Estuary

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Estuaries and coastal waters are among the most productive ecosystems on Earth, providing numerous ecological, economic, cultural, and aesthetic benefits and services.
Estuaries and coastal waters are among the most productive ecosystems on Earth, providing numerous ecological, economic, cultural, and aesthetic benefits and services.

An estuary is a semi-enclosed coastal body of water which has a free connection with the open sea and within which sea water mixes with fresh water. The key feature of an estuary is that it is a mixing place for sea water and a significantly-sized river to supply fresh water. A tide is a necessary component to maintain a dynamic relationship between the two waters. Though something in the nature of an estuary can exist in a non-tidal sea, such areas go by names such as lagoon, étang or laguna. In non-tidal seas, the rivers naturally form deltas rather than estuaries.

An estuary is typically the tidal mouth of a river, and estuaries are often characterised by sedimentation of silt which usually comes mainly from the sea though in some cases, that from the river predominates. The sand and mud banks and marshes are relied upon as habitat by, for example, wading birds. Estuaries are more likely to occur on submerged coasts, where the sea level has risen in relation to the land, as this process floods valleys to form rias, fords etc, which can be classified as estuaries in cases where there is a significant river flowing into them.

The estuaries are sometimes confused with fjords. The Lim bay in Istria, Croatia (Limski kanal in Croatian), is often called "Lim fjord" although it was not actually formed by glacial erosion but by the river Pazinčica.


Estuary is also a term used to describe the region of the Thames River and adjoining communities east of Central London in the United Kingdom. The term 'Estuary English' is frequently used to describe the accent of the people in this region, though it has since spread across South East England. It is sometimes mistaken for the Cockney accent by listeners unfamiliar with the varieties.

See also

References

  • Pritchard, D. W. (1967) What is an estuary: physical viewpoint. p. 3–5 in: G. H. Lauf (ed.) Estuaries, A.A.A.S. Publ. No. 83, Washington, D.C.
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