Since September 2018,the persistent operation of the Xinglong Hub below the dead water level has significantly altered the navigation conditions of the new estuary reach,resulting in frequent occurrences of navigation obstruction phenomena.To address the problem,we employ comprehensive data analysis and comparative research methodologies to analyze the variations in flow-sediment characteristics under abnormal hub operations on the basis of hydrological data of Huangzhuang and Shayang stations in Hanjiang River,along with measured topographic data of the new estuary reach.We further elucidate the underlying mechanisms by which these changes contribute to navigation obstruction risks.The results demonstrate that prolonged low-water-level operation of the Xinglong Hub has led to insufficient channel depth near the new estuary sluice.Furthermore,constrained by both channel morphology and upstream flow-sediment conditions,accumulated sediment cannot be effectively transported downstream,resulting in frequent navigation obstructions during dry seasons.Through the implementation of river channel regulation and targeted dredging projects,the beach-trough pattern can be effectively improved,navigation safety during the dry season can be ensured,and the collaborative improvement of waterway governance and ecological stability can be achieved.