Foreword

This book describes the properties of earth materials that are relevant to groundwater flow and delineates the principles governing the flow of water through the Earth’s subsurface. As such, it provides the foundation for other GW-Project books by introducing basic concepts and terminology concerning groundwater occurrence and flow. It expands on Chapter 2 of the 1979 Freeze-Cherry book titled GROUNDWATER which provided the seed for the GW-Project. This book, like many of the GW-Project books, is layered by including locations where readers can link to boxes which provide deeper information such as equation derivations, analysis methods, and learning tools, among other items. However, the information in each book is complete without the supplemental links if the reader chooses not to pursue them. The materials presented here are supplemented by a GW-Project Learning Module titled: Conceptual and Visual Understanding of Hydraulic Head and Groundwater Flow. The Module is a stand-alone book that expands on the relationship between Darcy’s law and hydraulic head.

For a broad introduction to groundwater occurrence and flow, we recommend reading the GW-Project book titled “Groundwater in Our Water Cycle” because it provides a qualitative background for the quantitative coverage of groundwater flow in this book. The ‘water cycle’ book explains groundwater in our environment and presents groundwater problems faced by humanity and ecosystems, while this ‘physical principles’ book provides the fundamentals needed for the task of assessing and solving those problems.

This book was written by a groundwater scientist and engineer who taught a variety of introductory and advanced hydrogeology classes at the university level. They are specialists in field investigations, groundwater problem analysis, groundwater model development and computer simulation. Nine experts, who taught courses related to the topics presented herein, provided thorough reviews of this book to ensure its accuracy and high quality. Thus, the material in this book provides information that the world urgently needs to support better groundwater management and protection.

John Cherry, The Groundwater Project Leader
Guelph, Ontario, Canada, July 2020