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Does centennial morphodynamic evolution lead to higher channel efficiency in San Pablo Bay, California?

Marine Geology

By:
,
Edited by:
P.L. Barnard, B.E. Jaffee, D.H. Schoellhamer
DOI: 10.1016/j.margeo.2013.06.020

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Abstract

Measured bathymetries on 30 year interval over the past 150 years show that San Pablo Bay experienced periods of considerable deposition followed by periods of net erosion. However, the main channel in San Pablo Bay has continuously narrowed. The underlying mechanisms and consequences of this tidal channel evolution are not well understood.


The central question of this study is whether tidal channels evolve towards a geometry that leads to more efficient hydraulic conveyance and sediment throughput. We applied a hydrodynamic process-based, numerical model (Delft3D), which was run on 5 San Pablo Bay bathymetries measured between 1856 and 1983.


Model results shows increasing energy dissipation levels for lower water flows leading to an approximately 15% lower efficiency in 1983 compared to 1856. During the same period the relative seaward sediment throughput through the San Pablo Bay main channel increased by 10%. A probable explanation is that San Pablo Bay is still affected by the excessive historic sediment supply. Sea level rise and Delta surface water area variations over 150 years have limited effect on the model results. With expected lower sediment concentrations in the watershed and less impact of wind waves due to erosion of the shallow flats, it is possible that energy dissipations levels will decrease again in future decades. Our study suggests that the morphodynamic adaptation time scale to excessive variations in sediment supply to estuaries may be on the order of centuries.

Geospatial Extents

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Does centennial morphodynamic evolution lead to higher channel efficiency in San Pablo Bay, California?
Series title:
Marine Geology
DOI:
10.1016/j.margeo.2013.06.020
Volume
345
Year Published:
2013
Language:
English
Publisher:
Elsevier
Contributing office(s):
Pacific Coastal and Marine Science Center
Description:
12 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Marine Geology
First page:
254
Last page:
265
Number of Pages:
12
Country:
United States
State:
California
Other Geospatial:
San Francisco Bay;San Pablo Bay