|
<br />'1-.. l'\"'"
<br />~
<br />, .
<br />
<br />Ne..... Mexieu .md the luwer-basin stalL'S
<br />uf NL'vada. An/ona. and California as
<br />determined intheColorado Ril er Compact
<br />Ill' 1922. Calendar-year nll....- \olumL's
<br />rre~ntt'd in Figure .lE were eomnined
<br />from three dOlta M:h lhal were measured
<br />or eSl1mateJ using different tl"Chmt.jues.
<br />The prima!)' dala for the Colorado
<br />Ri\er at h'e\ Fl'rTV were colle<:ted
<br />from the Sian of slrc~mtlow gaging in
<br />192.\ through 19h::!, (In.: year before
<br />Ilow regulatmn bc.'gan at Gkn Canyun
<br />Dilm. From IlN5 through 1922, we U\.:
<br />annual now \'lIlumcs al u'c's Ft'rry that
<br />wen' l'~tllllaled hy LIRuc ( I 'J25, p. JO~).
<br />From IlJ6.1 through ::!003, "I.'
<br />a'>.\umc Ihal 110w at I.CC'\ FeIT) can
<br />t>c appmximaled a.\ Ihe sum of flo"
<br />\Illumes of the principal ri\e~ !lowing
<br />into Lake Powell, hum 1950 Ihmugh
<br />19h2, comparhlln of lhcse lI1110ws
<br />with measured tlow al I.eo.:'s Ferry
<br />indicaled thai the inllow was on a\erage
<br />2'}(J.(X)() acre.ket rer year less than the
<br />mea~ured now (ahout 2'k of annual now
<br />m]ul1le). ..\llhuugh this is well within
<br />measurt'lllenl ,'TTor of gaging slatlOns,
<br />we u.ed th.' simple linear regr.'ssioll,
<br />
<br />Q'I = /.(J.N' Q... - 0./6,118. (R: =: O.f,lIJf)J
<br />
<br />wht're Ou =:annual 1111\1" vlllurlll:aILe,'\
<br />FeTTY and <2", =: annual mllnws tll L,J.kc
<br />Powell, h) irlCrl'a'l' the ml!..!"s 10 Lake
<br />Powdl for the p,,.'nod of 1963 thrnugh
<br />2003. Wcalsnesli11latcdannua] \OIUllIl'S
<br />for the pt.'ak TUJlnll seast'n of Apnl
<br />thmugh July (Fig. JF) for ] 9::!_~ Ihrou!!h
<br />21XB (LIRue (1925) did not ,',umate
<br />lll(,nth]y volu11l\'s).
<br />The linll' Sl'ne' of UIlW H,lullll'S (Fig.
<br />3E+) ,how, that tho.: aver.!ge annual
<br />\olumc h 12:.4 MAF fwm 1~\)5 through
<br />21MB. This vlllum,' b ks, than the mor,'-
<br />commonlv quot,'d annual v.olume III
<br />15.] ~IAf; t>cc3use ,)ur analy,\'s do nllt
<br />indude wat.:r Ihat is ~('Jl\umrll\'Cl~ u'ed
<br />in tho.: upper ha.'1Il 'latC\. This usage is
<br />panially reJ1e~led hy' r.'grl'sslun of annual
<br />and sea'onal (.'\pril thr\lugh July) flolA-s.
<br />whil'h indlC3h: lhal now \olumes in
<br />the Col.'rado Riwr .II I.ee\ FeIT). haw
<br />decreased h~ ahout 0.5 ~1:\F/dl'~ade
<br />l'l\lm IK95 thwugh .:!:t.lt).1 rFip. -,E, .~F).
<br />TIll' pt.'mlli I'JIJ5 to 1'J22, \-\ohi\'h
<br />wa, used 1\1 e'llmale water produt:ll\ln
<br />a!tncalcd under the Colorado Rl\,'r
<br />CI'mpa~I, ha,1 Ihe high",t long'll'rm
<br />annual n.}W \olume III the 2()<1> ~I'IIIUI},
<br />averagmg 16.1 milh\ln ;1\'re fel't \~IAF)
<br />.II I.o.:e's Fe~ The highcq annual 111,\1.
<br />wlume .X'\'urTed m IWi-l (22_1 .\IAFI.
<br />and the highe,t thn:e'~"ar a\l'r.!ge j, 20..'
<br />~1AF fl'r IWP-19X5. Th.: ],mesl annual
<br />11Iw, \'ulume " 3.~ MAFm 2{)(}2, folkw.ed
<br />tw _~.<) ~IAF In 19.'4 ;md 4.X MAF 1Jl
<br />1977. Th.' ('arl~ 11- ':"lI1ul)' drought IS
<br />
<br />.
<br />
<br />1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
<br />,
<br />
<br />A. Annual 501 (dimensionless)
<br />
<br />:~ C^l-t-
<br />
<br />2
<br />1
<br />o
<br />-1
<br />-2
<br />0,.
<br />03
<br />0,0
<br />'0.3
<br />-0.6
<br />.
<br />
<br />
<br />
<br />D. Utah state PDSI (dimensionless)
<br />
<br />,
<br />o
<br />-,
<br />-.
<br />2'
<br />20
<br />I.
<br />12
<br />8
<br />,
<br />o
<br />,.
<br />
<br />
<br />E. Colorado River annual flow (MAF)
<br />
<br />
<br />-lotRUl'lt92S)
<br />_let'~rt"ry
<br />-lotkt'Powt'ltinflow
<br />
<br />F. Colorado River
<br />April-July Ilow
<br />(MAF)
<br />
<br />12
<br />
<br />
<br />8
<br />
<br />,
<br />
<br />o
<br />1890 1900 19]0 1920 1930 1940 1950 1960 1970 1980 1990 2000
<br />
<br />Figure 3. Graphs shOWing mdlces of global climate and annual lIow volumes of the
<br />ColoradO River Irom 1895 through 2003. A Southern Oscillation Index (SOl). B. PaCllIc
<br />Decadal OSCIllation (PDO). C. AtlantiC Multdecadal OSCillation (AMO). D. Palmer Drought
<br />Seventy Index (PDSI) lor Utah. E. Annual/low volume. F April.July /Iow volume. (A.D are
<br />dimensionless; E and F are In mIllions of acre-feel).
<br />
<br />thc mH'1 "C\erc IIllerm\ l,f 11."" deficll III
<br />more than a .:cllluf)'. The ,.urrent drought
<br />alsl' h.h pr,lliuced the It,,,,cs! 110\-\0 pcrillli
<br />III th,' r.'cord, \-\ollh an ;I\t:~rage .,1' onl)'
<br />5A ~L\F fllr 20111-2011_lln contrast,th,'
<br />drought of the Du'! 80v.1 )eaJ'i t>ctw,'en
<br />I~.~O ;lnd 1~.~7 rrtlliuu'd an .J.\.'r;lfe uf
<br />10.2 .\IAF TIl<: predl.:ll'd m1\u" IIltll
<br />l...a~e Pnwdl for 2fX)4 is 4l)~ of the II'ng-
<br />
<br />lerm a\Crage (5.t> MAFl. ",hich llldicalc,
<br />lhat tht, ,'arly 21" ,'elllury droughl is
<br />on-g'llIlg (~kCai'>c and OIhcrs, 2()()..1.1.
<br />
<br />Colorado River Flow and
<br />Multidecadal Climate Variability
<br />
<br />Cull'raJ,1 RI\Cr 11.,,,, " rcbleJ to
<br />
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