FLOOD08079

• County: Statewide
• Basin: Statewide
• Title: Consumptive Use and Return Flows in Urban Water Use
• Date: 12/1/1996
• Prepared By: Colorado Water Resources Research Institute
• Floodplain - Doc Type: Educational/Technical/Reference Information

RESEARCH METHODS

Apparatus and Procedures r

The study was conducted at the I
Agricultural Engineering Research t
Center located in F6rt Collins, Colorado.
This facility has an 'automated weather
station, located on a turf grass plot with
dimensions of 25m X 25m, which
collects data needed to estimate potential
ET using the PenmAn equation. A large
Iysimeter is also located on the plot and
this Iysimeter is used as the reference to
which 24 smalllysimeters are compared.
I

.

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The study utilized two types of
smalllysimeters: a weighing type used
for the Cottonwood Water and
Sanitation District in Denver (Wheeler, 1987), and a drainage type used by the City of Colorado
Springs (Gronning,11989).

Weather station on turf grass plot

The control, in this research is the large Iysimeter which is a hydraulic weighing type with tank
dimensions I m X I m X 1.3 m deep (Fig. 3). The annular to surface area ratio of the Iysimeter is
0.08. The tank rests on two bearing plates which in turn rest on two flexible, hydraulically connected,
fluid filled "pillows". A hydraulic line connects the pillows to a mercury manometer located in a
,
control box.

The change in soil moisture in the Iysimeter is translated to a hydraulic signal which is read on
the manometer. A 0.3 m graduated gravel filter was placed in the bottom of the Iysimeter tank to
facilitate collection' of drainage water. The drainage is collected by a vacuum line to the control box
where a vacuum pump controlled by a timer removes the drainage water and collects it in a jar. On
top of the filter, soil was packed into the Iysimeter'to a bulk density of 1.3 g/cm3. Kentucky Bluegrass
sod was installed on the surface of the tank.

I
The small weighing Iysimeters were constructed from a 61-cm long section of30.5 cm
diameter PYC pipe with a small valve threaded into the bottom plate to collect drainage water (Fig,
4.a). These lysimeters are designed to be lifted out of the soil for weighing and drainage, and cable
loops at the top act 'as points ofattachment for a weighing and lifting apparatus. The annular to
surface area ratio for this lysimeter is 0.07. The small drainage Iysimeters consist of a 40 cm diameter
steel pipe 61 cm in!length with a fiberglass bottom cap (Fig. 4.b). A stand pipe is attached to the
bottom of the cap and is run to the soil surface on the outside of the pipe section. The drainage

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