Abstract: Aquifer testing of fractured rock aquifers has been undergoing a renaissance of new technologies based on hydrogeologic property of “hydraulic diffusivity”. Hydraulic diffusivity (α) is the property that governs propagation of a wave of drawdown or rebound through a geologic medium and equals:

One of the earliest applications of hydraulic diffusivity is the the Neuman and Witherspoon “ratio method”, which is designed to measure aquitard properties under very particular conditions. A second generation hydraulic diffusivity-based method is the Hsieh “cross-hole” technique, which is applicable to a wide range of hydrogeologic conditions, including both fractured rock and porous media aquifers. Multiple pumping tests and dozens of monitoring points allow the analysis of large amounts of data permitting definition of the ellipsoid of hydraulic conductivity, if applicable, or the “architecture” of the aquifer.

Convergent flow tracer tests can be conducted during many aquifer tests to cost-effectively define fracture porosity – a key parameter in understanding average linear groundwater velocity in fractured rock.

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