An Alternate Procedure for Analyzing Aquifer Tests Using the Theis Nonequilibrium Solution

Abstract

ABSTRACTA classical dimensional analysis of the Theis non‐equilibrium radial flow problem in a confined aquifer indicates that three dimensionless parameters are required for its representation. A new set of type curves based on three dimensionless parameters sT/Q, Qt/sr2, and S, is developed that can be employed to analyze aquifer test data by a curve‐matching procedure similar to the procedure used at present with two dimensionless variables.The possible advantages of the proposed new type curves are as follows: (1) The concave shape of the type curves along the x‐axis and particularly their point of vertical tangency permits curve matching with a minimum of ambiguity. Furthermore, the possibility of gross errors in the curve‐matching procedure is reduced because both type curves and the plot of field data use the same dimensionless parameter on the horizontal axis (x‐axis) so that the process of curve matching permits movement of the field curve only parallel to the vertical axis (y‐axis). (2) The shape of the proposed type curves provides a focus for aquifer‐test design‐that is, given very approximate estimates for the field parameters (T and S), the investigator can target a specific range for the field‐measured parameters for which curve matching will give best possible results.