Abstract:
Using on-site survey data from July 2019 and July-August 2020 in Zhejiang Province, combined with historical data, we systematically analyzed the characteristics of topological profiles, planar morphology, and surface sediment grain size of gravel beaches in various locations of Zhejiang Province. Meanwhile, using mathematical statistical methods such as correlation analysis, principal component analysis, cluster analysis, and non-metric multidimensional scaling,, the main factors affecting the development of the gravel beaches were explored, and the development pattern of the gravel beaches was elucidated. Results indicate that in the profile morphology, it can be seen that most of the gravel beach profiles are oblique line typed, and some of them have a beach berm. In planform, gravel beaches in the central Zhejiang sea area are relatively larger, have weaker headland, and thus the shielding ability is weak and undergo stronger wave action. In distribution pattern of sediment particle size, the gravel beaches north of Que'er Ao Island in the central Zhejiang sea area have coarsest pebbles and thicker deposits, while those in the central and southern Zhejiang sea areas have more prolate and club-shaped gravels. The gravel beaches in Zhejiang could be placed into three groups by cluster analysis. The first group is mainly seen in the central and southern Zhejiang, and is strongly affected by tidal currents. The second group is mainly distributed in the northern Zhejiang, with weaker tidal effects and smaller. The third group distributed more sporadically in the province and relatively coarser. The geological structure background, hydrodynamic environment, and sediment supply have important impacts on the formation process of the gravel beaches, among which the geological structure background is the main factor on beach development. For the ecological protection and ecological restoration regarding the gravel beaches, the influences of wave action and tidal action must be considered.