Mathematical modelling of bed shear stress and depth averaged velocity for emergent vegetation on floodplain in compound channel

A mathematical model is used to predict velocity and bed shear stress in a compound channel flow. Model parameters such as non-dimensional eddy viscosity and secondary flow term in the mathematical model based on Shiono and Knight Method (SKM) are reconsidered using the UK-FCF data. The turbulent shear stresses obtained by three turbulence models are compared with those in the FCF data and the results are no significant differences between them. The concept of the secondary flow in the SKM is redundant through the data analysis as a result a new one is introduced in representing the shear stress in the momentum equation. The shear stress is now expressed by three mechanisms of momentum transfer between the main channel and the floodplain. The analytical solutions to the SKM are used to predict velocity and bed shear stress with the new concept of the shear stress. An effect of various parameters in the SKM to the distributions of velocity and bed shear stress is also investigated.