Continuous modeling of infiltration rate for the management of sprinkler irrigation

The spatially and temporally variable characteristics of soil infiltration process are a major physical constraint for the irrigated lands to achieve higher irrigation efficiencies. Substantial works have been directed towards developing state-dependent models to estimate the infiltration characteristics of soils, which are not suitable for continuous simulation of the infiltration process under complex rainfall or irrigation intensities. In this study, the time compression approximation (TCA) method is coupled with the Philip's infiltration equation, and the coupled infiltration model is extended beyond the ponding time to estimate the postponding infiltration process. An offset time is then introduced into the coupled infiltration model for solving the problems caused by the necessities of refreshing the state-dependent variables stepwisely. This simplifies the determination processes of the model's variables and amplifies its applicability under complex rainfall or irrigation intensities. By using the soil expA(c)rimental data, the TCA based infiltration model shows good performance in predicting the cumulative infiltration. The deviation coefficients of the infiltration predictions range from 0.59% to 34.74%, and the Nash coefficient of efficiency is calculated to be 82% for all the simulated results. This suggests that the proposed TCA based infiltration model could be suitable for the management of sprinkler irrigation.