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<br />
<br />Climatic Fluctuations, Drought, and Flow in the
<br />Colorado River
<br />
<br />Introduction
<br />
<br />Climatic nUClualiiln~ h;l\'c prufounJ
<br />cffcl;lS on Waler n:sources in Ih... western
<br />United Slalt:s (Fig_ I). In Ih!.' arid and
<br />semiarid pans of tht' Soulhwc~l, climatic
<br />lIucluallllns afh't'[ many hydrologk
<br />charil1:lcrisln:s of waltnhcds. induJing
<br />the quantity llf na!>C flnw, the occurrence
<br />Ill" large Hoods, and the liming of
<br />snowTlIch runoff (Cayan and others.
<br />1999; Stewart and others, 20(4). Sincl'
<br />the start of a fX'rsiSh'llI dmu~hl in ahnUI
<br />the year 20CH), inllows In Like Powell
<br />on the Colprauu Ri~cr Il.I\'l' bn'n hdo....
<br />average. leading 10 Jrawllown of 1'Il.llh
<br />Lakes :\lcaJ and powdl. the primary
<br />l1ow-rcgulalloll structures on the riwr
<br />O-jg. 2). The rc..:cnI drought. rdcITcd 10
<br />here as tht' loarl)' 21" n.'nlury Jrnught.
<br />has ils ongin~ m scswal glllhal-s..:ak
<br />atmllspheric ;tnd on'anic prn..:esses thaI
<br />rcdu..:c ddin:ry 01 almospheric nllll~ture
<br />10 Ihe Cul"radn Riwr ha,m. Thl,.'
<br />purpose o( lhis Fal'l She!."t is h) dis.;uss
<br />the l'au'il'S of dnlu1-!hl in Iht' (,plnrad.)
<br />Riwr ha..,in and Ihl' predil'tahilily uf
<br />rivt'r lltw.s USlII!! !!Iobal dlm;\lt' llldil'l'~,
<br />
<br />Sources of Moisture to the
<br />Colorado River Basin
<br />
<br />Prccipitalllln IS bisl'asonal (wmll'r and
<br />SUnlTllCrj in lhl' C\lIUr;ldo River ha'lIl (Fig,
<br />I) on the C"I(lTad" Plaleau (Hndord
<br />and othns. 20(2), In Ihc hl.ad....atns
<br />prl'..:ipilall,m is l'\lonl)' di.'lTIhuted al"rus~
<br />the four ~l'a~IlIlSo m(l,tl~ al'l'umulalmg in
<br />slIllwp..d;,. ....II.1I'lur..: ":llml'S Irom ~tOH~r,11
<br />'Ilur..:es (Fi~, II. Fronl.!1 ,)',ll"lIIS III
<br />Wlnler and 'pnng ongmall' in thl' Nllnh
<br />P..nlie ('h:ean ;lIld pronde tht' largl.~t
<br />;lIId mO~1 imp"r1am ,nurce 01 mlll\luw,
<br />The~c ~Ht..:ms ll'nd tn tOam mOisture
<br />al high ol,'sd, 111 thl' alllll,,'phere. and
<br />prCClpllall,lII I' "mgraphK', ml'al11ng
<br />II mnca."'S ....l1h l'1e1.-allOn 11\ Ihl'
<br />l\It1unlain,lu, \V,,~1. Culd fronlal ~yslem~
<br />producc suh'tilnllal amounts ,ll' sn"....
<br />aOtHeal'll'uI5.{)1I11It'ct..ndralnfallal
<br />lown dnallOns in thl' RflCky, Llmla, and
<br />Wind Rlwr ~l(lUfllalm, ....hlch arl' lh,'
<br />h..:otd....al<:r' "I the C'ul..raJ" RI\,or .mJ
<br />It' pnnnp.ll lnNllaf) , thc (;rl'l'n Riser
<br />
<br />us [)epanl"'e"lof!lleIMBflOf
<br />us GeoIogoeal s~'W)/
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<br />
<br />WinTer ,.:::...
<br />~,.~.., ~
<br />Sy\lem~
<br />
<br />-
<br />'--
<br />. ..
<br />,
<br />
<br />~
<br />
<br />W"m /f
<br />Wmler
<br />Storm\,
<br />Tropl(al
<br />C)'tlont's
<br />
<br />''4~
<br />'-~ :mm..
<br />I ~(H'~n
<br />
<br />,w
<br />
<br />"-
<br />
<br />.--
<br />
<br />.........
<br />
<br />.,'-
<br />,
<br />
<br />Figure 1. MOisture sources 10 the Colorado River baSin.
<br />
<br />Thesc Monns huilll Srlllwp.ll:h that mell
<br />in the latt' ~pnng. rf\Jviding TUnOn to thtO
<br />Colorado Ris'cr. Wotnn ....lllIt.r ~It'ml'<
<br />....hK"h ongin,'ll' In the lrorical Pa.;iii....
<br />(kc;JlI.may,"auserJtIllall\lll,nnwpa..:k...
<br />rl',uhmg lfl high runnn .Iml llouds nil
<br />Ill.lJ"r n\'l'~ The Irt'4ucncy ;md m,'l\lure
<br />..:ontent III trolllal 'y'\\'/IlS arc slrnngl)'
<br />affc..:led by atllltl,ph,onc tOIri:ulatwn
<br />palt,.nt' Ipartlcularly their strength I
<br />,mJ W,l-\urlal'" 1,'lTIlXoraluu' (~ST'I' ~l'
<br />lhe LI"PIl"al .IILtl. Nt'rlh P,KiIK (),;cans
<br />:-'111IS1ure tkliscrcd 1(1 lhe Ctlloradn
<br />Riser "'a.'1n dunog '11m mer i~ I>ph:all~
<br />a mhturC'o!lIll'ISl illr lrnm Ihl,.'(.ull "r
<br />~lc\kll. Ih,' (,ulf 01 Callfornlao and Ihe
<br />,'astern Pal."iri..: O'':tO,Ul. Kno....n a" the
<br />nAn/tlnalll.lIlS('Io,l!1.:',hhllllli,lurl'ani,cs
<br />111 Juh and Au!!u" al 10\\ Ic\c:b In thl'
<br />illllltlspherl'. Th~ m.lj" ;m me, r..pidly
<br />(lSCr the dt......n lalllb..:arc. 'p.1wnmg
<br />thundl'rslnrms Ih..1 dch\n hl~h.illlt'n,"y
<br />r;unlallt(l d""Jljom Ie" than 7.000fc<'l
<br />;J!lJ 1\l\\l"r+HliCIIsIlY rall\lall ;ll higher
<br />c1nall11lls. rhundtOr,tllmlS Icnd to h..'
<br />Ili' ~ma'l1 ~p;lllal ,0'lento otnJ althl,ugh
<br />IhC} ,p;lwn ,es..:no Ib,h tk..JJmg
<br />locallyo fl'.... 11noo.I- arc gt'ner;lTed
<br />
<br />on lh... IM!;t'r rin'r~ In the region.
<br />Finallyo lropicJI cyclonc~_ which
<br />rail!:," from twpi..-,II dcpTl'ssi\lll~ lu
<br />humc;LIIe~_ turnl 11\ the t'a~lt.m Nonh
<br />1'....:llic (kcan olf Iht' w,',lt"oa't \11
<br />t1.k:\il'O. The,l' ,tnnn~ rarely make
<br />I..llldfall ron th... cpnlJntOmal Unitl'o.l
<br />Slale,o lll'tt'aJ they dissipale U\'er
<br />the ol."can. 1n,' rc~idual moisturl'
<br />trom tropical l."ydones_ Whll'h can Ix'
<br />..:onsiderahlc, l~ cllher carri,,'d inland in
<br />weak nwn,oo.lnal 11..).... during summer
<br />months or emh.:ddl'd wilhm stTllngcr
<br />":Ullltl I"w"pn's"ure s)'stl'ms from
<br />Iht' P'd..:ilic (kl,'an. Tlw cOll1hinauon
<br />o.,r Iropi"'JI ,,'yclOllt" and cutoff Ill....,
<br />..:n',l1,', <:l'lldllion' '"r gt'IllT;lli\lI1
<br />01 t,rgc ll"l,llh m th..o ~\'lIlh...m
<br />half of th.: Colorado Ri\'<:f ha..in.
<br />
<br />Indices of Global Climate
<br />
<br />S.:seral 'indicl.'~ 01 Jlmo."pheri.: .ll1d
<br />~t'anil." pnxe"...~ ar... uscJ 10 l"plam
<br />..:hmalC \anJhihl~ m Itl\' L'lIIlt'd Slal.:~.
<br />The h.:..I.kno..wn of Ih.:se j, Ihc EI
<br />;'IOuio - ~,'ulht'm (kcillalinn IENSOI
<br />phl'/lOlllt'nO/l 111 thc Paclf'l" O...-,'an.
<br />
<br />USGS Feel SIleeI 3062..().t
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