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.

An estuary is a semi-enclosed coastal body of water which has a free connection with the open sea and within which seawater mixes with fresh water. The key feature of an estuary is that it is a mixing place for sea water and a stream or river to supply fresh water. A tide is a necessary force 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 carried in from terrestrial runoff. 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 and fjords. These can become estuaries if there is a stream or river flowing into them.

The Estuary is also a term used to describe the region of the River Thames 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

• Bay mud
• Brackish water
• Firth
• List of waterways

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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