Numerical Comparison between Iterative and Noniterative Coupled Simulations for Surface Water Flow and Solute Transport with Unstructured Grid in Two-Dimensional Basin Fertigation

Abstract

Two-dimensional shallow water and advection-dispersion equations were applied to describe the surface water and solute transport processes in basin fertigation. Then the fully implicit temporal solution was constructed for all terms of the governing equations in triangular spatial grid and an iterative coupled model for basin fertigation was developed. Furthermore, the lower-upper matrix decomposition and symmetric Gauss-Seidel iteration solution methods were applied to construct a noniterative coupled model for basin fertigation. The convergence of the simulated results with decreasing time step was exhibited by the dam-break test. Furthermore, the performance comparison was analyzed on the basis of three basin fertigation experiments. The results show that the noniterative coupled model presents higher efficiency than and accuracy similar to the iterative coupled model. Thus, the noniterative coupled model was proposed for the management and design of basin fertigation. Finally, the noniterative coupled model was applied to obtain the diagram of the relationship between fertilizer application time and uniformity.