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<br />Prepared in cooperation with Ihe Grand Canyon Monitoring and Research Center
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<br />Monitoring of Coarse Sediment Inputs to the
<br />Colorado River in Grand Canyon
<br />
<br />Introduction
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<br />)
<br />
<br />Coar\l: \~'dill1~'nI 'p.1nl(I...\ "'I[h .1n
<br />m[.'rm~'(h:ue di,lIllel.'r ;. M Illlll) afkd\
<br />tlw prmMry .;nmponenl.\ of the Coloradn
<br />Ri.er ..cosy~lelll, 11lC dq..."iuoll of
<br />~'oar'<.' \edinlo.:nl ,It lrihUla~ Jun.;lurcs
<br />huilJ, large lkhrb Lms Ihal .'\\IlS[fid [h~'
<br />rl,(r and fonn r.1pid\ 1 h~. J 1_ l>ehri, failS.
<br />.md Ih... J...hri\ har- Ihat Je\c11'p Ill:lo\.',
<br />rarIJ,. rro\'idl' ,[ahk ,uh,[rale I'm aquatic
<br />Or)':lfll\lTl'. nolahly [hl' alga Cla.dof'hora
<br />1t/,'m.'Tald. Th( PfX11 aho\<.' and rl.....lreulal.
<br />1Il~ l'd.ly Ill:low the debns Ian elllx-lI\c1y
<br />lrap InK' \CJIIIl~'n1 for S10rage 011 [n.: Ix.J
<br />or 1I1 ,:mJ h:trs, fkhri, 1'.111\ an...l dehri,
<br />hars (onn Ihe fan"L'ddy c\lmpk\ thai
<br />allr:!':lS humph.:ld-, chuh IGila n."lIa). an
<br />...nd:mgcrl'd SpeCll'\. MOnthlrmg Ihl' inpm
<br />01 l'nar\~' \l'dlllk.nl 10 [IK' Colorado Ri\'l'r
<br />l.....I"y,I<:'t1land II.' 1''''~-l'''n11 r.'dlslnhu[1l111
<br />hy Ilw rih'r i, l'nlll"al [n Ih{" unlkr'landmg
<br />.md m;ulJ.g.'nl<:n1 of Ih,,,,,' ,alul'tl
<br />rl""url'~", Thi, fa(1 ,hL'~'[ rrl',...m, an
<br />11\'....r....'l.'" (,f IlK'l/hll.h ftlr monthlnng
<br />~'''''r'<.' \Cdink'n\ inpuI ..n.1 r~'tji'[f1nu[ion
<br />In (imnd CanYlllI. The'<.' n"-'I/lo,h are di\-
<br />.'u,\CJ 11l.,r.... [hor\lu~hly III ~1ch, i I'N7).
<br />~kl" :m.l ntlk'r\ II'N4. I'J'17). and Wenh
<br />.m.! o[h...r\ IIIN";I, I "99h. ~()(~l),
<br />
<br />Debris Flows and the River
<br />
<br />Dehri\ 11.1"''' t':1Il ha....:m ItlmledlalL'
<br />.\nd dran1<lli( .:111-':1 on the r;~cr rorn-
<br />\lor. [;\(n a ,tnglt' ,rnJ.1I Jchn\ 1\"....
<br />filii)' ,igt1lh.;;tI1ll~ alt...r Ih\.' Inpngr,lrh~
<br />and hyJraulu.:, of a .lchn' f:1Il ,IIlJ rapid
<br />III a man...r of minules. liu"'evl"f. Iht'
<br />Colorado Riv...r r~'dl\lflhule\ [he co:!.........
<br />'>l.'dink'nt imnxlu(ed by J~'nrj\ tJows
<br />;llmo,1 irlHl1,dialely all~'r ,kf"-I\I[iol1
<br />Jnd Juri,,~ ,uh\~"\lut'nt hIgh tlo......\,
<br />Ikfm~' dusure 01 Glen Cdn~un Dam.
<br />large 11lxxh un [Ik' ri\'t'r roulHlI.'l)
<br />.....IOtl\'eJ ..II lill.... '...-JIIll....nl ..nd sunK'
<br />\.'lIar...... \CdinlCtI[ from aggraJ...-J Ikori,
<br />fan, ia I'ro"'e,, ~-alkd f"\t'or~i/l.",I. [r<1I1\-
<br />p"ning rtlaf\C' .....JitlK'nl Ihruugh the
<br />ptl<ll "'-'low lhe: rapid ;11\..1 deptlSi[ing II
<br />;1\ d~'hf1' b:tr.. {lip. J). III .h~' r~'gul;tlt.'d
<br />rlh'r. 11.I<....h of fl"lJuced lIla~nilUlk .10
<br />nol h:l\~' ,ut'li..i....m ,[rt':Im po.....n 10
<br />....."'I'rf.. ,tggralkd dL'hri.. fan, a, thor-
<br />\lughl) tW..'hh and othef';. I <)<Na,
<br />I4'Nh). ('oar,... panidc\ Iha[ art'
<br />I.'ntrallled h~ the:...... lo.....er Jist.-hJ.rg...'
<br />may Ill: deposit~'d III the pnnl, Ill:lo....
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<br />rotpiJ,. pot~.nt;aIlY ah...rin~ [he eJdy p;tl-
<br />tern ;mJ itlrr<:'a,mg [II... length ul th, rapid.
<br />A' a r...,ull. d..'hri, fan' and rapid, may ho:
<br />;lggraJing oVt"r [IK' lon~ leml.
<br />
<br />Monitoring Debris Fans
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<br />Th... .:Ik"t:llv't' moniloring of (oar-..:
<br />sL'dlnK'l1l r~'l.Julres ho[h [he ..hon-[erm
<br />JOCIJlllt.'nlallOn nf IIll'uh b) dehris 110.....
<br />and Ih( 1.)n1;.l('Tn1 evalu:ilioll of lhe redi...-
<br />[rihulinn of Ih:11 ......JilllCnl by Ihe Colorado
<br />Rjv'er. BOlh t'llons tnvolve Illea\urmg UIC
<br />v'Olullle and panide-\lIL' Ji,trinu[illll of
<br />seJilllL'n1 ddiver.-.J. a' ....ell as Ilk' cfTl.'Cb
<br />of I[S r...di,tribul;on on In.: morrhology
<br />and hydrauli~'" of Ih~' riwr (hannd. Moni-
<br />lonng d,hri, 110....' a[ regular ml...rvals
<br />....111 nor only akon m<lnJ.g~'1"\ anti r...scaKh-
<br />ers [0 suddl.'n. pO[L'ntlall~ impo.>nanl
<br />(h;lI1g...~~ (0 ~'hanncl rc"IUr~'~'s hut aJ\j) will
<br />;tJJ 10 an C\lSlmg' Jalah;!\C de,ign....d 10
<br />enahk tIlod...hng of the InleraCllon of
<br />roar...... ......"lJimcn[ and InL' Colorado Riwr.
<br />The dlc...:ti~'.' and efliclent tllI1tllltmng "I'
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<br />In ,mall lnt'>u[an~', 01 tnl' ColuraJo
<br />RiH'r h...."'.....n 1'(1.......'11 and .\le:.d r...\er-
<br />\<111"\. cnar'<.' ,~'JltllL'nl I' Uall\pt:>rh'J to
<br />Ih...' fl\er JII1I(1\1 "',dIJsi,c1~ hy (khn\
<br />1\"'" \\'hil,' trlhu[;I~ \lr~'arntl(l'" dqll)'lh
<br />..r~' ",~'II.,,'nl'd and t~pl~'aJl~ h;IH' k"
<br />Ih..n :v~ (oap.e \C<hm'nt t>~ ....~.tght.
<br />J....hn'-tl,'''' (kpo.l\ll~ ar.... pt...>rly v.>n,d anll
<br />~.t1n[.tln 'i I" :h'~ ..oar'<.' s.'dink"nl t\\'dm
<br />..nd .,tlwr.... .:'l~~ll. Figure 1. SchematIC dIagram of lhe lan-eddy compleJo; on the Coiofado R,ver
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<br />us D<>pa'Imer1,,,'lt>eI,w.,ro<
<br />us tio>olO<......aISu'W..
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<br />USGSFaclsn,o..I019~'
<br />~P{>fua,v 21))'
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