Empirical Equations for Estimation of Water Distribution Uniformity Coefficient in Case of the Alternate Setting of Sprinkler Laterals

Among the operating and management practices that can increase the uniformity of water distribution in the portable sprinkler irrigation systems is the alternate setting of sprinkler laterals. Shifting the laterals by half the distance between laterals results in a single alternate set and shifting the laterals by half the distance between the sprinklers results in double alternate set. Data representing 66 patterns of water distribution for a single sprinkler of different types of sprinkler heads were used. By choosing many suitable sprinklers spacing and using Microsoft Excel to implement the field distribution that free of dry spots, the following coefficients were computed: uniformity coefficient, uniformity coefficient of single and double alternate set, distribution uniformity, distribution uniformity of single and double alternate set and coefficients related to sprinklers spacing. Then, using the nonlinear regression analysis provided in SPSS, empirical relationships were derived to estimate both the single and double uniformity coefficients and the single and double distribution uniformity with determination coefficients of 0.783, 0.810, 0.720, and 0.766, respectively. The spacing coefficients that lead to the maximum values ​​of the different uniformity coefficients were determined based on inferred equations. In addition, the functions proposed in previous studies used in estimating the single and double uniformity coefficients with determination coefficients of 0.608 and 0.539, respectively as well as the single and double distribution uniformity coefficients with determination coefficients of 0.584 and 0.491, respectively showed low accuracy as compared with the ones proposed in the current study.