Linking headland bypassing to the evolution of a spit and beach ridge system - Slocums River Embayment, Buzzards Bay, Massachusetts, USA

The northwestern Buzzards Bay shoreline in Massachusetts, USA is a complex system consisting of multiple headlands, dividing the coastline into several coastal cells containing tidal inlets and mixed-sediment beaches. While these compartments form (mostly) closed sediment cells during regular wave conditions, high energy events can generate sediment pulses past headlands. As a result, infrequent extreme events, like hurricanes, play a major role in the long-term evolution of this shoreline. The inlet of Slocums River is situated near the mouth of Buzzards Bay, between the two headlands of Barneys Joy Point and Mishaum Point. The western side of the inlet is characterized by a mixed sand-gravel beach, a sandy spit and a series of beach ridges. This study aims to link headland bypassing volumes and frequencies to the spit and beach ridge evolution near Slocums River inlet, closing the gap between the time scales of headland bypassing (storm-induced, hours to days) and spit and beach ridge evolution (years to centuries).  We developed two numerical models in Delft3D, a large-scale grid to model the headland bypassing on shorter time scales, and a finer grid to model the longer term morphodynamic evolution inside the embayment, using a morphological acceleration factor. The long-term spit and beach ridge evolution was studied using aerial and LIDAR images.