Lateral dissemination of depth-averaged velocity, boundary shear stress and stage-discharge curves for compound channels

The study establishes different analytical model for velocity distribution, boundary shear stress, stage–discharge curves and their application to the trapezoidal compound channel. The analytical solution to the depth-integrated Navier–Stokes equations is used for the same, and their results are validated using experimental data and numerical solution. The parameters used to predict the three-dimensional characteristics of the flow field over compound channel in the analytical solution require modelling of friction factor, eddy viscosity coefficient and secondary current term. The Shiono and Knight model (SKM), which is an analytical solution for RANS equation through empiricism, is compared with two similar analytical-based models, viz. K-method and extended SKM, and with one numerical method, i.e. K–ε model through simulation based modelling. The results obtained in the analyses show that the secondary flow parameter plays a vital role and its significance proliferates near side slope where momentum transfers takes place from the main channel to the flood plain. The contrast in the results is shown with the help of variation in percentage error over the cross section, root mean square error and Nash–Sutcliffe efficiency (E). © 2018 Indian Society for Hydraulics.