[Acoustics] Streamflow Velocity Analysis

[Michael Simpson]

Nick: hopefully some of the other members of the acoustics list will have
better answers for you.

What your colleague is requesting requires the development of a two
dimensional velocity matrix (each column being an ensemble and each row
being a bin) and then forming a histogram from the velocities found in each
cell of the matrix. Each value then must be weighted according to the
distance traveled during its corresponding ensemble (unless all ensembles
are nearly the same width).

This will require getting properly formatted ASCII output from the WinRiver
Software and then manipulating the data using a custom program written with
Matlab, An Excel macro, or a custom stand-alone program (.net suite or
Delphi).

I know you were hoping for an easier solution, and maybe list members have
done something similar and give you an easier solution.

-Mike Simpson


-----Original Message-----
From: acoustics-bounces at simon.er.usgs.gov
[mailto:acoustics-bounces at simon.er.usgs.gov] On Behalf Of Nick j Everard
Sent: Monday, February 06, 2006 3:13 AM
To: acoustics at simon.er.usgs.gov
Subject: [Acoustics] Streamflow Velocity Analysis


All

I have just had a query from a colleague that has me a little baffled!
He has been collecting data with his Streampro ADCP and is using it to
help Fisheries staff who are looking into habitats for various fish
species, with a particular view to river velocities. Here's what he
writes: -

'We need to know the percentage of the river that falls into various
velocity categories. ie 28% of the river has a velocity of between
0.1m/s and 0.2m/s.
Without just estimating from the velocity magnitude graph I am unsure
if this is possible. Although thinking about it, the raw data is all
there, velocities in each bin, number of total bins etc.'

I can't really figure out a neat way to do this! Averaging data and
doing an ASCII output is a possibility but is fiddly and of course the
averaged data still doesn't represent evenly sized chunks of the river
so working out proportions will still be difficult.

The best I could come up with was to 'bracket' the data in the velocity
magnitude plot by setting the velocity scales to only show certain
velocity ranges. For example choosing 0 to 0.1 will make all data above
0.1m/sec appear solid red. Setting to 0.1-0.2m/sec makes all data below
0.1m/sec appear purple and all above 0.2m/sec look solid red. It is then
possible to estimate proportions that fit in each range. You will of
course need to set your plot to 'length' for this to work out.

So, anybody have any more scientific ways to achieve this? 

We don't have access to Matlab or anything similar, but would that sort
of software be useful for this kind of analysis? Any other software that
would be good?

Any help much appreciated!

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


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