In this paper, we propose a numerical model to control and assess reservoir sediment flushing. The model can simulate flow field and suspended solid simultaneously. Specifically, the model solves 3-dimensional Reynolds averaged Navier-Stokes (RANS) equations together with sediment transport equation. Standard &kappa&epsilon&minus model is used for turbulence closure. The mesh generator works based on adaptive mesh refinement algorithm which gives the opportunity to accelerate the calculation time and expenses. The proposed model is applied to the Stramentizzo (Trentino, Italy) reservoir and to its catchment area. Three different scenarios based on 5, 20 and 100 years hydrograph and different opening condition of bottom outlet are implemented in the simulation. Comparison of total weight of sediments that are discharged through the bottom outlet during flushing and water level of reservoir after flushing shows that scenario 3 has higher efficiency in comparison to the other scenarios.