For the Hengsha East Shoal Promoting Siltation Project in the Yangtze River Estuary,this work developed a formula for calculating sediment carrying capacity based on variable coefficients and a mathematical model for suspended sedimentation using variable saturation recovery coefficients.Not only does the model yield good verification,preferably give the hydrodynamics and the sediment concentration,but also reach a good agreement between the simulation results and the measured topographical changes in the promoting siltation zone of the Hengsha East Shoal.Moreover,this article proposes a method for examing the net sediment transportation flux by tide for studying the effects of the project of promoting siltation and comparatively analyzes the current siltation of the Hengsha East Shoal and siltation mouth layouts,entrance widths,entrance bottom elevations,and the impact of the South Main Dike on promoting siltation through calculating the net sediment transportation flux by tide over the fixed bed and the direct movable bed numerical simulations.The results are in good agreement with each other,indicating that the method for calculating the net sediment transportation flux by the tide is also useful for assessing the project in promoting siltation.Finally,we use the modeling results to analyze the water and sediment diversion ratios and the changes in silting and scouring in riverbeds and draw the conclusion that the completion of the Hengsha East Shoal Promoting Siltation Project would not adversely affect the Yangtze River Estuary Deepwater Channel Project.