Fluxo tridimensional de água no solo: aplicação de volumes finitos na simulação da irrigação por gotejamento superficial

Abstract

In this work, a mathematical model was developed for the simulation of soil water movement under surface drip irrigation, being used the method of the finite volumes for the resolution of the partial differential equation of water flow in porous media. The soil water flow was treated three-dimensionally for the determination of your movement in the infiltration and redistribution phases. The model allows the determination dimensions and shape of the wetted bulb, of the partial and final dimension of the saturated disc radius and the determination of the saturated soil volume, when to deal about of isolated bulb. In the case of overlapping bulbs, the model allows the determination of the width and depth of the formed wetted strip, making possible the choice of the drippers spacing that better it is adapted to the conditions of the irrigation project and management. A computational program was developed with base in the model, and the obtained results were validated starting from comparisons with field data and results of simulations of other models. These comparisons demonstrated that the model presents reliable results and it can be used as tool for the designing of drip irrigation installations. The sensibility analysis accomplished starting from the variation of some parameters of the soil and of the emitter (initial moisture, saturated soil hydraulic conductivity and trickle discharge), it demonstrated that, with relationship to the final moisture inside of the bulb, the model is so much relatively sensitive to positive variations as negatives of those parameters.