The role of hydrodynamics in the secondary reworking of sediment in a tidal flat of the Yellow River delta was studied. Field hydrodynamic conditions were measured in the study area, and subsurface and surface samples at selected points were collected. Laboratory analyses were performed to measure variations in the grain sizes, mineral constituents, and microstructures of the sediment. Moreover, fractal dimension calculations were introduced to obtain additional quantitative sedimentological data. The results of the studies indicate clear responses of the seabed sediment to variations in the hydrodynamic conditions both in the vertical profile and in a seaward transect and indicate that hydrodynamic changes can play a significant role in sculpting the topographic features of tidal flats.