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WATER RESOURCES RESEARCH, VOL. 40, W12402, doi:10.1029/2003WR002998, 2004

Hydraulic tests in highly permeable aquifers

James J. Butler Jr.

Kansas Geological Survey, University of Kansas, Lawrence, Kansas, USA


Xiaoyong Zhan

Kansas Geological Survey, University of Kansas, Lawrence, Kansas, USA


Abstract

A semianalytical solution is presented for a mathematical model describing the flow of groundwater in response to a slug or pumping test in a highly permeable, confined aquifer. This solution, which is appropriate for wells of any degree of penetration and incorporates inertial mechanisms at both the test and observation wells, can be used to gain new insights into hydraulic tests in highly permeable settings. The oscillatory character of slug- and pumping-induced responses will vary considerably across a site, even in an essentially homogeneous formation, when wells of different radii, depths, and screen lengths are used. Thus variations in the oscillatory character of responses do not necessarily indicate variations in hydraulic conductivity (K). Existing models for slug tests in partially penetrating wells in high-K aquifers neglect the storage properties of the media. That assumption, however, appears reasonable for a wide range of common conditions. Unlike in less permeable formations, drawdown at an observation well in a high-K aquifer will be affected by head losses in the pumping well. Those losses, which affect the form of the pumping-induced oscillations, can be difficult to characterize. Thus analyses of observation-well drawdown should utilize data from the period after the oscillations have dissipated whenever possible. Although inertial mechanisms can have a large impact on early-time drawdown, that impact decreases rapidly with duration of pumping and distance to the observation well. Conventional methods that do not consider inertial mechanisms should therefore be viable options for the analysis of drawdown data at moderate to large times.

Received 30 December 2003; accepted 1 July 2004; published 4 December 2004.

Keywords: highly permeable aquifers; pumping tests; slug tests.

Index Terms: 1829 Hydrology: Groundwater hydrology; 1894 Hydrology: Instruments and techniques; 5114 Physical Properties of Rocks: Permeability and porosity.

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Citation: Butler, J. J., Jr., and X. Zhan (2004), Hydraulic tests in highly permeable aquifers, Water Resour. Res., 40, W12402, doi:10.1029/2003WR002998.