Theory question 304
Underground Water and Karst(a) What is an artesian well? (b) Highlight four conditions that favour the formation of an artesian well. (c) Outline two usefulness of an artesian well.
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(a) An artesian well is a well from which water rises to the surface by its own pressure, from a permeable layer trapped between impermeable layers.
(b) A permeable rock layer (aquifer) sandwiched between two impermeable layers; the layers form a basin (syncline); the aquifer is exposed at the edges in a rainy area where water can enter; the well is sunk at a point lower than the intake area; adequate rainfall; the aquifer is not broken by faults that let water escape.
(c) Water for domestic use; irrigation; water for livestock (e.g. Great Artesian Basin, Australia); water for industry; supply in dry areas.
Draw or describe the basin structure.