water table


water table
   1. The top surface of a body of slowly moving ground water that fills the pore spaces within a rock mass. Above it lies the freely draining vadose zone, and below it lies the permanently saturated phreas. In uniform aquifers, such as sandstone, the water table is a smoothly contoured surface intersecting the ground at rivers and lakes, but in limestone it is more complex. Individual cave conduits may be above or below the water table, and therefore either vadose or phreatic, and the water table cannot normally be related to them. The water table concept does, however, apply to the diffuse drainage of percolation water in the micro-fissure network of limestone, but its detailed structure may be complicated by the presence of conduits. The watertable slope (hydraulic gradient) is low in limestone due to the high permeability, and the level is controlled by outlet springs or local geological features. High flows create steeper hydraulic gradients and hence rises in the water level away from the spring. In France’s Grotte de la Luire, the water level in the cave (and therefore the local water table) fluctuates by 450m [9].
   2. The upper surface of a zone of saturation except where that surface is formed by a confining unit [22].
   3. The upper surface of the zone of saturation on which the water pressure in the porous medium equals atmospheric pressure [22].
   4. The upper boundary of an unconfined zone of saturation, along which the hydrostatic pressure is equal to the atmospheric pressure [10].
   See also potentiometric surface.

A Lexicon of Cave and Karst Terminology with Special Reference to Environmental Karst Hydrology. . 2002.

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  • Water table — Wa ter ta ble 1. (Arch.) A molding, or other projection, in the wall of a building, to throw off the water, generally used in the United States for the first table above the surface of the ground (see {Table}, n., 9), that is, for the table at… …   The Collaborative International Dictionary of English

  • water table — water tables N COUNT: usu the N The water table is the level below the surface of the ground where water can be found. Environmentalists say that diverting water from the river will lower the water table and dry out wells …   English dictionary

  • water table — water .table n technical the level below the ground where there is water …   Dictionary of contemporary English

  • water table — water ,table noun count the level below the Earth s surface where water is found …   Usage of the words and phrases in modern English

  • water table — ► NOUN ▪ the level below which the ground is saturated with water …   English terms dictionary

  • water table — n. 1. the level below which the ground is saturated with water 2. Archit. a projecting ledge or molding which throws off rainwater …   English World dictionary

  • Water table — The water table is the level at which the ground water pressure is equal to atmospheric pressure. It may be conveniently visualized as the surface of the ground water in a given vicinity. It usually coincides with the phreatic surface , but can… …   Wikipedia

  • water table — 1. the planar, underground surface beneath which earth materials, as soil or rock, are saturated with water. 2. Archit. a projecting stringcourse or similar structural member placed so as to divert rain water from a building. Also, watertable.… …   Universalium

  • water table — noun underground surface below which the ground is wholly saturated with water spring rains had raised the water table • Syn: ↑water level, ↑groundwater level • Hypernyms: ↑geological formation, ↑formation * * * noun, pl ⋯ tables [count] …   Useful english dictionary

  • water table — UK / US noun [countable] Word forms water table : singular water table plural water tables science the level below the Earth s surface where water is found …   English dictionary