Groundwater Hydrology

Preface

Water is an essential commodity to mankind, and the largest avail­able source of fresh water lies underground. Increased demands for water have stimulated development of underground water supplies. Inevitably, when progress magnifies and adds new problems, efforts are increased to solve these problems. This is especially true for ground water. Methods for investigating the occurrence and movement of ground water have been improved, better means for extracting ground water have been developed, principles of conservation have beto estab­lished, and research of several types has contributed to a better under­standing of the subject. As a result, knowledge of ground water hy­drology, once veiled in mystery, has expanded rapidly in recent decades. Anticipating the ever-increasing use of ground water, it is reasonable to presume that such knowledge will grow at an even greater rate in the future.

My purpose in writing this book has been to present the funda­mentals of ground water hydrology in a manner understandable to those most concerned with such knowledge. Few men specialize in ground water hydrology, yet, because ground water is a major natural resource, it is important to students and professional men in a variety of fields. Chief among these are civil engineers (including specialists in hy­draulics, hydrology, sanitary engineering, soil mechanics, and water resources), geologists, and agricultural and irrigation engineers. Per­sonnel in charge of municipal and industrial water supplies often have a vital interest in ground water. Men indirectly concerned can be found in the fields of mining, petroleum engineering, forestry, public health, and law, among others. Although it is impossible to present a subject fitted to the requirements of such a diversity of interests, the common need of all is an understanding of the fundamental principles, methods, and problems encountered in the field as a whole. Thus, this book is an effort to make available a unified presentation of ground water hydrology.

This book presupposes only a background of mathematics through calculus and an elementary knowledge of geology. I believe previous instruction in fluid mechanics and hydrology to be desirable but not essential.

By emphasizing only fundamental considerations of ground water, I have tried to restrict the book to a practical size without impairing its scope. A consistent nomenclature has been adopted with clarity as the criterion, although equivalent well-established expressions are men­tioned to avoid confusion. Illustrative examples from field data have been minimized, mainly because of their ready availability elsewhere. Publications of the United States Geological Survey are extensive and contain a wealth of material collected from field investigations. Also, many state water resource agencies have published comprehensive re­ports of local ground water situations. For instructors using this book as a text, I recommend that data from these sources be presented in the form of illustrations and problems to supplement the text material.

The contents of the book are based on a broad interpretation of ground water hydrology in order to embrace all elements of ground water as a water supply source. The first six chapters cover the basic quantitative aspects of the subject, including use, occurrence, move­ment, hydraulics, water wells, and ground water levels. Chapter 7 presents ground water quality, a topic as important as ground water quantity, with emphasis on measures of water quality and interpreta­tion of water analyses. Chapter 8 is concerned with the conservation of ground water, expressed by safe yield, and maximum water develop­ment by conjunctive use with surface water. Methods for investigating ground water by surface and subsurface procedures are described in Chapters 9 and 10. Two important problems unique to ground water hydrology are artificial recharge and sea water intrusion; these are discussed in Chapters 11 and 12. Economic and legal considerations affect ground water development. Economic aspects are included in Chapter 8, and Chapter 13 provides an introduction to ground water rights, a subject of considerable interest in the last decade in the United States.  The final chapter contains a review of the various types of laboratory model and numerical analysis studies that have become val­uable ground water research tools. An appendix lists useful conversion factors and constants.

At the end of each chapter appears a list of references pertaining to the specific topic treated. The ground water literature is voluminous, and a comprehensive bibliography not only would be a major under­taking but also would serve little practical purpose except for research workers. Therefore, I have tried to select those references which ould be most helpful to the reader desiring more information on a given topic. For many readers the references listed will be sufficient; for others wishing to go further, they will serve only as a beginning. In­cluded in the references at the end of the first chapter are general references and a few foreign books.

Many persons have assisted me, directly and indirectly, in the preparation of this book, including my colleagues at the University of California, members of the California Department of Water Re­sources, and members of the United States Geological Survey. In Europe, help on special topics was generously given by several engi­neers and geologists. Questions and reaction of students guided me in the presentation of many topics. Specific chapters were reviewed by F. B. Clendenen, S. T. Harding, and J. F. Poland. To all of these, and to my wife, I should like to acknowledge my indebtedness.

David Keith Todd

Berkeley, California March 1959