Author(s): B. Blamauer; M. Klosch; M. Tritthart; H. Habersack
Linked Author(s): Bernadette Blamauer
Keywords: Flow resistance; Drag force; Flexible vegetation; Vegetation bending
Abstract: For modelling erosion and sedimentation processes in rivers with vegetated bars detailed knowledge of the interactions between flow and vegetation is needed. Earlier studies showed that flexible vegetation significantly influences the flow by altering the roughness coefficient and velocity distribution, with the vegetation bending as a crucial factor. So far investigations were mostly limited to flume experiments, at the Drau River vegetation bending was measured in-situ during floods by using a time-lapse camera and applying photogrammetric techniques. Parameters like stem diameters and projected area were determined from willows and tamarisks. Together with data from literature, they were used in a 2-D hydrodynamic-numerical model which included an improved drag force approach to calculate variable roughness coefficients of flexible vegetation. Observed and calculated bending angles were compared for further model adjustment. Variations of parameters showed to strongly affect the calculated bending and the modelled flow field on a vegetated bar.
Year: 2011