Many of the reservoirs in the world are faced with acute sedimentation problems and in many cases the sedimentation led to closure of the sluice gates and it intensifies accumulation of sediment in these reservoirs. According to international reports, one of the most effective ways to removal of the deposited sediment from large reservoirs is partial Flushing. But this method erodes a small amount of sediment around the sluiceway and it cannot solve the sedimentation problems, completely. In this study, with knowledge about vortex flow around the sluiceway, there vortices were increased by using a specific structure in order to increase partial Flushing. The results show that with using a semi-cylinder structure, the flushing efficiency will increase up to 16.4 times. Therefore, the proposed method can be applied in the large reservoirs and in the reservoirs with serious conditions, for sluicing a significant amount of sediments out of the reservoir, in a short time, with a low loss in water resources.