WSP04649

• File Number: 8276.150
• Description: Grand Valley Unit-Colorado River Basin Salinity Control Project
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 2/1/1990
• Title: Draft 1989 Annual Report: Grand Valley Salinity Control Project Monitoring and Evaluation Program
• Water Supply Pro - Doc Type: Annual Report

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- Quantify deep pe~colation ~eduction ~esulting f~om
i~~igation system and management imp~ovements.

- Evaluate on-farm i~~igation system pe~fo~mance and
~ecommend desi gn imp~ovements based on actual system
performance.

Identify management follow-up needs and directions.

SCOPE

The initial USDA M&E plan was to monitor 35 sites at one time. Since
then, because of budgetary and man powe~ constraints, management
decided that at least 16 active monito~ing sites would be maintained
each yea~. Between 1985 to 1987, 16 monito~ing sites we~e ope~ated
each yea~. Ni neteen sites we~e mon i to~ed in 1988, and 20 in 1989.
However, a full season of i~~igation data could not be obtained from
all the established sites in 1988 and 1989 <Table 1>. In the futu~e,
mo~e sites may be added, depend i ng on the ava i lab i I i ty of equ i pment
and pe~sonne I. A tota I of 35 sites cou I d be mon i to~ed ove~ the life
of the M&E prog~am by maintaining 16 to 20 ope~ating sites each year
and ~otating the equipment to new fields afte~ 3 to 5 yea~s of
i~~igation monitoring.

The irrigation monito~ing data being collected includes; total
irrigation inflow to the field, total su~face ~unoff (tailwate~)
leaving the field, total ir~igation time fo~ each irrigation, number
of hou~s ir~igated per set, and ave~age flow at each fu~~ow. Othe~
data such as so i I mo i stu~e def i c i t (before and after i rri gati on), deep
percolation and depth infilt~ated a~e calculated from the data
GO I I ected in the fie I d. C~op consumpt i ve use fo~ each c~op at each
site was dete~mined f~om modified Penman equation.

In the past, on-site ET data was also collected f~om 3 selected sites
using atmometers. An atmometer is a porous porcelain piece made
eithe~ of cylinde~s, sphe~es, o~ Bellani plates fitted to a Ja~ of
water so that water loss by evaporation simulates c~op ET ~ates.
Bellani plates we~e used fo~ this study. In 1989, because of lack of
personnel and time, no atmomete~ studies we~e made.

METHODOLOGY

Twenty irrigation monito~ing sites we~e established during the 1989
i~rigation season, however, only 19 were fully ope~ational. A full
season of i ~~igation data could not be obtained f~om one site, #13
<Table 1). This site was ~eactivated after a two yea~ lay ove~. The
equipment installed at this site did not function p~ope~ly du~ing the

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