The confluence reach of the Jiuzhou River and the Pinglu Canal is characterized by a large confluence angle,a high discharge ratio,and a considerable elevation drop.During sudden tributary floods,these conditions readily induce flow disturbances and excessive transverse velocities,posing a serious threat to navigation safety.A 150 scale physical model is built to conduct systematic experiments.One baseline design scheme and three optimized alternatives are developed to analyze flow velocity distribution,transverse velocity,sediment deposition patterns,and water surface fluctuations.The results indicate that the maximum transverse velocity in the baseline design reaches 0.49 m/s,significantly exceeding the regulatory limit.Although optimization scheme I reduces the velocity to 0.44 m/s,some non-compliant zones remain.Optimization scheme II effectively controls transverse velocity but causes severe sediment accumulation in the gentle-slope zone.In contrast,optimization scheme III not only ensures compliance with transverse velocity standards but also directs sediment deposition into the settling basin while creating additional low-flow zones suitable for fish habitats.The combined arrangement of multi-stage energy dissipation basins and steep slopes can simultaneously safeguard navigation safety,manage sediment,and support ecological protection.The proposed “navigation-sediment-ecology” integrated management approach offers a practical reference for similar regulation scheme for mountainous confluence reaches.