The successful use of mathematical models in studies of solute transport in soil is dependent on the accuracy to which the transport parameters involved in this process can be specified. In general, these parameters are determined by using nonlinear optimization techniques to fit theoretical models to experimental data obtained in miscible displacement experiments. The use, therefore, of high-performance software to evaluate these parameters appears to be advantageous since, in addition to consistency and the availability of pre-existing numerical routines, such software allows for the incorporation of new routines that are specifically tailored for the phenomena being simulated. The main objective of this study was to develop a MATLAB 6.5 computational routine to optimize the evaluation of retardation factor (R) and dispersion coefficient (D) from miscible displacement data. This routine was applied to experimental data from three miscible displacement studies of potassium transport in columns filled with an Oxisol of sandy phase, with the setting quality being assessed by the coefficient of accuracy. The proposal routine gave excellent results, reinforcing the consistency of the numerical method used, and indicating that this routine can contribute to the advancement of theoretical studies of the solute-water dynamics in unsaturated porous media.
breakthrough curves; computational routine; miscible displacement
