Artesian aquifer

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Geological strata giving rise to an Artesian well.

See Great Artesian Basin for the water source in Australia.

An artesian aquifer is a confined aquifer containing groundwater that will flow upwards out of a well without the need for pumping.

1 Why is a well artesian?
2 Origin
3 See also
4 Notes

[edit] Why is a well artesian?

Image:Artesianwell.jpg

In recharging aquifers, this happens because the water table at its recharge zone is at a higher elevation than the head of the well.

Pascal's law predicts the theoretical hydrostatic pressure P:

<math>P = \rho \cdot g \cdot (z_\mathrm{recharge}-z_\mathrm{wellhead})</math>

where <math>\rho</math> (rho) is the density of the fluid, g the acceleration due to gravity, and z is the elevation. In practical terms the pressure is expressed as metres water column (z_r − z_w).

"Fossil water" aquifers can also be artesian if they are under sufficient pressure from the surrounding rocks. This is similar to how many newly tapped oil wells are pressurized.

[edit] Origin

Artesian wells were named after the former province of Artois in France, where many artesian wells were drilled by Carthusian monks since 1126 <ref>Frances and Joseph Gies, Cathedral, Forge, and Waterwheel subtitled "Technology and Invention in the Middle Ages". Harper Perennial, 1995 ISBN 0-06-016590-1, page 112.</ref> The technique was also known much earlier in Syria and Egypt<ref>For references on ancient uses, see: Michel Wuttmann, "The Qanats of 'Ayn-Manâwîr, Kharga Oasis, Egypt", in Jasr 2001, p. 1.
and Discoveries in the Western Desert of Egypt</ref> , although whether the monks of Artois learned of it from outside sources, or discovered it independently, is unknown.