Groundwater in the Environment: An Introduction
reviewed by David N. Lerner
GROUND WATER Vol. 45, No. 3 2007 pg. 253
What a pleasure this book is! If you teach introductory hydrogeology to students of any discipline, then this book, by Paul Younger, is the one to recommend to your students as precourse or supplementary reading. If they read it, you will not need to give any lectures explaining the context, concepts, or issues. You will be able to move straight to the things this book does not cover: equations, problem sets, case studies, and modeling exercises. So it is not a reference text for your bookshelf but a fluently and simply written overview of all the basic ideas (bar one) in hydrogeology.
And it is better than that. Younger´s book goes much further and covers new topics that are missing from most other textbooks. The 11 chapters cover the usual topics of occurrence, movement, quality, hazards, and modeling, but there are also chapters on sources of ground water, recharge processes, ground water discharge and catchment hydrology, ground water and fresh water ecology, ground water as a resource, and managing ground water systems.
Why do so few hydrogeology texts deal with the water balance, estimating recharge, and understanding discharge? Ground water is part of a larger flow system. Although permeable soils, aquifers, and aquitards provide the essential framework, recharge and discharge are the primary drivers of flow. They provide the input heads and discharge elevations that create ground water flow systems, which are then expressed in heads. The author has clearly and simply reviewed these issues, even recognizing the high rates of recharge in urban areas due to leaking water supply systems and septic disposal. He puts ground water in the overall catchment context and includes an interesting chapter on resources.
Younger summarizes the debunking of the ``safe yield´´ concept and goes on to describe some of the more sophisticated ground water–based water resource schemes in the United Kingdom. Despite its reputation as a wet country, the United Kingdom has much less than the world average of fresh water flow. There are very few private supplies, and a complex network of surface and ground water sources has been built up by the 26 water companies in Great Britain. This network enables conjunctive use, river augmentation, aquifer storage and recovery, and river compensation schemes that increase the overall yield from the limited flowing resources and storage. The thread on ground water resources continues through into a discussion on sustainability in the last chapter, on management.
Is this the first ground water textbook to devote adequate space to the role of ground water in supporting ecological systems? The author puts the record straight on wetlands, explaining how they are frequently supported by ground water discharge, are unlikely to be significant recharge areas, and are just as likely to generate floods as attenuate them. He explains basic ecological concepts and terminology and summarizes the recent recognition that ground water has its own specialized ecology. This runs from the ubiquitous and varied bacteria that are responsible for naturally attenuating so much pollution by biodegradation, through invertebrates living entirely in gravel aquifers, to larger species that seem to have a relaxed and predator-free life in karst.
This is a clearly written overview of almost all the important concepts in ground water science today; the one missing item for me is the concept of advective velocity and how it is very different from Darcy flux. The book includes plenty of nice touches, such as an excellent glossary, a chapter on the threats to ground water, some thought-provoking quotes, and examples from all over the world. A photo of ground water discharge on a beach is used to demonstrate that ground water discharge creates landforms, and that hydrogeologists do not stop, even on holiday. It is a relatively short book (257 pages plus references, glossary, and index), is not detailed, and has almost no equations or technical methods. Put it at the top of your courses´ reading lists!
Groundwater in the Environment: An Introduction, by Paul Younger (2006), is published by Blackwell Publishing (ISBN: 1405121432), 312 pages.