BIDIMENSIONAL ANALYSIS OF INFILTRATION IN FURROW IRRIGATION

Abstract

A good understanding and modeling of the infiltration of water in soils is indispensable for a better design of irrigation methods. In flood irrigation the infiltration process may be considered an unidimensional problem; however, in furrow irrigation the problem is bidimensional and hence more complex and more difficult to model. In this study the bidimensional Richards equation was used and it was discretized whithin a regular grid covering the transversal area of a furrow by means of a finite differences scheme, and transformed into a pentadiagonal system of algebraic equations, which was solved by means of the iterative alternanting direction implicit (IADI) method. Once the basic mathematical model was developed, a computer program (INSUR-2D), which allows for the simulation of the infiltration process under an irrigation furrow of sinusoidal form was implemented. For computations, the characteristics of two soils were used. The correct consideration of the boundary condition at the dry part of the furrow, above the water level, is the main contribution of this work and allows for a correct understandig and modeling of the bidimensional infiltration process in the furrow area.