Alain Dassargues - Hydrogeology: Groundwater Science and Engineering
CRC, 2019
pdf, 493 pages, english
ISBN-13: 978-1-4987-4400-3
One might wonder whether we need yet another hydrogeology textbook. Before we express our opinion on this, let us evaluate what this new book has to offer. Written for an undergraduate and graduate audience, it brings together both the science and the engineering of hydrogeology. The author draws on his more than 30 years of experience as a scientist and engineer, but especially as a lecturer in courses on hydrogeology and groundwater modeling. As a professor in hydrogeology and environmental geology at the University of Liège in Belgium and part-time professor at KU Leuven (1995–2012), his extensive teaching experience has clearly shaped this highly accessible text. The book covers a wide range of topics, from the basics of groundwater occurrence and flow (Chapters 1–4 and 9) to conductivity measurements (Chapter 5), land subsidence (Chapter 6), chemistry and contaminant transport (Chapters 7–10), heat transfer (Chapter 11), and modeling (Chapters 12 and 13).
The preamble to Chapter 1 sets out the philosophy of the author for the science and engineering of groundwater, which has to serve modern approaches such as, for example, the water-energy-food nexus for managing our water resources. Definitions are provided for hydrogeology and groundwater. For the latter, a contemporary definition of "water underground in pore spaces and fractures” is used. This deviates from the classical definition of "subsurface water beneath the water table,” which was already recognized as a limitation by Freeze and Cherry (1979), since the "study of groundwater must rest on an understanding of the subsurface water regime in a broader sense.” Chapter 2 presents a comprehensive overview of the hydrological cycle, including sections on evapotranspiration, recharge, and baseflow estimation methods. Chapter 3 elaborates the basic terminology of the science of groundwater and its occurrence in different geological environments. Next, Chapter 4 details the main laws and concepts of saturated groundwater flow. The book follows a mathematical and quantitative presentation approach, which is evident in this chapter from the very clear step-by-step derivation of the groundwater flow equations for steady and transient state in two and three dimensions for confined and unconfined conditions. Remarkable is the absence of the typical discussion in hydrogeology textbooks of Tothian groundwater flow systems. Instead, a strong warning is issued that the analytical approaches to calculate flownets "are of limited interest and can even be misleading” because the water table is often prescribed and isotropic-homogeneous conditions are assumed (see also Bresciani et al. 2016). Chapter 5, "Hydraulic Conductivity Measurements,” is one of the chapters that stands out in this textbook. With 47 pages, this chapter provides an excellent overview of the typical laboratory, slug, and pumping tests. However, it also contains a section on less well-known methods, including the use of air permeameter measurements on outcrops or coring material. Chapter 6 is a succinct and interesting summary of the coupling of geomechanics and groundwater flow, describing the physical relationships between land subsidence and pumping. It also illustrates this appropriately through five case studies of sinking cities. Chapter 7 is a solid "Introduction to Groundwater Quality and Hydrochemistry,” as its title suggests. In addition, it also discusses groundwater quality standards and sampling and monitoring strategies. Chapter 8 is the second highlight of this book. With 88 pages and 228 references, it is an outstanding primer on contaminant transport. It presents and discusses the physical and chemical processes affecting solutes in groundwater, while solute transport equations are rigorously developed. Other sections expand on non-aqueous phase liquid (NAPL) transport, remediation, tracer tests, transport and residence times, the use of isotopes and environmental tracers, and, finally, vulnerability and protection of groundwater. Chapter 9 concisely discusses flow and transport processes in partially saturated media. The corresponding equations are explained in detail. Similarly, Chapter 10 on "Salinization and Density Dependent Groundwater Flow and Transport” also includes the formulation of the respective equations. Chapter 11 on "Heat Transfer in Aquifers and Shallow Geothermy” is a welcome extension of the standard hydrogeological topics generally presented in groundwater textbooks. The use of heat data, as available from new sensors, is strongly increasing in hydrogeology, such as in groundwater–surface water interaction studies and tracer tests. Heat-based methods should be a standard topic in current hydrogeology teaching and therefore in any hydrogeology textbook. Interestingly, the discussion on the use of heat for flux estimation is extended with a description of the characteristics of different shallow thermal energy storage systems. The importance is stressed by the author in stating: "More generally, the transition toward renewable energy and power supplies necessitates increasingly more projects involving the underground storage of gas (methane, hydrogen, compressed air, and CO2), water and heat. Hydrogeologists are key actors in these projects.” With its total of 114 pages and almost 300 references, the last two chapters (12 and 13) are the final highlight of this book. Those chapters clearly elevate this textbook. On the one side, they are beneficial for an introductory hydrogeology course, and on the other side they are also highly relevant for an advanced groundwater modeling course. Likewise, they will serve the professional with a reference guide on the different methods for groundwater flow and transport modeling. Chapter 12 discusses the purpose of modeling, conceptual model building, initial and boundary conditions, model design and data, calibration, validation, sensitivity analysis, and inverse modeling. Moreover, advanced topics of geostatistical modeling and probability, including multiple-point geostatistics and Bayesian learning, are outlined. In the last chapter, the author discusses the mathematical basis of different numerical techniques for modeling groundwater flow and transport. In addition to the standard finite-difference (MODFLOW) technique, he also explains the finite-element and finite-volume methods and the whole gamut of numerical methods for solute transport.
In a field in which researchers are becoming increasingly specialized, it is a rare feat to have a single-author text covering such a wide range of topics. The style of writing is therefore consistent throughout the book, which is especially apparent in the focus on quantification and the mathematical rigor. This makes the book relevant, not only to its intended audience of undergraduate and graduate students, but also to postgraduates and researchers from other disciplines as a broad introduction to the field of hydrogeology. Finally, its highly up-to-date literature provides us with a reference for years to come.
While the book is comprehensive, it is not complete. The author has made clear choices: groundwater biology, groundwater-dependent ecosystems, groundwater–surface water interaction, hydrogeophysics, and management hardly feature in this book. As an educational tool, its structured style and clear black-and-white figures make it very attractive. On the other hand, it lacks review questions and calculation examples. The book is available in hardback and e-book, and a version in French will be published soon.
To conclude, we return to the initial question: every new textbook on hydrogeology is a further marker of the development of the science and practice of hydrogeology. Although no single textbook can ever be complete, the diversity of texts makes the field of hydrogeology rich. These textbooks capture the expertise of decades of research and teaching. Therefore, they not only become a giant’s shoulder to stand on for a new generation of hydrogeologists, but above all they are a celebration of the steady progress in hydrogeological science.
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Дата: 15 сентября 2020
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