Hydraulic Design of the Center-Pivot Irrigation System for Gradually Decreasing Sprinkler Spacing

Abstract

Design strategies that enhance modern irrigation practices, reduce energy consumption, and improve water use efficiency and crop yields are fundamental for sustainability. Although microirrigation is currently a widely applied method, center-pivot irrigation systems have become very popular on large farms, thanks to their automation, wide-coverage, and reliability. Different design procedures have been proposed, even though some aspects have not been solved yet. This paper presents a simple design procedure for center-pivot systems using a gradually decreasing sprinkler spacing along with a pivot lateral, which makes it possible to set favorable and uniformly distributed water application rates. The sprinkler spacing distribution along the radial direction is derived by considering just one dimensionless group accounting for the geometric and hydraulic input parameters. According to this outcome, the results showed that the suggested procedure made it possible to select the sprinkler characteristics and the pipe diameter based on the desired input parameters, i.e., the uniform water application rate and the lateral length. For assigned input parameters, the lateral length is delimited by a threshold value, indicating that lateral lengths longer than that threshold value require the modifications of a sprinkler flow rate or pipe diameter. Finally, applications based on the proposed hydraulic design procedure were performed and discussed for two different cases.