ABSTRACT
In a uniform two-phase motion (in a wide open-channel), it is assumed that the bed is covered by bed forms. The presence of bed forms means the elevation of the effective bed roughness. Therefore the resistance factor c corresponding to this (general) case must be smaller than cj corresponding to the (special) case of a flat bed. This chapter illustrates the application of the method of determination of c with a numerical example. Numerous methods have been produced for the determination of c; out of them, two are explained here: the method by White, Paris and Bettess and the method by van Rijn. It is assumed that bed forms do not alter the mathematical form of a transport equation as such; their influence on the transport rate can be taken into account by an appropriate modification of the flow velocities and shear stresses (entering that equation).
