Investigating the Use of Environmental Chemical Tracer Concentrations to Reduce the Uncertainty of Modeled Groundwater Flow and Transport in a Fractured Rock System
Presentation Type
Oral Presentation
Abstract/Artist Statement
Groundwater flow and transport within fractured rock systems has important implications for evaluating available subsurface water resources, the design of nuclear waste disposal systems, and identifying the role of groundwater in mountainous regions. The relative amount of water moving through a fractured zone compared to the surrounding rock matrix is often unknown. A principal uncertainty in simulating groundwater flow and solute transport within fractured rock is the characterization and explicit expression of the effective fracture parameters. Hydrogeologists have extensively utilized ‘apparent’ groundwater mean ages derived from environmental chemical tracer data to constrain subsurface flow and transport models. However, deriving a groundwater mean age from environmental tracer concentrations is ambiguous and uncertain. In this study we develop a 3D groundwater flow and solute transport simulation of the Bedrichov Tunnel in the Czech Republic to directly investigate the utility in utilizing environmental tracer concentrations, rather than inferred groundwater mean age, to constrain estimates of effective fractured rock parameters. The Bedrichov Tunnel simulation is on a portion of the tunnel that contains a single major fracture that has associated fracture discharge, stable isotope, and tritium measurements that span multiple years. Fracture and distributed tunnel discharge measurements, apparent ages of fracture discharge derived from environmental tracers, and the multiple environmental tracer concentrations are used to constrain the range of effective fracture and solid matrix parameters that control flow and transport to the Bedrichov Tunnel. We investigate the differences in estimated effective fracture parameter uncertainties when using environmental tracer concentrations and mean groundwater age to separately constrain the Bedrichov Tunnel groundwater flow and solute transport model. It is hypothesized that higher parameter uncertainties will be associated when groundwater age is utilized due to the bias and uncertainties associated with inferring a mean groundwater age from environmental tracers. This work will provide information on methods to assimilate and evaluate the information content of environmental tracer data in groundwater flow and transport models that can facilitate more accurate predictions of future subsurface hydrology conditions.
Mentor Name
Payton Gardner
Investigating the Use of Environmental Chemical Tracer Concentrations to Reduce the Uncertainty of Modeled Groundwater Flow and Transport in a Fractured Rock System
UC 330
Groundwater flow and transport within fractured rock systems has important implications for evaluating available subsurface water resources, the design of nuclear waste disposal systems, and identifying the role of groundwater in mountainous regions. The relative amount of water moving through a fractured zone compared to the surrounding rock matrix is often unknown. A principal uncertainty in simulating groundwater flow and solute transport within fractured rock is the characterization and explicit expression of the effective fracture parameters. Hydrogeologists have extensively utilized ‘apparent’ groundwater mean ages derived from environmental chemical tracer data to constrain subsurface flow and transport models. However, deriving a groundwater mean age from environmental tracer concentrations is ambiguous and uncertain. In this study we develop a 3D groundwater flow and solute transport simulation of the Bedrichov Tunnel in the Czech Republic to directly investigate the utility in utilizing environmental tracer concentrations, rather than inferred groundwater mean age, to constrain estimates of effective fractured rock parameters. The Bedrichov Tunnel simulation is on a portion of the tunnel that contains a single major fracture that has associated fracture discharge, stable isotope, and tritium measurements that span multiple years. Fracture and distributed tunnel discharge measurements, apparent ages of fracture discharge derived from environmental tracers, and the multiple environmental tracer concentrations are used to constrain the range of effective fracture and solid matrix parameters that control flow and transport to the Bedrichov Tunnel. We investigate the differences in estimated effective fracture parameter uncertainties when using environmental tracer concentrations and mean groundwater age to separately constrain the Bedrichov Tunnel groundwater flow and solute transport model. It is hypothesized that higher parameter uncertainties will be associated when groundwater age is utilized due to the bias and uncertainties associated with inferring a mean groundwater age from environmental tracers. This work will provide information on methods to assimilate and evaluate the information content of environmental tracer data in groundwater flow and transport models that can facilitate more accurate predictions of future subsurface hydrology conditions.