**Book Review:**Groundwater in Geologic Processes second edition (2006). Steven E. Ingebritsen, Ward E. Sanford, and Christopher E. Neuzil (eds).

Jeffrey M. McKenzie

Although the role of groundwater in various disparate geological fields has been studied for at least a century, it is only more recently that a more unified approach to the study of hydrogeology in large-scale geologic systems has emerged. Reasons for this shift include the advent of more transdisciplinary and interconnected theories within the earth sciences, the development of improved numerical models (and computational power) for studying larger scale three-dimensional problems, and advances in our theoretical and measurement abilities.

The book

**Groundwater in Geologic Processes**by Ingebritsen and Sanford (1998) played a key role in creating a unified view of groundwater in earth systems by developing a rigorous technical and theoretical framework for studying groundwater processes at large scales. The recently published Groundwater in Geologic Processes, 2nd edn. by Ingebritsen et al. (2006) further solidifies this book as an important teaching and reference tool in the research field. The book contains substantial new material and is much more than simply an update to the first edition. There is a new coauthor, Christopher Neuzil, and completely new chapters on compaction and diagenesis, metamorphism, and sub-sea hydrogeology. Additionally there are expanded discussions of the coupling of groundwater flow and deformation/compaction (i.e., hydromechanics).

The underlying theme of the book is the concept of coupled-flow, or to quote the authors, “everything is coupled.” For most shallow or low-temperature applications one assumes that groundwater has a constant density and viscosity, thereby simplifying much of the mathematics used to describe groundwater flow. In contrast, the flow of groundwater in a larger geologic setting requires a more comprehensive mathematical treatment as the movement of pore water is inextricably linked, or coupled, to properties of the water itself such as density and viscosity, and flow is driven not only by hydraulic pressure but also potentially by density variations resulting from thermal or solute gradients and/or by compaction.

Complicating this situation is the fact that although these gradients drive groundwater flow, their distribution is also controlled somewhat by groundwater flow, hence the concept of coupled flow. This situation is, in many ways, the primary driver and underpinning of the theory presented in the book.

The book is divided into two sections with a total of 13 chapters. The first section of the book focuses on the theory and development of mathematical formulations of coupled groundwater flow, starting with a primer on more basic hydrogeology, though cast at a crustal scale. The authors then develop mathematical formulations for coupling groundwater flow with individual ‘couplings’, including solute transport, heat transport, regional-scale flow and transport, and hydromechanical stresses. Each coupling is treated individually, although obviously in real-world settings these couplings can occur simultaneously (e.g., heat and solute transport).

The second section of the book presents the application of coupled flow in specific geologic settings. The settings include ore deposits (with a focus primarily on Mississippi Valley Type deposits), hydrocarbon maturation (i.e., optimal thermal conditions) and migration, geothermal processes (crustal heat flux, hydrogeology and magmatic bodies, and geysers), groundwater and earthquakes, and sub-sea hydrogeology. The sub-sea chapter was very interesting, and a nice addition to the 2nd edn of the book. The authors also discuss the role of groundwater in the formation and dissolution of evaporites and in metamorphism and diagenesis in sedimentary-basin environments.

The book is ideal for an

*upper-level or graduate course in hydrogeology*. For an undergraduate or first course in hydrogeology the book likely would be too advanced, though some instructors have used the book as supplemental class reading. The book includes four or five questions at the end of each chapter, and answer keys (restricted to instructors) for all of the questions are available through the publisher’s website (Cambridge University Press 2008). Two particular aspects of the book, in addition to the content and synthesis, will be appreciated by students.The authors provide a very readable treatment of potentially complex mathematical concepts that are required to describe coupled flow equations and dynamics, including extensive text that guides the reader through the objectives of the mathematical derivations. This will help students understand the purpose of the derivations and also provide them with examples of how to approach these types of equations. The book also has a bibliographic feel with numerous annotated citations that point readers towards additional subjects or case studies not covered in the text. There are six pages of symbol definitions and a 71-page reference list.

The book will also be an excellent resource for

*geoscientists*requiring supplemental information on groundwater processes. The extensive background sections in the opening chapters, which starts from first principles, should provide the detail required for those who are not groundwater specialists to gain insight into coupled-flow

**hydrogeology**theory and its application to geologic processes. For many environmental groundwater applications, the book would likely not be applicable. The authors provide only limited discussion of groundwater modeling techniques and aqueous geochemistry, although there are extensive references pointing readers to relevant material and both of these topics are well covered by other texts.

Overall, this book is an excellent text that covers coupled groundwater flow systems in a geologic process context. The first edition of the book has been established as a standard for the study of groundwater in geologic processes, and the second edition, with the new material, will solidify this position. This book is strongly recommended as a textbook for an upper-level or graduate level class in hydrogeology or as a reference for those interested in coupled groundwater flow systems in a geologic context.

**Source:**Hydrogeology Journal 2008, Volume 16, Number 7, Pages 1453-1454.

**Book Review:**Groundwater in Geologic Processes, second edition (2006).