Enhancement of a numerical model system for reliably predicting morphological development in the Saalach River

Rivers are dynamic systems, changing over time on their own or due to engineering measures and structures. At rivers which are regularly monitored, information on sediment balance can be used to evaluate the morphological development and to assess the impact of such measures. In this paper, we show that the performance of a numerical model can be improved by quantify boundary conditions, and that the simulation results of such a well-developed model will be more useful for civil engineers. As a case study, we develop a model system based on TELEMAC-SISYPHE to study the morphology of the Saalach River, where erosion and sedimentation impacts local ecology and human safety. Based on the available measurements and a sediment balance concept, we estimate the amount of sediment supplied to the river section downstream of a reservoir as well as the volume of the bed sediment transported along the river channel in different years. Using this information as boundary conditions for calibration and validation cases, the model provides a realistic and accurate representation of the river. Furthermore, our model has been successfully employed on the Saalach River to evaluate an alternative strategy for a more sustainable river management.