Intertidal flats represent an important deposition environment and there is a close relationship between the hydrodynamic and sedimentary conditions and the evolution pattern of the coastal profile characteristics. In the present contribution, we report the coastal profile characteristics of two transections in the northern Yellow River Delta (i.e. the Yellow River mouth area from 1964 to 1976). Levelling of the profiles and sampling in 100 m interval were carried out along the profiles. The Profile P1 is 1175 m in length (along which 13 surficial sediment samples were collected) and Profile P2 is 2250 m in length (23 samples collected). We analyzed these samples with a Cilas 940L laser particle size analyzer) and computed their grain size parameters (i.e. mean grain size, sorting coefficient, skewnness and kurtosis).The result shows that from the mean high water level (MHWL) to the mean low water level (MLWL) the sediment becomes coarser and better-sorted. The skewness is decreased, whilst the kurtosis is relatively stable. These observations indicate that the sediment has a unified source. The general characteristics described above are consistent with those of the Jiangsu intertidal flat. Along both profiles there are significant changes in the grain size parameters in the places where small wave-eroded cliffs are present. Likewise, along Profile P2 the grain size parameters change rapidly at a distinct elevation; this pattern differs from that of Profile P1 where grain size parameters changes are not well correlated with the elevation. Such a difference may result from the difference in the intertidal zone width.

In addition, over the northern part of the Yellow River delta, the grain size distribution patterns show some temporal variations from the early 1980s to the present time following the shift of the Yellow River mouth towards the south in 1976. This may be a response to wave action. Furthermore, spatial changes in grain size from MHWL to MLWL observed in the study area may be a result of different hydrodynamic processes from those observed elsewhere. For instance, on the Jiangsu coast, the spatial variations in sediment size over the intertidal flat are caused by hydraulic sorting mainly by tidal currents, but at the Yellow River delta the changes are largely due to wave modifications.