On a reduced-complexity shoreline model combining cross-shore and alongshore processes

We present a new empirical shoreline evolution model integrating longshore and cross-shore processes. It is designed for wave-dominated sandy coasts and includes feedback between shoreline and wave dynamics. It can also take into account non-erodible (e.g. rocks, artificial structures) contours and complex wave propagation patterns through the coupling with the spectral wave model SWAN. While the longshore-transport-based modeling approach can reproduce the shoreline variability on large temporal scales, say from years to decades, inclusion of the equilibrium-based crossshore model enables shoreline variability to be addressed at the scales of changes in incident wave energy, say from hours to years. In this paper, the basic assumptions of the model are presented. The model is tested to synthetic cases before being applied to a real case scenario (Narrabeen Beach, Australia). Finally, guidelines for future model developments are given.