Keywords: 
• Yellow River delta /
• grain size /
• sedimentary environments /
• hydrodynamic-conditions

Abstract: Based on the measured data of bottom sediment samples, combined with sediment texture, topography and hydrodynamics, a new triangular diagram advanced by Fleming is applied to reveal the sedimentary environments and their hydrodynamic processes. The results indicate that the nearshore zone of the Yellow River delta is divided into three sedimentary environments: the area near abandoned delta, estuarine area, and Laizhou Bay. In nearshore zone of the abandoned delta, there are two parts, Wanwan'gou and Feiyantan, which were abandoned in 1953 and 1976, respectively. Due to long-term scouring of wind wave, the grain composition of the majority bottom sediment near Wanwan'gou is coarse showing the strong erosion- resisting characteristics. For Feiyantan, because of combined effect of wave and tidal current, there is a large percentage of the sand at the underwater slope, which is shallower than -5~-6 m, however, slit and clay predominate at the underwater slope, which is deeper than -5~-6m. For the area near the current estuarine, the grain size has a changing tendency of coarse-fine-coarse that results from the effect of strong tidal current zone in front of sand spit. For the area near Laizhou Bay, because of the influence of tidal current field, grain size of the bottom sediment particles is coarser in the area south of Guangli River estuary than the area north of that.