Using Hybrid Modelling to Analyse Bedload Transport in River Bends

The complex river bends hydrodynamic and morphodynamic interaction processes are hardly covered, neither by physical nor numerical modelling. Therefore, the simultaneous use of a physical and a numerical model, called “hybrid modelling,” is promising. The effects of river training measures in bends are investigated using a parameterizable physical model together with a two-dimensional numerical model as its digital twin in lab scale and also in nature scale. The lab scaled numerical model was calibrated using the measured water levels, longitudinal and lateral bottom slopes and transport rates from the physical model. A good agreement between the results of the numerical model and the physical model could be found. In addition, the numerical model was run in natural scale with sand instead of the artificial model sediment polystyrene. The results of the scaled models with the artificial material were compared with the full-scale numerical model with sand. The hybrid use of a physical model and a numerical model as its digital twin can overcome the drawbacks of both types of models. The results from both types of models provide better reliability, which is important for the evaluation of river training measures.