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Research at San Francisco, CA
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Sediment flux through tidal channels
Tidal exchange and sediment transport are key drivers of change in estuaries. Resulting patterns of sediment deposition and erosion in tidal channels and marshes will largely dictate how an estuary responds to accelerating sea level rise. Particularly in the upper reaches of estuaries, rising sea level is expected to increase tidal range, tidal velocities, bottom shear and sediment transport. Modeling efforts are underway to predict how such increases will affect embayments and tributaries throughout the San Francisco Estuary but few data are available to test the robustness of these regional models on smaller scales.
The San Francisco Bay Reserve has recently begun measuring current velocities and suspended sediment concentration at a variety of locations in San Pablo Bay and Suisun Marsh. These data will be combined with meteorological data and optical measurements of turbidity to quantify sediment flux as a function of site, tidal forcing, wind forcing and depth. The overarching goal of this research is to produce a coherent set of data that can be used to test hypotheses about effects of rising sea level on critical processes such as tidal flow and sediment erosion, deposition, resuspension and accretion. Empirical measurements of sediment flux in tidal channels within and adjacent to the marsh will not only inform local management of these important habitats but will also provide an objective test of model predictions developed using data collected over much broader scales.
Vegetation change
San Francisco Bay Reserve is monitoring emergent vegetation along permanent transects spanning key habitat transitions (e.g., high marsh to uplands) to detect patterns in the distribution of plant species that differ in their requirements for water inundation, salinity and soil characteristics. Because sea level rise will alter spatial and temporal patterns of these environmental parameters, monitoring of vegetation will be an important aspect of marsh conservation and restoration as uplands become increasingly subject to inundation. These data will also be compared with salinities of porewater and the water column to better understand the importance of salinity as a driver of vegetation change.
Last Updated on: Monday, November 02, 2009
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