Zur morphodynamischen Modellierung am Beispiel der Tideeider
The highly dynamic morphology of the Eider estuary at the German North Sea Coast is strongly affected by a storm surge barrier at the river mouth. The operation of the five sector gates influences the estuary hydrodynamics, sediment dynamics and morphology in different scales reaching from small-scale scour evolution behind the gates, to medium scale meandering of the main river channel, to large-scale sedimentation trends of the whole estuary. In order to investigate the morphodynamic processes a 2DH process based model has been set up, covering the whole tidally influenced estuary area from the weir to a dam 36 km upstream. Hydrodynamics, sediment transports and bottom evolution have been calculated in successive modules coupled to a morphodynamic modeling system. A thorough calibration and validation of the single computational modules was carried out for short-term events, so that the model is capable to simulate short-term morphodynamic events in reasonable quality. The application of process based numerical models to medium to large scale (years to decades)events requires reduction and simplification techniques as input- and process filtering. Common techniques (e.g. representative boundary conditions) are described and discussed. A modified approach for defining a representative tide is presented. Its application to medium scale morphodynamic simulations for periods up to two years shows promising results. Results of large scale simulations are presented and discussed.