[Acoustics] Extrapolation of velocity values from shallow ADVdevices

[Nick j Everard]

David

Not really sure if there's much that you can easily do to extrapolate
beyond measurement range of Streampro but a couple of things to bear in
mind first of all: -
1. The 2m range of the Streampro is the actual depth of water that is
profiled (ie the depth of water that velocity data is collected for) -
you will always have to add in the top section for transducer submersion
and (admittedly small) blanking distance and the roughly 6% that is the
zone of side lobe interference at the bottom. What this actually means
in simple terms is that by the time you have added in these bits you
will lose no data in a stream up to 2.4m deep.
2. When the Streampro exceeds it's water profiling range it is still
bottom tracking and will have a stab at extrapolating to the bottom - it
actually does a pretty good job... You can fine tune the bottom
extrapolation method in WinRiver (which you should be using for data
checking and adjusting edge settings etc) and knowledge of streambed
will help you here.

Also, I believe there may be a development of the Streampro allowing a
longer profiling range soon?

Hope this helps!

Regards, Nick Everard

Nick Everard
FMD Officer 1 (Hydrometry)
Environment Agency - W Area
Thames Region 
Windrush House
Howbery Park
Wallingford
Oxon, OX10 8BD
UK

Tel: +44 (0)1491 828400
Mobile: +44 (0)7831 559379
E-mail nick.everard at environment-agency.gov.uk
Internet www.environment-agency.gov.uk


>>> "David Hunter" <David.Hunter at cityofdenton.com> 13/07/05 15:56:42
>>>
Hello,

We have a Stream Pro from RDI and I was wondering if anyone had
information on extrapolation flow values.

The Stream Pro only shows velocities down to 2 meters but a portion of
our streams are deeper than this.  We will have the velocity numbers
down to 2 meters and also the stream morphology information and I wanted
to know if there was a way to fill in the area that was not being
measured by the ADV.

any suggestions will be helpful.

Thank You,



David H. Hunter, R.S., MPA
Watershed Protection Manager, Water Utilities
City of Denton
901-A Texas Street
Denton, Texas 76209
940-349-7123
940-391-7851 mobile
940-349-7334 fax
940-380-5756 pager



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