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Wind waves and sediments Calm Stephen Monismith Jeremy Bricker, Satoshi Inagaki, and Nicole Jones Stanford University Windy Supported by UPS Foundation and CALFED ERP
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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
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(kg/m 3 ) Tide Only Waves: H=0.6m T=2.8s Effects of waves on computed concentrations (1 m below MLLW)
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Wave Estimation Shore Protection Manual (US Army Corps of Engineers, 1984)
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Wave Estimation Fetch SF PORTS winds Wind from W Winds + N
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Comparison: Measurement vs Prediction at Coyote Point (using SFO wind)
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Modeled sediment concentrations with and without winds
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Effect of more realistic waves (kg/m 3 ) From 4/19/1993, 6 days Suspended sediment concetration at 1m below MLLW hindcast with tides, winds, and waves
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Two wave models Shore Protection SWAN (Bricker)
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Wind waves over shallow estuarine shoals Steady bottom boundary layer Steady surface boundary layer Whitecapping-affected layer Wind stress z U(z) -dP/dx (tides) Oscillatory bottom boundary layer
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Coyote Pt. observations
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Tidal stage and sea state at Coyote Point, June-July 2002
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Conditions at Coyote Point, June-July 2002
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currents dominate waves dominate Wind waves dramatically enhance bottom stress (Bricker et al J. Hyd. Eng. 2005) 10 -2 10 -1 10 -3 Mean velocity/orbital velocity No waves
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Effect on drag coefficient 15 x 10 -3 10 x 10 -3 5 x 10 -3 “canonical”
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Wind waves in Suisun Bay Jones and Monismith JPO 2008 Wind
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Breaking
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Turbulence due to breaking Breaking Bottom BL
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Langmuir cells (Franks Tract)
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Wind wave evolution Day
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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
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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
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The bottom (Elkhorn Slough)
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