A new infiltration model for simulating soil water movement in canal irrigation under laboratory conditions

To determine the main influencing factors of the two-dimensional process of channel section infiltration, an accurate and effective soil water infiltration model was constructed to dynamically simulate the infiltration process of farmland irrigation channels. Based on laboratory experiments, an infiltration system consisting of a water supply unit and a cuboid plexiglass unit was set up. Five different initial conditions were established for soil bulk density, initial water content, channel bottom width, infiltration head and slope coefficient. On this basis, the cumulative infiltration and wet front processes along the section of the artificial channel were explored and the two-dimensional soil water motion equation under the experimental setting conditions was established. The model was solved using HYDRUS-2D software, and an error analysis between the simulated value and the measured value was carried out. The results show that the software simulation results are good. Additionally, based on the experimental data, models of cumulative infiltration and wetting front migration distance were proposed. According to the modeling results, the standard regression coefficients of each influential factor were calculated for the fitting parameters, and the effect of each factor on the fitting parameters was analyzed. The error analysis showed that the established model of soil water movement could effectively simulate the process of soil water infiltration under experimental conditions. The analysis of the standard regression coefficients suggested that the slope coefficient had the smallest influence on the fitting parameters and could be eliminated. The model results showed that the calculated and measured values were all distributed around the 1:1 line, and this result reflects the accuracy of the model. The results can provide theoretical support for the design of irrigation systems and improve the efficiency of irrigation water use.