Mike,
 You could use a doppler radar to measure the surface velocity, but you wou=
ld have to do a calibration as the water flow across the section is not the=
 same everywhere.
I used to work for a company making such a radar for the Geological survey.


> On Mar 26, 2017, at 9:47 AM, mike brown <mike@n5qmg.com> wrote:
>=20
> I've got an open ditch behind my home that is becoming an increasing thre=
at
> to my flood risk.  Measuring the water depth is a fairly simple project
> using ultrasound, but I'd also like to measure flow volume.  The dimensio=
ns
> are easy enough, but how do I measure the average speed of the water?
> Extra credit for devising a method that doesn't involve touching the wate=
r.
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Just my $0.02,

Jean-Paul
N1JPL




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