[Acoustics] Depth Sounder usage in WinRiver

[Tracy Vermeyen]

Hi Dan,

I have done several evaluations using depth sounders with a Rio Grande for bathymetric surveying and to some degree discharge measurements.

I will answer your questions and send you a paper I wrote that covers the depth sounder/adcp depth comparisons.

1) Have you compared the [ADCP] calculated depths to the external DS depths,
and how much do they differ?  I collected data in a concrete lined stilling basin with a flat floor and the Depth Sounder was accurate to within +/- 0.125 for 300+ data points.  Some of this error can be attributed to pitch/roll since I was on a small Zodiac at the time.  Obviously, ADCP depths near the stilling basin walls were skewed by including the truncated depth from the beam that intersected the wall.  This problem can occur in rivers for transects that cover highly variable bed elevations and/or steep banks.  In this case I think a depth sounder will give better results.

Wilson and Morlock(http://in.water.usgs.gov/bathymetry.web/) performed a similar depth measurement evaluation in a reservoir survey project that compared average ADCP water depths to depth measurements collected using a survey rod.  They found for 41 data pairs that the mean discrepancy was +0.03 ft with a standard deviation of 0.29 ft for depths ranging from 2 to 27 ft.  

2) Does it affect the discharge calculated by WinRiver, and how much?  I haven't looked at this in much detail.
3) Under what kind of conditions have you done this?  I have compared depth sounders/ADCP in rivers, stilling basins, in and around other hydraulic structures (pumping plant intakes, fish screening structures, flumes, etc...) and the comparison is good for gradually varying bottoms.

4) Do you think you get more accurate discharge numbers by using an external
DS?  My depth sounder can be unreliable at times (sometimes I get a depths 2x the actual in very shallow streams) whereas ADCP depths are very reliable.  

I feel for most discharge measurement applications at good sites the ADCP is superior to most depth sounders on the market in both accuracy and reliability.

Tracy





Tracy B. Vermeyen, P.E.                           
Hydraulic Engineer                      
U.S. Bureau of Reclamation                        
Water Resources Research Laboratory    
P.O. Box 25007, D-8560
Denver, Colorado  80225-0007

Phone:  303-445-2154
FAX :     720-544-0551 
Cell:       303-870-9178
e-mail: tvermeyen at do.usbr.gov 
http://www.usbr.gov/pmts/hydraulics_lab/tvermeyen/index.html

>>> "McBride, Daniel J MVR" <Daniel.J.McBride at mvr02.usace.army.mil> 04/05/06 02:11PM >>>
I was wondering how many of you use external depth sounders when collecting
ADCP data with WinRiver.  For those of you who do, I have a couple questions:

1) Have you compared the [ADCP] calculated depths to the external DS depths,
and how much do they differ?
2) Does it affect the discharge calculated by WinRiver, and how much?
3) Under what kind of conditions have you done this?
4) Do you think you get more accurate discharge numbers by using an external
DS?

I tend to think that anytime you can get more accurate values for the various
parameters that you're measuring, it will only make your measurement that
much more accurate.  I'd like to see if that's what people are finding with
their data.

Thanks for any input!
--Dan McBride

	Daniel McBride
	Hydrologist
	U.S. Army Engineer District, Rock Island
	Water Quality and Sedimentation Section
	CEMVR-EC-HQ
	Clock Tower Building, P.O. Box 2004
	Rock Island, IL  61204-2004
	Phone: (309) 794-5720   Fax: (309) 794-5584
        E-mail: daniel.j.mcbride at mvr02.usace.army.mil 




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