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Sediment transport patterns in the San Francisco Bay Coastal System from cross-validation of bedform asymmetry and modeled residual flux

Marine Geology

By:
, , , and
Edited by:
P.L. Barnard, B.E. Jaffee, and D.H. Schoellhamer
DOI: 10.1016/j.margeo.2012.10.011

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Abstract

The morphology of ~ 45,000 bedforms from 13 multibeam bathymetry surveys was used as a proxy for identifying net bedload sediment transport directions and pathways throughout the San Francisco Bay estuary and adjacent outer coast. The spatially-averaged shape asymmetry of the bedforms reveals distinct pathways of ebb and flood transport. Additionally, the region-wide, ebb-oriented asymmetry of 5% suggests net seaward-directed transport within the estuarine-coastal system, with significant seaward asymmetry at the mouth of San Francisco Bay (11%), through the northern reaches of the Bay (7–8%), and among the largest bedforms (21% for λ > 50 m). This general indication for the net transport of sand to the open coast strongly suggests that anthropogenic removal of sediment from the estuary, particularly along clearly defined seaward transport pathways, will limit the supply of sand to chronically eroding, open-coast beaches. The bedform asymmetry measurements significantly agree (up to ~ 76%) with modeled annual residual transport directions derived from a hydrodynamically-calibrated numerical model, and the orientation of adjacent, flow-sculpted seafloor features such as mega-flute structures, providing a comprehensive validation of the technique. The methods described in this paper to determine well-defined, cross-validated sediment transport pathways can be applied to estuarine-coastal systems globally where bedforms are present. The results can inform and improve regional sediment management practices to more efficiently utilize often limited sediment resources and mitigate current and future sediment supply-related impacts.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Sediment transport patterns in the San Francisco Bay Coastal System from cross-validation of bedform asymmetry and modeled residual flux
Series title:
Marine Geology
DOI:
10.1016/j.margeo.2012.10.011
Volume
345
Year Published:
2013
Language:
English
Publisher:
Elsevier
Contributing office(s):
Pacific Coastal and Marine Science Center
Description:
24 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Marine Geology
First page:
72
Last page:
95
Country:
United States
State:
California
Other Geospatial:
San Francisco Bay