Depending on the conditions of a region, different irrigation systemsare usually practiced. Each system has its own advantages and disadvantages which
should be evaluated. and then the best system based on the climatic. soil. plant. and topography conditions. could be determined. The evaluatinof each
system requires some evaluation factors in order to compare the performance of two different systems. Evaluation of two systems not only can increase
system effciency, it also determines applicability of each system based on the existing conditions. The major objective of this study was to compare the
evaluation factors of two irrigation systems (Center Pivot and furrow) and factors which usually affect irrigation performance and then to present a
solution for the improvement of irrigation water use and to point out the design problems. In order to achieve this. the characteristics of the soil and
the growing plant (seed corn) along with design parameters were determined. In order to evaluate the furrow irrigation system. four experimental plot. each
plots including fifteen furrows was selected and all the required factors for system design were determined. Two parshall flums. one at the entrance and
the other at the end of furrows were installed to measure in and outflows. At
each irrigation, SMD & MAD with respect to the root zone depth were determined. The infiltration equation with respect to measured data of
discharge and advance time were also determined. The depth of infiltrated water through these information was calculator, then the performance factors
such as DU. PELQ. AELQ, CU, and the totallnss of water were determined.
To evaluate the center pivot irrigation system, the system was designed on the basis of soil and the growing plant characteristics. Then it was examiped with
existing condition. Four radial rows of catch containers spacing 6 meter were set up and then the necessary factors for evaluation were determined. The
evaluation factors were calculated with the analvsis of the field data. The
result of this study are as follows:
The volume of irrigation water used in the furrow and the center pivot systems
were about 12583, X465 m3 ha, respectively (the calculated crop water use for seed corn was about 6890 m3 / ha). Therefore, the furrow system was used about 32.7 percent or 4] IX m] / ha irrigation water more than center pivot system. During the growing season the average PELQ for the center-pivot and
furrow irrigation, were about 79 and 69.5 percent. respectively. The average AELQ for the center-pivot and furrow irrigation systems were about 79 and
69.5 percent, respectively. The average AELQ and DU values for the center-pivot and the furrow irrigation systems were about (75.8 and 56.8) and
(84 and 91) percent. respectively. DU, PELQ values were low at the center-pivot system because it was not properly desigend for the existing
condition. In the mean time, it seems that the difference between PELQ and AELQ values in both systems arc meaningful which may indicate the cxistance
of management problems.
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