Theis (1935) devised a method of analyzing data from a recovery test in a confined
aquifer in which residual drawdown, s', is plotted as a function of t/t', where t is the
time since pumping began and t' is the time since pumping stopped. In a confined
aquifer, the data from a recovery test are expected to fall on a straight line on a plot
of s' vs t/t'.
Figure 1. Theis (1935) residual drawdown solution for a fully penetrating
line source following a constant-rate pumping test in a confined aquifer.
Double-Porosity Aquifers
Figure 2. Pumping test in a double-porosity fractured aquifer with well
bore storage.
Fractured media are sometimes represented by double-porosity models in which the
fractures and matrix are treated as overlapping media. Dougherty and Babu (1984) and
Moench (1984) proposed models for the analysis of pumping tests in double-porosity systems
(Figure 2). Figure 3 compares the response for recovery tests in single- and
double-porosity media.
Figure 2. Recovery test in a double-porosity aquifer using Moench (1984)
solution for a double-porosity aquifer with slab-shaped blocks.
