Modification of a method-of-characteristics solute-transport model to incorporate decay and equilibrium-controlled sorption or ion exchange
Water-Resources Investigations Report
89-4030
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Abstract
The U.S. Geological Survey computer model of two-dimensional solute transport and dispersion in ground water (Konikow and Bredehoeft, 1978) has been modified to incorporate the following types of chemical reactions: (1) first-order irreversible rate-reaction, such as radioactive decay; (2) reversible equilibrium-controlled sorption with linear, Freundlich, or Langmuir isotherms; and (3) reversible equilibrium-controlled ion exchange for monovalent or divalent ions. Numerical procedures are developed to incorporate these processes in the general solution scheme that uses method-of- characteristics with particle tracking for advection and finite-difference methods for dispersion. The first type of reaction is accounted for by an exponential decay term applied directly to the particle concentration. The second and third types of reactions are incorporated through a retardation factor, which is a function of concentration for nonlinear cases. The model is evaluated and verified by comparison with analytical solutions for linear sorption and decay, and by comparison with other numerical solutions for nonlinear sorption and ion exchange.
Suggested Citation
Goode, D., Konikow, L.F., 1989, Modification of a method-of-characteristics solute-transport model to incorporate decay and equilibrium-controlled sorption or ion exchange: U.S. Geological Survey Water-Resources Investigations Report 89-4030, vi, 65 p., https://doi.org/10.3133/wri894030.
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | Modification of a method-of-characteristics solute-transport model to incorporate decay and equilibrium-controlled sorption or ion exchange |
| Series title | Water-Resources Investigations Report |
| Series number | 89-4030 |
| DOI | 10.3133/wri894030 |
| Year Published | 1989 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Contributing office(s) | National Research Program - Eastern Branch |
| Description | vi, 65 p. |