ASSESSMENT OF EFFECTS OF VARIOUS PRESSURE LOSSES IN LATERAL PIPES ON THE FORAGE CROP YIELDS IN THE HAND MOVE SPRINKLER IRRIGATION SYSTEMS

摘要

In developing agriculture, the goal is high crop yield and in order to achieve this goal waterrnlosses should be reduced and irrigation efficiency should be increased. Higher frictionrnlosses in the laterals of sprinkler irrigation systems, would require higher driving pressurernand will result to non-uniform water distribution, giving rise to more water losses. If lateralsrnare designed with less allowable pressure variation, irrigation uniformity will be better, whichrnwill improve water application efficiency and enhance crop yield. In this study, sample fieldsrnwith manually shifting sprinkler irrigation system were designed with 5 to 30% allowablernvariation of application pressure of sprinkler for irrigating alfalfa in Khuzestan. In each field,rnsystem’s uniformity coefficient, water application efficiency, and crop yield were obtainedrnfor different friction losses. Results showed that an increase friction losses from 5 to 30%rnreduced system’s uniformity efficiency by 4%, application efficiency by 5% and relativernproduction of crops by 1%