Three multiple well pumping tests were performed in low-permeability Wisconsin-age weathered glacial till in Iowa, USA. A radial flow model based on the Dupuit assumptions and a radial and vertical flow model were used to estimate flow parameters. A numerical solution to the Dupuit equation and an analytical solution to the Dupuit equation using Jacob's correction gave similar parameter estimates but both showed a trend of increasing hydraulic conductivity with distance from the pumped well. The trend most likely indicated a weakness in the modeling. When a radial and vertical flow model was used to estimate parameters, the trend disappeared though the parameter estimates were similar. The field site consisted of 15 fully penetrating observation wells fanning out in three rays from a central fully penetrating pumping well. Of the four parameters (Kr, Kz, Sy, and Ss) estimated using the Neuman radial and vertical flow delayed yield model, Kzvaried the most between rays. The anisotropy ratio ( KzKr) varied from 0.05 to 5 among the three rays. Representative parameter values for the till can be summarized: Krand Kzare 4 × 10-4cm s-1, Syis 0.04, and Ssis 6 × 10-5cm-1. © 1993.
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