|
<br />Pel(>7" E. BlIrkmll'l1l
<br />
<br />critical to d41r.Kkrizing ha"jc ;.:rouodwatL'r tluw of tht' t'mift"
<br />,Iquifn ~YS!t'm, btl1 it i~ :.11-;0 uilical to undt'NanJin;.: wdl
<br />perfnml.ann: in multi-bye-rt'J aquikr:-. Ttwrt. j;., uncert;Jinl~'
<br />about how the pr~:'<"nn: of bYl'rin~ \\"ithin l';I~h aquift'r will
<br />affn1 pumping cap"Kitil~ 111 individual wdl:. a:. rt"gional
<br />water k'n'ls drop Ix-low thl" top of Ih<: de:-.i~;llt-J aqllift'f", It
<br />i... r'l,:Ik'\'t'O th;H pUl11pin).: l':lpacity will be Tt'l.llKl'd r1llm: sig-
<br />nific.mdy th.m u}L"()ry would prt-tliL1 (Black ;md \i:atch. (.'1 ;II..
<br />20lJ.i), TIll:- ll:l" profound enmulllic r,unillc:.l1iorb on the
<br />O\'er.lll pert'onnann.' of \\':,uer "lIpply wdb. since r.Jpidly
<br />diminishint:: well yidds will nL'n:~"itu(.' in..tallin!ol. mort- well..
<br />and expandin).: tlw ~upporting infi.NnKtUft' in uf(lL'r to pro-
<br />duce .In ;,:qui\'.lknt \\JIUllU: of W;Ut"r; llL'n\'e. a lllUl'h higher
<br />unitt'o."t fOTwall"r.
<br />Rt'cenl ..imuLl!ions pert'ormnt ;1," P;1I1 of tht' -"otuh ,\ktro
<br />\'\'att'r Supply Study (Black and \'eatcb. d al.. 2(l(l.--/) included
<br />:1 ..;en..itiyity analy:-.is wheTt'in dlffeTI.'nt \'t'llic;d hyJr.Julit' \."(JO-
<br />ductiyit}' \'alLU,,".. of the ..h:lk Iayt'~ in ;1 lllulti-ltyeTt-tl aquiflor
<br />Wl'rl' IN;"(I in m;llh"1ll:11ical "imubtion" UM,--d tn pft"Jict how
<br />well pt'rt"ornuncc Illay dt'l.'lint' oYer tinK-" a," rt:~ional wateT
<br />ll:'\"\~ls dc'dine (!',llumbo, 200.H, Chan~\'~ of one or t\\'o
<br />l)f(lt:("..; of nu~niludt' in \L'rticd hydraulic conductivity
<br />rl'.<;ultt'd in wry <;i~nifiGmt ditll'rt:nct."s ill pn'tlit,ted well pt:'r-
<br />form:lI1ce a~ shown in Figuft. :;. Till.... reLuion..hip under-
<br />"cort's the 11~.t:d fur unJcf"tandin).: ;md qU:ll1!ifyin~ vcrticll
<br />hydrJ.ulit" l"fmdllcti\'ity throll~hout the aquifL'r ...y..ll'm
<br />
<br />VERTICAl. IfYllRAUJC CO:"liDccrnTIT
<br />~IfA<;l'Rt:.\II":l'.'TS
<br />
<br />111e hydrologic prop~.'rtil;'<; of e;Kh of the
<br />hl,t'n bidy well dOt"tHTIL'l1!ed (Rohson,
<br />
<br />aquifer.. h;I\-l'
<br />19Hj. 19H71.
<br />
<br />HOwt'\"\;'r, the chaT:lCteriza.tion of aquifer par.lllleters
<br />focusl":O- on thl' ahility of an :'lqllifer to yidd water to wells.
<br />or 10 tr..mspon watt'r lhrou~h till' aquift'r. Oire('t me-a5urt:'-
<br />Illt'ms on tht' scalI:' of an aquifer typically il1\'(llvt' pumping
<br />te..!:' whert'lll :lnalytiCal mt'thlxJ<; :llIow intt'f!)retation of
<br />dr.lwdown data to arrin' at t',stim:.lle.. of lran..mi-....,i\"ity,
<br />hydr.tulil' condUdinty, :lnd ~tor;lgt' capKit~' l-'loOft:'" 2002),
<br />It i... also po....ihlc to estimate: 1c::.lk:lj.W values for overlying
<br />confining unit.. (Lohman, 1972), Ho\\,\:\'er" the parameter:-
<br />arri\'t;;~d at thi:- \'I.'ay typicllly art:.' ;;lver.lge v,\lut's for an
<br />entir(.' ;Iquik'r, or al lea:o-t dUll pJn of the :.lquifer thai i.'"
<br />open to the well in which th... k:o-t i.<; l'ompl\:'tt'd, By nature
<br />of Ihl:' way tile' wdb are complt'tt'd in the Illulli-layert'd
<br />;Iqllifl'l"~ of th... De-H\ l'] B:'l:o-in, with many Jifferent wat(.'r-
<br />I)\.'aring sandstone' byers open to the \\'\,'11. it is not r()'''':-.i~
<br />hie to characterize individu;;tl by<:r..;.
<br />CharaCll'Tizing indiyidual byer... require.. mort' rohust
<br />tt'stin).: lllC'lhnds slldl a.. obt:JininK core s;lmples, perform-
<br />inK straddle-packer te..l.. O\'t'l" i...obll'd layer.. (Rohson and
<br />Banta. 199,3). or other tet:hnolngit''' including spinnt'r
<br />now ..ur..ep performed in lunlunClion wilh pumping
<br />tests and integtJted horehole logging melhod.. (Paillet
<br />:lnd Pedler" lo/X)). \'("hile the:o-L' melhod... may provide t'~ti-
<br />ll\;lle-.. of hydraulic ollldul"liYity for indi\'idu;;d w:lll'r-hl~ar-
<br />ing layers, tht--y still will not provide direl.t information
<br />;lbolJt the ..urrollndinjo! :o-h;;J1t- ill!L'Tvals, Funhermore, thl'
<br />results \\'(Juld provid~' e,qimales of horizonlal hydraulic
<br />conductivity, not n~nical.
<br />Direl:l II/-SIru mt';t<.,urement.s would pf{)\'ide the best rep-
<br />re~ntati\"l' dat;], Howt'\'t:r, pl'rrormlllg il1'SI11/ \'t'nical per-
<br />meahility Illeao,curt'mem.. on mdividua1 ..hale byers in :I hasin
<br />whert' depth.. (";;In reach :\000 It :lnd hydro~t.llic heall.. above
<br />
<br />Figure 5, M.llhemallcal model simulations used to
<br />predicI well reriormance in an individual well as
<br />water I('ve-I~ in a multi.layered aqtlifer decline
<br />using different varu~ for vertical hydraulic con- I
<br />ductivitv (Kvl show thaI very low Kv valu~ result
<br />in rapid'ly declining well yields Ix-cause Woller can- i
<br />nOI move downward through the entire aquifer. J
<br />From Palumbo, 2004,
<br />
<br /> 500
<br /> High Kv (cmlsec) 5.6)\ 10"'
<br /> 5,61110.a
<br />E 400 5,6111Q-1
<br />~ 5,6)\ 10-'
<br />.!!! 56111Q-1 2,81110"'
<br />. 300
<br />I!' ""-
<br />.
<br />~ Low Kv (cmlsec)
<br />u
<br />. 5,6111Q--
<br />5 200
<br />~ 5.6)\ 10"'0
<br /> 100
<br />
<br />o
<br />o
<br />
<br />2<l
<br />
<br />40 60
<br />Time in Years
<br />
<br />HRSW.tMConsulta.....Inc,
<br />
<br />TIll' Koch' .\tounI3ln ....."""0311nn <>/ (;"0101<"'-'
<br />
<br />]
<br />/
<br />I,
<br />I
<br />
<br />80
<br />
<br />100
<br />
<br />176
<br />
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