Sediment accumulation in reservoirs is one of the serious problems in the dam management works in Japan. In this paper, two series of experiments are conducted to simulate the sediment release from the dam reservoir with an operation of water surface elevation of the reservoir. Onedimensional numerical calculation is tested using the experimental condition. It is found that the one-dimensional model can predict the behavior of the sediment movement. However, it is suggested that two-dimensional model is required to predict more accurate sediment movement.