Vadose zone


Vadose zone

[
capillary fringe, water table, and phreatic or saturated zone. "(Source: United States Geological Survey.)"]

The vadose zone, also termed the unsaturated zone, is the portion of Earth between the land surface and the phreatic zone or zone of saturation ("vadose" is Latin for "shallow"). It extends from the top of the ground surface to the water table. Water in the vadose zone has a pressure head less than atmospheric pressure, and is retained by a combination of adhesion ("funiculary groundwater"), and capillary action ("capillary groundwater"). If the vadose zone envelops soil, the water contained therein is termed soil moisture.

Movement of water within the vadose zone is studied within soil physics and hydrology, particularly hydrogeology, and is of importance to agriculture, contaminant transport, and flood control. The Richards equation is often used to mathematically describe the flow of water, which is based partially on Darcy's law. Groundwater recharge, which is an important process that refills aquifers, generally occurs through the vadose zone from precipitation.

In speleology, cave passages formed in the vadose zone tend to be canyon-like in shape, as the water dissolves bedrock on the floor of the passage. Passages created in completely water-filled conditions are called phreatic passages and tend to be circular in cross-section.

See also

*Aquifer
*Groundwater
*Water retention curve

References

*
*

Further reading

*web cite | url = http://vzj.scijournals.org/ | title = Vadose Zone Journal | accessdate = 2006-07-01


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  • vadose zone — ▪ hydrology       region of aeration above the water table. This zone also includes the capillary fringe above the water table, the height of which will vary according to the grain size of the sediments. In coarse grained mediums the fringe may… …   Universalium

  • vadose zone —    1. The zone between the land surface and the water table [22].    2. The zone between the land surface and the deepest water table which includes the capillary fringe. Generally, water in this zone is under less than atmospheric pressure, and… …   Lexicon of Cave and Karst Terminology

  • vadose cave —    1. A cave that underwent most of its development above the water table. Within the vadose zone, drainage is freeflowing under gravity, and cave passages therefore have air above any water surface. The gravitational control of vadose flow means …   Lexicon of Cave and Karst Terminology

  • vadose water —    1. That part of the underground water in a karst limestone which circulates freely under gravity above the level of saturation the vadose zone. Caves formed by flowing water are said to be vadose caves [19].    2. Water in the zone of… …   Lexicon of Cave and Karst Terminology

  • zone of aeration —    The zone in permeable soil or rock that is above the zone saturated with water; the zone of vadose water [10].    See also vadose zone …   Lexicon of Cave and Karst Terminology

  • vadose — /vay dohs/, adj. Geol. found or located above the water table: vadose water; vadose zone. [1895 1900; < L vadosus shallow, equiv. to vad(um) a shoal, ford + osus OSE1] * * * …   Universalium

  • vadose — adjective Of or pertaining to water beneath the surface of the earth which is located above the level of the permanent groundwater. Research has shown bone apatite to undergo chemical exchange with carbonates in either vadose water or groundwater …   Wiktionary

  • vadose — va•dose [[t]ˈveɪ doʊs[/t]] adj. gel found or located above the water table: vadose water; vadose zone[/ex] • Etymology: 1895–1900; < L vadōsus shallow …   From formal English to slang

  • vadose shaft —    A vertical tube in the vadose zone that may be a few inches to several feet in diameter and may be a few feet deep to hundreds and over a thousand of feet deep. They commonly occur as complexes. A drain hole is usually evident at their base.… …   Lexicon of Cave and Karst Terminology

  • vadose — [vā′dōs΄] adj. [< L vadosus, shallow < vadum, shallow place, ford, akin to vadere, to go: for IE base see WADE] designating or of water that clings to solid matter in an unsaturated zone between the earth s surface and the water table …   English World dictionary