Due to the high sedimentation rate in reservoirs located along the Kurobe River (e.g. Dashidaira reservoir), sediment flushing with water level drawdown is employed to preserve the effective storage capacity. During a flushing operation with full drawdown, the incoming flood erodes a flushing channel into the deposited sediment. The flushing channel evolution procedure is a complex phenomenon especially in steep reservoirs owing to the dynamic interaction between the unsteady flow field and bed variations. The flushing channel formation and evolution procedure were investigated in meandering channel of Dashidaira reservoir utilizing field measurements and numerical simulations. A 3D numerical model which applies the Finite Volume Method (FVM) in ombination with a wetting/drying algorithm was used together with different bed load transport formulas. Numericaloutcomes disclosed a reasonable agreement with the field measurements. In addition, a further insight in the correlation between the flushed out sediment discharge and the water discharge as well as the water level was found.