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Wind waves and sediments

Wind waves and sediments. Stephen Monismith Jeremy Bricker, Satoshi Inagaki, and Nicole Jones Stanford University. Calm. Windy. Supported by UPS Foundation and CALFED ERP. Sediment model (ca. 1999). TRIM3D - Casulli code as modifed by Ed Gross - calibrated for Winter/Spring 1995

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Wind waves and sediments

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  1. Wind waves and sediments Stephen Monismith Jeremy Bricker, Satoshi Inagaki, and Nicole Jones Stanford University Calm Windy Supported by UPS Foundation and CALFED ERP

  2. Sediment model (ca. 1999) • TRIM3D - Casulli code as modifed by Ed Gross - calibrated for Winter/Spring 1995 • Sediment model = 3D transport + standard cohesive sediment model (Inagaki and Bricker) • Use Krone’s (1962) values for sediment model parameters (Erodability etc.) • (for seds) Increase bed stress to min. drag coeff. value • (for seds) Include wave friction factor in bed stress calculation • Waves modeled using USACE Shore Protection Manual

  3. Effects of waves on computed concentrations (1 m below MLLW) Waves: H=0.6m T=2.8s (kg/m3) Tide Only

  4. Wave Estimation Shore Protection Manual (US Army Corps of Engineers, 1984)

  5. Wave Estimation Fetch Winds N + SF PORTS winds Wind from W

  6. Comparison: Measurement vs Prediction at Coyote Point (using SFO wind)

  7. Modeled sediment concentrations with and without winds

  8. Effect of more realistic waves From 4/19/1993, 6 days Suspended sediment concetration at 1m below MLLW hindcast with tides, winds, and waves (kg/m3)

  9. Two wave models Shore Protection SWAN (Bricker)

  10. Wind waves over shallow estuarine shoals Wind stress Whitecapping-affected layer z Steady surface boundary layer U(z) -dP/dx (tides) Steady bottom boundary layer Oscillatory bottom boundary layer

  11. Coyote Pt. observations

  12. Tidal stage and sea state at Coyote Point, June-July 2002

  13. Conditions at Coyote Point, June-July 2002

  14. Wind waves dramatically enhance bottom stress (Bricker et al J. Hyd. Eng. 2005) 10-1 10-2 No waves 10-3 currents dominate waves dominate Mean velocity/orbital velocity

  15. Effect on drag coefficient 15 x 10-3 10 x 10-3 5 x 10-3 “canonical”

  16. Wind waves in Suisun Bay Wind Jones and Monismith JPO 2008

  17. Breaking

  18. Turbulence due to breaking Breaking Bottom BL

  19. Langmuir cells (Franks Tract)

  20. Wind wave evolution Day

  21. Summary • Waves important to sediment dynamics on shoals • Waves modify bottom drag and thus flows and transport on shoals • Waves modify vertical turbulent mixing of sediments on shoals

  22. Needs • Validated wave model for SF Bay (SWAN?) • Wave data for whole bay • Spatially variable parameters for sediment model (Sedflume?) • Parametrization of effects of wave damping by soft muds • Compare sediment model (with waves) to both short and long term data sets

  23. The bottom (Elkhorn Slough)

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