Effect of vegetation on local erosion downstream of a rigid bed: experimental analysis in a laboratory flume

The plane evolution of a meander wave is determined by the erosion processes at the banks. Particularly, the outer- bank is considerably vulnerable to the erosion processes. Indirect techniques, which act upon the reduction of the effect of the cross-circulation motion, have been recently proposed to limit the outer-bank erosion. This paper shows preliminary results on the role played by vegetation on cross-circulation motion. The analysis is conducted on the basis of experimental data collected in a large amplitude meandering channel constructed at the hydraulic laboratory of DICAM. Maps describing the cross-stream flow, both over the no-vegetated bed and over the vegetated bed, are shown in peculiar sections along the meandering flume. The comparison between such maps highlights how the intensity of flow velocity and the bank erosion rates reduce as effect of vegetation.