Modeling two-dimensional infiltration with constant and time-variable water depth

Abstract

Water infiltration is simulated by obtaining the time infiltrated depth evolution and humidity profiles with the numerical solution of the two-dimensional Richards' equation. The contact time hypothesis is accepted in this study and used to apply a unique form on time of the water depth evolution in the solution domain (furrow), as boundary condition. The specific form of such evolution in time was obtained from results reported in the literature based on the internal numerical full coupling of the Saint-Venant and Richards' equations in border irrigation. Moreover, the equivalent hydraulic area between the border and the furrow was achieved by scaling the values of water depth. The analysis was made for three contrasting soil textures, and the comparison was done by computing the root mean square error (RMSE) indicator. The comparison was performed from the selection of five finite element meshes with different densities to discretize the solution domain of the two-dimensional Richards' equation, combined with several time steps. Finally, a comparison was made between infiltrated depth evolution calculated with a constant water depth in the furrow to the one proposed in this work, finding important differences between both approaches. To expand the scope of this study and for a fuller exploration of the subject, the results were compared with results obtained by applying the HYDRUS-2D software. The results confirm that it is important to consider an internal full coupling of the Saint-Venant and Richardś equations to improve furrow irrigation simulations.