| heal.abstract |
The use of a plane flow model that takes into account evaporation and water extraction by roots, in order to analyze local infiltration from a surface line source of trickle irrigation is presented. The numerical results were the base for the development and testing of an empirical method to determine the depth of the wetted soil volume. The implementation of the mathematical model took place against 3 of the 12 USDA soil classes, Schaap and Leij (1998) using four water application rates for each one. The empirical methodology separates the irrigation process into two phases; the length of each one depends on the duration of the irrigation. The application of two simple, time-dependent empirical relationships, a power law for the stage of the infiltration and a polynomial for the stage after the end of the irrigation, had very satisfying results. Different statistical criteria were used to evaluate the quality of the method's results and average class values of the empirical coefficients were introduced, based on the corresponding confidence intervals. The agreement between the numerical results and the values calculated by the empirical relationships shows that the combined use of a power law and a polynomial empirical relationship could be used to calculate the vertical movement of the wetting front through the soil profile, in order to reduce the deep percolation losses. Copyright © 2005 John Wiley & Sons, Ltd. |
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