The sediment exchange between groynes and mainstream and topographic change in the groyne fields under different plane layout schemes of engineering work are important issues of the siltation mechanism and sedimentation reduction measures of the deep water navigational channel in the Yangtze estuary.However,there was not much research related to it in the past.The sediment exchange between the groynes and the mainstream and the topographic change are related to the turbulent structure and the time-averaged flow field,that is,the large-scale coherent structure of the mix layer between groynes and the mainstream interface,and the time-averaged large-scale circulation in the groyne fields.In the case of unsubmerged and submerged groynes,the mass exchange coefficient between the groynes and mainstream has little change,about 0.02.There is no equilibrium profile(Rouse distribution)of suspended sediment in the groyne fields.Both suspended and bottom sediments have net sediment transport to the groyne fields.It needs about 5~6 years to reach the quasi-equilibrium state for sedimentation in the groyne fields,but it was basically completed in the first two years.