A river plume is a freshened water mass that is formed in the sea as a result of mixing of river discharge and saline seawater. River plumes are formed in coastal sea areas at many regions in the World. River plumes generally ocuppy wide, but shallow sea surface layer bounded by sharp density gradient.
Area of a river plume is 3-5 times greater than its depth, therefore, even small rivers with discharge rates ~1-10 m/s form river plumes with horizontal spatial extents ~10-100 m. Areas of river plumes formed by the largest World rivers are ~100-1000 km². Despite relatively small volume of total freshwater runoff to the World Ocean, river plumes occupy up to 21 % of shelf areas of the World Ocean, i.e., several million square kilometers.
River plumes play an important role in global and regional land-ocean interactions. River discharge provide large fluxes of buoyancy, heat, terrigenous sediments, nutrients, and anthropogenic pollutants to the ocean. River plumes are characterized by strong spatial inhomogeneity and high temporal variability caused by external forcing and mixing processes. Regional features (delta/estuary, enclosed bay/open sea, shoreline, bathymetry, etc.) also significantly influence morphology and behavior of river plumes. River plumes strongly influence many physical, biological, and geochemical processes in the coastal and shelf sea areas including stratification of sea water, coastal currents, carbon and biogeochemical cycles, primary production, seabed morphology, etc.
- Steven Lohrenz. "River Plume Processes and Dynamics". School for Marine Science and Technology, University of Massachusetts, Dartmouth. Retrieved 2021-02-13.