The US Army Engineer District, San Francisco (SPN) and the Coastal Inlets Research Program conducted a pilot study to consider various placement locations for dredged material in vicinity of Noyo Harbor, CA. Approximately 30,000-40,000 cu yd/yr of beach-quality sediment is dredged from the navigation channel and the lower Noyo River, located on the north central California coast. The pilot study investigated several potential locations for placement of dredged sediments in one of two areas north of Noyo Bay. The investigation included field data collection and numerical modeling of near-field sediment transport and suspended sediment concentration during and after placement of the dredged sediments under combined wave and current conditions. The numerical model provided the technical information necessary for SPN and Noyo Harbor stakeholders to evaluate a location site that is economically feasible for the optimum sediment placement. Upon acceptance by the stakeholders and receipt of additional funds, a demonstration project will be conducted, and the Dredged Material Management Plan (DMMP) for Noyo Harbor will be updated to include a beneficial use site for nearshore placement.

The U.S. Army Corps of Engineers (USACE) San Francisco District (SPN) and Coastal Inlets Research Program (CIRP) are presently performing hydrodynamics, wave, and sediment transport numerical modeling study with the Coastal Modeling System (CMS) to evaluate a designated dredged-material placement site nearshore the beach erosion hot spot and onshore nourishment alternatives on Ocean Beach, California. Both model results and measurements reveal that tidal forcing is the main process in the nearshore area where the tidal current is predominantly along the shoreline. The calculated sediment transport shows more longshore movement than cross-shore shoreward the dredgedmaterial placement site. The model result also indicates significant sediment erosion at Ocean Beach.

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This paper presents the littoral sediment transport numerical modeling effort of simulating physical processes of high energy coastline, including inlet and coastal zone, at Ocean Beach and San Francisco Bight, California. The study site is dominated by strong tidal current and breaking wave-induced longshore current. The numerical models for waves, currents, water levels, and sediment transport are provided by the Coastal Modeling System developed at the US Army Engineer Research and Development Center. The water level, current, wave, sediment, and bathymetric data collected by the US Army Engineer District, San Francisco, and USGS in recent years are assembled and utilized for model calibration and validation. One main effort of the study is to demonstrate the beneficial use of dredged clean material from the ship channel maintenance for onshore beach nourishment and nearshore berm placement at Ocean Beach to remediate the chronicle erosion threatening the structural integrity of the adjacent Great Highway. The modeling effort is intended to guide future dredging activities, dredged material placement site selection and evaluation, beneficial use of dredged material for nearshore and onshore beach nourishment for shore and beach protection. The model result can support and improve decision making for regional and local sediment management, enhance cross-mission benefit, and ultimately reduce the dredging project life-cycle costs.