Grain Size Characteristics and Distribution of Typical Fluvial Sediments in Maoming City, Guangdong Province

To investigate the spatial distribution characteristics of sediment grain size parameters in the surface sediments of rivers, this study collected 115 surface sediment samples from eight typical rivers in Maoming City, based on the geographical environment and the course of the rivers in the city. The collected samples were analyzed using a laser particle size analyzer. The study revealed that only three particle size components, namely sand, silt, and clay, were detected in the surface sediments of rivers in the research area. Silt was identified as the predominant component, with all eight rivers exhibiting silt content exceeding 50%. The content of sand and clay was similar, both registering below 20% in the studied rivers; however, they displayed contrasting distribution patterns within the river systems. The average grain size of surface sediments in the study area falls within the range of 4.37 to 7.3φ, indicating a relatively small variation. The sorting coefficients range from 1.53 to 2.48, suggesting overall poor sorting. Skewness values range from-0.09 to 0.73, with most sediments exhibiting positive skewness. Kurtosis values range from 0.70 to 1.17, indicating a generally flat peak. Specifically, sediments from the Jianjiang River and Luojiang River demonstrate a trend of low sorting coefficients and large average grain sizes. In contrast, sediments from the Xiaodong River and Huanghua River exhibit a pattern of high sorting coefficients and small average grain sizes. The average grain size of the main stream of the Jianjiang River, midstream ＞ downstream ＞ upstream, showed a trend of increasing and then decreasing. The main stream of Huanghua River showed a decreasing trend in particle size, and the sediment tended to be coarse-end. The average particle size of Luojiang River main stream showed a decreasing trend, and the river flow was not easy for fine grain deposition. The conclusions of this study on the characteristics of particle size parameters and grain size distribution provide data support and theoretical reference for related studies.