Transport, retention and transformation of material in Australian estuaries

Australian estuaries can be classified into five groups on the basis of their hydrology: Mediterranean, Temperate, Transitional, Arid Tropical and Subtropical, and Wet and Dry Tropical and Subtropical. Most Australian estuaries (68%) are wet and dry tropical and subtropical systems. The five groups of estuaries found in Australia are similar to those found in other parts of the world, but within each individual category the estuaries are more variable. This variability reflects a combination of the extreme hydrology of Australian rivers and the geomorphology of Australian estuaries, which are shallow due to tectonic stability and low coastal relief. Episodic freshwater flows control the transport, retention, and transformation of material in most Australian estuaries, and for only a small part of the year during high flow events do most Australian rivers and estuaries contribute a significant amount of material to the continental shelf. Research and monitoring efforts need to be directed toward evaluating the role episodic freshwater discharges play in the functioning of Australia's estuaries.