Abstract
A knowledge of the nature of turbulent flow with small relative submergence plays an important role for clarifing fluvial hydraulics of mountain rivers. Because of the existance of “roughness sublayer” which is a near-bed layer affected by roughness elements, the flow with small relative submergence is different from that with sufficient relative submergence. In the present study, the fundamental characteristics of flow with small relative submergence are discussed through flume experiments of flow over rough beds which are composed of glass beads and of natural gravels. In the roughness sublayer, the velocity profile becomes more uniform than the log-law profile and the turbulence intensity is suppressed. These characteristics are proved to be closely related with the measured distribution of Reynolds-stress.
