A Comparison of Possible Model and Parameter Errors Associated with Solute Retardation in Groundwater Transport

L. G. Langley
William F. McTernan

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DOI: 10.2190/LAEY-QV64-LLFP-ANE3

Abstract

Groundwater solute transport models were developed which compared linear to one type of non-linear adsorption. Most traditional transport simulations rely upon linear adsorption in the form of solute retardance. While generally held to be appropriate at low solute concentrations, linear approximations are inadequate for some other applications. The subject work addressed this model uncertainty by comparing simulations completed assuming that Freundlich adsorption was appropriate with those developed under linear assumptions. A non-linear retardance equation was derived. Solute concentration is an equation variable rather than a constant and its estimation becomes critical in accurately defining transport times and distances. Errors associated with the selection of linear adsorption when non-linear retardation more appropriatedly applied ranged to 18.5 percent at low solute concentrations with variations in the Freundlich exponent. Error values approaching 13 percent were associated with solute concentration variation, while uncertainty in selecting the partition coefficient accounted for less than 7 percent.

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