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Tidal Oscillation of Sediment in San Pablo Bay
 The Cisnet study in San Pablo Bay made
measurements of SSC at several sites in northern San Francisco Bay. We combined
their results with ours to identify a process of sediment resuspension,
advection, and deposition that explained unusually high contaminant
concentrations at the mouths of the Petaluma River and Sonoma Creek. In
addition, deposition rates at adjacent marshes were higher than average, due to
the large sediment supply.
A conceptual model of fine sediment transport between a river and a bay was
then developed, based on these observations at two rivers feeding the same bay.
The conceptual model consists of river, transitional, and bay regimes. Within
the transitional regime, resuspension, advection, and deposition create a mass
of sediment that oscillates landward and seaward. While suspended, this
sediment mass forms an estuarine turbidity maximum. At slack tides this
sediment mass temporarily deposits on the bed, creating landward and seaward
deposits. Tidal excursion and slack tide deposition limit the range of the
sediment mass. Tidal variability of suspended-sediment concentration markedly
differs between the landward and seaward deposits, allowing interpretation of
the intratidal movement of the oscillating sediment mass. Application of this
model in suitable estuaries will assist in numerical model calibration as well
as in data interpretation. A similar model has been applied to some
larger-scale European estuaries, which bear a geometric resemblance to the
systems analyzed in this study.
Publication
Ganju, N.K., Schoellhamer, D.H., Warner, J.C., Barad, M.F., and
Schladow, S.G., 2004, Tidal oscillation of sediment between a river and a bay:
a conceptual model. Estuarine, Coastal and Shelf Science, 60, 81-90.
PDF File
Oscillating sediment mass in Petaluma River
Image: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team
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