The integration of coastal dunes planted with vegetation and dikes combines traditional infrastructure with dynamic aeolian sediment and ecological processes to enhance coastal resilience. The functioning of such dune-dike hybrid Nature-based Solution strongly depends on aeolian sediment transport and the vertical growth rate of vegetation. We used the AeoLiS numerical model to investigate the relative importance of aeolian and vegetation dynamics in the evolution of a 120 m long and 20 m wide marram grass-planted dune field on a Belgian sandy beach backed by a seawall, constructed in 2021. AeoLiS proved to be a promising tool for predicting these systems, effectively capturing aeolian sediment deposition, vegetation growth, and profile development three years post-construction. Seasonal variations in vegetation trapping efficiency, driven by sediment burial, and seasonal plant growth emerged as important factors controlling dune growth. Profile development discrepancies were attributed to unaccounted biotic and abiotic factors, highlighting the complexity of coastal eco-geomorphological processes. Dunes planted with vegetation wider than 20 m were identified to enhance sediment trapping without an increase in dune height. These findings offer actionable insights for coastal management, promoting strategic dune design and planting approaches to reinforce shoreline resilience. Additionally, the findings underscore the necessity for advancing eco-morphodynamic models and deepening our knowledge of coastal dune dynamics.

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Traditionally, independent tools have been used to simulate wave- or wind-driven processes to simulate coastal morphology change. Coupled models that cross the land-sea division and integrate these collective processes can increase our knowledge on complex morphodynamic interactions and improve predictions of the foreshore, beach, and dune evolution. In this paper we present the initial development of a coupled modelling framework capable of numerically predicting the integrated development of coastal landforms, including both marine and aeolian processes, by using a generic model coupling approach that leverages the Basic Model Interface. The aim of this tool is to support the interdisciplinary design of Nature-based Solutions on varying spatiotemporal scales. As shown for the Marker Wadden case, the implemented model functionalities allow for the numerical description of the coast in an integrated manner and thus create opportunities for modeling coastal landform of the nearshore, beach, and dune that would not be possible with a discrete model approach. Specifically, by coupling two discrete numerical models, AeoLiS and XBeach, the aeolian and marine interaction resulted in a more realistic behavior of processes in the intertidal area. After coupling, bed levels compared better to the observations compared to the superpositioned results of both separate model components, which showed the added value and potential of coupled modelling. These findings have implications on the ability to predict spatio-temporal integrated coastal development – including these interacting aerodynamic, hydrodynamic, and ecological processes, which are essential in the interdisciplinary design of NbS.@en

In order to improve the current aeolian modeling, a process-based model is developed by implementing biological and physical processes adapted from different existing models. The current version of the model is capable of simulating barchan and parabolic dunes and the initial stage of coastal dune formation: Embryo dunes. Potentially the model can be used to determine the influence of tidal ranges, storm frequencies, armoring, salinity and precipitation on dune building processes. This will result in a greater insight in the general behavior of coastal systems and on the other hand the model can also be used for engineering purposes.@en