Two-Phase-Reactive Solute-Transport Simulation in Unsaturated Zone

Abstract

A numerical model is developed for the simulation of vertical unsteady-state, two-phase reactive solute-transport through the unsaturated zone. Advective transport is simulated using the method of characteristics, whereas diffusive-dispersive transport and interphase lateral diffusion are accounted for by an implicit finite-difference scheme. The soil moisture and flux distribution required for solving the solute-transport equation is obtained by solving Richards' equation. The model is verified by comparing model-simulated solute-transport with the results of an existing analytical solution. A good agreement is obtained for different sets of parameters. Also for very small dispersivity values no numerical dispersion is present. The proposed model is also used to simulate reported experimental data of a field experiment and shows adequate agreement.