Fine-grained sediment transport and sorting by tidal exchange in Xiangshan Bay, Zhejiang, China

Abstract

During the winter of 1983, 25-h measurements of current speed, flow direction, water depth and suspended sediment concentration were carried out at six stations located in the inlet section of Xiangshan Bay, during spring and neap tides. An analysis of the data obtained shows that tidal exchange, in the form of either vertical residual circulation or bay-mouth water mixing, is responsible for the observed net landward movement of suspended sediment, though the ebb currents are stronger than the flood currents in the inlet. The analysis suggests also that the tidal exchange processes, in combination with the settling behaviour of the suspended sediments and the morphological features of the inlet section, lead to marked sorting of the fine-grained sediments with the clayey material predominating in the inner part of the bay and the silty material in the outer part.