Quantitative and qualitative comparison of grain-size parameters in different types of sediments using graphic and moment methods

Previous studies have explored the differences in sediment grain-size parameters calculated using the Folk and Ward graphic method and the Friedman moment method. However, in terms of both quantitative and qualitative results for different types of sediment, systematic analysis of the consistency between two methods is still relatively scarce. In this study, we selected Leizhou Bay, Jiangsu tidal flats, and the Changjiang River Estuary as typical research areas, where a total of 608 sediment samples (surface sediments, short cores, and suspended sediments) from tidal flat and estuarine environments were analyzed. The consistency of the two methods in quantitative results of grain-size parameters and qualitative description was evaluated. The results indicate that in terms of quantitative parameters, the mean grain size and sorting obtained from the two methods show high consistency (R² ⩾ 0.91) across all three types of sediments. The skewness parameter of suspended sediments is significantly correlated (R² = 0.72), but the correlation for skewness in surface sediments and short cores is low (R² ⩽ 0.11). The kurtosis parameter shows low correlation across all sediment types (R² ⩽ 0.20). In terms of qualitative description of sediment grain-size parameters, the sorting consistency of suspended sediments reaches 100%, far exceeding that of surface sediments (72.81%) and short cores (69.23%). Additionally, the skewness consistency (77.10%) and kurtosis consistency (73.83%) for suspended sediments are also higher than those for surface sediments (50.87%, 52.34%) and short cores (65.38%, 55.77%). These results suggest that suspended sediments exhibit higher compatibility with both methods compared to surface and short core sediments, with better adaptability in both quantitative results and qualitative descriptions. However, the correlation of quantitative results still does not fully reflect the consistency of qualitative descriptions, especially as for skewness and kurtosis. This study provides a case involving various types of sediments, including surface sediments, short cores, and suspended sediments, helping deepen the understanding of the differences in grain-size parameters. The findings provide practical guidance for selecting appropriate sedimentological methodologies.