Measuring Low Flow in San Pedro River
Detailed Description
Measuring low flow in the San Pedro River with flume.
Details
Date Taken:
Location Taken: Charleston, AZ, US
Transcript
(water flowing)
- Okay, what we're looking at here
is the gage pool at the Charleston
at San Pedro gage.
The gage pool extends downstream
to a point where
there is a change in
velocity or a flow regime.
And you can see, during
these underflow conditions,
we're looking at an area that is about
1.1 feet wide.
The deepest point of this riffle
is going to be right about...
here.
0.11 feet.
Our flume section is just
about 30 feet downstream.
We have here an area that
has been used previously
for a Parshall flume measurement,
and what I'm going to do now is
I'm gonna fill that in a little bit
with some very fine sediments.
I'm going to set it,
I'm going to fill in around the flume.
(water flowing)
This device right here is
a three-inch Parshall flume.
It's constructed in such a way that it has
a very precise throat.
Dimensions of the inside
of the Parshall flume are very precise.
It has been computed
using a rating table,
that at different elevations of water
flowing through the Parshall flume,
a discharge can be associated
with that elevation.
We actually measure the
elevation in the stilling well
of the Parshall flume.
This is the stilling well, this part here.
The purpose
is at very low flow conditions,
like we have here at the San
Pedro at Charleston gage,
we have an accurate method for determining
and computing the discharge
using the rating table.