Concluding Statements

1. Catchment Scale Concluding Statements A Shortcourse on Isotope Hydrology Concluding Statements Prof. Jeff McDonnell Richardson Chair in Watershed Science Dept. of Forest Engineering Oregon State University

2. Hillslope Hydrology Isotope Basics Concluding Statements Related programs to consider in the future • The International Atomic Energy Agency (IAEA) • The UNESCO-IAEA Joint International Isotope Hydrology Program • The International Commission on Tracers • The International Association of Hydrological Sciences PUB Initiative • IGBP Biospheric Aspects of the Hydrological Cycle

3. Hillslope Hydrology Isotope Basics Concluding Statements Web sites to check out • IGBP http://www.igbp.kva.se/cgi-bin/php/frameset.php • GEWEX http://www.gewex.org/ • WCRP http://www.wmo.ch/web/wcrp/wcrp-home.html • JWP http://www.igbp.kva.se/cgi-bin/php/frameset.php • PUB http://www.cig.ensmp.fr/~iahs/PUBs/PUB-proposal-250602.htm • HELPhttp://www.nwl.ac.uk/ih/help/ • BAHC http://www.pik-potsdam.de/~bahc/ Check these out on the web

4. Hillslope Hydrology Isotope Basics Concluding Statements International journals where you will see papers that explore this

5. Isotope Basics Concluding Statements References - Textbooks • Clark, I. and Fritz, P. 1998. Environmental Isotopes in Hydrogeology. Lewis Publisher (w/ web-link) • Kendall, C. and McDonnell, J.J. (eds.), 1998. Isotope Tracers in Catchment Hydrology. Elsevier (w/ web-link) • Ferronsky, V. I. And Polyakov, V. A., 1982 . Environmental Isotopes in the Hydrosphere. Wiley & Sons. • Mazor, E., 1991. Applied Chemical and Isotopic Groundwater Hydrology. Open University Press.

6. Isotope Basics Concluding Statements References - Internet • USGS Isotope Interest Group Home Page (http://wwwcamnl.wr.usgs.gov/isoig/) • ISOGEOCHEM Web Page with an E-mail Discussion List in Stable Isotope Geochemistry (http://geology.uvm.edu/geowww/isogeochem.html)

7. Isotope Basics Concluding Statements Critical Thinking Is Inherent in Isotope Hydrology • Data are scant • Data are insufficient • Data are wrong • Hydrogeologic systems are open • Mathematical solutions are inexact

8. Hillslope Hydrology Isotope Basics Concluding Statements Isotope Hydrology Physical Chemical Isotopic Photo: Kevin McGuire Explicit solution of water and tracer mass balance

9. Catchment Scale Isotope Basics Concluding Statements Summary • Day 1 • Morning: Introduction, Isotope Geochemistry Basics • Afternoon: Isotope Geochemistry Basics ‘cont, Examples • Day 2 • Morning: Groundwater Surface Water Interaction, Hydrograph separation basics, time source separations, geographic source separations, practical issues • Afternoon: Processes explaining isotope evidence, groundwater ridging, transmissivity feedback, subsurface stormflow, saturation overland flow • Day 3 • Morning: Mean residence time computation • Afternoon: Stable isotopes in watershed models, mean residence time and model strcutures, two-box models with isotope time series, 3-box models and use of isotope tracers as soft data • Day 4 • Field Trip to Hydrohill or nearby research site

10. Isotope Basics Concluding Statements Why spend money on isotopes? • Isotopes can be powerful tools for testing hypotheses about sources of water and solutes. • While isotope analyses are not CHEAP, they can be much less expensive than being wrong. • In many cases, they are more useful “fingerprints” of waters or solute sources than other physical constituents because… Kendall (2001)

11. Isotope Basics Concluding Statements Isotopes are useful “fingerprints” because… • Many isotopes are relatively conservative in reactions with matrix materials. • Waters of different ages, recharge zones, hydrologic/geochemical history, etc., are often isotopically very distinctive. • If the water from one area gets to another area, it must be hydraulically and hydrologically possible for it to get there regardless of what the models predict. Kendall (2001)

12. Hillslope Hydrology Concluding Statements Why Spend Money On Isotopes? • Isotopes can be powerful tools for testing hypotheses about sources of waters and solutes. • In many cases they are more useful “fingerprints” of waters or solute sources than other physical constituents because: 1) Many Isotopes are relatively conservative in reactions with matrix materials. 2) Waters of different ages, recharge zones, hydrologic/geochemical history, ect., are often isotopically very distinctive. 3) If the water from one area gets to another area, it must be hydraulically and hydrologically possible for it to get there, regardless of what models predict. • While isotope analyses are not CHEAP, they can be much less expensive than being wrong.

13. Hillslope Hydrology Concluding Statements Why Do Environmental Hydrogeologists Under-utilize Isotopes? Possible Explanations: • Awkward terminology: one of the major obstacles to using isotopes is often the unfamiliar terminology, including: **compositions are in terms of δ (pronounced delta), not ppm. **units are 0/00 (spelled permil, per mil, or per mile. **values of isotopic compositions are often negative number. • Price? Not a problem. Many analyses are in the range of $50 to $150 per sample. • Complicated collection procedures? Not a problem: typically procedure are no more complicated than for chemical analyses. • Fear of the unknown.

14. Hillslope Hydrology Concluding Statements Fretwell’s Law “Warning! Stable isotope data may cause severe and contagious stomach upset if taken alone. To prevent upsetting reviewers’ stomachs and your own, take stable isotope data with a healthy dose of other hydrologic, geologic, and geochemical information. Then, you will find stable isotope data very beneficial.” (Marvin O. Fretwell, USGS, pers. Comm. 1983)

15. Concluding Statements Thank-you