Application of XBeach to model erosion of a beach fronted by seagrass

Large parts of the Australian coastline are fronted by aquatic vegetation, such as seagrass and mangroves. Although it is widely accepted that vegetation plays an important role in dissipating wave energy and reducing current magnitudes, there is limited understanding how this affects coastal morphology. In this study we apply a process-based storm impact model to make a preliminary assessment of the effect of seagrass presence on short-term beach erosion. A model-data comparison using field measurements obtained in April 2016 in Middleton Bay, Western Australia shows that the model is able to calculate wave height evolution over the seagrass meadow well. Subsequently, a number of model scenarios are defined to explore the sensitivity of short-term beach erosion to seagrass presence. The results show a clear difference in beach erosion volume between a case with and without seagrass, suggesting that seagrass may be an important factor in limiting beach erosion, although no field data is available to validate these results. More research, in particular laboratory and field measurements, are required to confirm this finding.