[Acoustics] use of ADCP's in High Sediment Concentrations

[Robert R Holmes]

Recently, I had sent in the following question to the user group

"Does anyone have experience or knowledge of how well the ADCP (or any of 
the other acoustic instruments) work in high sediment concentrations.  I 
am specifically interested in performance in waters with concentrations 
between 10,000 mg/l to 40,000 mg/l....... "

I received a few responses back and because they responded only to me and 
I had a few others send me email asking for me to share what responses I 
received, I figured I would post the responses.....since  I am not sure 
how comfortable these folks are with having their responses shared with 
all, I have removed the names...............

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Response 1
 With the experience on the MO River I almost sure it will not work as 
listed conc. are much higher that MO River and we couldn't always make a 
complete measurement with a BB 300. 

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Response 2

>From all the curves I have seen, attenuation really kicks in around 10 
g/l.  The problem is worse at the highest frequencies and I remember a 3 
MHz unit we had installed in Taiwan while I was still working for Sontek - 
at 5 g/l the range was down to 1 m.  The problem is less at low 
frequencies but at 40 g/l I don't think  any of the commercial Dopplers 
will give you much range.

Of course, bottom tracking starts being a problem a long time before the 
range becomes significantly reduced. 

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 Response 3

It will obviously be frequency dependent.  XXXXXXXX  has some Grand Canyon 
data at about 2,000 mg/l, but that is the most I have seen in print. Your 
target concentrations can be penetrated by low frequency acoustics. If 
this is the goal I would suggest contacting the USGS Geophysics office in 
CT.


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Response 4

If you are not getting good data using 1 water ping (WP1) try 2 water 
pings (WP2)


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Robert R. Holmes, Jr., Ph.D.,  P.E.           bholmes at usgs.gov
Director, Illinois Water Science Center
U.S. Geological Survey                             Urbana, Illinois
217-344-0037, ext3005                              il.water.usgs.gov
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