Two-Dimensional Coupled Model of Surface Water Flow and Solute Transport for Basin Fertigation

Abstract

A two-dimensional coupled model is proposed for the diffusion and channeling of both surface water and solute in all possible directions in basin fertigation. In the spatial discretization of the governing equation based on the unstructured triangle grid, the physical variables at grid interfaces are reconstructed by means of the grid center values. Then, the scalar-dissipation finite-volume method is used for the spatial discretization of the advection flux gradient vector. Meanwhile, the zero-dissipation finite-volume method is used to spatially discretize the water level gradient vector, diffusion vector, roughness vector, and infiltration vector. For the temporal scheme, the splitting method is implemented for the spatially discretized governing equation. The two-dimensional coupled model for surface water flow and solute transport in basin fertigation based on the scalar finite-volume method is proposed. The proposed model was validated based on observed data of three field experiments. Results show that the average relative errors between the simulated and observed data for the surface water advance and recession phases are from 3.8 to 4.7% and 10.4 to 12.7%, respectively. The water quantity conservation error is from 0.2 to 0.6%. The average relative error for the solute transport process between the simulated and observed data is less than 15%, and the solute quantity-conservation error is from 0.072 to 0.085%. At the same time, the convergence rate of simulation results is close to two-order. Therefore, the proposed model presents well-simulated performance.