Modeling of groundwater contaminant transport with nonlinear sorption
MetadataShow full item record
A new algorithm based on the split-operator approach, henceforth referred to as the mass balance (MB) approach, was evaluated for modeling groundwater contaminant transport with nonlinear sorption isotherms. Particularly, the performance and utility of the new algorithm were thoroughly investigated through comparison with two commonly used numerical approaches: the fast kinetic and lagged retardation factor algorithms. In addition, the new algorithm was compared with public domain software packages MT3D and PHREEQC through a set of bench mark contaminant transport problems. The results indicated that the accuracy of the MB method can be improved by specifying a smaller time step, and agreement with an approximated "exact" solution was achieved without excessive computation. Performance of the MB method was robust and not subject to numerical artifacts associated with the lagged retardation factor and fast kinetic methods. For the fast kinetic algorithm, it was necessary to specify the dimensionless sorption rate in the range of approximately 1 to 10 to provide a balance of comparable accuracy without producing "stiff" numerical behavior. In comparisons with MT3D and PHREEQC, the MB algorithm exhibited similar accuracy and efficiency to MT3D, but performed much better than PHREEQC in terms of both time efficiency and accuracy.