Abstract
The Theis equation is an important mathematical model used for analyzing drawdown data obtained from pumping tests to estimate aquifer parameters. Since the Theis model is a nonlinear equation, a complex graphical procedure is employed for fitting this equation to pump test data. This graphical method was originally proposed by Theis in the late 1930s, and since then, all the groundwater textbooks have included this fitting method. Over the past 90 years, every groundwater hydrologist has been trained to use this tedious procedure for estimating the values of aquifer transmissivity (T) and storage coefficient (S). Unfortunately, this mechanical procedure does not provide any intuition for understanding the inherent limitations in this manual fitting procedure. Furthermore, it does not provide an estimate for the parameter error. In this study, we employ the public domain coding platform Python to develop a script, namely, PyTheis, which can be used to simultaneously evaluate T and S values, and the error associated with these two parameters. We solve nine test problems to demonstrate the robustness of the Python script. The test problems include several published case studies that use real field data. Our tests show that the proposed Python script can efficiently solve a variety of pump test problems. The code can also be easily adapted to solve other hydrological problems that require nonlinear curve fitting routines.
Highlights
Groundwater pumping tests are routinely used to characterize two important aquifer properties—transmissivity (T) and storage coefficient (S)
We provide a simple open-source Python script that can fit the Theis model to pump test data to evaluate T and S values, and it can provide the estimate of error associated with these parameters
We present the details of a Python tool, namely, PyTheis, for evaluating the aquifer properties T and S, and the error associated with these two important hydrogeological parameters
Summary
Groundwater pumping tests are routinely used to characterize two important aquifer properties—transmissivity (T) and storage coefficient (S). The Theis model has been used to develop a variety of graphical procedures for estimating T and S values from drawdown data [1]. Kruseman and de Ridder [3] presented detailed graphical methods for analyzing pump test data for various types of aquifers. These graphical methods can be subjective and their results can have considerable variations [7,8,9,10]. McElwee [10] was one of the early studies that employed a least-squares method to analyze pump test data and they demonstrated that the automated technique provided better results than the traditional graphical fitting method
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
