Katrina surge info from a Structural Engineer

[Pearl River]

https://www.cnmoc.navy.mil/nmosw/tr8203nc/norleans/text/sect4.htm

This info was copied from the above. It is located at the bottom of the report.

In addition, the following are comments from a structural engineer doing disaster survey/assessments:

"...I just got back from doing a ground survey of the coast from Hurricane Katrina. Words cannot describe the level of destruction witnessed. The community of Waveland was completely destroyed by storm surge. Mile after mile of one and two story coastal homes were gone. Many homes had been elevated up on pilings - but it didn't matter. Only the pilings remained standing. Ironically, a sign dedicated to the memory of those who perished in Hurricane Camille remained. There were two, steel-framed homes that had third stories. The first two stories were gone except for the steel framing that held up the third story. These homes looked like large tree houses elevated up in the air. This was the highest storm surge and the worst hurricane damage, I have ever observed.

Using a surveyor's level and rod, I measured the elevations of still water levels in various buildings (nice bathtub ring left by max surge) to the water level in the Gulf. Waves would be a few feet higher.

Here are the preliminary results:
15-16 feet - S Slidell
31-32 feet - Waveland
27-28 feet - Bay St. Loius
25-26 feet - Pass Christian/Long Beach
22-23 feet - Gulfport
20-21 feet - Biloxi
19-20 feet - Ocean Springs
17-18 feet - Pascagoula
15-16 feet - SE Pascagoula..."

[MWatkins]

The official report from Waveland...in the NHC report...was 27 feet according to the prelim. This is interesting to me because the engineer estimate seems to be more in line with what happened...I wonder why the NWS uses official data readings for estimating storm surge totals...while they use engineer estimates and damage patterns to estimate tornado strength...for example. Seems like the forensic evidence would almost be a better indicator...the water lines are pretty well defined in structures not devistated by the surge at least in Waveland.

I wonder if things like this will work their way into the final data...thanks for passing along the info.

MW

[Derek Ortt]

I'm not sure as well, but one question I would have is did the engineer measure the storm surge or the storm tide (what I refer to as the tidal surge). The storm tide does not account for the effects of high or low tide and high tide occurred just a couple of hours before landfall, trapping it along the coats, adding a couple of feet to the tidal surge

[Pearl River]

The engineer said he used the still water level.

[Derek Ortt]

still water level would be the storm tide, not the storm surge

[Pearl River]

I don't mean to be ugly, but whether it's tide or surge at high or low tide, it's a heck of a lot of water. 31 to 32 ft of water in Waveland. This small city basically no longer exists because of the "surge". I don't get it with you pro-mets. If it doesn't fit into your thinking, then it doesn't happen.

[wxman57]

For the record, high tide in Gulfport occured at 6:43am - 1.73 ft. above mean sea level.

http://myweb.cableone.net/nolasue/tides.gif

[Javlin]

Funny I brought up how the SS Camille remained along 90 it was said she was full of concrete"yep".Alot of other things that day made of concrete was lost also.Just Odd.

[Derek Ortt]

did you even read what I wrote Pearl River? (comments like yours make this board downright unenjoyable to be honest).

I explained the difference between storm tide and storm surge. Apparantly, what you said applied to you because you did not understand the difference and attack the one who explains the difference to you

[Audrey2Katrina]

I'm not sure as well, but one question I would have is did the engineer measure the storm surge or the storm tide (what I refer to as the tidal surge).

It would be interesting to hear that from the engineer himself; perhaps being more involved with still water levels, he was less concerned with what ultimately caused the highest levels attained beyond the fact that they came with the arrival of this storm. I can only conjecture on that point as only this particular engineer could clarify it.

I explained the difference between storm tide and storm surge.

Point taken. This does not, however necessarily explain the difference in the NHC reported 27 ft. storm tide, and one that appears to have been 31-32 ft. although it does narrow the window of possible error. The reticence on the part of the NHC to cite higher numbers is indicated clearly in that despite what it calls an "unofficial" reported surge in Hancock county of 28 feet, they conclude that it "probably" had a 27 ft. surge. In their defense they DO cite that findings are as yet coming in and all data not collected--from which one could conclude that this report clearly is prelim; and that which is called "official" is not always final.

For the record, high tide in Gulfport occured at 6:43am - 1.73 ft. above mean sea level.

http://myweb.cableone.net/nolasue/tides.gif

Well the math is easy enough to do in that by adding to the NHC's report of 27, one should see a tidal surge/storm tide/tidal surge of 28.73, you can round it off if you're less concerned with decimal accuracy; and that does make the NHC's report only about 2.27 to 3.27 feet of surge off the mark. One might present a case that this high tide reading was from Gulfport, and not Waveland; but the NHC's report cites only "Hancock County" having "probably" had a surge of 27 ft., which, for whatever it's worth does include both Waveland and Gulfport.

One could validly contend that the engineer may have rounded numbers as well, narrowing the margin of error; but from his own records one must assume that the decimal variation would be between the 31 and the 32, hence a probable error of anywhere from 2.27 to 3 feet of actual, vs. reported surge. Either way the reported surge is not fully validated by this particular engineer's findings.

A2K

[Derek Ortt]

and if the unofficial 28 foot value is used, the error then ebcomes 1.27 to 2.27 feet, which may be within the noise level

[Pearl River]

Derek wrote

did you even read what I wrote Pearl River? (comments like yours make this board downright unenjoyable to be honest).

I explained the difference between storm tide and storm surge. Apparantly, what you said applied to you because you did not understand the difference and attack the one who explains the difference to you

Your right Derek I didn't read it correctly and I apologize. I'm not trying to be ugly in saying this,but apparently you didn't read what I posted either in the original post. He said he measured the still water levels. I'm not an expert nor do I claim to be one. When I post things here I usually do it when I have something it can be referenced to. But it seems when I do, then others come back and tell me it can't happen that way or basically without saying it in words, I'm wrong. Just because it's not in the precious NHC report, doesn't mean it cannot have happened.

[Audrey2Katrina]

and if the unofficial 28 foot value is used, the error then ebcomes 1.27 to 2.27 feet, which may be within the noise level

Yes, if one uses the unoffical report as opposed to the probable report, and rounds all figures optimally, the room for the report's error is well within "noise" levels, defining that as being within 1-2 feet of error.

[Derek Ortt]

the still water levels would give the storm tide, since that is the peak base water level rise. To get the storm surge, one must eliminate the 1.73 feet rise caused by the normal high tide (storm tide is storm surge plus the normal tidal levels)

if a storm hits about 3 hours after low tide, the storm tide likely would be lower than the storm surge (or at low tide for a new england cat 1 moving at Gloria's speed)

[Pearl River]

If you round the tide level of 1.73 ft up to 2 ft, then the water level was still at least 2 ft higher in Waveland than the official report of 27 ft, where ever that occured. With that said, I believe the NHC came out with this report far to early. This storm was far too important to come out with a report, before any TD reports or other lower end Hurricanes or TS or even Wilma. It's my opinion and I just want someone to respect it, whether or not they agree with it.

[thunderchief]

He said he measured the still water levels but I am not sure that can be done using damage marks, which will top out at the height of the highest waves.

Regardless... thats a crapload of surge and arguing about a few feet is pointless.

[Normandy]

Frankly who cares. 31 feet is 31 feet.

[Ixolib]

He said he measured the still water levels but I am not sure that can be done using damage marks, which will top out at the height of the highest waves.

Regardless... thats a crapload of surge and arguing about a few feet is pointless.

Well, in my case "a few feet" made a HUGE difference. Pointless to the number crunchers perhaps, but quite meaingful in my struggle to rebuild my home... Had she come in at low tide, my situation would not have been as significant as it was.

As for the damage marks in my home, they are EXACTLY at the "still water level" as there were no waves in my neighborhood on the south shore of Biloxi Back Bay - just an absolute and intense rise in sea water.

Pics below show my livingroom as the water was coming in, and outside my front door looking northwest. Notice the lack of waves on the still water - both inside and out... The water came up about another two feet after these pics were taken, but by then, taking pictures had taken a back seat to more pressing needs.

[thunderchief]

Well, in my case "a few feet" made a HUGE difference.

Of course. But I doubt you care whether the NHC officially calls it 28 or 31 feet or whatever, since that changes nothing.

[HurryKane]

One might present a case that this high tide reading was from Gulfport, and not Waveland; but the NHC's report cites only "Hancock County" having "probably" had a surge of 27 ft., which, for whatever it's worth does include both Waveland and Gulfport.

Gulfport is wholly within the eastern half of Harrison County, not Hancock, and is around 20 miles east of Waveland.

Hancock County contains, from west to east:

Shoreline Park
Pearlington
Waveland
Bay St. Louis, Kiln to the north
Diamondhead