Morphological models for IRM : Rhine branches 1D

Until recently, river maintenance was mainly concerned with single-function interventions to, for instance, improve the river's navigability or reduce flood risk. This type of interventions framework has the negative consequence that an improvement in one function may not be beneficial for another function or service. For this reason and having in mind the long-term impact of interventions, Rijkswaterstaat has devised an Integral River Management (IRM) programme. This programme develops the necessary policy for providing both short-term and long-term solution to river problems from a multidimensional and multidisciplinary point of view, contrary to past single-function interventions. The IRM programme requires a tool to evaluate the long-term and large-scale morphological effects of river interventions as well as the impact of different future scenarios related, for instance, to climate change. To help Rijkswaterstaat in gaining insight into the morphological impact of river interventions, a numerical model of the Rijntakken is built. The model is one-dimensional and uses the D-HYDRO Suite. It comprises the Dutch Rhine River branches and downstream part of the German Rhine. The upstream end of the domain is found at the confluence of the Lippe with the Rhine at Wesel (Germany, Rhine kilometre 815). The downstream ends of the domain are found at Hardinxveld, Krimpen aan de Lek, and the Ketelmeer. The model stems from combining the official SOBEK-3 schematizations of the Rijntakken and an existing model, also in SOBEK-3, of the German Rhine. These models have been built for hydrodynamic studies and need to be adjusted for being suitable to predict morphodynamic changes.