Estimation of sediment transport rate and bed variation in stony-bed rivers needs to understand the effects of stones sizes and shapes in streams. However, measurements of forces acting on sediment particles in active are difficult, especially for rapid stony-bed rivers. To investigate the dynamic mechanism of stones moving in streams, we have developed a numerical movable bed channel in which three-dimensional motion of each shaped-stone is calculated, respectively. The dynamic interaction between stones motions and hydrodynamic forces on movable bed surface in numerical experiment is investigated. It is demonstrated that large stones form static stone clusters. Stones clusters have an important mechanism to stabilize stony-bed surface against hydrodynamic forces of flows.
