Morphological model for the river Rhine : model of the IJssel branch (v1.0)

The riverbed of the Rhine branches is dynamic, influenced by morphological processes and human intervention. The current DVR model used to predict morphodynamics is outdated due to: - Calibration based on periods before key interventions (Room for the River, Water Framework Directive). - Transition to new software (6th generation models in the D-HYDRO Suite). - New data and insights on morphological developments. A new model and tools are being developed, starting in 2023, with progress reported for 2023-2025, resulting in model version v1.0. The final model will be fully described in a future report. In 2025, calibration has been finalized, resulting in an optimum parameter set for the IJssel branch model. These might have to be adapted in the following phase, when the separate branch models are connected into one model for the entire Rhine branches area. The model reproduces the location of sedimentation and erosion reaches along the IJssel rather well, with some local exceptions. The speed of sedimentation or erosion is however overestimated due to the hydrodynamic results of the model. Bend patterns are well reproduced in the Middle and Lower IJssel. Along the Upper IJssel, the river bed is not behaving as a fully alluvial bed in reality, leading to less good representation of bend patterns. Recommendations are made for the last steps to make the model available for use in projects, as well as for extension of the model's functionality.