[Acoustics] bottom mounted velocity question

[Henry J Zajd Jr.]

Greetings all
                          The questions I have about bottom mounts are
dealing with securing the meter and cable (I will have direct
communications, SDI12, to a data logger in a gag house) to the bottom in
varying velocities in the stream? What experiences worked  and which ones
did not work.  I have seen some general setups for the meter and have seen
the commercial ones, so I have some ideas, but no experience. I have been
using side looking velocity meters and securing them is relatively straight
forward and close to the shoreline. The sites that I am looking at have
discharges ranging from 300 to 15,000 cfs. and I may have 100 to 150 ft. of
cable in the stream.  I am not sure what the actual velocities would be at
the higher discharges, hence the questions about securing to the bottom. We
have some ideas, but I wanted to here from people with actual experiences -
good and/or bad.

                        A little history - the need for the bottom mount
versus a side looking velocity meter is due to bidirectional flow, reverse
flows and a few other flow  situations that I have been told about, but
have not seen as of yet. The study area is located in an active canal
system, outflowing from a lake. that all of this is controlled by others
with dams up and downstream of the area.

                     Again thanks in advance for any information that you
will offer.

                                    Hank Zajd
------------------------------------------------------------------------
   Henry J. Zajd, Jr. (Hank)        Tel: (607)266-0217 ext. 3023
   U.S. Geological Survey           Cell phone (607) 227-3897
   30 Brown Road              Email: hzajd at usgs.gov
   Ithaca, NY  14850-1573           Fax: (607)266-0521
                              Web: http://ny.usgs.gov/