HR: 1340h
AN: H33H-1713    [Abstracts]
TI: Simulating advective transport through locally refined grids
AU: * Mehl, S
AF: US Geological Survey, 3215 Marine St, Boulder, CO 80303, United States
AU: Dickinson, J
AF: US Geological Survey, 520 N Park Suite 221, Tucson, AZ 85719, United States
AU: Hanson, R
AF: US Geological Survey, 4165 Spruance Road, San Diego, CA 92101, United States
AU: Hill, M C
AF: US Geological Survey, 3215 Marine St, Boulder, CO 80303, United States
AB: Simulation of advective transport with particle tracking is an effective way to approximate contributing areas associated with pumping wells. Using a local-scale model embedded within a regional model improves representation of the hydraulic response due to pumping, and therefore, better representation of the particle trajectories. A consequence of this finer-scale representation near the pumping well is that particles may follow different trajectories than those produced using an unrefined grid. This further implies that failure to represent fine-scale flow features near pumping wells can cause an underestimation of the variability, and therefore, uncertainty, of particle trajectories tracked backward from the pumping well. This work uses new capabilities for tracking particles through locally refined grids to examine the effects of grid refinement and to investigate sensitivity relationships between hydraulic conductivity and porosity parameters and simulated particle termination location and timing. This information is used to assess why some particle trajectories are more sensitive than others and why hydraulic conductivity has greater control over particle trajectories than porosity. These issues are investigated using the shared-node local grid refinement method of MODFLOW-LGR and the particle tracking code, MODPATH. Due to abrupt changes in grid spacing at the interface between grids, a correction of the flows between the locally refined grids is required to simulate accurate particle trajectories. To determine sensitivity and uncertainty in particle termination locations and timing when using embedded models, a universal sensitivity analysis code, UCODE-2005 is used.
DE: 1847 Modeling
DE: 1873 Uncertainty assessment (3275)
SC: Hydrology [H]
MN: 2007 Fall Meeting