Field-scale solute transport modelling from horizontally variable local-scale transport parameters

Solute concentration and water content profiles were intensively measured in a 40x7 m2 plot to a depth of 1.0 m in an unsaturated sandy Andosol. A deterministic convection-dispersion model (CD) and stochastic model (SC) were used to simulate transport through the vadose zone. Comparison of the simulation results with the field experimental data showed that the CD model, with effective parameters Deff and veff described the mean concentration reasonably well. Failure of the SC model to suitably predict solute displacement does not negate the model’s validity. The failure only reflects the incorrect SC’s assumption that pore-scale dispersion has an insignificant impact on estimating mean concentration in this soil