INFLUENCE OF DETERMINISTIC AND STOCHASTIC HYDRAULIC CONDUCTIVITY DISTRIBUTIONS ON PREFERENTIAL FLOW PATHWAYS IN A GLACIAL AQUIFER SYSTEM
MODPATH was used to track the pathways of 100 particles released as line sources at five depth intervals with documented 1,4-dioxane concentrations along the boundary of the contaminant source area. Pathways for 100 realizations of each ensemble were combined to produce cross sections showing the frequency of particles passing through individual model cells along transects spaced at 1 km intervals downgradient of the line source and adjacent to the hypothesized groundwater discharge location along the Huron River approximately 8 km from the line source. Results revealed dispersion of preferential flow pathways related to stochastic K variability proximal to the line source, followed by increasing channelization into preferential flow pathways related to the deterministic hydrostratigraphic framework farther downgradient. Differences in the spatial distribution of particle pathways observed between the ensembles of SIS and SGS ensembles increased with increasing travel distances. These results suggest that the relative influence of deterministic versus stochastic components of hybrid models depends upon the scale of the flow and transport problem under investigation.