Flow resistance of vegetated oblique weir-like obstacles during high water stages

At high water stages obstacles in the floodplains of a river contribute to the flow resistance. In particular the elevated vegetated parts are expected to play an important role. The objective of this study is to estimate and parameterize the form drag due to vegetated oblique weir-like obstacles. An experimental study has been carried out in the Laboratory of Environmental Fluid Mechanics of Delft University of Technology. Measurements for energy head losses were carried out for a range of discharges and downstream water levels covering submerged and subcritical flow conditions. The Head loss due to submerged vegetated dikes has been modeled by an expansion loss form drag model. Expansion loss form drag model has been derived from one dimensional momentum conservation equation and accounts for the energy loss associated with a deceleration of the flow downstream of a sudden flow expansion. The results have been compared with experimental data.Hydraulic EngineeringCivil Engineering and Geoscience