An underrelaxed-modified Picard iteration scheme for simulation of 3D wetting pattern under drip irrigation using Richards’ equation on non-orthogonal grids

The knowledge of soil wetting pattern dimensions is one of the most important design parameters in drip irrigation systems. In this study, a three dimensional (3D) FORTRAN code based on finite volume approach is provided to investigate about wetting pattern characteristics under line source and point source drip irrigation systems. The coordinate transformation method is used to transform the governing equation from physical space to computational space. The model was validated with data obtained by HYDRUS 2D software. The results showed that the model is able to predict soil wetting pattern under both line source (2D model) and point source (3D model) irrigation systems in different soil textures. Eventually, the ability of this model for simulation of soil water redistribution process was investigated and acceptable results were obtained

Keywords:

Numerical model , Subsurface flow , Finite volume , trickle irrigation , Coordinate transformation