Bed morphological changes near a finite submerged patch of vegetation in open channel flows

This laboratory experiment described the sediment patterns of erosion and deposition in response to a patch of submerged cylinders in open channel flows. For flows below the threshold of sediment motion, the erosion took place primarily opposite the patch and near the leading edge due to accelerated velocity and the diversion of flow, respectively. The degree of scour observed at both regions increased as the flow blockage, which was the non-dimensional parameter (Wv). For flows above the critical value of sediment, sediment was deposited near the patch due to reduced bed shear stress, and as the flow blockage increased the deposition in and behind the patch decreased because of higher diversion of flow. A two-dimensional model employed the empirical relationship for submerged conditions applied to the experiments performed in present study. The model simulated well the flow and sediment patterns of erosion and deposition with the patch. From comparisons with experimental data, the degree of scour was under-predicted due to additional turbulence and vortex motions caused by cylinders, and the simulated amount of deposition in and behind the patch agreed well with experimental data.