A shoreline evolution model for embayed beaches based on cross-shore, planform and rotation equilibrium models

Coastal stakeholders, engineers, and scientists have long sought a simplified and practical model to predict shoreline change along sandy coastlines; this model could be applied for several purposes, such as public safety, natural environment conservation and coastal management. This study focuses on embayed beaches, which are physiographic units where the incident hydrodynamic conditions determine the interrelation between the beach profile and planform, resulting in a characteristic beach-planform curvature. This article presents a new equilibrium shoreline evolution model. It is a reduced-complexity model based on the integration of cross-shore, planform and rotation equilibrium-based models, and it is exclusively applicable to embayed beaches. This new approach obtains the entire beach coastline evolution over time scales spanning months, several years or decades. In contrast, previous similar models needed to discretize the beach into transects or stretches to evaluate the entire embayed shoreline beach evolution, and this process represents a significant computational cost. The proposed model has been applied to the Collaroy–Narrabeen embayment, Australia and shows overall good performance. The results demonstrate that the model successfully achieves the general erosion–accretion trend along with beach orientation variability of the entire shoreline and the dry beach area evolution at a qualitative and quantitative level. Nevertheless, observations in different sites with diverse beach characteristics and wave conditions are needed to widely validate the proposed model. •Equilibrium shoreline evolution model based on the integration of cross-shore, planform and rotation equilibrium-based models.•Model exclusively applicable to embayed beaches.•Simulation of the entire beach coastline evolution from a single monitoring beach profile.