An Assessment of Hydrologic Variability on

1. An Assessment of Hydrologic Variability on R. boylii Habitat Hydraulics using 2-Dimensional Hydrodynamic Modeling Sarah Yarnell1 Sarah Kupferberg2 Amy Lind3 Jeff Mount1 1Center for Watershed Sciences, University of California, Davis, CA 2Questa Engineering, Point Richmond, CA 3USDA Forest Service, Sierra Nevada Research Center, Davis, CA Acknowledgments * PIER program - CA Energy Commission and SWRCB * Pulsed Flow Program, Center for Aquatic Biology and Aquaculture, UC Davis

2. Research Questions Addressed with 2D Hydrodynamic Modeling How does R. boylii habitat suitability change throughout a river reach during a simulated pulsed flow event? • Spring pulsed flow event - egg habitat suitability • Aseasonal pulsed flow event - tadpole habitat suitability • Potential loss due to scour Why are some suitable habitats unoccupied? • Buffering Capacity; Habitat connectivity

3. Overview of Modeling Process • Survey 3D topography in field • Create bed topography file suitable for modeling • Create and refine calculation mesh • Run model (River2D) and calibrate to surveyed data – iterative process • Prediction

4. Modeling Study Sites

5. Modeling Study Sites South Fork Eel River North Fork Feather River

6. SF Eel River Calibration – 1.45 cms Velocity - reach Depth - reach Depth – egg locations Velocity – egg locations

7. SF Eel 2.5 cms SF Eel 2.5 cms SF Eel 1.45 cms SF Eel 1.45 cms NF Feather 15.7 cms NF Feather 15.7 cms NF Feather 4.4 cms NF Feather 4.4 cms Mean Error – Surveyed vs. Modeled Values Depth (m) Velocity (m/s) Mean +/- 2 SE • Mid-channel • Near-shore • Egg locations

8. Simulated Pulsed Flow Events • 3 simulations each site using River2D* - various low flows to a high spring or ‘boatable’ flow: • SF Eel River - NF Feather River • 1.0 to 7.0 cms - 4.4 to 30.0 cms • 1.45 to 7.0 - 7.1 to 30.0 • 2.0 to 7.0 - 10.0 to 30.0 • Evaluate each for potential loss • Potential for scour of eggs in spring • Potential for swept tadpoles in summer (aseasonal) *River2D (Steffler and Blackburn, 2002)

9. Habitat Suitability Criteria Suitable Egg Habitat = depth = 0.0 - 0.5m, velocity = 0.0 - 0.1 m/s ** Field Observations 2006 Suitable Tadpole Habitat = depth = 0.0 - 0.5m, velocity = 0.0 - 0.05 m/s ‘Tolerable’ Tadpole Habitat = depth = 0.0 - 0.5m, velocity = 0.0 - 0.1 m/s ** Experimental Results – Kupferberg et al 2007

10. Simulated Pulse Flow – Habitat Suitability Suitable Habitat = depth = 0.0 - 0.5m, velocity = 0.0 - 0.1 m/s

11. Simulated Pulse Flow – Habitat Suitability Suitable Habitat = depth = 0.0 - 0.5m, velocity = 0.0 - 0.1 m/s

12. Simulated Pulse Flow – Habitat Suitability Suitable Habitat = depth = 0.0 - 0.5m, velocity = 0.0 - 0.1 m/s

13. Simulated Pulse Flow – Habitat Suitability Suitable Habitat = depth = 0.0 - 0.5m, velocity = 0.0 - 0.1 m/s

14. Simulated Pulse Flow – Habitat Suitability Suitable Habitat = depth = 0.0 - 0.5m, velocity = 0.0 - 0.1 m/s

15. Simulated Pulse Flow – Habitat Suitability Suitable Habitat = depth = 0.0 - 0.5m, velocity = 0.0 - 0.1 m/s

16. Simulated Pulse Flow – Habitat Suitability Suitable Habitat = depth = 0.0 - 0.5m, velocity = 0.0 - 0.1 m/s

17. Simulated Pulse Flow – Habitat Suitability Suitable Habitat = depth = 0.0 - 0.5m, velocity = 0.0 - 0.1 m/s

18. Simulated Pulse Flow – Habitat Suitability Suitable Habitat = depth = 0.0 - 0.5m, velocity = 0.0 - 0.1 m/s

19. Simulated Pulse Flow – Habitat Suitability Suitable Habitat = depth = 0.0 - 0.5m, velocity = 0.0 - 0.1 m/s

20. Spring Pulsed Flow Event SF Eel Study Site NF Feather Study Site Less than 30% and 5% of initially suitable habitats remain suitable Associated Loss*: <0.1 m/s = ~10% cumulative loss of eggs; 0.1 - 0.4 m/s = ~45% cumulative loss; >0.4 m/s = ≥ 50% cumulative loss *Spring Rivers Ecological Sciences, 2003, FYLF studies for PG&E Pit River Hydroelectric Project

21. Aseasonal Pulsed Flow Event SF Eel Study Site NF Feather Study Site Greater than 30% and 75% of initially suitable habitats show high potential loss Associated Loss*: <0.1 m/s = ~ 25% loss of tadpoles; 0.1 - 0.25 m/s = ~ 50% loss; >0.25 m/s = ~ 75% loss *Kupferberg et al, 2007

22. Channel Morphology SF Eel Study Site NF Feather Study Site

23. Why are some suitable habitats unoccupied? • Buffering Capacity (refuge from velocity increases) • Connectivity between breeding and rearing habitats • Non-flow related factors (predation, cover, food availability, etc)

24. Buffering Capacity 1.45 to 7.0 cms 7.1 to 30.0 cms • Egg locations on SF Eel in sites with moderate velocity increases • Egg locations on NF Feather in sites with low velocity increases

25. Habitat Suitability as Flow Decreases Suitable Habitat = depth = 0.0 - 0.5m, velocity = 0.0 - 0.1 m/s

26. Habitat Suitability as Flow Decreases Suitable Habitat = depth = 0.0 - 0.5m, velocity = 0.0 - 0.1 m/s

27. Habitat Suitability as Flow Decreases Suitable Habitat = depth = 0.0 - 0.5m, velocity = 0.0 - 0.1 m/s

28. Habitat Suitability as Flow Decreases Suitable Habitat = depth = 0.0 - 0.5m, velocity = 0.0 - 0.1 m/s

29. Non-flow related factors Predation Shade Tree

30. Conclusions – Pulsed Flows • During simulated pulsed flows, small percentages of suitable breeding/rearing habitat remained suitable – “buffered” (SF Eel: 25-30%; NF Feather: <5%) • In the aseasonal pulse scenarios, large percentages of suitable rearing habitat became highly unsuitable with >75% potential tadpole loss (SF Eel: 30-45%; NF Feather: 75-90%)

31. Conclusions – Unoccupied Suitable Habitat • NF Feather - occupied breeding habitat overlapped with buffered habitats. • SF Eel - occupied breeding habitat overlapped with large areas of suitable tadpole rearing habitat • Non-flow factors (predation, food availability) important