WSP08820

• File Number: 8273.600.30
• Description: Colorado River Basin Salinity Control - Federal Agencies - USDA
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1989
• Title: Use of Saline Drainage Water for Irrigation - Imperial Valley Study
• Water Supply Pro - Doc Type: Report/Study

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USE OF SALINE DRAINAGE WATER FOR IRRIGATION

29

TABLE I

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Average compositions of Colorado River and drainage waters

Water/
Statistics

EC SAR' Solute concentration (mmole L -I)
(dSm-') (mmo~L-')'/2
Bb Ca Mg Na K Alk SO, CI NO,
50 50 46 48 50 50 49 45 40 48 11
1.25 3.2 0.31 4.1 2.6 5.7 0.11 2.6 6.6 3.1 0.05
0.13 0.5 0.12 1.2 0.3 1.0 0.04 0.5 0.9 0.5 0.02
0.02 0.07 0.02 0.2 0.04 0.1 0.01 0.07 0.1 0.1 0.01

Colorado River
Number of
samples
Mean value
Standard
deviation
Standard error
of mean

Alamo River
Number of 34
samples
Mean value 4.0
Standard 0.3
deviation
Standard error 0.06
of mean

33

32 31 34

34 33 34

20 31 16

8.2
1.5

0.8 10.3 8.9
0.3 2.1 1.2

25.1 0.32 4.4
4.4 0.05 1.3

22.2 18.4 0.7
4.0 2.1 0.6

0.3

0.06 0.4. 0.2

0.7 om 0.2

0.9 0.4 0.2

'SAR: Sodium adsorption catio= Na/ J (Ca + Mg)/2. where all solute concentrations are in mmole L _1.
bConcentration in mg L _I.

while Colorado River water was used during seedling establishment. For the
wheat and alfalfa crops, only Colorado River water was used. It was hypothe-
sized that wheat would withstand the salinity developed in the soil from irri-
gating the previous two cotton crops with the saline drainage water and would
yield well when irrigated with Colorado River water. Enough desalination of
the soil during the wheat crop was expected to occur during irrigations with
Colorado River water to permit alfalfa to be grown subsequently without any
loss of yield from excess salinity.
The average amounts of water applied to each crop and the totals over the
entire four-year period are given in Tables 2 and 3 for the "successive" and
"block" rotations, respeCtively. These data include all water applied, including
that used for preplant irrigations and land preparation purposes. Rainfall was
insignificant. These data show that substantial amounts of drainage water were
substituted for Colorado River water in the irrigation of these crops. The es-
timated amounts of water consumed by the crops through evapotranspiration
and lost as deep percolation are given in Table 4 by individual crop and by
succession of crops for both rotations. It was assumed that consumptive use
was the same in all treatments, since no substantial yield differences occurred
among treatments.
Crop yields in the "successive" and "block" rotation(s) are given in Tables

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