An in situ method to measure the longitudinal and transverse dispersion coefficients of solute transport in soil

SummaryThe knowledge of hydraulic conductivity and solute transport parameters of top-soil is important in a variety of fields and their measurement has been an interest in both theory and practice. In this paper we present an in situ method to measure the longitudinal and transverse dispersion coefficients of solute movement by modifying the double-ring infiltrometer into a triple-ring infiltrometer. Water flow in the apparatus is controlled in one dimension and solute movement in three dimensions. The solute transport parameters can be measured simultaneously with the hydraulic conductivity. Analytical solutions are derived to describe the solute movement, and field experiment was carried out to calculate the solute parameters in homogeneous soil using a simple method developed based on the analytical solutions. Simulating results using these estimated parameters predict the observed breakthrough curves reasonably well.