Modeling the Effects of Bed Drag Coefficient Variability under Wind Waves in South San Francisco Bay

This paper reports on the results of a study of the variation of shear stress and the bottom drag coefficient C(D) with sea state and currents at a shallow site in the San Francisco Bay. Via field experiments, the paper found that the model of Styles & Glenn (2002), though formulated to predict C(D) under ocean swell on the continental shelf, accurately predicted enhanced drag under wind waves in an estuary (Bricker et al., 2004). Knowing this, the paper applies the enhanced drag coefficient determined by Styles & Glenn to the estuarine circulation model TRIM-3D of Casulli & Cattani (1994) and Gross et al., (199), and use it to examine the effects of variable roughness on contaminant and sediment transport in South San Francisco Bay. The paper also investigates the importance of the wave model used in TRIM-3D, by comparing the results of Inagaki et al’s (2001) fetch and wave model with those of SWAN (Booj et al., 1999). The different wave models used in the paper generate noticeably different trends in sediment transport and roughness variation. Given a wave model, the paper finds that tidal stage in South San Francisco Bay is quite insensitive to variability in roughness, but tidally-averaged RMS and residual currents are quite sensitive (modified by about 10%), and channel-shoal asymmetry is enhanced. Along with this, the deep channel experiences more erosion of sediment, and the shoals more deposition. Furthermore, variable roughness extends the hydraulic residence time (inhibits flushing) south of the Dumbarton Bridge from 18 days to 19 days.

• Availability:
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• Corporate Authors:

  American Society of Civil Engineers

  1801 Alexander Bell Drive
  Reston, VA  United States  20191-4400
• Authors:
  • Bricker, Jeremy D
  • Inagaki, Satoshi
  • Monismith, Stephen G
• Conference:
  • Estuarine and Coastal Modeling. Eighth International Conference
  • Location: Monterey California, United States
  • Date: 2003-11-3 to 2003-11-5
• Publication Date: 2004

Language

• English

Media Info

• Media Type: Print
• Features: Figures; References; Tables;
• Pagination: pp 89-107
• Monograph Title: Estuarine and Coastal Modeling

Subject/Index Terms

• TRT Terms: Asymmetry; Hydraulics; Ocean waves; Roughness; Sediments; Stream channels; Tidal currents; Wave drag; Waves; Wind
• Geographic Terms: San Francisco Bay Area
• Subject Areas: Marine Transportation; Operations and Traffic Management;

Filing Info

• Accession Number: 01005954
• Record Type: Publication
• ISBN: 0784407347
• Files: TRIS
• Created Date: Oct 11 2005 11:36AM