Optimal discharge for closed-end border irrigation under soil infiltration variability

Abstract

Traditional border irrigation designs have rarely considered that soil infiltration can vary. The design of border irrigation systems can be improved by the optimization of border irrigation discharge. Therefore, the objectives of this study were (1) to expand the scope of the existing model for estimating and verifying the performance indicators of closed-end border irrigation; (2) to analyze the effect of infiltration variability on infiltration depth variability of closed-end border irrigation; and (3) to propose a method for determining the optimal discharge of closed-end border irrigation for variable soil. Physical and simulated experiments were conducted. The results revealed that for both variable and uniform soil, the estimated irrigation performance indicators were in good agreement with the measured values as well as values simulated using WinSRFR 4.1; the corresponding mean relative errors were less than 10%. The variance of infiltration variability explained a high percentage of the variance in infiltrated water depth (51.71%–95.68%). The optimal discharges were consistent for both variable and uniform soils, signifying that the optimal discharge of uniform soil can be used for the discharge design of a closed-end border irrigation system in variable soil.