Quasi two-dimensional model for straight overbank flows through emergent vegetation on floodplains

The paper presents a quasi two-dimensional (2D) model calculating depth-averaged velocity and bed shear stress in a straight compound channel with a vegetated floodplain. The model numerically solves the depth-averaged Navier–Stokes equation for the streamwise motion of flow (quasi 2D). Reduction in volume of water due to vegetation is modelled as porosity. Drag force due to vegetation is modelled as an additional momentum sink term in the Navier–Stokes equation. Estimation methods for model parameters—drag coefficient, shading factor, porosity, friction factor, eddy viscosity and advection term—are discussed. The predictive capability of the model is assessed against experimental data with regard to distributions of depth-averaged velocity, bed shear stress, transverse shear stress and stage-discharge. The results show that the quasi 2D model reproduces a reasonable simulation of the flow field.