Estimation of width and depth of the wetted soil volume under a surface emitter, considering root water-uptake and evaporation

A cylindrical flow model that describes local infiltration from a surface point source, by incorporating evaporation and water extraction by roots, was used to obtain numerical results that were the base for the development and testing of an empirical method for determining the surface and vertical components of the wetting front. The implementation of the mathematical model took place against two of the twelve USDA soil classes, using three water application rates for each one. The empirical methodology consisted of two simple, time dependent empirical relationships: a power law for the stage of the infiltration, which was applied in both directions and a polynomial for the stage after the end of the irrigation, applied only for the vertical component, to account for percolation losses. The statistical criteria used for the evaluation of the method showed good agreement between the numerical results and the values calculated by the empirical relationships. Based on the limited availability of necessary experimental data for detailed analysis of multidimensional transient infiltration, the introduction of such an empirical model, as a design tool for trickle irrigation systems, may contribute to the selection of the optimum application rate and lateral spacing.