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<br />FL.OOD HISTORY
<br />
<br />The Colorado River ha, a lonjl: hi.tory "I
<br />~n()wmelt n()odinjl,'. but, due w tbe rural
<br />natureo[ the region, detail~d informatIon on
<br />flood e"""ts in the ~tudy area i, not available
<br />The fint Ilo,w.1 of r~cord on the Colorado Riv~,.
<br />in tbestunyareaocc\lrred in,/un\'-,july 1884,
<br />
<br />FLOOD DAMAGE PREVENTION
<br />
<br />Th.'r.' arp M fl<...; "',ntrn! prni"e!>llhat
<br />ha"eaneffeetinthestud;:ar"a,lwserv"irsin
<br />the Colorado Hiver Basin abo"e the study area
<br />are operated for watcr conservatiQn purposes
<br />a"d consequently p"ovide only incidental flood
<br />protecti"n to the Palisade area. However.
<br />in~idental storajl,'e, trans.mountain diversion.
<br />a"d irrijl,'ation use~ hav~ served a"d will
<br />probably conlinlle to ~erve i" reducin" p"ak
<br />nowoofverylarl':eflood~ in the atudy re,wh.
<br />Flood plain regulations hav~ I:><,en adop1.fd
<br />b~r ;,.resa County. Dcsil':nat"d flood plains.
<br />indurliTlll'lnw ha,ard and ft""dwny ",<)Tle8. arc
<br />incorporated inw "OlUlty wnln" maps.
<br />AIJPlieationsfornewd~velopnLemorr(,visinn
<br />ofexi,tinl':devdopmentinthL"'''areasmusthe
<br />allprowd by the County Cnmmi"\ion, and
<br />
<br />OBSTRUCTIVE STREAM CROSSINGS
<br /> El<lvallon'
<br /> Und<lr_ Topol 100-year 500_y<lar
<br />locallon' Str~<lmb<ld c1~aromce' ~oad"'ay' Flood Flood
<br />~3,O6 41;05 4625 16:JO ,1,,::H l()29
<br />100.:';;; 4677 11,96 4701 ,1';~8 ntH)
<br />402.81 1fi91 171~ 1721 4721 4723
<br />
<br />Other floocis on the river wert' rewr,IKJ i"
<br />1917, 1~20, 1921. 19:;.\ 19,,2,lInd 1%7. Th,'
<br />1:384 floon i, Il:enerally con,ider~d lhe most
<br />s",'pr"kl\(\wn i"thePali"ld.'area.!tresulwd
<br />from ranid rndting 01' a d"l'P mowpack and
<br />eon~un'ent fwa",y rain"
<br />
<br />fh.-lflows fnr th~ Colm'ado River at Palisade
<br />we..., det€rmined [rom the rej("i<l1\al ~nvelop~
<br />curves, Peak flows thus dct.'rmined were
<br />63,000 and 82,WtO euhi~ fL",t per 8eeond.
<br />regp<'etively,fortheIOQ-andSOO.yearfloods
<br />at the upstr~Jm limit of the study area.
<br />
<br />~lJeh new or ,,'vi,,'d d~wlopment is ~"hj,'rt Ii\
<br />pro"i~i"n" desi!,:ned to prohibit:
<br />a. Stora'-i"e o[material"thar are floatable
<br />or may be d"tt'im~ntal to human, animal, or
<br />plant life.
<br />b. Di,;po~al of !lad",l':~ or other solid
<br />wagl<' materiHI~.
<br />t_ ",'sidenti"lllse_
<br />d, Crcation or deposition of additional
<br />debris.
<br />e, Placement offill, in~tallatio" ofstrue'
<br />turt.s, or ,l"rage of materials that tould
<br />adv~''''ely afleet rloodflow and pos,ibly ~au"~
<br />~dditional flooding.
<br />Pali,aui!h"gamningl'l'dinaneo.iJutitd"""
<br />Ilnt addr<'~s fh..-J haz~...l<.
<br />
<br />OBSTRUCTIONS
<br />
<br />~atural obRtructiuns to f1oodflow include
<br />tr~~s. brush and other vegetation growin!':
<br />alonl< streams. During floods. vel(etation
<br />ilOped,,*, fl""dflow and resull' in baekwawr
<br />conditions and increa,ed flood height.~. Brush
<br />or tree, wa"hed out during floods and ~arried
<br /><lownatreamcouldcolleetonbridl':esnroth~r
<br />obstruction" thll' ~reatingad:J.lOm:ngeffcct
<br />ami nverbank nnw. Ag rJoodrJow increa'<eS,
<br />maSilelofdcbriscande~tr<>yabridgeorcaU;l€
<br />water lm'cb to rise higher and more rapidly
<br />than normal, thu~ erorling and damajl,'inl';
<br />abtltrne"ts, apl)roach('~. a"d the ovcorlyinl':
<br />
<br />FUTURE FLOODS
<br />
<br />100- AND SOO-YEAR FLOODS
<br />
<br />Th,' WO-Yl'ar r!"od i'.me with a peak flow
<br />magnitude that has a 1 percl'nt ehan"o of
<br />oci")l'''quilll,'dor,'x"".~hjinanYl':;H'nyear.
<br />"nd a freque"~y of o~currco"e of ab<}ut on~e in
<br />100 ypar. on thplonll:.tprm 'wprag". Similarly.
<br />the ;>O(J-y<:u flood ha~ a u.2 !,.'rc~nt ~h"m,,~ "t
<br />Lei,,!,: l'<lualletl or ,'xc..~led in alLY l':i"l'n y"ar.
<br />and a rre'-iUl'n~y olocctlrrcnceof",hilUtonee:n
<br />.300 y~ar< on the lonl':,u>rm ,,,'c,',,,,,,,. ,\,
<br />pr€viously indicated, "M\\'mdt runoff fr"'"
<br />UL<' Cn[onvlo Kiv..,' drain"l!"" ha~ln l'r"atr' th~
<br />
<br />IdenllflClltion
<br />
<br />Hl()~t Sl'v.'re floodconditi')nS in th~Stlldy "rt'''_
<br />H"ltional jOo- and ;;OO.yr:!r p<'ak Onw
<br />vall,,,, wpr" dewrmin,~l from dis~har;t"
<br />frequency data compiled for r<.>pre<enti\tiH'
<br />"tream v,a,;:inl\' stRtion, in ,'arlier Colorado
<br />River Ha,in ~tudil'>i. The p'~ak flow "alu~.
<br />wpre co"verted to discha)'"e in cubi~ root pl'r
<br />~econd' per !'-quare mile (CS.\l). "nd enwlop<,
<br />"urvt,<,w,','cd",'eloIWd,howin\t IOO-and,,(\().
<br />y~.u C,n(\wnw!t !Joe!! Cl'nn.s G" ,; ,c.:i""ul
<br />h"<I.< Th<' till). ~nd .)l~."Y""e ,nowm<'lt
<br />
<br />:lZRoad
<br />U_S. Hil'(hwu.y 6-24
<br />1.70 Turnoff to
<br />!'ali,ade
<br />
<br />l"formationonlll-:<nd5tl'rearfloodl'wnl,
<br />wa, al",> developed as part of the hydrolnp:ic
<br />studies conducted for this report.Tlw"", would
<br />also h<: snowmdt flO<l<:ls, hut with the e~cep'
<br />tionof.~huwi"I';their watersurfa<:eprolil",;on
<br />Plale<27.31,,.renote()\'eredinthcrep<l.-t.
<br />
<br />roadbed.
<br />In ll:e""rRLobstrLldion~rt'Striet f100dflow,
<br />and may eausc o,'erbank flows. u"predict~hle
<br />areas of f100dinl':. possible dama.'(" to or
<br />d~atruetinn of brid",s and otlwr stream
<br />cros~inl'(" and inercascd velocil.\' of flow
<br />immediately downstr"am_ Two river
<br />c,,"'sinll:~ in Uw ~tudy ar~a arc ou,trudive to
<br />ftoodflows.Pertin<'ntdataonthe<estruetorc,;
<br />are "hown in the following: tabulation, Th,'
<br />"ffect of ob~trudions ma)' be seen on Plates
<br />27,31J,and31.
<br />
<br />.\l tho u!-"i,,"," h"."i <"."lrucwro(oxc,'r'f"''''f',"".,dwa)),,,,,, n<1",1 "'tn"h''''''''!''''. n"",,, ,,',:,'wl.ht<,"',
<br />'~;Il',ul"'tr"ar" r"m, lA',"" F,',,,_,,, ,x';,..n.,
<br />"IM"f<",I,tl'l"',",(p<';nlo".tr\:"'"''''
<br />'M'.h, "'''~,' Ii'~'n("",j :mm,-,ll."I,' "1m_ ,,,"1""1..,,,,,"., I";"'.
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