A NEW APPROACH ACCOUNTING FOR SPECIES-SPECIFIC PLANT CHARACTERISTICS ON SAND CAPTURE EFFICIENCY IN AN AEOLIAN TRANSPORT MODEL

Coastal dunes are natural landforms that develop in the backshore of sandy coastlines through complex ecomorphodynamic interactions (Hesp, 2002). They provide a wide range of ecosystem services (Barbier et al., 2011) but are threatened by both increasing anthropogenic pressures and climate change (Vousdoukas et al., 2020). In most ecomorphodynamic numerical models which attempt to understand coastal dune evolution, the influence of vegetation on sediment transport is significantly simplified given the complexity of these interactions. Shear stress partitioning models are widely used to assess the effect of vegetation on wind force (Raupach, 1992; Okin, 2008), but to date only discriminate between vegetation type (e.g., grass, shrub, tree), without differentiating between the species-specific characteristics that play a role in the spatiotemporal evolution of dunes, their response to storms, and their recovery. Indeed, different dune grass species can build dunes of different shapes and sizes due to their unique ecological characteristics (Hacker et al., 2019). Using observations from a wind tunnel experiment that assessed sediment capture efficiency of the three main dune grass species of the U.S Pacific Northwest coast (the two non-native species Ammophila arenaria, AMAR, Ammophila breviligulata, AMAR, and the native species Leymus mollis, LEMO), the objective of this study is to develop model parameterizations that represent the sand capture efficiency of different dune grass species within a process-based aeolian sediment transport and dune evolution model.