Pump Test Analysis of Leaky Aquifer

The storage coefficient, transmissivity, and leakage factor are the useful parameters that assess the ground-water potential of a leaky aquifer. These parameters can be determined with the help of pump test data by using graphical as well as numerical methods. Graphical methods are not very reliable as these are subject to personal error of judgment. On the other hand, numerical methods void of such errors rely on evaluation of the well function either by numerical integration or through approximation valid for small values of the arguments. Due to lack of a full-range equation for the well function, an entire set of pump test data is rarely used in analysis. In this paper, a high-accuracy expression for the well function for a leaky artesian aquifer valid for entire range of arguments is developed. A methodology for determination of cutoff error is evolved. By using this approximated well function and minimizing the sum of a criterion function based on the concept of cutoff error, aquifer parameters can be determined.