Keywords: 
• grain-size characteristics /
• sedimentary environment /
• grain-size trend analysis /
• coastal waters of Shantou City

Abstract: Grain size analysis and parameter calculation have been carried out based on 70 surface sediments collected from the coastal waters of Shantou City, and characteristics of frequency distribution have been researched. The results show that the surface sediments of the area are made up of 9 kinds of sediment types, the main types are clayey silt, sandy silt and sand-silt-clay. The content of gravel, sand, silt, and clay in the surface sediments is 1.4%, 29.2%, 51.0 %, and 18.4 %, respectively. The mean grain size of sediments in this area is 0.12~7.30  and the average is 5.53 . The coefficient of sorting is 0.50~2.94 and the average is 1.82. Skewness is -0.65~0.30 and the average is -0.02. Kurtosis is 0.63~2.67 and the average is 1.11.  The modern sedimentary environment in coastal waters of Shantou can be classified into 4 types by system cluster analysis and factor analysis. Spline interpolation method was employed to the data of grain size parameters over the study area. Then, the sediment transport trends were simulated by using GSTA (Grain Size Trend Analysis) model. The grain size trends analysis shows that: In Shantou harbor that the water depth ＜10 m, sediments from the runoff and sea were converged to the estuaries and offshore; Sediments in Shantou harbor that the water depth ＞10 m are transported towards the northeast along the coast. In Zhelin Bay, the sediments’migration trends are from coasts/islands to bay. This pattern is highly consistent with the provenance of sediments and the local hydrodynamics, which could be applied to the decision-making in port and waterway engineering.