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Pacific Coastal and Marine Science Center

Coastal Processes

Open Coast

Open Coast

These scientific papers describe the sand and mud in the entire San Francisco Bay area, including the open coast.

Sediment transport in the San Francisco Bay Coastal System: an overview, Barnard, P.L., Schoellhamer, D.H., Jaffe, B.E., McKee, L.J., Marine Geology, 2013,

  • Overview of 100 years of sediment transport research in San Francisco Bay region
  • Summary of current understanding of physical processes in estuarine-coastal system
  • Identify key research questions to be addressed in the Special Issue volume

Bedrock geology of the San Francisco Bay area: a local sediment source for bay and coastal systems, Elder, W.P., Marine Geology, 2013,

  • Franciscan oceanic bedrock dominantly underlies San Francisco Bay watersheds
  • Transform tectonism led to volcanism, small basin development and displacement
  • Fine-grained sedimentary rocks provide most modern sediment in local watersheds

Comparison of sediment supply to San Francisco Bay from watersheds draining the Bay Area and the Central Valley of California, McKee, L.J., Lewicki, M., Schoellhamer, D.H., Ganju, N.K., Marine Geology, 2013,

  • Fluvial suspended sediment loads to the tidal zone of San Francisco Bay
  • Suspended sediment loads in Central Valley Rivers vary 21-fold between years
  • Suspended sediment loads in small tributaries vary 53-fold between years
  • Step-changes in sediment loads between wet and dry periods were observed
  • Small tributaries covering 5% of the watershed area, supply 61% of the sediment.

Adjustment of the San Francisco estuary and watershed to reducing sediment supply in the 20th century, Schoellhamer, D.H, Wright, S.A., Drexler, J.Z., Marine Geology, 2013,

  • A conceptual model of the effects of increasing then decreasing sediment supply
  • Adjustment to decreasing sediment supply propagated downstream in the 20th century
  • Rivers and upper estuary adjusted to increasing supply quicker than decreasing supply
  • Adjustment to increasing supply was slower in the lower estuary than upstream
  • Step adjustments throughout the system may occur now only during greater floods

Cross-validation of bedform asymmetry and modeled residual sediment flux to determine sediment transport patterns in the San Francisco Bay Coastal System, Barnard, P.L., Erikson, L.H., Elias, E., Dartnell, P., Marine Geology, 2013,

  • ~ 45,000 asymmetry measurements used to identify sediment transport directions
  • Results cross-validated against residual transport from a numerical model
  • Net seaward asymmetry also corroborated by flow-sculpted seafloor features
  • Approach useful to identify transport patterns in estuaries worldwide

Distribution of biologic, anthropogenic, and volcanic constituents as a proxy for sediment transport in the San Francisco Bay Coastal System, McGann, M., Erikson, L., Wan, E., Powell II, C., Maddocks, R.F., Marine Geology, 2013,

  • Sediment is transported from the Delta throughout the Bay and out to the marine realm
  • Marine biota are transported into the Bay to the farthest reaches of the estuary
  • The channel is a conduit for sediment movement and where scouring occurs
  • A multi-proxy use of sediment constituents identified sediment transport pathways

A Sr-Nd isotopic study of sand-sized sediment provenance and transport for the San Francisco Bay Coastal System, Rosenbauer, R.J., Foxgrover, A.C., Hein, J.R., Swarzenski, P.W., Marine Geology, 2013,

  • Isotopic tracers and REE used to examine sediment sources, sinks, and transport paths
  • Provenance determined by geographic distribution and statistical analyses
  • Sediment in SF Bay derived from varied sources and subject to mixing processes
  • Deciphered complex arrays of local and distal sediment sources through SF Bay System
  • Integrated multi-faceted approach for assessing provenance

Sand sources and transport pathways for the San Francisco Bay coastal system, based on X-ray diffraction mineralogy, Hein, J.R., Mizell, K., Barnard, P.L., Marine Geology, 2013,

  • XRD of bulk sand is a viable tool for provenance study
  • Cluster analysis of XRD spectra successfully groups source with sink
  • Mineralogical links define critical pathways
  • Detailed transport pathways can be inferred from the XRD data

Heavy mineral analysis for assessing the provenance of sandy sediment in the San Francisco Bay Coastal System, Wong, F.L., Woodrow, D.L., McGann, M., Marine Geology, 2013,

  • Most of the sand-sized sediment in San Francisco Bay is from Sierran sources
  • Franciscan terranes in San Francisco Bay contribute minor amounts of sand
  • Russian River sediment is not a contributor to sandy sediment in the Golden Gate area

Integration of bed characteristics, geochemical tracers, current measurements, and numerical modeling for assessing provenance of beach sand in the San Francisco Bay Coastal System, Barnard, P.L., Foxgrover, A.C., Elias, E.P.L., Erikson, L.H., Hein, J.R., McGann, M., Mizell, K., Rosenbauer, R.J., Swarzenski, P.W., Takesue, R.K., Wong, F.L., Woodrow, D.L., Marine Geology, 2013,

  • 9 provenance techniques are integrated to track sand in a coastal-estuarine system
  • Cross-validation results in robust model of beach-sized sand transport pathways
  • Sources and pathways highlight scale of anthropogenic influences in the system
  • Historical decline of primary sediment source linked to erosion of ocean beaches
  • Unique approach applicable for coastal-estuarine systems worldwide

Factors controlling floc settling velocity along a longitudinal estuarine transect, Manning, A.J., Schoellhamer, D.H., Marine Geology, 2013,

  • Presents new observations of floc properties throughout San Francisco Bay
  • Individual floc sizes & settling rates measured by a high resolution video system
  • Mass-weighted population mean settling velocity ranged from 0.5 to 10 mm/s
  • Macrofloc dynamics dominated San Pablo Bay; microfloc mass dominant in Central Bay


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