Biological Systems Engineering
Date of this Version
2-2019
Citation
Martin, D. L, Heeren, D. M., Melvin, S. R., & Ingram, T. (2019). Effect of limited water supplies on center pivot performance. Proceedings of the Central Plains Irrigation Conference, Kearney, Nebr. 27 pages.
Abstract
When appropriately designed and operated, center pivot irrigation systems can efficiently irrigate many crops grown on diverse soil and terrain conditions. However, a significant number of pivots are not supplied with an adequate water to operate as envisioned.
We simulated the hydraulics of a center pivot irrigation system, including the pump curve, flow rate, pipeline hydraulics, pressure regulators, nozzle flow rate, and irrigation application uniformity. This was used to analyse the performance of a center pivot for a sloping field for both adequate and inadequate water flow rate. The performance was simulated for a range of inlet pressures when pressure regulators were used and for systems without pressure regulators.
Inadequate inflow causes major degradation of the uniformity of water application and the ability of the system to meet crop needs. Results show that regulators improve uniformity for high-flow conditions but do not improve the discharge uniformity when inlet pressures—and therefore system inflow—drop below design specifications. The variability of discharge at the distal end of the pivot is less for unregulated conditions than when regulators are used for limited inflows.
Comments
For more information on pump curves, see the following paper:
Martin, D. L. (2018). Pumping plants - Preserving performance. Proceedings of the Central Plains Irrigation Conference, pp. 15-34. Available at: https://digitalcommons.unl.edu/biosysengpres/75/