Simultaneous transport of solutes and water under transient unsaturated flow conditions

Theoretical and mathematical tools for analyzing transient one-dimensional (vertical) simultaneous transfer of noninteracting solute and water in unsaturated soils are developed. The transient diffusion convection equation is solved numerically by an approach that eliminates the effect of numerical dispersion. The numerical results are compared with some analytical solutions for steady water flow. For transient infiltration the results are compared with field data reported by Warrick et al. These comparisons indicate that the theory as well as the numerical method is reliable and can be used with confidence. Results are given for typical cases of infiltration, redistribution, and evaporation of water from the soil and their effect on dispersion coefficients and salt concentration profiles.

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