Confined Aquifer Parameters from a Pump Test Near an Impermeable Boundary

A simple method is presented for determining aquifer transmissibility, $T$, and storativity, $S$, for a single well pumping in the vicinity of an impermeable barrier in a confined aquifer. The method makes use of the long‐term log‐linear relationship between time and drawdown of the piezometric surface at an observation well to determine $T$. The early time drawdown is then used for direct solution of $S$. The distance from the image well to the observation well, $r_2$, is determined using these estimates of $T$ and $S$ as well as the long‐term log‐linear drawdown. For the synthetic example used, $T$ and $S$ were determined within an error of 1% of their true values and $r_2$ was estimated within an error of 4.5% of the actual distance in the absence of errors in measured drawdown or time.