Grain Size and Shape Analysis as Indications of Sediment Transport in a Headland Bay Beach

［Objective and Methods］The basic properties of sediment particles（grain size and shape）provide infor⁃ mation about their transport history，mode，and sedimentary environment. The grain size and shape of 253 sediments from 52 beach profiles in Baoding Bay were analyzed using the dynamic image method. The cross-shore and longshore distribution characteristics of the grain size and grain shape are analyzed and discussed. A trend analysis model was established for grain size and shape.［Results］The grain shape in exposed，intermediate and sheltered parts of the Baoding Bay beach show little difference longshore，but there is a trend of gradually decreasing size from land to sea cross-shore. When the size of the grains in different parts of the beach is less than 2.5 Φ，their shape gradually shows a downward trend longshore from the exposed section to the sheltered section. The grain-shape increase direction indi⁃ cates the transport trend of the sediment. The grain-shape trend analysis model is highly accurate and useful for calcu⁃ lating the transport trend of any grain size range，and works well in combination with other grain-size analysis methods for different research purposes.［Conclusions］The results of the study provide theoretical support for beach evolution mechanism analysis and beach stability research.