WSP07488

• File Number: 8111.805
• Description: Arkansas River Compact Administration - Keesee Ditch
• Basin: Arkansas
• Date: 1/1/1986
• Author: HRS Engineering
• Title: Keesee Ditch Change of Water Rights Technical Information Request Responses
• Water Supply Pro - Doc Type: Publication

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based on 'typical diversion rates determined from diversion records for the
1950 thro~gh 1987 study period. Using these diversion rates and the seepage
relationship illustrated in Figure B-1, monthly estimates of seepage loss and
corresponding delivery efficiency were calculated and are included in Table
B-2.

FIELD EFFIGIENCY

As a means of estimating field efficiency, irrigation design
recommendations outlined in the Colorado Irrigation Guide (SCS, 1979) were
used. Because Mr. Broyles consulted with the Soil Conservation Service (SCS)
in the d~sign of his irrigation system and aerial photographs indicate a
consistent 'pattern of irrigation practices, it was assumed that the SCS design
recommendations are representative. This assumption is supported by
measurements obtained from aerial photographs and topographic maps of
irrigation' run lengths, border widths and field slopes, all of which fall
within the'SCS recommendations.

Discussions with Mr. Broyles indicate that two basic irrigation methods
have been' used within the Keesee Ditch system; level border irrigation and
furrow irrigation, depending on the type of crop. Essentially, level border
was used for all alfalfa and winter grain irrigation, and for about half of
the milo., Furrow irrigation was used for corn, sugar beets, silage and the
remaining milo. Based on the 1950 - 1987 crop distribution, this corresponds
to an average of 79 percent border irrigation and 21 percent furrow irrigation
for the farm.

For level border irrigation, the Colorado Irrigation Guide (CIG) provides
recommende~ design efficiencies for different soil intake rate groups and net
field app~ication rates. For most crops, the net field application rate is
based on ,the depth of water necessary to satisfy a 50 percent depletion in
available soil moisture. Using the estimated available soil moisture storage
of 0.62 afl;acre, this corresponds to a net field application rate of about 3.5
inches. Using the design efficiencies given in Table 6-A-4 of the CIG, and
weighting them according to the areas of the various soil groups, an average
design efficiency for level border irrigation of 80.0 percent was calculated.

For furrow irrigation, Table
efficiencie,s based on field slope.
all fieldi would fall within the 0
furrow irrigation design efficiency

6-8-4 of the CIG lists recommended design
For the Keesee system it is estimated that
- 0.5 percent slope range, resulting in a
of 70 percent.

Combining the estimated irrigation efficiencies for the two irrigation
methods, and adjusting for the proportionate areas, resulted in an overall
field eff~ciency estimate of 78 percent for the Keesee Ditch system. It
should be noted that the design efficiencies given in the CIG account for
normal vapiations in field characteristics and irrigation water deliveries.
Therefore, tit was assumed that the calculated 78 percent field efficiency was
applicable ,for the main irrigation season of May through September. For other
months, the field efficiency was reduced to account for less favorable field
conditions .such as initial wetting requirements and freeze/thaw conditions in
the sprinro, and frozen soil conditions in late fall and winter. Table 8-2
includes th~ monthly field efficiency percentages based on these assumptions.

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