Plume-to-plume interactions in the Pearl River Delta in winter

Abstract

River plumes are important carriers of terrigenous materials being transported into coastal seas. Previous studies of river plumes focused on large and single river plumes and paid less attention to the plume-to-plume interactions among the small river plumes. In this study, we used the ROMS (Regional Ocean Modeling System) model to study the plume-to-plume interactions in the Pearl River Delta area during wintertime, when the river discharge is relatively low and downwelling-favorable winds prevail. During the wintertime, the river plumes inside the Pearl River Estuary are well developed, and their interactions are extensive. Both the downstream and upstream plumes affect each other, and the interactions include both barotropic and baroclinic effects. The barotropic effects of a sub-plume could repel or suppress the spread of other plumes into its territory, but with limited spatial coverage. The baroclinic effect (buoyancy input) could alter salinity stratification, generate current fields, and greatly influence the dispersal of other sub-plumes over a broader spatial extent. The river plumes in the Pearl River estuary further affect the dispersal of waterborne materials in the downstream Modaomen estuary. Our results have distinct implications for regional environmental management.