MODELING SOIL WATER REDISTRIBUTION UNDER SURFACE DRIP IRRIGATION

ABSTRACT The main objective of this study was to develop a numerical model to simulate water distribution, and the shape of the wetted soil volume, resulting from a point source irrigation at the ground surface (dripper), given soil hydraulic properties and irrigation system parameters. The mathematical model was developed in Fortran 90 at the Department of Biosystems Engineering, at the Luiz de Queiroz College of Agriculture, ESALQ/USP. The computer program was structured to allow the user to input information such as: a) flow and transport related to soil properties, b) information on irrigation type, c) boundary conditions, d) simulation time, and e) water application time through irrigation. Data from another experiment carried out at the Department of Biosystems Engineering were used to validate the model. Model performance was evaluated based on Willmott concordance index, coefficient of efficiency, root mean square error, mean error, and maximum absolute error. Based on comparisons of the model deviations from the measured data and with other results reported in the literature, it was clear that the predictions of the proposed numerical model were very satisfactory.