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<br />GROUND.WATER RESERVOIRS WITH PERENNIAL OVERDRAFT
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<br />51-o.oge p.og,euively deplele-<f
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<br />A.eos of enuooc,",menl of ,,,fe.iot ""0101"
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<br />Ilemed,ol mea.u,es undertol.en 10 balance d.off and .eplenlshment
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<br />.nsvff,cienl dolO 10 be ce'loln thaI o...,d<oft u..t~
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<br />FIGt'Rf: 7--Ot'udrawn CTound,!('atn rnuvoiTs in fi' ntnn Slatn.
<br />(Fr"", pnu..", ",,,'.r "",,, lI)' R_ 1:, T....."., T~~ ('""u~n.Il.... 01 O~o"..d Wdr~~: .\'rv- y....t, Jlrl}~ftV- 1/11I ro.)
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<br />gu..h from the pun("turc hole. The water in the
<br />hose has lxTn confined under prcs.~lIre and is
<br />rdt'ased b} .he accidental P,lfl("tUH'. In tht" same
<br />way. if an aquifer confined under pf(':'i,.~urr:- })('-
<br />tw~en layef"!' of impt~mleable rock is pierccd by a
<br />well. watt'r will ri1<o(" abon- thl.' top of the aquiCcr
<br />and may e\'en flow from the well ~pont.ant-ou.Jy
<br />(fig. 6). ,,'ater confined ill this way i~ So,id to be
<br />under nT/Ulan P'I'HlHI'. and the aquifer i.. called
<br />an artesian aquila.
<br />The word artesian come!' from the town of
<br />_\rtois in France. the old Roman cit\ of .-\rtcsium.
<br />It wa,. at .-\rtois that Ihe be-t known flowing
<br />artesian wells were drilled in the ~(iddI(' Age:.
<br />Deep wcll~ bored into rock to intef"('cl the
<br />water tahle and rl'ach far below it arc often called
<br />artesian wells in ordinar: COll\'ersation, but thi..
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<br />i~ an incorrect u~e of the term. Such deep wcll~
<br />are jlLq like ordinar:' welk The word artl'sian
<br />can be properly u"ed only wh~n the water is un-
<br />der pre."",ure_ and the aquifer is confined between
<br />layers of impenneahle rock,
<br />When .'{fOund water is not confined under
<br />pr~"ure. we describe it as occurring und~r watl'T-
<br />table conditiom. For practical rea."Om hydrolo-
<br />gists need to know whether thcy are dealing with
<br />water under arte;ian or water-table condition....
<br />Generally. we can assume that artesian water i..
<br />continuous for some di~tanf(: under the confining
<br />layer of rock. and that it i~ repleni..hed ~me dis-
<br />lanc~ away. Cndcr wat~r-tab1e conditions_
<br />ground water i~ recharged locally and i" more
<br />immediately rC'iponsiw tD precipitation. In ~en-
<br />eral. an artesian supply i.~ I~ reliable fDr long,
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