Jump to Main Content
Simple derivation of the retardation equation and application to preferential flow and macrodispersion
- Bouwer, Herman
- Ground water 1991 v.29 no.1 pp. 41
- aqueous solutions, aquifers, chemical substances, dispersions, equations, porosity, preferential flow, saturated flow, sorption isotherms, unsaturated flow, vadose zone, water content
- The equation to calculate the retardation factor of sorbing chemicals moving in aqueous solution through aquifers and vadose zones is derived using a linear sorption isotherm and a mass-balance approach. The procedure is very simple and clearly illustrates the roles of porosity and water content, including those for saturated flow, unsaturated flow, and preferential flow or other systems with both mobile and immobile phases of the water. Applications of the equation to preferential flow in the vadose zone and macrodispersion in a layered aquifer are illustrated with numerical examples for hypothetical cases.