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Geosciences LibreTexts

14.1: Introduction

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  • Learning Objectives

    After reading this chapter, completing the exercises within it, and answering the questions at the end, you should be able to:

    • Explain the concepts of porosity and permeability and the importance of these to groundwater storage and movement
    • Describe the relative porosities and permeabilities of some common geological materials
    • Define aquifers, aquitards, confining layers, and the differences between confined and unconfined aquifers
    • Explain the concepts of hydraulic head, the water table, potentiometric surface, and hydraulic gradient, and apply the Darcy equation for estimating groundwater flow
    • Describe the flow of groundwater from recharge areas to discharge areas
    • Describe the nature of groundwater flow in karst systems
    • Explain how wells are used to extract groundwater and the implications of over-pumping a well
    • Describe how observation wells are used to monitor groundwater levels and the importance of protecting groundwater resources
    • Distinguish between natural and anthropogenic contamination of groundwater
    • Describe some of the ways that groundwater can become contaminated, and how contamination can be minimized

    Figure 14.0.1 A spring flowing from a limestone cave on Quadra Island, B.C. [SE]

    As we saw in Chapter 13, fresh water makes up only 3% of the water on Earth. Approximately two-thirds of that is glacial ice and most of the rest is groundwater. We can’t live without water, and it’s easy to see that groundwater represents a critically important component of our water supply. Groundwater is not as easily accessed as surface water, but it is also not as easily contaminated as surface water. If more than 7 billion of us want to continue living comfortably here on Earth, we have to take great care of our groundwater and learn how to use it sustainably.