Laboratory Method for Estimating Solute Transport Parameters of Unsaturated Soils

Modeling the contaminant transport process in soils requires the solute transport parameters. Displacement experiments were carried out on soil columns (Sand – Silt – Clay) by injecting a solution of 0.8 M KCl in a steady state. Breakthrough curves are symmetrical, characteristics of an equilibrium solute transport. The hydrodynamic dispersion coefficients were estimated by optimizing the measured breakthrough curves with the analytical solution of the advection-dispersion equation (EAD) by the software CXTFIT. The validations of the results were performed by a direct simulation with Hydrus-1D model. The estimation results were assessed by calculating the mean square error RMSE, the average geometric error GMER and the non-parametric Mann-Whitney test. Statistical analysis showed the success of the used method to estimate the solute transport parameters of the studied soils.