Of, relating to, or found in an area where a freshwater river meets the ocean and tidal influences result in fluctuations in the salinity of the intermixed waters.

A sedimentary deposit laid down at the head or floor of the wide part of a river where it flows into an ocean, and characterized by fine-grained, clayey, or silty sediments mixed with decomposed organic matter.

The physical conditions that characterize the mouth of a river where it connects with the open sea and fresh water mixes with salty ocean water.

The study of the physical, geological, chemical, and biological properties or characteristics of the wide parts of rivers where they come close to the sea.