WSPC04421

• File Number: 8064.100
• Description: Ute Tribes
• State: CO
• Basin: San Juan/Dolores
• Water Division: 7
• Date: 9/1/1986
• Author: Boyle Engineering
• Title: Agricultural Engineering Study - Southern Ute and Ute Mountain - Ute Indian Reservations - Task A Report - On-Farm Water Requirements
• Water Supply Pro - Doc Type: Report/Study

I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I

CO~s1]ptive use methodologies have been developed

in carefully

controlled

and

monitored

research

plots.

Evapotranspiration

estimates produced by these methods reflect the research environment

in which they were obtained.

Actual ET expected in a commercial

farming operation will likely be less due to growth suppression under
hay windrows, infrequent and/or non-uniform irrigation, and soil

variability ii, ~/.

Correction factors may be applied to compensate

for these effects, however, caution must be exercised in their use to

assure their applicability to the given project.

Correction

factors are discussed further under "Application to Project Area".

Water

use

production

functions,

or

yield-evapotranspiration

relationships have been developed for various crops in many areas.

They relate the productivity of a given crop to the ET rate. Most
annual crops show a very weak correlation between ET and yield.
Alfalfa, however, shows a strong linear correlation in most areas,
and calibrated production functions of the form:

Y = a + b x ET (10)

can fit data with high coefficients of determination.

Figure A-I.l

is the recommended production function for alfalfa on the NIIP.

Production functions may provide an alternate method of determining

crop ET in certain areas ~/.

Known or expected yields in a gi ven area

can be used in the production function to determine the seasonal

consumptive use.

A comparison of various production functions

1- 10