It's difficult to rate this book. It's not a bad book at all but it's an unusual book to me. In the beginning, I thought this could be a new kind of introductory book into theoretical and applied hydrogeology. But it's not. It can't be an introduction into "hydrogeology" (in a broad sense, and the book title should have told me) because it goes too fast and jumps to conclusions that are not self-intuitive for a beginner. For instance, in chapter 2, page 25, the fact that at the bottom of a well the "pressure is equals the weight density of water times the water column H" is only stated in a practical example that shows how incompressible water is. There is no previous paragraph which explains this fact and why it is so and terminology-wise weight density is for me specif weight. A quick refresh in physic mechanic would be necessary. In Chapter 2.6 (Measuring Hydraulic Head with Wells and Piezometers) the initial and mid part are a bit overcomplicated to understand to me - why not mentioning the height of water column in the well which is something everybody can see? - and perhaps with the example Nr. 20 at the end of the chapter. On the other side, the rest of same chapter is excellent in informing the reader that the water level in a newly installed piezometer is not the same as in the surroundings because the system needs to adjust itself. In chapter 3, the Darcy Law is explained but quickly again. Concerning "Heterogeneity and Anysotropy of the Hydraulic Conductivity" (Ch. 3.5), anysotropy and heterogeneity are almost synonyms in the chapter ("In a heterogeneous material the value of K varies spatially" - "Anysotropy implies that the value of K at a given location depends on directions" page 59). Instead, my understanding is that anysotropy (and isotropy) applies to hydraulic conductivity K only while heterogeneity applies to more parameters such as hydraulic conductivity K, porosity and so on. As a consequence, there are three different types of aquifers due to geology: homogeneous and isotrope, homogeneous and anysotrope, heterogeneous and anysotrope.
But the book as many more chapters (12) and most of the book is about applied hydrogeology from an engineer point of view (the author is an engineer) with experience in site remediation and groundwater pollution, I understand, and going through all the necessary chapters which cover (sometimes quickly) all relevant aspects of, yes, the book's title says it, "Groundwater Science" : so field exploration, quantitative hydrogeology, pumping test, hydrology, modelling, one can only name it. You want to know one or two ways how to measure a river flow for instance? You get it (Chapter 5.2, Surface Water Hydrology, page 132;). I was surprised to see also a generous chapter on slug test exclusively which was "distilled" (p.307, ch.8) from a famous book on the topic, state of the art so to say. This is in the end what made me consider what this book is all about: a distillation of all knowledge about and around groundwater. Or better, again, yes, Groundwater Science. And there is even a chapter (12), the last one, about "Subsurface Heat Flow and Geothermal Energy".
Each chapter of the book has got examples and exercises within the text and at the end of the chapter (with solutions for parts of the exercises at the end of the book for the latter). For time reasons, I could only check some of the problems in Chapter 2 and 3 and found the exercises ok but a bit too quickly explained and solved which was the same approach for the exercises within the text of the chapters.
With the book, comes a companion website which should be enriched with more materials in my opinion (for instance there are no videos, nor links, nor else for chapter 2, "Physical properties", including hydrostatic) and other chapters could be richer in content, too.
In the end, I think that this book is for an advanced beginner or a professional in need for a quick overview of a topic. Above all, the book is excellent at giving key reference texts and papers. The author knows probably everything relevant which has been done and written in the field and he is a guide to look at. However, the book is not always easy if the subject is completely new or, alternatively, one will tend to consider reading the reference material as well for a deeper understanding.
I gave three stars because of that. I cannot recommend this book to a total beginner (the classic Fetter's "Applied Hydrogeology" or Freeze et al. "Groundwater" are probably better), and an expert professional will probably rather consult a book on a specific topic (e.g. Batu's "Aquifer Hydraulics") or read fundamental scientific articles. The book is very good for expanding one's knowledge in a single attempt. After all it can easily be carried around and read through with real pleasure because it is graphically appealing, dense and concise.