1. Sediment transport Part 2: transport rate GEOL/CE/EEB 8601 Intro to Stream Restoration

2. Steps in analyzing sediment mobility 1.Determination of bed sediment characteristics: grain size distribution and texture 2.Will it move? Apply the Shields criterion (Shields diagram) 3.Estimation of bed-material transport rate 4.Understanding channel change: watershed, natural history and effects of imposed changes

3. Bedload: the movie! John Gaffney movie

4. Measuring bedload Helley-Smith sampler

5. Estimating bedload: Meyer-Peter & Müller K MPM = 8 in the original formulation; corrected to 4 by Wong & Parker (2005)

6. Form drag: Smith & McLean Indirect estimate of skin friction component of total stress h bf

7. Surface layer thickness L a  [1-2]D s90 fraction of material in the surface (active) layer in the ith size range = F i unit bedload transport rate in the i th size range = q bi Mixed sizes: definitions LaLa surface subsurface

8. Bedload vs suspension Fw ~ w’ (turbulence) Fw ~ bed (collisions, contact) suspension bedload Turbulent fluctuations w’ ~ u *  suspension if u * ~ settling vel w s

9. Bedload vs suspension Turbulent fluctuations w’ ~ u *  suspension if u * ~ settling vel w s Low Ro: turbulence > settling, suspension > bedload; sediment column is well mixed High Ro: turbulence < settling, bedload only; sediment transport confined to bed region

10. Bedforms

11. Bedform types: unidirectional flow ripples

12. Bedform types: unidirectional flow dunes

13. Bedform types: unidirectional flow plane bed

14. Bedform types: unidirectional flow antidunes

15. Bedform stability Southard (1991) 0.2 0.4 0.6 1.0 2.0

16. Bedform stability Southard (1991) 0.2 0.4 0.6 1.0 2.0

17. Bedform stability Southard (1991)

18. Bedform stability Southard (1991)

19. Bedform stability Southard (1991)

20. Bedforms - summary Ripples D < 0.5 mm < 0.3 m /h bf ~15 u  ~ u  c Dunes D > 0.2 mm h bf ~ 0.3 h /h bf >15 w s > u  >> u  c Upper plane bed D = any u  > w s Antidunes D = any Fr = U/  gh ~ 1

21. Can you explain this? Pigeon Roost Creek, Mississippi

22. Total load formulas Engelund-Hansen (1967) Brownlie (1981) r = hydraulic radius (Area/wetted perimeter K = 1 for lab data = 1.268 for field data

23. Bedload, suspended load, gravel and sand: adding fines to a gravel channel Establish steady-state slope profile with constant sediment feed Q s_coarse of a fixed coarse grain size, fixed water supply Q w Double Q s by adding an equal supply rate of a second finer grain size Measure new steady-state slope with the additive Q s_coarse + Q s_fine John Gaffney, Sarah Baumgardner, Kimberly Hill, Peter Wilcock

24. Adding fines to gravel channel John Gaffney, Sarah Baumgardner, Kimberly Hill, Peter Wilcock

25. D 50 coarse/D 50 fine Adding fines to gravel channel John Gaffney, Sarah Baumgardner, Kimberly Hill, Peter Wilcock

26. Adding fines to gravel channel John Gaffney, Sarah Baumgardner, Kimberly Hill, Peter Wilcock

27. Adding fines to gravel channel