The Effects of Relative Submergence on Flow Patterns around Large Particles in a Gravel Bed River

The flow patterns around large particles in mountain gravel bed streams were examined. An emphasis was placed on the effects of these flow patterns when the relative submergence exceeded 3. To provide an improved understanding of the flow structures around the clasts, an in depth analysis of mean flow measurements was performed. On average, the velocity profiles were characterized by an inner layer that reflected mostly grain/skin resistance and an outer layer that mostly reflected form resistance. With the knowledge gained from these experiments, a practical application is to use strategically placed clast particles in a stream to help trap or entrain incoming particles near spawning grounds, thus helping to make and sustain a cleaner habitat for fish and other aquatic organisms.