Foreword

Isotope hydrology uses isotopic measurements of water constituents for understanding of hydrology, and its most diverse applications are those directed at groundwater. Given the importance of this topic, the Groundwater Project (GW Project) has launched a series of books about isotopes, starting with Introduction to Isotopes and Environmental Tracers as Indicators of Groundwater Flow by Peter Cook, which will be followed by in-depth books. Stable Isotopes Hydrology by Roger Diamond is the first in depth book of the series.

This book concerns the most fundamental isotopes for groundwater studies, the non-radioactive elements of oxygen and deuterium in water molecules. The analysis of oxygen and deuterium give water a voice. Since the first use of these isotopes for research in the 1960s, their application has become routine in the pursuit of answers to many groundwater questions. Use of these isotopes, and a few others, became more feasible as water analysis laboratories became more common and the cost of running such tests ceased to be restrictive. Subsequent tests showed a number of successful applications resulting in increased use of the technique. Of the many isotopes useful in groundwater studies, the stable isotopes of water are the easiest to use because the required sample size is small and sampling methods are uncomplicated. In many circumstances, these water isotopes identify the geographic or temporal origin of the water, such as paleowater, or distinguish water zones of different origins in an aquifer. The small sample volume needed for analysis enables study of aquifer-aquitard systems to address questions relevant to water resources and contamination. Of the many techniques that have been added to the hydrogeologist’s toolbox over the past half century, the stable isotopes of water are amongst the most essential.

The author of this book, Roger Diamond, is a Senior Lecturer in Hydrogeology and Geochemistry at the University of Pretoria in South Africa. He has published extensively on a wide variety of applications of these isotopes in the southern part of Africa. Isotopic tools have proven to be especially effective in this region where there is much complexity in the hydrogeology and diversity in groundwater.

John Cherry, The Groundwater Project Leader

Guelph, Ontario, Canada, September 2022