Effects of swell waves on the dynamics of the estuarine turbidity maximum in an idealized convergent partially mixed estuary

Abstract

The dynamics of estuarine sediments plays a key role in the morphological evolution, water quality, and ecosystem health of estuaries. Estuarine turbidity maxima (ETMs) are ubiquitous in estuaries worldwide and have drawn enormous attention from researchers. Here, we use a coupled ocean–atmosphere–wave–sediment transport modeling system to examine the effects of swell waves on the location, extent, and suspended sediment concentration (SSC) of ETMs in a convergent partially mixed estuary. Our results reveal that swell waves influence the residual circulation, mixing, and bottom stress in the estuary. The wave–current interaction increases the bottom stress in the estuary but reduces mixing in the lower to middle reaches of the estuary, owing to the enhanced landward salt transport, and the increased stratification. The reduced mixing enhances the estuarine circulation in the middle reach of the estuary. These changes cause a landward shift of the primary ETM and an increase in the SSC in the lower estuary. Moreover, the Coriolis force changes the ETM distribution and influences the wave effects. Overall, the findings of this study further elucidate ETM dynamics in an estuary. • Swell wave advects more saline water in the estuary and increases stratification. • Wave-current interaction increases the bottom stress in the lower estuary. • Swell wave causes a landward shift of the primary estuarine turbidity maxima (ETM).