Abstract
Experimental investigation was conducted on the dynamic equilibrium state of bed which was composed of extremely wide range of sediment. A void of larger stones was filled with medium gravel which moves as bed load and finer sand which moves as suspended load. Experiment was conducted with supplying gravel and sand. The flow discharge and the sediment supply discharge of gravel were set as fixed value, and the sediment discharge of sand was changed. The layer of only gravel was exposed on the bed surface under the condition that the discharge of sand was small. On the other hand, if the supplying rate of sand was large, the layer which was composed of both gravel and sand was formed below the bed surface. It was verified that this results were not changed even if the flow rate and the discharge of gravel changed.
