Bed development of an open-channel bend in a backwater situation

In practice, the application of depth-averaged 2d-models based on a fixed bed approach is now standard. However, under mountainous conditions the bedload and the corresponding morphological changes are processes which can not be neglected. Thus, for many tasks (e.g. to establish hazard maps) a moveable bed approach is more appropriate. An important aspect of bedload is the lateral transport of sediment due to secondary currents. In an open-channel bend, this is the dominant process for the bed morphology. To implement this aspect of the lateral transport in the context of a 2d-model, some laboratory experiments were carried out. In this investigations, the focus was given on backwater situations as they are typical for river power plants. Based on these experiments, a 3d-model has to be validated and should then serve as a tool to develop a relation for the lateral bedload.