The Groundwater Project

Making Groundwater Understandable

Stable Isotope Hydrology

Book Cover for Stable Isotope Hydrology

Publication year: 2022
Number of pages: 102
ISBN: 978-1-77470-043-3
https://doi.org/10.21083/978-1-77470-043-3

Author:
Roger E. DiamondUniversity of Pretoria, South Africa

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Released: 10 December 2022

Book Description

The stable isotopes of hydrogen and oxygen in the water molecule can provide insights into the movement of water that chemistry and physical methods (water levels, etcetera) sometimes cannot. Whether in the atmosphere, biosphere, hydrosphere or geosphere, stable isotope compositions can be used to trace flows of water, sometimes quantitatively. These flows include the key steps such as evaporation, condensation, precipitation, recharge, transpiration and discharge at springs or boreholes.

The book begins by explaining what isotopes are, how they behave (fractionation, distillation, etc.) and how they are measured and reported in the delta notation. Then follow sections on calculation and significance of meteoric water lines, isotopic effects like the temperature or altitude effect, use of the deuterium excess parameter, and methods like mass balance and hydrograph separation. Several case studies are included to illustrate the application to problems like recharge estimation, leakage of surface water into groundwater and residence time of groundwater. Finally, there are some tips on water sampling for stable isotopes and some exercises with worked answers.

Contents

1 INTRODUCTION

2 ISOTOPES AND ISOTOPOLOGUES

3 MEASUREMENT AND STANDARDS

3.1 Mass Spectrometry

3.2 Laser Cavity Spectroscopy

4 ISOTOPE FRACTIONATION

4.1 Kinetic Fractionation

4.2 Equilibrium Fractionation

4.3 Fractionation and Enrichment Factors

4.4 Rayleigh Distillation

5 METEORIC WATER LINES

5.1 The Global Meteoric Water Line

5.2 Local Meteoric Water Lines

5.3 Calculation Of Meteoric Water Lines

5.3.1 Least Squares Regression
5.3.2 Reduced Major Axis Regression (RMA)

5.4 Weighted Regression Line Equations

6 STABLE ISOTOPE HYDROLOGY

6.1 Environmental Factors Affecting Water Isotopes (Isotope Effects)

6.1.1 The Temperature Effect
6.1.2 The Latitude Effect
6.1.3 The Continental Effect
6.1.4 The Altitude Effect
6.1.5 The Amount Effect

6.2 The Deuterium Excess

6.3 Event Variation

6.4 Mass Balance

6.5 Hydrograph Separation

6.6 Geothermal Waters

6.7 Paleowaters

6.8 Plant Waters

7 CASE STUDIES

7.1 Moisture Source Region

7.2 Recharge Area

7.3 Selective Recharge of Heavy Rains

7.4 Recharge Estimation

7.5 Piston Flow of Groundwater During a Storm

7.6 Groundwater Circulation and Age

7.7 Detecting Surface Water in Groundwater

7.8 Detecting Groundwater in Surface Water

7.9 Residence Time

8 WATER SAMPLING FOR STABLE ISOTOPE ANALYSIS

8.1 Practical Considerations

8.2 Precipitation

8.2.1 Spatial and Temporal Variation in Precipitation
8.2.2 Standard Daily or Cumulative Monthly Collectors

8.3 Surface Water

8.4 Groundwater

8.4.1 Natural Groundwater Sources: Springs and Seeps
8.4.2 Artificial Groundwater Sampling Points: Wells, Boreholes and Piezometers

9 FURTHER READING

10 WRAP-UP

11 EXERCISES

12 REFERENCES

13 EXERCISE SOLUTIONS

14 NOTATIONS

15 ABOUT THE AUTHOR

Interview with Author