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

I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I

SUPPLEMENTAL REPORT B

KEESEE DITCH

MAXIMUM IRRIGATION EFFICIENCY ANALYSIS

As a result of questions raised concerning the maximum irrigation
efficiency used in the Keesee Ditch consumptive use analysis (HRS, Vol, 1
report), a completely revised irrigation efficiency analysis has been
performed. This revised analysis incorporates a new methodology for
calculating ditch seepage (previously only an assumed value was used), a more
detailed evaluation of field irrigation efficiency utilizing the revised crop
distribution, and a comparison to other Arkansas River ditches.

For the Keesee Ditch and other water rights transfers,
efficiency' is usually defined as the maximum amount of
available for crop consumption and/or root-zone soil
calculated as a percentage of ditch diversions. The
efficiency (or consumptive use efficiency) of the system
consumptive use as a percentage of ditch diversions.

maximum irrigation
irrigation water
moisture storage,
actual irrigation
is the calculated

For the estimation of maximum irrigation efficiency, the Keesee Ditch
system was divided into two components, the ditch delivery system and the
field irrigation system. The delivery system includes the main Keesee Ditch,
three maiq ditch laterals and numerous field laterals. The field irrigation
system incorporates either the level border or furrow irrigation methods
typically used under the Keesee Ditch. The efficiency of the delivery system
determines the amount of water available at the fields, while the field
efficiency' determines the amount of water available for crop consumption and
soil moisture storage. Multiplication of these two efficiency factors results
in the overall maximum irrigation efficiency of the system.

DELIVERY EFFICIENCY

The delivery efficiency is a function of ditch losses due to seepage and
evapotranspiration. Because there is a limited amount of phreatophyte
vegetation lining the ditch and the water surface area is small, it was
assumed that evapotranspiration losses were insignificant in comparison to
seepage. Therefore, the analysis of ditch losses and delivery efficiency
focused on seepage losses.

Based on a literature review of available techniques for estimating
delivery efficiency and seepage losses, a method outlined in a paper entitled
"Estimating' Seepage Losses from Canal Systems" by Robert V. Worstell (Journal
of the Irrigation & Drainage Division, ASCE, March, 1976) was selected as the
most applicable to the Keesee Ditch analysis. This paper incorporates seepage
test data from numerous irrigation canals to determine average seepage rates
for general soil textures used in canal construction. The paper outlines a
method for estimating seepage by combining the appropriate seepage rates with
canal water surface area measurements.

1