Pamarayan Weir is a sluice weir located in Ciujung River, Banten Province. It is one of the most important weir of Ciujung River as it serves for irrigation of 21,350 ha of rice fields. The capacity of Paramayan weir is reduced not only for irrigation but also for flood control. Furthermore, the weir safety is then trend to be threatened during the rainy season as the peak discharge of flood hydrograph is trend to increase and the weir capacity is trend to decrease. The purpose of this study to assess the potential sedimentation distribution during the dry season and bed erosion pattern around the weir. The assessment is done based on the flow pattern generated by each of the flow scheme using mathematical model HEC-RAS 6.2 of 2D Unsteady Flow. The dry season scheme is assessed using dependable flow of Q90%. Meanwhile, the flood flow assessment scheme is done using Q50 years of return period. Current simulation results show that the flow velocity on the right side of the weir is higher than on the left side. The flow velocity on the right side shows the occurrence of river bank scouring and on the left side the accumulation of sediment