A coupled model for simulating water flow and solute transport in furrow irrigation

Abstract

A B S T R A C TFor optimal water and fertilizer management under furrow irrigation, it is important to understand the water and solute dynamics on the land surface and in the subsurface. An efficient mathematical tool is required to describe these dynamic processes. We propose a coupled model in which surface water flow and solute transport are described using the zero-inertia equation and the average cross-sectional convection-dispersion equation, respectively, while the two-dimensional Richards equation and the convection-dispersion equation are used to simulate water flow and solute transport in soils, respectively. Solutions are computed numerically using finite differences for surface water flow and finite volumes for solute transports in furrow. Subsurface water flow and solute transport equations are solved using the CHAIN_2D code. An iterative method is used to couple computations of surface and subsurface processes. Both surface and subsurface water flow and solute transport modules are coded in program subroutines and functions in the Intel FORTRAN environment. The coupled model was validated by comparing its simulation results with measured data. Results showed that simulated water front advances in the furrow and water contents in the soil agreed with the observations reasonably well. Good simulations can be achieved with a relatively fine temporal resolution. Numerical oscillations can be eliminated by adopting appropriate time steps. As compared with the traditional furrow irrigation model, the proposed model can better quantify soil water and solute dynamics by considering interactions between surface and subsurface water flow and solute transport processes. The proposed model can be used as a decision tool to design and manage furrow irrigation.

Moment Analysis for Modeling Soil Water Distribution in Furrow Irrigation: Variable vs. Constant Ponding Depths

“…The subsurface flow of water in this study was simulated using HYDRUS 2D/3D, previously shown to successfully simulate the two-dimensional subsurface water flow from irrigation furrows (e.g., Ebrahimian et al [10], Deb et al [11], Šimůnek et al [12], Liu et al [13], and Bristow et al [14]).…”

Modeling Two-Dimensional Infiltration with Constant and Time-Variable Water Depth

“…In the literature, studies on infiltration modeling in surface irrigation can be found; for example, Liu et al [2] proposed a coupled model in which surface water flow and solute transport are described using the zero-inertia equation and the average cross-sectional convection-dispersion equation, respectively, while the two-dimensional Richards' equation and the convection-dispersion equation are used to simulate water flow and solute transport in soils, respectively. Dong et al [3] developed a new numerical methodology based on the physical-based model of surface irrigation and the Monte Carlo simulation method to improve the modeling accuracy of surface irrigation performance at a field scale.…”