HR: 0830h
AN: H11G-0922    [PDF]
TI: Freshwater-Saltwater Interface Configuration in a Heterogeneous Fractured Aquifer, Saturna Island, BC, Canada
AU: * Liteanu, E
EM: eliteanu@sfu.ca
AF: Simon Fraser University, Department of Earth Sciences, 8888 University Drive, Burnaby, BC V5A 1S6 Canada
AU: Allen, D M
EM: dallen@sfu.ca
AF: Simon Fraser University, Department of Earth Sciences, 8888 University Drive, Burnaby, BC V5A 1S6 Canada
AB: In coastal aquifers, heterogeneity due to variable fracturing introduces complexity to the configuration of the saltwater wedge and to chemical transport in the vicinity of the fresh water-salt water interfaces. Field geologic and structural mapping studies, in combination with the analysis of pumping tests and numerical simulations of flow and transport provide insight into the complexity of groundwater flow on the Gulf Islands in southwestern British Columbia, Canada. The islands consist of an alternating sequence of sandstone-dominant and mudstone-dominant formations, which were extensively fractured during numerous tectonic events. In contrast to typical layered porous media sedimentary aquifer systems, fine-grained rocks exhibit denser fracturing compared to coarse-grained rocks, and thus, mudstone-dominant layers and interbeds are thought to act as primary water-bearing units. Numerous pumping tests conducted in water supply wells suggest an equivalent porous media approach may be valid for representing permeability at a regional scale. A range of hydraulic conductivity (permeability) values was estimated for different geologic formations. These values were used as input in a series of models that reflect the heterogeneity of the aquifer owing to the variable fracturing of the layered aquifer system. Simulations were carried out using USGS SUTRA. Models simulations indicate that the magnitude of the permeability and the nature of layering exercise a major control of the magnitude and appearance of the freshwater-saltwater interface.
DE: 1829 Groundwater hydrology
SC: Hydrology [H]
MN: 2003 Fall Meeting