The applicability and scale dependence of aquifer testing methods: An integrated geophysical and hydrogeological characterization of two fractured systems.

摘要

Characterization of groundwater flow regimes in fractured bedrock aquifers on Southern Vancouver Island and the Gulf Islands of British Columbia are presently based on simple hydraulic testing methods and analytical models. Transmissivity, storativity and well capacity are derived from porous media (radial flow) analytical models that to do not fully represent the more complex boundary conditions inherent to fractured bedrock aquifers. In this study, geological, horizontal loop electromagnetic (HLEM) and borehole geophysical surveys were used to characterize the lithology and structure of two fractured bedrock aquifers of low primary porosity (limestone/argillite and sandstone/mudstone), and to identify hydrostratigraphic and hydrostructural units and the associated boundary conditions. The applicability of constant-discharge aquifer testing and slug testing for determining hydraulic parameters of fractured aquifers was investigated by evaluating quantitatively each testing method and its associated analytical models (radial, linear, double porosity, unconfined). Pressure derivative analysis of the hydraulic test data aided in identifying boundary conditions and component flow regimes, thereby enhancing the analytical procedures. (Abstract shortened by UMI.)