Solute Transport in Heterogeneous Field

A laboratory study was conducted to study inert solute transport in a heterogeneous field. Twenty-one relatively undisturbed soil columns were sampled from a field plot, and chloride tracer tests were carried out in these soil columns. These tests provided local breakthrough curves at the scale of the individual soil columns. A large variability in convective transport in the study area was evidenced by the very rapid solute breakthrough at some soil columns, in contrast to the late arrival and slow passage of solute at others. The spatial variability of two measured transport parameters, velocity V and diffusion coefficient D, was analyzed. It was found that the spatial structure of these two transport parameters can be represented through a set of spherical semivariograms. Validation tests of the selected semivariograms showed that the selected semivariograms were theoretically consistent. The kriging technique, coupled with the simple advection-dispersion equation was used to predict solute concentration at a scale of the entire field. A validation test of this approach showed that kriging is a promising tool for the estimation of transport parameters and prediction of solute transport.