Abstract
Vertical water infiltration in a heterogeneous-unsaturated flow field was generated through a small rainfall simulator. Solute transport characteristics with cation exchange reaction in this flow field were investigated. Temporal changes of electric conductivity and concentrations of cations and anions in the leachate accumulated at the bottom of the laboratory flow tank were observed. Macroscopic characteristics of solute transport were evaluated with a theoretical solution of the one-dimensional convective-dispersive equation. Dye tracing technique was used to investigate detailed behavior of the solute. Numerical simulation of the saturated-unsaturated infiltration analysis and convective-dispersive analysis were conducted to reproduce the lab-experiment. The heterogeneity of the water retention characteristics heavily affects solute movement. As such, power law decay of the concentration was clearly observed. Temporal change of cation concentration was difficult to reproduce using the linear adsorption model. However it can be reproduced using nonlinear adsorption isotherms of Freundlich type which considered the difference of the soil configuration.
