An EXCEL Tool for Teaching Theis Method of Estimating Aquifer Parameters

Hydraulic conductivity and storage coefficient of aquifers are often estimated from nonequilibrium well pumping test data using Theis method. This method requires matching a typecurve with time-drawdown data curve from a pumping well. Typically, this is done by using a type-curve plotted on a graph paper and the data curve plotted on another transparent graph paper, and superimposing and sliding the transparent one over the other to get the best possible match. This is a tedious approach. Though commercial software package programs are available to perform this analysis, they are not transparent enough for instructional purposes. This paper presents an EXCEL tool to solve Theis equation. This method requires only basic EXCEL skills such as data entry and handling plotting features of EXCEL effectively, for example plotting the data in log scales, changing color and transparency of plot area, and moving the plot. Macro programming is not required. Moreover, all operations in this method could be done within EXCEL. Most of the junior and senior students are fairly conversant using EXCEL. This will be an effective educational tool to teach and demonstrate Theis method to students. The proposed EXCEL method can also be used for different aquifer types i.e., confined, unconfined, and leaky with appropriate tabulated type-curve data.