Aquifer
permeable rock containing groundwater
An aquifer is an underground layer of water-bearing material consisting of permeable or fractured rock, or of unconsolidated materials (gravel, sand, or silt). Aquifers vary greatly in their characteristics. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology. Related concepts include aquitard, a bed of low permeability along an aquifer, and aquiclude (or aquifuge), a solid and impermeable region underlying or overlying an aquifer, the pressure of which could lead to the formation of a confined aquifer. Aquifers can be classified as saturated versus unsaturated, aquifers versus aquitards, confined versus unconfined, isotropic versus anisotropic, and porous, karst, fractured, or transboundary.
Groundwater from aquifers can be sustainably harvested by humans through the use of wells. This groundwater is mainly used for agricultural purposes but is used for other reasons such as home or industrial use. Groundwater is a major source of fresh water for many regions, although it can present various challenges for the environment, such as overdrafting (extracting groundwater beyond the equilibrium yield of the aquifer), groundwater-related subsidence of land, and the salinization or pollution of the groundwater.
Etymology
The word aquifer is derived from the latin prefix aqui-, the combining form of aqua meaning "water," and suffix -fer, meaning "bearing."
Properties
Depth
Aquifers occur from near-surface to deeper than 9,000 metres (30,000 ft). Those closer to the surface are not only more likely to be used for water supply and irrigation, but are also more likely to be replenished by local rainfall.
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This entry incorporates text from “Aquifer” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.