A Novel Biomorphodynamic Model to Enhance Bedload Transport Modelling in Emergent and Submerged Rigid Vegetation

Riparian and floodplain vegetation play a key role in controlling flow resistance, sediment transport, and channel morphology, shaping the dynamics of riverine ecosystems. Accurately representing these vegetation–flow–sediment interactions in numerical models is essential for predicting system responses and supporting sustainable river management. This study introduces an enhanced biomorphodynamic model in the open-source framework openTELEMAC, which combines multiple vegetation friction approaches with a method for predicting sediment transport in vegetated flows. The modular structure of the framework enables flexible configurations for different vegetation types (rigid or flexible) and flow conditions (emergent or submerged) by selecting suitable vegetation friction approaches, improving usability and extending model applicability. Model performance is evaluated using two laboratory experiments on bedload transport through emergent and submerged rigid vegetation. Simulations reproduce the measured bed and water surface profiles with high accuracy, yielding low goodness-of-fit errors (RMSE ≈ 0.5–1.8 cm, MAE ≈ 0.5–1.6 cm). The results highlight the sensitivity of predictions to vegetational input parameters such as the drag coefficient. Overall, the enhanced biomorphodynamic model advances the representation of vegetation–sediment interactions and provides an adaptable, open-source tool for eco-hydraulic and morphodynamic research.