1. Comparison of Tracer-Dilution and Current-Meter Measurements in a Small Gravel-Bed Stream, Little Lost Man Creek, California Gary W. Zellweger, Ronald J. Avanzino, and Kenneth E. Bencala (1989)

2. Purpose of Study Present and compare discharge measurements taken by two different methods: ◦ Tracer-dilution ◦ Current-meter Suggest how much discharge is flowing through the channel gravel

3. Background Current-meter technique preferred method to determine discharge Issues with current-meter method: ◦ Shallow depths o Rough bottom ◦ Flow through gravel o Discharge variation Continuous tracer-dilution methods can accommodate these factors

4. Can be used to calculate discharge at multiple sites Requirements: ◦ Tracer thoroughly mixed with stream ◦ Conservative tracer Tracer-Dilution Method

5. Can be used to calculate discharge at multiple sites Requirements: ◦ Tracer thoroughly mixed with stream ◦ Conservative tracer Tracer-Dilution Method …Plateau Concentration Tracer injection. Concentration rises to… Tracer injection. Concentration rises to…

6. Can be used to calculate discharge at multiple sites Requirements: ◦ Tracer thoroughly mixed with stream ◦ Conservative tracer Tracer-Dilution Method

7. Stream discharge below injection point: Q b = Q i (C i –C a ) (C b – C a ) Qb = Stream discharge below the injection point Qi = Injectant discharge Ci = Tracer concentration in injectant Ca = Tracer concentration in stream above injection point Cb = Tracer concentration in stream below injection point Tracer-Dilution Method

8. Site Description Little Lost Man Creek, CA Coastal 3 rd order stream ◦ 10 km length, N-NW flow ◦ Late summer flows 6 L/s ◦ Winter high flows 5,700 L/s Study reach = 330 m ◦ Poorly sorted, sand-boulder ◦ Gravel sediments > 1 m thick

9. Cl-Li pumped into stream continuously (8d) ◦ Chloride concentration = 170.1 g/L ◦ Daily injection rate = 37.29±.32 mL/min ◦ Mixing length = 300m Secondary injection on 7 th day ◦ Na, Cl, rhodamine WT (24 h) ◦ Mixing length = 25m Sampled hourly with automatic samplers ◦ 300m above ◦ 330m below Tracer-Dilution Method

10. Cl analysis: ◦ Filtered and stored w/o light, few months ◦ Dionex ion chromatograph Na analysis: ◦ Filtered and stored w/o light, few months ◦ Spectrophotometer Rhodamine WT analysis: ◦ Stored in glass bottle w/o light < 10d ◦ Fluorescence measured, Fluorometer Tracer-Dilution Method

11. Current-Meter Method Discharge measured with current meter ◦ Three sampling days ◦ Two measurements/site/day Modified 4 locations Depth and ave. velocity ◦ Measured at 17 to 25 vertical sections Stream discharge determined by summing flows through each measured subsection

12. Tracer (Chloride) Concentrations

13. Current-meter Discharge Data

14. Method Comparison

17. Discussion Calculated discharges: ◦ Current-meter 13.0 L/s ◦ Tracer (25m) 15.9 L/s ◦ Tracer (300m) 14.4 L/s ◦ Average 13.0 L/s

18. Discussion Gravel zone = 25% of channel flow Gravel moves in and out between the surface water and gravel zone Current-meter = surface flow only Tracer 300m = most mixing

19. Conclusion Water in gravel zone moves down channel as underflow ◦ Can be measureable Affects discharge measurements Tracer-dilution and current-meter methods can yield different values Tracer-dilution method yields different results over different stream lengths

20. Testing and Comparison of Four Ionic Tracers to Measure Stream Flow Loss by Multiple Tracer Injection Gary W. Zellweger (1994)

21. Purpose of Study Toxic metal transport, need to know ◦ Where stream is losing water ◦ How much water is being lost Calculate discharge for 4 tracers used in simultaneous multiple tracer dilution ◦ Li, Na, Cl, Br Define limitations of method

22. Site Description St. Kevin Gulch, CO 3 rd order stream ◦ Flat, wetlands source ◦ Summer flow =  10 L/s  pH ~3.6 in August Study reach = 570 m ◦ Upper stream = forested, steep, narrow ◦ Lower stream = smaller gradient, little vegetation, minimal hillslope

23. Study Description Tracer solution continuously injected at 5 wells ◦ Lithium chloride and sodium bromide in stream water Injection sites ~100m apart Parshall flumes installed, 4 sites

24. Parshall Flume

25. Results Only 3 injection sites operated at a time

26. Results

27. Results

28. Discussion Precision of 2% Discharge decreasing downstream (8%) More effective to use different tracers at each injection site All tracers were conservative in St. Kevin Gulch (116m reach) 4-18% difference in discharge measurements between flume and tracers

29. Evaluating the Reliability of the Stream Tracer Approach to Characterize Stream-Subsurface Water Exchange Judson W. Harvey, Brian J. Wagner and Kenneth E Bencala (1996)

30. Quantifying Hyporheic Interactions: An in-depth look at three studies Geology 230, CSUS, Spring 2013 Presented by Emily Siegel and Jessica Bean