But overall, the Bush administration's funding requests for the key New Orleans flood-control projects for the past five years were slightly higher than the Clinton administration's for its past five years. Lt. Gen. Carl Strock, the chief of the Corps, has said that in any event, more money would not have prevented the drowning of the city, since its levees were designed to protect against a Category 3 storm, and the levees that failed were already completed projects.

But yes - that's all water under the bridge, as they say. So let's move on to that response piece of the puzzle.

(Part II is here.)

Posted by Greyhawk at 02:58 PM | Permalink | Comments (24) |

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Isn't that the 2d landfall when it hit the LA-MS border? Hadn't it already hit and passed over the southern tip of LA, with the western eye-wall having passed over eastern New Orleans at that point?

Posted by Mile Wise at September 10, 2005 03:26 PM

First landfall was in Florida. Second in Mississippi near Louisiana. Major wind damage ocurred in Mississippi - New Orleans took a good whack too. See also the photo essay linked in previous post.

Posted by Greyhawk at September 10, 2005 03:32 PM

I remember that. I was horrified when they said it was a Cat 5 over the ocean. And when it hit landfall it had lessened to a Cat 3. I actually said to my 12 year old son, "Thank God. It went down. They'll be okay."

Not that a category three hurricane is anything fun. Just that I was expecting much less damage.

Posted by Suzi at September 10, 2005 03:39 PM

Just wanted to point out that the report you posted was from 1000 CT, which I think is some hours after "landfall".

As the report indicates, the hurricane is already north of NOLA at that time, so it had already made landfall in LA and was now hitting the south coast of MS.

Seems plausible that it was Cat-4 when it first hit land (in Southern LA).

Posted by LagunaDave at September 10, 2005 04:07 PM

Note added: typing the coordinates (30.2N, 89.6W) into GoogleEarth confirms my previous comment.

Posted by LagunaDave at September 10, 2005 04:08 PM

Not many hours before the Louisiana landfall NOAA was reporting 175mph max sustained winds. Think about that. And think about how there's no law requiring storms to weaken just before landfall or to veer eastward before approaching a major urban area.

There are no engineering trick available to protect large populated areas from a 175 mph storm.

Posted by George at September 10, 2005 05:05 PM

Hi according to the same site landfall was cat 4. Your msg was giving current windspeeds, not land fall speeds.See http://lwf.ncdc.noaa.gov/oa/climate/research/2005/katrina.html

Posted by Heather at September 10, 2005 06:08 PM

Perhaps Grayhawk can explain what the hell difference it makes now. It was the response to the hurricane damage that sucked, not the forecasts. Are you waying it wouldn't have sucked had the hurricane really been cat 4 or 5?

Posted by maha at September 10, 2005 08:02 PM

Perhaps that the levees were built shoddily to not even withstand the Cat 3 they were built to withstand.

Posted by Cutler at September 10, 2005 08:33 PM

A long-time resident of New Orleans, architect and friend of mine spent a quite a while twenty years ago lecturing me about the compression strength of concrete. The rule-of-thumb that sticks in my mind is that 15 minutes of a garden hose stuck in the truck's mixer makes the work twice as easy and lowers the strength by half.

I was shocked when the concrete, not one of the older,earthen levees was breached. I hope they are able to recover enough of the concrete along the edges of the break to determine if the sub-contractor took the easy way out. The financial ramifications (not to mention suffering of a much more than financial significance) would dwarf ENRON. If it's not a "protected class" contractor, the Mainstream Media Party will, justifiably, have a field day. Of course, if it is, will we ever know?

Posted by Richard at September 10, 2005 08:52 PM

You've printed the 1000 NOAA bulletin, AFTER the hurricane had already come ashore around 0630 near Grand Isle, LA. Note the word AGAIN in the first line.

Here's the 0400 NOAA Bulletin pointing to a landfall near Grand Isle.

CBS News (CBS/AP) Hurricane Katrina came ashore just east of Grand Isle, Louisiana, at 6:30 a.m. ET.

If you watched the wind circulation on a map, you could also see that the hurricane was blowing directly from the gulf into Lake Pontchartrain.

CNN 7 Sep Katrina weakened slightly to a Category 4 hurricane with maximum sustained winds estimated at 145 mph as it made landfall early Monday, but it maintained a storm surge that is only generally found in category 5 storms.
"Katrina was a very large storm, high energy, high intensity coming across the gulf," said Elizabeth English, an associate professor at Louisiana State University's Hurricane Center.

"When the wind speed began to go down the storm surge did not dissipate. ... There was essentially a lot more momentum in the water than there was in the wind," said English.

Posted by Mile Wise at September 10, 2005 11:37 PM

Several thoughts:

First, I would be very sceptical of the accuracy of land-based anemometers at speeds even approaching 100 mph. The error is most likely to be extremely high.

Second, the winds in the NW quadrant of a northbound hurricane are significantly less that of the NE quadrant.

Third, storm surge may have played a signicicant role in breaching the levees.

Posted by Rod Smith at September 11, 2005 12:04 AM

There is some suggestion that a loose barge may have caused one of the levee breaks.

A barge was found inside the city, near one of the breaks, which was about the width of the barge.

Posted by LagunaDave at September 11, 2005 09:49 AM

the winds in the NW quadrant of a northbound hurricane are significantly less that of the NE quadrant

I think the winds are the same speed, it's just that in the NE quadrant, they are blowing in the same direction that the storm as a whole is moving, so you have to add the speed of the storm (which IIRC was about 10-15 mph) to that of the winds.

Maybe "significant" (especially if you're right at the limit of what you can withstand) but not dramatically different...

Posted by LagunaDave at September 11, 2005 09:55 AM

I am trying to find out what government entity actually owns the levees around New Orleans. Also what government entity is responsible for maintaining the levees. I would appreciate any help in finding out this information.
Thanks,
Lefty Flynn

Posted by Lefty Flynn at September 11, 2005 02:13 PM

According to Knight Ridder, the levee broke before Katrina made landfall.

Posted by iocaste at September 11, 2005 05:33 PM

Actually, what was being said before Katrina was that the levies could probably handle a fast-moving category 3 storm, but would have trouble if the storm was slow-moving or if it was larger. So clearly, it was recognized all along that the levies were borderline even for category 3.

Posted by tgibbs at September 11, 2005 08:50 PM

The levies clearly were not designed to survive being overtopped. It appears that the concrete itself did not fail, but the concrete was held up only by dirt on the landside. Once the water started coming over the top, the dirt that supported the concrete walls washed away, and the concrete simply tipped over.

Posted by tgibbs at September 11, 2005 08:54 PM

I suspect that a built-up storm surge will fall much more slowly than the winds can. The measuring of hurricanes is by the windspeed, not the kinetic energy of the disturbed water.

Posted by htom at September 11, 2005 10:21 PM

I really do not know what difference the strength of the levee walls would make. We have people saying that if they were only built to withstand a cat 5 they would not be breached or overtopped. In this instance yes, it may have made a difference, but remember this was a cat 5 that was headed right at N.O., even if the levees had held storm surge at bay in a cat 5, any house, stick framed apt. buildings, most likely the superdome, several skyscrappers, and what ever else would be laying in rubble. The problem was that LA and N.O. did not have a comprehensive plan to make sure as many people as possible were to be evacuated. The problem with what is going on now is that we had people who should have been out of the city, trapped and without help. I still think that the people that were in the Superdome and convention center were alot better off than someone trapped in their attic for 3 or 4 days up to their necks in water and breathing super heated air, ever been in an attic when the temps above 90 degrees, many died this way.

Posted by patrick at September 11, 2005 11:53 PM

Did you hear that one of the levee breaches was not caused by the storm but by a barge that became loose from it's moorings and hit one of the walls causing it to collapse? I'm looking into it further but last week the stock of Lafarge Concrete Company (Check spelling) fell to all new lows.. Apparently they were the ones responsible for the barge that caused the damage. Can anyone else verify this?

Posted by Ken Atlanta at September 12, 2005 02:23 AM

One thing you would do is what they used to do before funding was cut. Mobilize the the hospital ship that was stationed in Boston. It was usual for it to sail at first hint of a storm and follow it from a distance of 24hrs sailing. This is not to mention the fact the national guard was but into action... but we won't go down that path will we?

Posted by paul at September 12, 2005 12:11 PM

I did some checking on the barge...it looks like the barge went past the levee after it had broken - it didn't cause the levee to fail. This was according to the US Corps of Engineers.

Posted by Bob Smith at September 20, 2005 07:02 PM

I also saw the report from the US Corps of Engineers - it definitely was not the Lafarge barge that caused the break, but it just happened to go over after the levee broke

Posted by Robert at September 20, 2005 07:55 PM

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