SPATIO-TEMPORAL DISTRIBUTION AND VARIATION OF SUSPENDED SEDIMENT BY THE ACTION OF TIDE IN PENGLAI COASTAL AREA

The change in suspended sediment concentration of a water body is an important manifestation of sediment movement, which may objectively reflect the difference in hydrodynamic environment. Using the measured data of nearshore current as well as the suspended sediment from the Penglai area, this paper concentrates itself into the temporal and spatial distribution patterns and variations in suspended sediment concentrations in the area, and their response to tidal current. Results show that the average sediment concentration in the ebb tide period is usually larger than that in the high tide period, and that in the spring tide is larger than that in the neap tide. The cyclical fluctuation of the suspended sediment concentration in different layers is stronger in the spring tide rather than in the neap tide. The periodic change in the suspended sediment concentration on a scale of 9 ~ 16 h in the study area is same as the global. With regard to the spatial distribution, the average suspended sediment concentration increases from the surface to the bottom. During the spring tide, the vertical gradient of the suspended sediment concentration is the smallest in the Island area, but the largest in the Strait area. However, suspended sediment concentration in a neap tide is the smallest in the west but the largest in the east area. And the vertical distribution of suspended sediment concentration is in an exponential and linear relationship with depth. In a tidal cycle, the largest average suspended sediment concentration is at the Island area, followed by the Strait area, with the western region as the smallest. There is a good correlation between the suspended sediment concentration and the tidal current velocity. When the current velocity exceeds 40 cm/s, significant resuspension will occur.