Wave-Induced Erosion on a Tidal Marsh Shoreline in Corte Madera Bay

Liang, Han-Bin; Cuffe, C. Kelly; Florsheim, Joan; Goodwin, Peter; Abbe, Timothy; ,

Wave-Induced Erosion on a Tidal Marsh Shoreline in Corte Madera Bay

by Han-Bin Liang, Philip Williams and Associates, Ltd, San Francisco, United States,
C. Kelly Cuffe, Philip Williams and Associates, Ltd, San Francisco, United States,
Joan Florsheim, Philip Williams and Associates, Ltd, San Francisco, United States,
Peter Goodwin, Philip Williams and Associates, Ltd, San Francisco, United States,
Timothy Abbe, Philip Williams and Associates, Ltd, San Francisco, United States,

Document Type: Proceeding Paper

Part of: Coastal Engineering Considerations in Coastal Zone Management

Abstract:

One of the primary factors controlling the formation and configuration of a shoreline is the interaction of waves with the shore. A monitoring program was set up at the Corte Madera Ecological Reserve in order to monitor shoreline erosion of the marshfront over a period of four years, 1989-1992. Information regarding wave climate was recorded using a wave gage set up at a stationary position within the Corte Madera Bay, supplemented by wind data collected from a weather station set atop the Larkspur Ferry Terminal. The average erosion rate along the bayfront edge of the Corte Madera Ecological Reserve for the 4-year period is 1.1 m-year (3.6 ft/year). The source of wave energies within Corte Madera Bay was subdivided into five different sources: erosive and non-erosive wind waves, storm waves, ferry boat wakes, commercial vessel waves, and recreational boat waves. Erosive wind and storm waves constitute approximately 70% of the total erosive energy; erosive wind waves are considered to be those coming in from NNE to S directions. Ferry boat waves and commercial ship waves constitute approximately 18% and 12% of the total erosive energy, respectively. Contribution from recreational boat waves in insignificant. The study period coincides with a 6-year continuous drought in California and hence wind and storm energies may be significantly under-represented.

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