Evaluation of variable-rate water distribution uniformity from a modified centre pivot irrigation system

Variable rate water application can be achieved along the length of centre pivot by variable-rate control systems. But to attain a satisfactory level of irrigation efficiency, high water application uniformity over area with same irrigation rate is required. In this research, the water distribution uniformity was evaluated with a modified centre pivot irrigation system that was able to vary the amount of water along the length of centre pivot and vertical to movement direction. Uniformities along the length of centre pivot and vertical to movement direction were calculated at three movement speeds and seven solenoid valve pulsing levels. Results showed that modified centre pivot is able to apply water with acceptable uniformity coefficient (82 to 96%) under different pulsing level and movement speed. Uniformity was increased by increasing pulsing level and decreasing movement speed.