The Ganjiang Estuary Main Tributary Hub project is a core initiative aimed at improving waterway transportation along the Ganjiang River.To evaluate the impact of downstream drainage pumping stations on navigation water flow conditions, a two-dimensional hydrodynamic model is established.Different upstream inflow conditions are selected during the dry season(500-5 000 m3/s)and flood season(5 500 m3/s)to simulate and analyze the flow field evolution characteristics before and after drainage.The results show that the drainage operations at the Fengchan drainage pumping station have a significant impact on the flow field, leading to an increase in the number of recirculation zones and a reduction in the size of individual recirculation areas.The impact of drainage operations at the Lianwei drainage pumping station is mainly confined to the drainage channels and riverbanks, with relatively minor effects on the navigation channel flow field.The flow velocity changes caused by the drainage of the drainage pumping station are relatively small, with a maximum amplitude of about 0.10 m/s and an impact range of about 200-350 m, and the impact range decreases with the increase of the outer flow rate.After the water spreads onto the floodplain, the impact of drainage operations on the hydrodynamics of the river channel is significantly reduced.The impact of drainage on navigation water flow conditions is limited and will not have significant adverse effects.The results of this study can provide valuable support for ensuring the navigational safety of the downstream channel of the main tributary hub in Ganjiang estuary.