1 Introduction
This book provides the basic theory and tools needed to assist readers in understanding the responsible application of hydraulic testing methods to generate field‑scale hydrogeologic properties of groundwater systems. We describe methods used to conduct pumping tests, slug tests, and open borehole testing with packers, analyze test results, and use results to forecast future responses of groundwater systems to the extraction or injection of water. The material in this book is supported by extensive literature covering hydraulic testing. This includes newly published groundwater books and copies of original works available for free on the Groundwater Project website↗ (e.g., Groundwater Storage in Confined Aquifers, Wang, 2020; Transient Groundwater Hydraulics, Glover, 1974; Ground‑water Hydrology and Hydraulics, McWhorter & Sunada, 1977; Groundwater, Freeze & Cherry, 1979; Analysis and Evaluation of Pumping Test Data, Kruseman & de Ridder, 2000). Additional literature includes hydrogeology textbooks (e.g., Walton, 1970; Fetter, 2001; Schwartz & Zhang, 2003; Kasenow, 2001; Todd & Mayes, 2005; Weight, 2019), and numerous free federal, state, and local agency publications (e.g., Ground‑Water Hydraulics↗; Lohman, 1972). This book summarizes and condenses much of the material found in these references and provides detailed descriptions of field methods and hydraulic testing data analysis techniques.
The magnitude and extent of water level changes observed during hydraulic tests reflect the distribution of storage and transmission properties of the saturated material being tested. Hydrogeologists rely on hydraulic testing to evaluate well performance and to characterize the groundwater system including values of hydraulic conductivity, transmissivity, and storativity, as well as recharge sources, rates of leakage between geologic units, and the presence of local boundary conditions. Results of testing are used to predict the response of the groundwater system to changes in pumping and recharge and to assess contaminant movement.
Hydraulic tests can be conducted using a single pumping well, a pumping well with observation wells, and in open boreholes. Hydraulic tests usually include measuring changes in water levels over time. Water levels during some hydraulic tests reach steady state. Analysis of both transient and steady‑state water‑level data can yield estimates of hydrogeological properties. Hydraulic tests can be performed on aquifers that freely yield water to wells, and in lower permeability units such as aquitards and fractured rock systems. Testing can also include the pumping of multiple wells to investigate the interaction and interconnection of groundwater in complex geological settings.
Methods described in this book focus on the application of analytical solutions derived from governing equations, stated initial conditions, and boundary conditions. Once mastered, standard analytical techniques can be applied to a wide variety of hydraulic testing settings.
It is assumed the reader has a general knowledge of hydrogeology such as is covered in the Groundwater Project book Hydrogeologic Properties of Earth Materials and Groundwater Flow↗ (Woessner & Poeter, 2020). Additional hydrogeologic terms used in this text will be defined when introduced.