Abstract: Since the operation of the Xiaolangdi Reservoir, flow and sediment entering the lower Yellow River (LYR) has been altered significantly and this leads to a process of channel re-forming in this reach. This study examines flood evolution under different combinations of flow and sediment and its effect on erosion and deposition based on the water and sediment regimes regulated by the reservoir. A one-dimensional flow-sediment coupled model is developed to simulate flood routing along the braided reach of LYR, and it is verified using the measurements of a flood event occurring in this reach from May to October 1982. Calculations agree well with the measurements, including the calculated flow, sediment concentration and variation in flood peak level along the channel. Then, we regulate this 1982-flood into different flow and sediment processes by fixing the total volumes of flow and sediment but adopting different peak discharge Qmax and peak sediment concentration Smax in different processes. Using these regulated flood processes and our coupling model, we calculate flood routing and channel deformation, and analyze the influence of different flow-sediment processes on riverbed deformation in the braided reach. The results show that different flow-sediment processes produce significantly different channel deformation. In term of channel deposition volume, the combination of Qmax = 10000 m3/s and Smax = 60 kg/m3 would create the largest while Qmax = 4000 m3/s and Smax = 30 kg/m3 the smallest. According to the comprehensive effect of floodplain deposition and main-channel scour, the combination of Qmax = 6000 m3/s and Smax = 40 kg/m3 would be most advantageous to riverbed evolution in the LYR braided reach. Keywords: one-dimensional morphodynamic model; overbank flood; erosion and deposition; braided