Physical Hydrology, Third Edition

Book Preface

The goal of Physical Hydrology is to develop an understanding of the conceptual basis of the science of hydrology and to introduce the quantitative relations that implement that understanding in addressing scientific and water-resources-management questions. Previous editions apparently fulfilled a need for a comprehensive text in hydrology for upper-level undergraduates and graduate students, and I have been pleased with its reception by colleagues and students.

At the time of the first edition (1992), hydrology was still in the process of establishing itself as a distinct discipline with vital insights to fundamental and practical environmental problems (Eagleson et al. 1991), and the book was intended as a contribution to that process. By the time of the second edition (2002), much progress had been made in that regard, and my primary goals in revising Physical Hydrology were to incorporate significant advances in hydrologic science, to provide an explicit connection of that science to hydrologic modeling, and to make more complete and useful the treatment of the relation between scientific hydrology and water-resources management.

Hydrology is now well established as a distinct geoscience and, in the decade-plus since the second edition, there has been what seems to be exponential progress in the field. Much of this progress (which has been published in many dozens of different journals) is due to improvements in the ability to observe hydrologic variables and to assimilate and analyze large areally distributed data sets. But there has also been significant conceptual progress in understanding the ways in which the physics of micro-level processes relate (or don’t relate) to the larger scales dictated by hydrologic questions and data availability; in understanding the connections among hydrology, climate, ecosystems, soils, and geology; in understanding the nature and limitations of simulation models; and in developing new statistical techniques appropriate to the quantity and quality of hydrologic data.

It has been a daunting challenge to incorporate this progress in the third edition, and one that can be, at best, only partially met. In this attempt I have, in addition to making essential updates, made major changes in the organization and scope of the book: Former chapters 1–9 and portions of some appendices have been substantially reorganized into 10 chapters within three major sections, plus seven appendices, as described below.