The Formation of Coastal Turbidity Maximum by Tidal Pumping in Well-Mixed Inner Shelves

Coastal turbidity maxima (CTMs) have been recognized on open coastal seas with elevated suspended sediment concentrations. Tidal pumping is often considered the major contributor to turbidity maxima in well-mixed estuaries. However, its role in CTM formation on well-mixed coasts remains unclear. Here, we propose a two-dimensional depth-averaged analytical model to explore residual sediment transport influenced by interactions between cross-shore and along-shore tidal currents. Observation data collected on the well-mixed central Jiangsu coast (southern Yellow Sea), China, are analyzed by the model. The results display a persistent CTM close to the shore and show that the large along-shore tidal velocity strongly influences the cross-shore tidal pumping flux. The model calculation presents landward tidal pumping flux under horizontally homogeneous bed sediment distribution, illustrating the dominant role of tidal pumping in CTM formation within well-mixed coastal water bodies. The model suggests that the significance of alongshore tidal current to cross-shore sediment transport should be addressed in similar coastal environments.