Modelling dynamic coastal vegetation establishment and ecosystem engineering in hydro-morphodynamic models with DYCOVE

Abstract. Coastal areas are complex environments with diverse hydrodynamic, morphological, sedimentological, and biological contexts. Vegetation is increasingly recognized as a crucial agent that shapes the geomorphology and hydrology of coastal and riverine systems by inducing a hydraulic roughness that influences flow velocities, inundation, erosion, and deposition. At the same time, vegetation growth depends on the environmental habitat conditions, which it modifies continuously, resulting in a biophysical feedback-loop. This loop between plant growth and the physical environment is inherently dynamic, meaning they both vary spatiotemporally through their interactions; however, these dynamics are currently excluded from most hydro-morphodynamic models that predict long-term coastal change. We present the DYnamic COastal VEgetation model DYCOVE: an open-source, process-based vegetation model that simulates dynamic coastal marsh vegetation by representing key ecological processes such as seed dispersal, establishment criteria, growth curves, and mortality rules. Vegetation dynamics are governed by species-specific thresholds for inundation, desiccation, bed level change, and flow conditions while age-dependent stress tolerance enables realistic transitions from seedlings to mature plants of multiple species. Based on literature-derived parameterizations of ecological thresholds, DYCOVE reproduces realistic vegetation distributions and zonations both in tidally- and fluvially-impacted coastal environments with an F1 score above 0.8 and species distribution with a total accuracy of 70 %. DYCOVE’s flexible, species-agnostic framework allows exploration of how various vegetation types influence coastal hydrodynamics, sediment transport, and land-building, representing a crucial advancement in process-based eco-hydro(morpho)dynamic modelling.