WSP03457

• File Number: 8276.100
• Description: Grand Valley Unit - Colorado River Basin Salinity Project
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 4/1/1992
• Title: Grand Valley Salinity Project Monitoring and Evaluation Program -- 1990 Annual Report
• Water Supply Pro - Doc Type: Annual Report

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c.' METHODOLOGY

In 1990, twenty five irrigation monitoring sites were established in
19 different fields with improved irrigation systems. Of the 19
fields monitored, 13 of them had one monitoring site each, four of
them had two monitoring sites for side by side comparison of
conventional with surge irrigation, one field had two M&E sites
because two crops were monitored in different areas of the same field,
and another field was double cropped so that the same field was
monitored twice.

AI I 1989 sites were monitored in 1990 with the exception of sites 14,
28 and 35. These three sites were dropped because of problems with
ownership changes and field irrigation operations. However, three new
fields (43/44,45/46,47) were added in 1990 <Table 1).

As stated earl ier, four surge sites (39, 41, 44, 46) were added to
four different fields in conjunction with conventional sites for
comparison of surge with conventional irrigation (Table 1). These
sites were establ ished in conjunction with Colorado State Cooperative
Extension's and the Bureau of Reclamation's "Surge Project" in order
to provide them with accurate inflow and outflow data. Each
cooperator was prov i ded 101 i th a surge va I ve and a contro II er and
trained in the use of surge valves. The surge system was set up prior
to the first irrigation and used throughout the season.

The original site 32 from previous years had two crops, small grain
and onions, therefore, two different monitoring sites were establ ished
(32 and 42). Site 29, monitored for four years, was double cropped
this season - small grain followed by pinto beans. 130th crops were
monitored, one following the other, therefore two sites were set up in
the same field. This is the first time that double cropping has been
practiced in this field and it is not a common occurrence in the Grand
Va II ey.

Of the 25 fields monitored, one had microspray system, two had
sideroll sprinkler systems and 22 had surface irrigation systems
<Table 2). At each site with a- surface irrigation system, automated
electronic flow recorders were installed to measure the volume of
inflow and outflow. These flow recorders were connected to electronic
data recorders. The recorders measured inflow and outflow every 10 or
30 minutes. The measured flow data was recorded and stored in the
data recorders.

At siderol I sprinkler or microspray irrigation system sites, the
volume of inflow was obtained from in-I ine mechanical flow meters
located on the sites. There is no surface runoff and the volume of
outflow was therefore not measured. For these sites, outflow values
were considered to be evaporation losses (Table 2).

The Team monitored 186 irrigation events throughout the season. Total
inflow and outflow for all 25 sites were measured du,-ing each
irrigation using electronic flow recorders and sensors as described
above. Each site was we II ma i nta i ned and serv iced, and equ i pment
ca Ii brated and checked to ensure accurate data.

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