To address the issue of cross currents intruding into the main navigation channel at the Feifengjiao waterway downstream of the Datengxia ship lock under low discharge conditions (700-2,000 m3/s),which poses risks to vessel navigation safety,this study investigates the hydrodynamic causes of cross currents and develops targeted remediation methods.By integrating geological surveys,numerical model simulations,and engineering quantity calculation using cross-sectional area method,an optimized phased remediation scheme is proposed through multi-scheme comparative analysis,tailored to local topographic and hydrological characteristics.The results indicate that the cross currents primarily originate from three factors:significant narrowing of the dam's discharge channel (21 m contour width reduced by approximately 50%),elevated riverbed morphology,and flow concentration under low discharges.Short-term measures,including optimized channel alignment design,excision of the S-shaped shoal bend,and expansion of the flow cross-section,effectively reduced cross-current intensity (lateral velocity decreased by 18.5%-29.2%) and water surface gradient (70%-84% reduction),substantially improving navigability.The long-term scheme reserves expansion capacity to triple the current width of the channel throat,balancing cost efficiency with adaptive flexibility while allowing dynamic adjustments for future hydrological uncertainties.The findings demonstrate that the phased remediation strategy successfully alleviates critical bottleneck constraints,validates the efficacy of the “short-term mitigation + long-term resolution” framework,and offers actionable insights for managing similar navigation challenges downstream of hydraulic hubs in mountainous river systems.