Manual of Applied Field Hydrogeology
Providing plenty of practical examples, this hands-on guide offers actual procedures and real-world decisions that will help you to stay leagues ahead in field hydrogeology.
TABLE OF CONTENTS Manual of Applied Field Hydrogeology
Chapter 3: Aquifer Properties
It is important to be able to translate the geology (Chapter 2), when it becomes saturated, into hydrogeology. The physical properties of geologic materials control the storativity and ability of fluids to move through them. Rock units that do not allow fluids through them become barriers to fluid flow and in turn change the direction of groundwater movement (Chapter 5). Other features such as fault zones may serve as conduits to fluid flow or act as barriers. In this chapter the physical properties of saturated geologic materials are presented to provide a basic understanding of aquifers, confining layers, and boundary conditions as a basis for understanding groundwater flow presented in Chapter 5. Boundaries are often determined directly through drilling (Chapter 8), pumping tests (Chapters 9 and 10), or geophysical methods (Chapter 4).
3.1 From the Surface to the Water Table
When precipitation hits the land surface, some water enters the soil horizon. This process is known as infiltration. Water that accumulates on the surface faster than it can infiltrate becomes runoff (Chapter 1, Figure 1.1). The rate at which water infiltrates or runs off is a function of the physical properties of the surficial soils. Some of the important factors appear to be thickness, clay content, moisture content, and intrinsic permeability of the soils' materials (Baldwin 1997). (Additional discussion on intrinsic permeability is given in Section 3.2). Infiltrating water that encounters soils with higher clay content tends to clog the pores, causing precipitation to mound up and run...
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