Author(s): Christina Baumgartner; Nils P. Huber; Bernd Hentschel

Linked Author(s): Nils P. Huber

Keywords: Waterway engineering; Scale model; Sedimentation; Bedload; Danube; Hybrid model

Abstract: The simulation of morphodynamic processes in a scale model is usually realized with a combination of a certain kind of sediment scaling plus model adaption like distorted scale or tilted slope. But the scaling of sediment characteristics is limited, therefore scaling laws propose e. g. replacing the natural sediment material with a uniform lightweight synthetic pellet. This practice cannot be used for the simulation of morphodynamic processes in a river with a wide grain size distribution from sand to coarse gravel like the Danube river in south-eastern Germany. Therefore, a new method was used to investigate the hydrodynamic and morphodynamic processes at the confluence of the Isar and Danube rivers in a scale model. This confluence is a hydraulically and morphodynamically highly complex area because of a huge variety of possible flow characteristics conditioned by the rivers' different hydrographs and slopes. As a result, the sediment of the Isar creates a large-scale, fan-like deposit in the Danube, called Isarschuttkegel, consisting of heterogeneous gravel material with a highly dynamic morphology. In recent years, bedload inflows from the Isar into the Danube have repeatedly caused lateral, delta-shaped growth of the Isarschuttkegel, causing a narrowing of the navigation channel of the Danube and considerably impeding waterway transport. Extensive investigations have been carried out to improve navigability by the Federal Waterways Engineering and Research Institute (BAW). To simulate the behavior of the natural sediment a mixture of plastic granules with different material densities is used in the scale model. Different real-life discharge scenarios are combined to a synthetic hydrograph to simulate the morphodynamics of the Isarschuttkegel over a wide range of hydraulic conditions. In this paper, the design of the large-scale model and the achieved agreement of morphodynamics between nature and model are presented.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p0543-cd

Year: 2023