Equilibrium shoreface profiles: A sediment transport approach

Large-scale coastal behaviour models use the shoreface profile of equilibrium as a fundamental morphological unit that is translated in space to simulate coastal response to, for example, sea level oscillations and variability in sediment supply. Despite a longstanding focus on the shoreface profile and its relevance to predicting coastal response to changing environmental conditions, the processes and dynamics involved in shoreface equilibrium are still not fully understood. Here, we apply a process-based empirical sediment transport model, combined with morphodynamic principles to provide new insight into equilibrium shoreface profile development and shape. The quantitative model is based on field measurements and shows that a balance between onshore sediment transport due to oscillatory wave motion, and offshore sediment transport due to gravity, produces profile shapes that are similar to natural shoreface profiles from the Danish North Sea coast and the southeast Australian coast. Model predictions of equilibrium profile response to the effects of climate change, such as rising sea level, or changing wave climates, are examined. Implementation of the model is straightforward; there is no tuning or calibration and computation times are short. It is therefore easily implemented with repeated iterations to manage uncertainty.