A hydrodynamic model is developed for the calculation of shear stress and pressure along a sinusoidal boundary that is fixed or propagating very slowly in a wide rectangular open or closed channel. The model uses curvilinear coordinates that follow the wavey boundary, and it is similar to that for two-dimensional wavy boundary flows of infinite extent proposed by Benjamin (1959), except that the present model takes account of turbulent stresses on the basis of the turbulent eddy viscosity concept employed by Hussain and Reynolds (1970). The compact analytical expressions for the perturbed shear stress and pressure on the wavy boundary are derived for the cases of hydraulically smooth turbulent and fully rough turbulent flows. The developed model is shown to be in good agreement with the experiments conducted by Zilker et al. (1977). The developed hydrodynamic model is applied to the problem of the formation of ripples in erodible channels by Kobayashi and Madsen (1985).