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Kansas Geological Survey, Open-file Report 93-44

An Approximate Technique for Analysis of Slug Tests in Wells Screened Across the Water Table

by Z. Hyder, J. J. Butler, Jr., and C. D. McElwee

KGS Open File Report 93-44
Prepared for presentation at The American Geophysical Union Fall Meeting
December 1993


The slug test has become one of the most commonly used techniques for the in-situ estimation of hydraulic conductivity in unconfined flow systems. Although several approaches are available for analysis of data from wells screened below the water table, no methods have been developed for the case of a well screened across the water table, a common configuration at suspected sites of shallow groundwater contamination. An approximate approach for the analysis of data from such wells has been developed through an extension of the Bouwer and Rice model to the case in which the effective screen length changes during the course of the test. This extension, which employs the Dupuit-Forchheimer approximation for free surface flow, is able to reproduce some of the key features seen in field data from slug tests in wells screened across the water table. The most important of these features are that the duration of a slug test (and thus the conductivity estimate) is dependent on the magnitude of the initial displacement and that a log-linear displacement versus time plot is concave upward for an injection slug test and concave downward for a withdrawal slug test. Applications of this approximate model to field data are presented.

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Kansas Geological Survey, Geohydrology
Placed online May 8, 2015; originally released Dec. 1993
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