Evaluating the Use of Environmental Tracers to Reduce Conceptual Model Uncertainty of Hydrogeologic Models

Author

Andrew Nordberg, University of Montana, Missoula
Jon Graham, University of Montana, Missoula
W. Payton Gardner, University of Montana, Missoula

Year of Award

2023

Document Type

Thesis

Degree Type

Master of Science (MS)

Degree Name

Geosciences

Department or School/College

Department of Geosciences

Committee Chair

W. Payton Gardner

Commitee Members

Jon Graham, Marco Maneta

Keywords

conceptual model uncertainty, groundwater simulation, environmental tracers

Subject Categories

Environmental Monitoring | Geology | Hydrology | Numerical Analysis and Scientific Computing

Abstract

Environmental tracer concentrations for CFC12, SF6, and tritium are used in groundwater simulations to assess the ability of these tracers to reduce conceptual model uncertainty due to uncertainty of a site’s geologic and recharge characterization. The resulting groundwater simulations are characterized by site-specific hydrologic and geologic data, and with coordination from a field team with years of knowledge about the site. First-order (conceptual) uncertainty is directly addressed by using a stochastic modeling approach for spatial variability of the proposed subsurface configurations. Simulations of environmental tracer concentrations and water levels are used to assess six alternate conceptual models that are based on three alternate geologic interpretations and two levels of spatial complexity in groundwater recharge. Our results show that water levels and tracers both provide unique information, but tracers enhance our ability to distinguish between models throughout multiple analyses. Tracers CFC12 and tritium show how simulating environmental tracer transport in groundwater is better than using water levels at testing alternate hydrogeologic conceptual models and reducing conceptual uncertainty between them.

Recommended Citation

Nordberg, Andrew; Graham, Jon; and Gardner, W. Payton, "Evaluating the Use of Environmental Tracers to Reduce Conceptual Model Uncertainty of Hydrogeologic Models" (2023). Graduate Student Theses, Dissertations, & Professional Papers. 12138.
https://scholarworks.umt.edu/etd/12138