UC Davis

Estuarine beaches are unique, critical landscapes that serve a variety ecological, social, and shoreline protection purposes. They differ from ocean beaches in several ways, including their form and governing hydrodynamic processes. In San Francisco Bay, the historically widespread estuarine beaches that protected landward tidal marshes have been largely eliminated. One constructed beach that borders a tidal marsh, Marina Bay Beach in Richmond, was studied to examine how the morphology of this beach responds to a range of wave conditions. This study is motivated by a broader understanding of estuarine beaches in S.F. Bay, as an increasing number of nature-based sea-level rise adaptation strategies are constructed on the shoreline.

Through a combination of methods, including topographic transects, grain size analysis, particle tracking, wave data collection, remote sensing, and historical data analysis, the evolution of Marina Bay Beach on an annual and event-based timescale is described. In agreement with established theory of low-energy beaches, Marina Bay Beach exhibits quiescent stability in planform with isolated periods of morphological change driven by storm events wherein high-energy waves associated with high landward winds are coupled with high tides. These morphological changes include the formation of washover fans and could be leading Marina Bay Beach to transgress faster than sediment supply can replenish displaced mass. This dynamic could potentially create a future scenario of a breached barrier and lack of wave protection for the backbarrier marsh and eventually the shoreline trail.