A stochastic model of solute transport in groundwater: Application to the Borden, Ontario, tracer test
- Univ. of Florida, Gainesville (United States)
- Massachusetts Inst. of Tech., Cambridge (United States)
Results from the Borden tracer test are used to evaluate the performance of the stochastic model developed by Graham and McLaughlin. The model assumes that spatial variations in hydraulic conductivity induce variations in a steady state velocity field which, in turn, induce variations in solute concentration. Analytical expressions for the unconditional ensemble moments of velocity are derived from the unconditional ensemble moments of log hydraulic conductivity. The velocity moments are related to the ensemble moments of concentration by a set of coupled partial differential equations. The dependent variables in these equations are the concentration mean and covariance and the velocity-concentration covariance. Macrodispersion is not assumed to be Fickian. The moment equations are solved with a dual-grid finite element algorithm. The nonstationary concentration covariances obtained from the finite element solution provide that information needed to condition estimates of velocity and concentration on a small set of concentration measurements. In the Borden application considered here conditioning is performed sequentially, at 85 days and at 260 days after the injection of a pulse of conservative tracer (chloride). The conditional mean concentration provides a better estimate of the true chloride concentration than the unconditional mean. The concentration variance and macrodispersive flux both decrease at conditioning times but gradually increase after the solute plume moves out of the sampling grid. The performance of the stochastic model, as indicated by an analysis of measurement residuals, is generally consistent with the model's own estimates of concentration uncertainty.
- OSTI ID:
- 5884900
- Journal Information:
- Water Resources Research; (United States), Journal Name: Water Resources Research; (United States) Vol. 27:6; ISSN 0043-1397; ISSN WRERA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
540220* -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (1990-)
58 GEOSCIENCES
580000 -- Geosciences
CANADA
DEVELOPED COUNTRIES
ENVIRONMENTAL TRANSPORT
FIELD TESTS
FLOW MODELS
FLUID FLOW
GROUND WATER
HYDRAULIC CONDUCTIVITY
HYDROGEN COMPOUNDS
HYDROLOGY
ISOTOPE APPLICATIONS
MASS TRANSFER
MATHEMATICAL MODELS
MONITORING
NORTH AMERICA
ONTARIO
OXYGEN COMPOUNDS
PERFORMANCE TESTING
PLUMES
POLLUTION
SITE CHARACTERIZATION
SOLUTES
STOCHASTIC PROCESSES
TESTING
TRACER TECHNIQUES
WATER
WATER POLLUTION