WSP10689

• File Number: 8273.600
• Description: Colorado River Basin Salinity Control - Federal Agencies - USDA
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1994
• Author: USDA
• Title: Grand Valley Salinity Project - 1993 Annual Monitoring and Evaluation Report
• Water Supply Pro - Doc Type: Annual Report

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the sprinkler systems.
surge and conventional
acre was 42.5 and 61.3

When the 20 surface sites are separated by
irrigation, average water application per
inches respectively.

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'2. Average water application for different crops varied from a high
of 88.7 inches per acre for soybeans to a low of 43.8 acre inches
for si1aq.~ corn. .

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.3. The actual evapotranspiration varied for different sites based
on crops, time of planting, and harvest date. Table 2 shows the
average actual ET to be about 27.0 inches for the 22 sites. ETa
rates may be overestimated for some crops.

4. The average deep percolation was 11.8 inches for all the sites;
12.8 inches for the 20 surface sites, and 1.2 inches for the.
sprinkler sites. When the 20 surface sites are separated by surge
and conventional systems, the deep percolation is 4;3 and 18.5
inc~es respectively, Deep percolation for different crops varied
considerably, from 38.9 inches for soybeans, to 4.9 inches for
orchards. There is about SO percent difference in deep percolation
between annuals and perennials; 14.1 inches versus 7.2 inches. The
deep percolation on some improved sites increased due to disturbed
soil conditions the first year after construction.

5. The average effipi~ncy for all monitoring sites was 48.0
percent, an increase. of 3 percent from 1992. The s,easohal
application efficiency ranged from a low of 21% for a corn site to
a high of SOt for an alfalfa site with a sprinkler-system, and 77%
for an orchard site with a surge system. This orchard site was
under second year of surge irrigation and had an inch of deep
percolation per acre. The average efficiency for the 8 surge sites-
was 63% versus 39% for the 12 conventional sites; an increase of
24% in application efficiency with surge irrigation over .
conventional irrigation. .

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6. Surface runoff from sites varied considerably ranging from a low
of 5'.4 inches to - a 'high of 27.2 inches. On the average, 15; 1
inches of water coming to the- field was lost to surface runoff, or
29% 'of the total water applied to the field.

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b. Summary Of Pield Evaluations

The following is a brief summary of the 1993 monitoring field
evaluations:

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1. The average irrigation efficiency of 48% for the monitored
sites exceeds the 33% goal set by the USDA in its Planning
Document under Alternative Plan 4B.

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