estuary

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estuary

(ĕs`cho͝oĕr'ē), partially enclosed coastal body of water, having an open connection with the ocean, where freshwater from inland is mixed with saltwater from the sea. One type of estuary, called a drowned river valley, can be caused by crustal subsidence or a rise in sea level. Chesapeake Bay is one of the largest estuaries of this type in the United States and was formed during the melting of the Pleistocene ice sheets (see Pleistocene epochPleistocene epoch
, 6th epoch of the Cenozoic era of geologic time (see Geologic Timescale, table). According to a classification that considered its deposits to have been formed by the biblical great flood, the epoch was originally called the Quaternary.
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). Fjordsfjord
or fiord
, steep-sided inlet of the sea characteristic of glaciated regions. Fjords probably resulted from the scouring by glaciers of valleys formed by any of several processes, including faulting and erosion by running water.
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, or drowned glacial troughs, form similar types of estuaries, particularly in Norway, Alaska, New Zealand, and other glaciated, mountainous coastal regions. Salt marshes and lagoons found behind barrier beaches, such as along the south shore of Long Island, and down faulted sections of the earth's crust, such as San Francisco Bay, are additional types of estuaries. The shape of an estuary affects the height of the tide; some estuaries (such as the Severn and the Bay of Fundy) are characterized by a wavelike tidal borebore,
inrush of water that advances upstream with a wavelike front, caused by the progress of incoming tide from a wide-mouthed bay into its narrower portion. The tidal movement tends to be retarded by friction as it reaches the shallower water and meets the river current; it
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. Estuaries represent one of the most sensitive and ecologically important habitats on earth. They provide sanctuary for many species of waterfowl, store nutrients for larval and juvenile marine life, and serve as breeding grounds for many desirable species of ocean fish. Since estuaries commonly provide excellent harbors, most of the large ports in the United States (New York, Philadelphia, Baltimore, Mobile, Galveston, Seattle, and San Francisco) are located in estuaries. However, the development of high-density population centers causes deleterious effects that can destroy the very properties of the estuary that made development of the region possible. Human impact on estuaries includes reclamation of tidal land by filling; pollution from sewage, solid waste, industrial effluent, and hot water; increased sedimentation filling the estuary; and alteration of the salinity of estuarine waters by withdrawal or increased influx of freshwater. Increasingly, federal and state governments are passing legislation to protect estuarine environments.

Estuary

 

a single-channel, funnel-shaped seaward end of a river that widens toward the sea. Estuaries form in cases where the sediment carried by the river is removed by sea currents or tidal movements and the adjacent part of the sea is very deep. In such cases no sediment is deposited at the mouth, even if the sediment load is large. The Enisei and the Thames are two of the many rivers that have estuaries.

estuary

[′es·chə ‚wer·ē]
(geography)
A semienclosed coastal body of water which has a free connection with the open sea and within which sea water is measurably diluted with fresh water. Also known as branching bay; drowned river mouth; firth.

estuary

1. the widening channel of a river where it nears the sea, with a mixing of fresh water and salt (tidal) water
2. an inlet of the sea
References in periodicals archive ?
Five strains of Thraustochytriales were isolated from both, a saline continental environment and an estuarial one from Argentina.
Garcia V, Ojeda C (1995) Estructura del bentos en areas con enriquecimiento organico en el complejo estuarial de los rios Calle-calle, Valdivia y Cruces.
The benefit of Northumbrian Water's billion pound investment programme in coastal and estuarial sewage treatment works in the North-east, for example, is clearly demonstrated by the continued improvements in the quality of the region's bathing waters.
Burns Bog is a raised estuarial dome-shaped bog created when the super absorbent sphagnum moss allows the water to wick above the level of the surrounding land.
73 requires every person who is engaged in any capacity on a seagoing vessel of 200 GRT or more, engaged in the transport of cargo or passengers for the purpose of trade, and registered in a territory for which the Convention is in force (except wooden vessels of primitive build such as dhows and junks, fishing vessels and estuarial craft), to produce a certificate attesting to his fitness.
If estuarial environments can be restored, or even enhanced, these creatures will absorb tremendous amounts of carbon, and basically make it into rocks (limestone).
Rather than limit the consultation options for the Thames Estuary to a new airport at Cliffe Marshes, a range of estuarial options, including offshore Cliffe and Marinair, should have been--and should still be--fully considered and debated.
There are shocking examples from around the world where estuarial wetland communities have crashed when river flows disappeared into upstream irrigation.
First geographic types: insular, peninsular, estuarial and rivermouth settlements (with illustrative figures).
The result has been pollution of the estuarial areas with wastewater from the ponds (contaminated with chemical medicines and biological waste), causing advanced eutrophication of the estuarial zone, occasional fish kills and the spread of diseases into wildlife populations.
However, these problems are far from uniform: nitrates in surface water are a particular problem in intensive livestock-rearing areas of Flanders, less so in Wallonia, though Walloon rivers frequently fail to meet the water quality standards that would be required for their popular recreational uses, because of insufficient wastewater treatment facilities; a concentration of chemical and petrochemical industries near the border of Flanders with the Netherlands gives rise to trans-boundary issues, as does the flow into shared estuarial and coastal waters of the two major Belgian river systems; urban traffic problems are particularly acute and growing in Brussels.