Plume Dynamics of a Lateral River Tributary Influenced by River Discharge From the Estuary Head

Abstract

AbstractRiver plumes are important pathways for the transportation of terrigenous materials to coastal oceans. This study uses the Regional Ocean Modeling System to investigate the dynamics of a small river plume from a lateral river tributary discharging into an estuary. In particular, the plume is surface advected under buoyancy force alone, and the Earth's rotation helps to increase the plume's spread in a downstream‐biased pattern. Adding tides to the model changes the plume into a bottom‐advected one, and the plume is advected in an alongshore direction, with its spreading more upstream biased. Tide‐induced mixing and tidal advection are responsible for the changes in the plume structure, especially the tidal asymmetry between ebb and flood tides; the tidal residual circulation is insignificant. When river discharge from the estuary head is imposed, the plume is forced to propagate downstream extensively. This study offers insights into the transport and fate of riverine materials in tributaries that flow into semienclosed waterbodies.