[Coral-List] [EXTERNAL] USACE used bad science to rule out useful instrument for siltation monitoring

Jordan-Sellers, Terri SAJ Terri.Jordan-Sellers at usace.army.mil
Sat Jan 23 12:24:27 EST 2016

Dr. Erlingsson - I am surprised that it took more than 2 years for you to review the two assessment reports conducted on the Sedimeter by the USACE Research and Development Center (ERDC) released in 2013 and 2014. It is my understanding from the researchers I spoke with that you were aware of the faults identified in their reviews and were working to remedy them in a newer version of your sedimeter. 

There were two reports prepared that I have previously posted to this list in response to your comments that USACE reviewed the use of the sedimeter for the Miami Harbor project. One from laboratory testing and one from field testing. It is my understanding that the device failed both reviews. I have included the links to both reports for folks to download and read them for themselves.



I was also told that you provided a revised version of your device and that it would be tested again beginning early in 2015.  I will forward your comments to the reviewers so that they are aware of your criticisms and they can work  to address your comments before they complete the restudy of your new version of the device. I will also check on the status of the new device review.

As I have previously stated, USACE-Jacksonville district NEVER considered your device for monitoring, as the testing for this device had been completed prior to the advertisement of the contract and the device was deemed unable to detect the sediment to the level advertised. I have also previously stated that when the Sedimeter passes the assessment of the research scientists at our lab, it will be made available as a tool across all of USACE and may in fact be utilized in future monitoring programs, including those in Jacksonville. If you have independent laboratory and field testing conducted that shows the devices effectiveness, I would suggest providing those studies both here and to the reviewers at ERDC.


Terri Jordan-Sellers
Biologist/Regional Technical Specialist
Coastal Section
Environmental Branch-Planning Division
Jacksonville District-US Army Corps of Engineers

-----Original Message-----
From: coral-list-bounces at coral.aoml.noaa.gov [mailto:coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of Ulf Erlingsson
Sent: Saturday, January 23, 2016 12:16 AM
To: Coral List <coral-list at coral.aoml.noaa.gov>
Subject: [EXTERNAL] [Coral-List] USACE used bad science to rule out useful instrument for siltation monitoring

Before the dredging of Miami harbor (which caused a lot of siltation on the coral reefs) the US Army Corps of Engineers evaluated an instrument I invented, the SediMeter. It is capable of detecting as little as 100 grams per square meter of sedimentation (about 0.01 mm) and the accuracy is in the order of 1 mm. However, in this document (el.erdc.usace.army.mil/elpubs/pdf/doert11.pdf) the USACE used a series of flaws to arrive at the conclusion that the SediMeter is only useful for measurements "where bed-level changes are on the order of centimeters". Today for the first time I took the time to read their "study", and found that it wouldn't pass as an undergraduate paper if I had evaluated it.

The problems start small with a too small measurement tank, but that's a minor thing. Next they moved the instrument rather than the bottom, and they noticed that it led to errors but kept doing it. Still worse, they don't seem to grasp the concept of statistics, believing that all data have a Gaussian distribution if you measure enough many times. From a standard deviation of 0.84 mm they thus extrapolate that the 95% confidence interval is "±1.7mm" even if the data they present never exceed +1.1 mm or -1.0 mm in 89 samples. The last error is the worst, however. The ±1.7 mm value refers to the difference between two bed levels, but in the conclusions they state that it is an error in the bed level, and double it to arrive at "total" error for the difference. This value, 3.4 mm, they then use to argue that the instrument is only useful when the difference is several centimeters.

This is simply a junk study from the part of USACE. I will personally do a proper measurement and will be happy to provide a correct estimate of the uncertainty to any coral lister who is interested in monitoring siltation on coral reefs, especially WHEN IT COMES TO SUPERVISING THE DREDGING ACTIVITIES OF THE USACE.

Ulf Erlingsson, Ph.D.
President and CEO
Lindorm, Inc.
10699 NW 123 St Rd
Medley, FL 33178

ceo at lindorm.com
+1-305 888 0762 office

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