Overview

One of the key pieces of information hydrogeologists need to solve problems in the field of hydrogeology is an understanding of the hydraulic properties of an aquifer. Many questions, such as, how long will it take water from the recharge area to reach a production well? How long will it take a contaminant to move from point A to point B? If this production well is activated, how far will the cone of depression reach? And how many other wells will be affected? What distribution of hydraulic properties should be assigned to the layers within this groundwater-flow model? In order to answer such questions, it is necessary to perform pumping tests (Chapter 9) and slug tests (Chapter 11) to measure the aquifer stress response in wells over time. This chapter begins by discussing the traditional analytical methods followed by a discussion of applications when the data do not fit the ideal case. Unfortunately, this is the more common scenario found in the field. It is beyond the scope of this chapter to provide an in-depth discussion of aquifer hydraulics, but it hoped that the presentation here will be useful. There are excellent discussions in Hantush (1964), Lohman (1979), Driscoll (1986), and Kruseman and deRidder (1991). Slug-test analytical methods are all presented in Chapter 11.

The Theis (1935) method is used first to evaluate time-drawdown data to see what they look like. There is a danger in some individuals immediately launching into a more complicated analytical method without first attempting...