A method to estimate soil-water movement under a trickle surface line source, with water extraction by roots

摘要

The analysis of local infiltration from a surface line source of trickle irrigation in two homogeneous, unsaturated soils, using three wetting rates in each soil is presented. A method to determine the depth of the wetted soil volume under a trickle line is described. The proposed method is based on numerical results from a plane flow model, which takes into account water uptake by roots, and separates the phenomenon in two phases; the length of each phase depends on the duration of the irrigation and the soil. The empirical relationships, an exponential for the stage of the infiltration and a polynomial for the stage after the end of the irrigation, are only time dependent in order to achieve simplicity. Five statistical criteria were used to evaluate the quality of the method's results: average error (AE), root mean square error (RMSE), root mean square (RMS), modeling efficiency (EF) and coefficient of residual mass (CRM), in combination with goodness of fit, R-2. The agreement between the numerical results and the values calculated by the empirical relationships was very satisfactory, showing that the combined use of an exponential and a polynomial empirical relationship can reasonably be used to calculate the vertical movement of the wetting front through the soil profile.