Modelling soil water and its uniformity under linear-move sprinkler irrigation

Crop yield is strongly affected by soil water distribution near the root zone. The redistribution of soil water in sprinkler irrigation results in higher soil water uniformity (CUs) than irrigation uniformity (CUi). A soil water transport model for sprinkler irrigation based on the COMSOL-2D model has been constructed and validated to investigate soil water movement and redistribution. Furthermore, the relationships between CUs, soil hydraulic parameters, and sprinkler irrigation parameters has been analysed. The results showed that 1) the residual distributions of the vertical wetting front (VWF) and soil water content (SWC) were in the ranges of -0.04-0.05 and -0.09-0.10, respectively, with mean values close to 0 and R-2 greater than 0.85, indicating that model predictions were reliable; 2) the lower CUi was, the lower CUs, the lower the VWF transport rate, and the higher the chances of deep percolation; 3) the VWF transport rate depended on soil texture (loam > clay loam > silty clay), but CUs was highest for silty clay (76.43 %), medium for clay loam (67.48 %), and lowest for loam (60.36 %); 4) the wetted area and VWF transport distance were positively correlated with soil water at the same moment; and 5) dimensional analysis showed that CUi had the greatest effect on CUs, followed by saturated hydraulic conductivity and water transport time. This study provides a theoretical basis for adequate values of CUi for optimal management of linear-move sprinkler irrigation systems.