Abstract
This study focuses on the hysteresis of dynamic equilibrium bed composed of fixed bed and movable bed. By experimental results, the irreversibility of bed deformation between the movable and fixed beds was observed. By supplying sediment, in a rate lower than the equilibrium rate from the upstream, the bed was widely exposed. Then, we increased the sediment rate to be equal to the equilibrium rate, however the bed stay exposed without sediment layer. By increasing the sediment rate to be higher than the maximum bed load rate on the fixed bed, the bed was covered by sediment layer. In numerical analysis, the bed load layer model was applied, considering the maximum bed load rate on the fixed bed. The results of numerical analysis showed a good agreement with the experimental results. Moreover, numerical analysis showed that when the longitudinal exposed area was large, the area was hardly filled with sediment even if supplied sediment was more than the maximum bed load rate on fixed bed.
