Treatment of parameter uncertainties in modeling contaminant transport in geologic media: stochastic models vs deterministic models with statistical parameter sampling

Conference · Tue Jan 01 00:00:00 EST 1985

OSTI ID:5538851

Gutjahr, A L; Bonano, E J; Cranwell, R M

The transport of dissolved species in porous media is of interest in many applications, one of them being the migration of radionuclides away from a geologic radioactive waste repository. When modeling this and other geologic transport processes, one is often faced with uncertainties due to lack of knowledge of point-to-point variations in parameters such as permeability, porosity, hydraulic head, and various geochemical parameters within the medium. In this paper we compare two different approaches that have been used to account for parameter uncertainties in modeling contaminant transport in ground water. One approach is to treat the varying parameters as spatially random fields and solve the appropriate stochastic equations for the mean quantities and the variance of their respective fluctuations. The other considers the varying parameters as random variables with a distribution of values (ideally described by a probability density function) and employs statistical sampling to select the input variables for a deterministic model to generate a distribution of output values. Using both modeling approaches we examine the effects of parameter variation on the concentration of a parent isotope at a chosen observation point. Statistical analysis of the distribution of output obtained with the coupled deterministic model/statistical sampling approach seems to indicate that the two approaches are not equivalent. Furthermore, it is also possible that the stochastic model is more conservative than the other approach. 3 refs., 7 figs., 1 tab.

• Research Organization: New Mexico Inst. of Mining and Technology, Socorro (USA). Dept. of Mathematics; Sandia National Labs., Albuquerque, NM (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5538851
• Report Number(s): SAND-83-2455C; CONF-8506124-1; ON: TI85012838
• Resource Relation: Conference: International symposium on the stochastic approach to subsurface flow, Montvillargenne, France, 2 Jun 1985
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
58 GEOSCIENCES
54 ENVIRONMENTAL SCIENCES
GROUND WATER
RADIONUCLIDE MIGRATION
MATHEMATICAL MODELS
DATA COVARIANCES
GEOLOGIC DEPOSITS
PERMEABILITY
POROSITY
POROUS MATERIALS
ENVIRONMENTAL TRANSPORT
HYDROGEN COMPOUNDS
MASS TRANSFER
MATERIALS
OXYGEN COMPOUNDS
WATER
053000* - Nuclear Fuels- Environmental Aspects
052002 - Nuclear Fuels- Waste Disposal & Storage
580100 - Geology & Hydrology- (-1989)
520301 - Environment
Aquatic- Radioactive Materials Monitoring & Transport- Water- (1987)