On the morphological development of embayed beaches

- The evolution of a schematic embayed beach is simulated with a 2D morphological model.
- Variations in environmental conditions and geological setting affect bay shape.
- Bay development can be approximated/predicted with an exponential function.
- Shoreline rotation determines degree of cellular circulation and beach curvature.

The typically curved and stable planform shape of embayed beaches is often observed in the presence of rigid headlands. The long-term alongshore equilibrium shape is variable and is controlled by headland geometry, cellular circulation patterns and wave obliquity at the shoreline. We use a process-based morphological model to simulate the development of embayed beaches depending on different environmental conditions and geological settings (i.e., topography and geometry). The embayment is allowed to develop from an initially straight beach to one which is curved under idealized wave forcing conditions and without external sediment input. Bay development can be approximated with an exponential function with coefficients representing rate of growth and bay size. Long-term shoreline cutback is both uniform (shoreline translation) and non-uniform (shoreline rotation) and is parameterized. Alongshore gradients in flow and transport patterns are related to long-term non-uniform shoreline cutback. Rotation of the beach ceases as the bay matures, leading to a curved shoreline planform, which is a remnant of decaying erosion processes.