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" <br />.<1 <br /> <br />',I <br />" <br /> <br />,hO <br />~U a <br /> <br />J' <br /> <br /> <br />, I <br />, <br /> <br />.. <br /> <br /><. <br /> <br />. <br />o ,,~ <br /> <br />IJ <br /> <br />"" <br /> <br />I <br />I <br />I <br />I <br /> <br />l <br />{~ <br /> <br /> <br />" <br />. <br /> <br />e <br />o <br />o <br /> <br />,\ <br /> <br /><'j] <br />I <br /> <br />" <br /> <br />C[ <br /> <br />[ <br /> <br />[ <br /> <br />, <br /> <br />. <br /> <br /> <br />06 <br /> <br />aJ <br />c::> <br />= <br /> <br />,>> <br />,]" <br />,,,'" <br /> <br />'" <br /> <br /> <br />, <br /> <br />D <br /> <br />I <br /> <br />; <br /> <br />~ <br /> <br />I <br /> <br />,[ <br />1 <br />i.l <br /> <br />, <br /> <br />'I <br /> <br />1/' <br /> <br />J:; <br />J <br />o <br /> <br /> <br /> <br />(la <br /> <br />- <br /> <br /> <br />I<'~ <br />,- <br /> <br />o <br /> <br />ft" <br /> <br /> <br />) <br /> <br />~./~ <br />~~ <~... <br />,,\ <br /> <br />f <br />v'J" .... <br /> <br /> <br /> <br /> <br /> <br />L':l <br /> <br />r;:J= <br /> <br /> <br />- <br /> <br />u.,""...... <br /> <br />" <br /> <br />~ <br /> <br />I <".......:l <br />/1 ..~..... I' <br />"........1: <br /> <br />o <br /> <br />.= <br />'" <br /> <br />,~ <br />r-- <br /> <br /> <br />Topogrllph,cmap lurnlshedby <br />C,ty 01 Boulder,Colorado <br /> <br />Topograph,c map lurnlshed by <br />C,tyol Boulder Colorado <br /> <br />FIGURE 6 -ESTIMATED AREA INUNDATED AND WATER.SURFACE CONTOUR LINES FOR HYPOTHETICAL 100,YEAR FLOOD ON BOULDER CREEK AT BOULDER COLORADO <br /> <br />FIGURE 4 -HISTORICAL FLOOD DATA AND ESTIMATED AREA INUNDATED BY HYPOTHETICAL 25,YEAR FLOOD ON BOULDER CREEK AT BOULDER, COLORADO <br /> <br />, <br />! <br />r I <br />I <br /> <br />-~ <br /> <br /> <br />1100 <br />Estimated water. surface contours of hypothetical floods <br /> <br />J <br /> <br />FREQUENCY AND EXTENT OF FLOOD <br /> <br />INUNDATION ON BOULDER CREEK <br /> <br />AT BOULDER, COLORADO <br /> <br />IntrodlLctwn -ThiS atlas summarizes the results of an <br />investigation of the flood f10\\ charactenstlcs of Boulder <br />Creek and Its tnbutarJes 10 a selected area at Boulder, <br />Colorado HIstoncal data for past floods are compiled. and <br />hazards of future floodmg are estimated ComputatIons of <br />C100d elevations, boundanes of Inundated area. and velocltle~ <br />of flow are based on the conditIOn of the creek valley and Its <br />constnctlOns eXisting m the fall of 1959 All elevatIOns are <br />referred to the datum. 4,2480 feet above mean sea level, <br />used by the city of Boulder The Sixth Street crest.stage <br />gage IS located on the left (north) bank of the Boulder Creek <br />channel, 100 feet upstream from thecenterhne of SIxth Street <br />Flood H,story of Boulder Creek -Outstandmg floods <br />occurred on Boulder Creek In May-June 1844, June 1864, May <br />1876, May 31-June I, 1894, June 2, 1914, and June 6, 1921 <br />The flood In 1894 probably was the greatest. although the <br />flood In 1864 was comparable The only data concermng <br />elevatIOns reached by past floods on Boulder Creek In the <br />stud,} area are those shown in figure 4 for the flood of 1894 <br />Two floods m the penod 1889-1959. those of 1894 and 1914, <br />caused damage m Boulder The flood of 1921. mIght have <br />caused damage If present channel constnctlons had eXIsted at <br />that time FIgure 1 shows the estimated elevatiOns the floods <br />of 1894, 1914. and 1921 would have reached at the Sixth Street <br />crest-stage gage under present conditions of flood plam <br />de\elopment SIX outstanding floods occurred durmg the <br />period 1844-1959, an average of one flood every 19 yearn <br />Hov. ever, durmg the penod 1894-1959, three floods occurred <br />at mtervals of 20,7, and 38 years, respectively (fig. 1) The <br />erratic occurrence of floods 18 eVident <br />Eletatwn andfrequency offloods -Frequency of floods wa.~ <br />computed from the combIned record of flood peaks at seven <br />gagmg stattons on Bou\deT CTeeK and on foul' otneT I.'.trcaml.'. <br />In the area All fIVe streams havf' SImilar ("hardcteTlstla;. <br />their sources are at the Contmental DIVide, and thelr dramage <br />basinS are subject to Blmtlar meteorological phenomena The <br />gagmg stations are located near the base of the foothills of <br />the Rocky Mountams The penod of record of annual peaks <br />at the gagtng statIOns ranges from 62 to 70 years, WIth <br />certam hlstoncal mformatlOn available for floods as early as <br /> <br />~a \ <br /> <br />II"')'~!~ <br /> <br />i' \'"L~ l: \~ c <br /> <br />/" <br />~ <J !;co <br />".-----~ <br />/Q, " ~:...o CJ <br />I~.""" <br />o , <br />. <br /> <br />,- <br />'i <br />~ <br /> <br />11",\\ <br />I'D <br />II jJ <br /> <br />,~ ";r <br /> <br />.0 <br /> <br />m <br /> <br />'" <br /> <br />\ <br /> <br />\ <br />I <br /> <br />" <br /> <br />b~ <br />a~O <br />c::> <br />= <br /> <br />_~f <br />, <br /> <br />I <br />I <br /> <br />~).J \ <br />I --- I) <br />) d <br /> <br />1, <br /> <br />, 1 <br />o "fl '" <br />~ ~ ~ ~ ~ 04 a 0 [j,;,;;:.[ <br />",,~1JO?O'D'" \.' <br />~ ODol;rf. 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"....""_ <br /> <br />EXPLANATION <br /> <br />, <br /> <br />~ <br /> <br />o <br /> <br /> <br /> <br /> <br />J-.i'J...QP_" _ <br />o <br />'" <br /> <br />. <br /> <br />. 0 <br /> <br />I <br /> <br />Boundary of estimated area mundated by hypothetical floods. <br />based on the conditIon of Boulder Creek Valley and Its <br />constnctlOns eXisting m the fall of 1959 <br /> <br /> <br />o <br /> <br />r <br /> <br />... <br />, \ <br /> <br />'. <br /> <br />-+- <br />~" <br /> <br />0- <br /> <br />L':l <br /> <br /><~ <br /> <br />(;:J <br /> <br />-. <br /> <br />. \ \ \ \ <br /> <br />v <br /> <br />n~ <br /> <br />(UL: --\ <br /> <br />,..... <br /> <br />.".i.""" IT'''cM <br />_~T1: 'r <br />I, 'I <br />"""""'_1 <br />1-'- to'" <br />".,u"11 <br /> <br />.= <br />o <br /> <br />u........... <br /> <br />~ <br /> <br />" <br /> <br />, <br /> <br />\ <br /> <br />TopographiC map furnished by <br />C,ty of Boulder Colorado <br /> <br />FIGURE 5 -ESTIMATED AREA INUNDATED AND WATER.5URFACE CONTOUR LINES FOR HYPOTHETICAL 50. YEAR FLOOD ON BOULDER CREEK AT BOULDER COLORADO <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />HYDROLOGIC INVESTIGATIONS <br />ATLAS HA-41 <br /> <br />I <br /> <br />"\IJ ~""" .. 0'--, r <br />.r.q- F5"%: ...../ ot:"1 <br />~ _ '" ~L <br />,01 ;.l i \I. it. r , <br />.- r(')o). ~ {) r"\ ci.~ \J \C, 1:;: .... \~"~ <br />q <;;;; "II\) ,c" ~~ " \ ~ ':"0 <br />fl.~~DOt"I~ t. l,.}~f'I ~ of ,01[100. oo~ r')"~..~ ~C- / <br />",' '..{ 'd"9\Y ,<')0\10 ,," (' il ,Cl 0000 .11.. 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Iltlllllll,I,/~!111111 <br />,1,.,g, -r rr"\ ':- 1111'tll111111'Jl.1t'III',jII'I'lt,tlllllljll'I'111111111111\lllllljl',III\I)" , l'llllllllllllll )1!II'l\llllllllllll <br />;p ....,...-....-..-\\ \J \\ ..-J' It,II)llttlllljl,I,!ll,'I',)jlllll,'I)llilll,II'I'III'Illlllll,lll!'I"!1'111'JII I 1IIIjJ,'llltl'llllll,II',IIIJ11IJjllllllll <br />2 ,~ 1I,11I,-Illl'ljlllllllll'II/1 Ihl)I,I,II',llllltllllll'II,llfl'L'I',llrllll.IIIJ'lllI 1'/II'III'lltlllll)ljllljllltllljll'I)lllllll'lllllll <br />"\ \....) ....~ 1IIIllll)Jlljll'IIIII'I!IIII:lllllll,JIII'III'III'lllf,ltIIJllllrll'rllll!1tltlllll'IIII;IIIIIII;I,IIIIIIJltllltllllllj'-tlj'III'I',III,lllll,II)III)1111. <br />.r' J. I I I I ) I I I I III I I I I I I I I 1 I I , , I t I I I I I I I I 1 I ! I ! I ) I 1 I I I I I ) I I ) ~ r ! 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II'r/'J,IJI"11 '1'111'111 ,"1' , 1111!111111 <br />'1Illllllllllllt)lIl"I~1 1 d II Illl)1tII~ <br />1,llllll'I',IIII!,IIIIIIIII,I]ll1! 1lllllllllWater-surface elevations within hachure area WI rangeJIIIIIIII!II!,1 I II <br />, I il!IIIII'lll'lllllllll!I'IIIIII,lJII'l' f'l "I from 0 to 2 feet above general ground level 111)1111~1:11111111Itl,I:I;11 <br />"11':11,11'111'11,1,11111111111('11,1,1111""'111111It'+II'ltl'I'I!I",111,IIII[llll('tl,llllllllllll <br />1I,IIII,I,I,II'lllllllll'III!)llt,I,III"II,IIIII,III,'11!111111111111)1111,1+111,1)111(111)1111111111111IllIltltlll(llt',111 <br />'I I I I.l,) .I.I,I,J, I 11/11]1,11111, J "11111/,1,1 t'~1 I 1111 I' ,! 1111) II I I I II, + 1111,11111,111111 1 lJ II: I <br />tl,I!'I!11111,11111111111,III'111111 <br />) 1'11111' . I ~ ' 1/1111 r.llll ,I 111) 11111 ' II t' \ II f I , 11111111111,) I <br />1 I Ij t 1111,) III~ II I I,ll' tl 1111I j, III t-lllll, 111111',111111 <br />I 1111111.1 j'~II!.J 111111' I~I) I Illlllllll)1 III <br />111,111,IJljlllllllj()I'lllllllllIJIIII <br />'Itlllllll,llllll',II),IIIIII'111111 <br />f ' 1,1/11111 ~ll) 111111111,1111' <br />I I ~1!I'llll tIll ,1)11 <br />"II,III! <br />',' <br />',' <br />',' <br />" <br />lC'l tll <br />~ ,II <br />_ II, <br />,', <br />,II <br />" <br />1111 <br />II <br />t',l, <br />1111 <br />I ~IJ <br /> <br />~ ~<)~ ~ ~;\ ~... <br />100\ "'",a CJ: 1,l_ <br />., _'I'l\ ~ 0." c, ' <br />~n.. ';U'" ~'1 .1"1 ~ <br />- v & 0<::' ~Go <br />.p-c 't),..".."r J..... \ - <br />'y.- - ~'t. <br />~ C <br />, ,~",o~.\l <br />Q 0\ \r 6~--~ <br />r- ) [JocoOD][ 10 r"} <br /> <br />" <br /> <br />. ---.. ... ~ . ,,,.., <br />"" <br /> <br />-n-:-~v~ <br />. <br />,ll <br /> <br />, <br /> <br />~ <br /> <br />I<lO <br /> <br />Lf C Tod <br /> <br />- '\ <br />L-, <br />'\ , <br />~ <br /> <br />Ilr>:'jo <br /> <br />llff' <br />.. one I <br /> <br />o <br /> <br />QOu <br /> <br />[ <br /> <br />'l <br /> <br />-' <br /> <br />'g ,: <br /> <br />, <br />':\ <br />, <br /> <br />,:!, <br /> <br />oc,i'lJ - f <br />....<;\ 0 <br />- ~ <br />::n If.lao'Q ~ <br />'t <br />~(Iac JDUOG.u!1- <br />a ~'n' f' <br />liD ....0 <br />GO 111 <br />OO(JOO 'GOOtl or <br /> <br />g, <br /> <br />"i) <br /> <br />,c-: <br />'" <br />g <br />7" q- <br />~l <br />~~,,) <br />or AC; <br />( ""'0 <br /> <br />, <br /> <br />. <br /> <br />JJr.. <br />" <br /> <br />, <br /> <br />o <br /> <br />" <br /> <br />,~ <br /> <br />'- <br /> <br />, J[ <br /> <br />(\W' <br /> <br />,s <br />o <br /> <br />y-l <br /> <br />ir <br />rfD <br /> <br />~ <br /> <br />') , <br />, <br />c- <br /> <br />~ <br /> <br />,< <br /> <br />~\ \' <br /> <br />~ <br />D <br /> <br />~ <br /> <br />l' <br /> <br />;:i( <br /> <br />" <br /> <br />n <br /> <br />" <br /> <br />~ <br /> <br />~o. tf <br />n ~t <br /> <br />. <br /> <br />j <br />ul ~ <br />...., p~JrDO 00- r <br />o . <br />;:: <br /> <br />o <br /> <br />on <br /> <br />if <br />10 <br /> <br />o <br /> <br /><<- <br />\0, <br /> <br />~ <br /> <br />t'1~~'r"'-l <br />.c> '-. .. t) <br />.II 0:0 c, <br />[J Q q,l r: <br />_nutAIlf <br />-h1~lal <br />1'1. ,"'~ . <br />o '" "'010"", <br /> <br />II .,"" <br /> <br />."Ct< <br /> <br />~ <br /> <br />~ <br /> <br />-')'1...-' <br />:)t::l' <br /> <br />)CJl , _ <br /> <br />~r <br />o <br />'" D>-;: <br />;:,9', ,c <br />~ <br />1\ <br />,p <br /> <br />'" <br /> <br />" <br /> <br />~ <br /> <br />~ <br />196 <br /> <br />"' <br /> <br />I <br />7 <br /> <br />0,1 <br />~ <br /> <br />~ <br /> <br />( <br />.\: <br /> <br />l- <br />II <br /> <br />OCJ,"< <br />," <br /> <br />....t. <br /> <br />~ <br /> <br />, <br />]c <br /> <br />\I <br /> <br /> <br />~ <br />.\'1\\ <br /> <br />II <br /> <br />;~ <br /> <br /> <br />--- <br /> <br /> <br />10 <br />'" <br />" <br /> <br />o <br />0> <br />o <br /> <br />" <br />" <br /> <br />- <br /> <br /> <br />~ <br />CS <br />, <br /> <br />~ <br />" <br />, <br /> <br />- <br /> <br /> <br />i <br /> <br />~'\. <br />- <br /> <br />'''''b <br /> <br />HYDROLOGIC INVESTIGATIONS <br />ATLAS HA~41 <br /> <br />~ <br />C <br /> <br />~ """ --"I <br />" . <br />o <br />~ 00001 <br /> <br />6000 <br />Q oo~ <br />r::l~~"" <br />;(\1\'1 <br /> <br />v...- . 1'4 ~ou u" <br />. J{iOO""\O <br />00 0 <br />olf' <br /> <br />" <br /> <br />(, "'7"1:"0-' <br />oJ , <br />II r?"1 <br />~( <br />,'^ U OGIl \\c <br />-!} 0 'P. \1OU <br />\ on IJ\ <br />(Ii) 0 1::000 <br />Q \J \\1 0 .. ~ " <br />)\> 0 "'a 1\ <br />.' 't\oOIlot' <br />\1\10 " <br /> <br />~ <br /> <br />'lloPOU~:::' ~~ooqlJ[Jo.l~~~; ~. <br />000\\(\ u....<U,,1I o'\1a~ b.... <br />1000~ oR\" -o;",o~o ,0 . 10 <br />II Q a:~~ ~ DOoo _ ~ ~ \ji L.-..J 0 <br />Utfooa ~ 0 ~ ...:~.... \. _ <br />~ \\, ",.. J.... c <br />QO-'. o~\ _/- <br />y~l.V'- (\ __/__ , ) <br />d~ / ~ <br />" t iJ' ~~t-' <br />/- <br />...--- <br /> <br />0\10 0 <br />,0 <br />~.,..1 ~' <br /> <br />aO <br />~ . <br /> <br />,Il <br /> <br />," <br /> <br />00 <br /> <br />,0 <br /> <br />~ <br />Tlu <br /> <br />\\UO <br />o <br /> <br />y <br /> <br />)1 <br /> <br />~ <br /> <br />, <br /> <br /> <br />.4!, <br /> <br />" <br /> <br />00 <br />"'vn <br />, U <br />(..:> <br />~.::> <br /> <br />u <br /> <br />I <br />, <br />\ <br />I <br />I, <br />I T <br />I <br />I; <br />'- <br /> <br />. <br /> <br />- <br />- <br /> <br />o <br />.; <br />" <br /> <br />.; <br />o <br /> <br />!' <br /> <br />rt <br /> <br />II, <br /> <br />[ <br /> <br />~ <br />o <br /> <br />r <br />I <br />I <br />I <br />I <br />I <br />I <br />L !I" <br />f r <br /> <br />-----.I) <br /> <br />10 <br />'" <br />o <br /> <br />o <br />'" <br />o <br /> <br />.;. rl <br />II <br />u' <br />":l <br /> <br />- <br /> <br />- <br /> <br />f> <br /> <br />10 <br />o <br /> <br />, <br />J <br /> <br />A <br /> <br />J" <br />':J <br /> <br />-" <br />~ <br />.... l c,_, <br />" ~ =, <br />'-'I "-.... <br /> <br />w <br /> <br /> <br />\l l1D[)'I" <br />,(\. 'J'f" <br />DOl <br /> <br />l-LOOU-""" <br />- <br />01 ' <br />. <br />IDa 1.., '"' <br />iJoL ,~ <br /> <br />.I',QI <br /> <br />IF <br /> <br />, <br /> <br />'" <br /> <br />hh <br /> <br />'0 <br /> <br />J' <br /> <br />J'WQ9( II ]0 lQ -u <br />- <br /> <br />;( <br /> <br />J' <br /> <br />[ <br /> <br />, ~ <br />r:p{ "" '" <br />11 lrlod~ jr r:I C- <br />_tt! <br /> <br />~li: <br /> <br />, <br />c ~ <br /> <br />, <br /> <br />uoo <br /> <br />'I <br /> <br />r <br /> <br />" <br />o/~ <br /> <br />] <br /> <br />,., <br /> <br />~ <br /> <br />" .~ L_.i..LI... <br /> <br />1844 LocatIOns of the statIOns are shown In figure 2 The <br />relatIOn between flood elevatIOn and recurrence Interval at <br />the Sixth Street cre8t-sta~e gage site under present conditions <br />of channel constrictIOn IS shown In figure 3 ItlS emphasized <br />that recurrence Intervals are average figures-the average <br />mterval wlthm which floods of a gwen ma~"fiItude "'0111 be <br />equaled or exceeded once Another way of companng flood <br />frequencies IS 10 terms of theIr probablhtws of occurrence <br />(the reciprocals of their recurrence mtervals) Thus. a flood <br />"-Ith a recurrence Interval of 50 }eal'S has a 2 percent chance. <br />and a flood With a recurrence Interval of 100 years has a 1 <br />percent chance, of bemg equaled or exceeded In any given <br />year. The recurrence Interval of the 1894 flood IS about 95 <br />years; of the 1914 flood, about 40 years, and of the 1921 flood, <br />about 23 years The probablhtIes of these floods bemg <br />-equaled or exceeded In any given year are. respectl\ely.about <br />1 0, 25, and 4 3 percent The recurrence mtervals of the <br />h)'pothetlcal floods whose estimated areas of inundation are <br />shown 10 figures 4-6 are 2.5. 50. and 100 years <br />Flood depths -Depth of flooding can be estimated for the <br />hypothetIcal 50.year flood from figure 5 and for the h)'"l)()- <br />thetIcal l00-year flood from figure 6 by computmg the dif- <br />ference between the elevatIOn of the water surface, shown <br />by the heavy contour hnes, and the elevation of the ground, <br />shown by the light contour hnes Depths In the shaded areas <br />shown on fIgure 5 and 6 will be WIthin the ranges mdlcated <br />Plood t'floclt,f8 -VelOCities probably Will be In excess of <br />20 feet per second m the center of the main channel during <br />both the 50- and 100-year hypothetical floods, on the other <br />nand, there WIll be points on the overflov. plam where the <br />velOCity may be zero .Mean velOCities on the o\erflow plam <br />to the left of the maIO channel near 6th and 9th Streets wdl <br />be about 5 feet per second for the 50-year flood and about 6 <br />feet per second for the l00-year flood In the VICInity of the <br />IClty Hall, these velOCities are estimated as 7 and 10 feet per <br />lsecond respectively Mean velOCitIes In the overflow plam <br />will decrea.~e gradually downstream from the City Hall to 1es8 <br />than 1 foot ver second fOT both the 50- and l00-year floods m <br />the area Just upstream from 28th Street. It IS emphaSized <br />that some JX>lnt velOCIties probably Will exceed mean velOCIties <br />substantially It IS not pOSSible to accurately predIct what <br />the velOCity will be for a given flood at a gl\.en pomt 10 the <br />channel <br />Tnbutary streams - Floods on Sunshine Gulch and Gregory <br /> <br />J<' <br /> <br />, <br />5 <br />. <br />o <br />- . <br />, . <br />l!' ~ <br />; <br /> <br />, <br />. <br />. <br />. <br /> <br />U'.~ox,,~~t( 'HM" <br />!lU:I."U'"'' 1%1 <br /> <br />'Joe.]l- <br />0l:J~", <br />UOD <br /> <br />n <br /> <br />1 <br /> <br />r <br /> <br />,0 <br /> <br />.J?11'DJf' <br /> <br />I' <br /> <br />" <br /> <br />" <br /> <br />, <br /> <br />u ~(~ <br /> <br />n~ <br />a <br />Th~l>~, <br /> <br />~ <br />,-,,, <br />, <br /> <br />,~ <br /> <br />Creek Will Inundate portIOns of the area shown on the maps <br />There are insuffICient data to form a basIS for dependable <br />analYSIS of floods on small streams draining the foothills of <br />the Rocky Mountams, but It IS known that at least one flood, <br />that of July 8. 1906. on Sunshme Gulch caused appreCiable <br />damage An estimate of the area Inundated by that flood IS <br />shown by the shaded portIOn of figure 4 The delineatIOn of <br />the area IS the result of a very rough field estimate. and <br />should not be conSidered fmal No data are avaIlable con- <br />cerning floods on Gregor".} Creek. although field inspectIOn <br />mdlcates that areas contIguous to the stream WIll be mun- <br />dated by large floods <br />fJlect of alteratIOns -Changes In the regtmen of Boulder <br />Creek, either by substantial artIfiCial regulatIOn of flood peaks <br />by storage and dlVernlOns or by alteratIOns to the flood plam <br />and maIO channel. \I, III modify the results shown In the past. <br />regulatIOn of flood peaks has been neghglble, but there has <br />been mcreasmg encroachment on the flood plam Areas of m. <br />undatlOn. flood depths, and velOCities In the overflow sectIOn <br />Will be mcreased If bridges become plugged with debrIS, If <br />additIOnal encroachment takes place on the C100d plam. or If <br />additIOnal growth of trees and underbrush occurs along the <br />mam channel but will be reduced If the main channel is Im- <br />proved hydrauhcally. and there IS no additional encroachment <br />on the flood plam <br />Addttwnal data -Other informatIOn concern 109 floods on <br />Boulder Creek can be obtained at the office of the U S <br />Geologtcal Survey, Room 1227, Building 25, Denver Federal <br />Center, Denver. Colorado. and from the followmg report <br />U S Geological Survey. 1948, Floods In Colorado, U S <br />Geol Survey Water-Supply Paper 997 <br />Cooperatwn and acknowledgments - The preparation of <br />thIS atlas IS a part of an investIgatIon fmanced through a <br />speCial cooperatl\e agreement between the Geological Survey <br />and Boulder County, Colorado <br />The topographiC base map used 10 fIgures 4-6 was furnIshed <br />by the city of Boulder Mr Theadore MIkesell. Planmng <br />Director of the city of Boulder, furnished prevIous engineer- <br />Ing reports concerning floods In Boulder <br />The atlas was prepared by Chfford T Jenkms. under the <br />directIOn of Wallace T Miller. Dlstnct Engmeer, Geological <br />Survey Mr Enc Me}'er aSSisted the author In the field tn~ <br />\'estlgatlOns and computatIOns <br /> <br />- <br /> <br />--... <br />-- <br /> <br />-- <br /> <br />r- <br />\ <br />\ <br />'- <br /> <br />i:'--... <br /> <br />'-...r-,-- <br /> <br />--- <br /> <br />I' <br /> <br />"J <br /> <br />. <br />I:;] J <br /> <br />~ <br /> <br />J <br /> <br />\I <br /> <br />,lO ~~, <br />i">{: <br /> <br />" " \'6 <br />1: 0 \1 r <br />,10 "~If[ <br />1) ~ 0 = <br /> <br />~, <br /> <br /><C., <br /> <br />), <br /> <br />- <br /> <br />r' <br /> <br />\ <br /> <br />/ <br /> <br />;> <br /> <br />1 <br /> <br />0(,1 <br /> <br />" <br /> <br />,~ , <br /> <br />----- <br /> <br />~ <br /> <br />~--_......... <br /> <br />"re <br /> <br />WYOMING 105" <br />41<- - --- -- --COi:U'RAOO-----,--- <br /> <br />." <br /> <br />1124 <br /> <br /> <br />~ <br />~ <br />~ <br />~ <br /> <br />z <br />z <br />o <br />~ <br />~ <br />~ <br />" <br />~ <br /> <br />1122 <br /> <br />"'0 <br /> <br />, <br />\, <br />\! <br /> <br />1118 <br />~ <br />, <br /> <br />'\ <br />~ <br />\. <br />\ <br />\ <br />( <br />\ <br />I <br />) <br />() <br />\ <br />( <br />) <br />('r--' <br />1 <br />r. <br /> <br />~.~..-t <br />, ~. <br />, , <br />I DENVER I <br />, , <br />On, ~_.. <br />, , <br />, , <br />--- <br /> <br />~ <br />" <br /> <br />. <br />o <br />" <br /> <br />~ <br />" <br /> <br />~ <br />" <br /> <br />~ <br /> <br />o <br />;; <br /> <br />~ <br />" <br /> <br />FIGURE 1 -fLOODS ABOVE ELEVATION 1118 FEET <br />1889-1959 AT SIXTH STREET CREST STAGE GAGE <br />SITE ON BOULDER CREEK AT BOULDER COLORADO <br /> <br />lire <br /> <br />1124 <br /> <br /> <br />40'- <br /> <br />~ <br />~ <br />~ <br />~ <br /> <br />z <br />Z 1122 <br />o <br />~ <br />~ <br />~ <br />" <br />UJI120 <br /> <br />c..e81r <br /> <br /> <br />-.. <br />- <br />) <br /> <br />~ <br /> <br />]0 <br />, <br /> <br />2O,""lLES <br />, <br /> <br />~Gaglng alation <br />I Cache la Poudre RlVerat mouth of canyon. near Fort eonlfUI <br />2 St. Vram Creek at Lyon, <br />3 Boulder Cl"e('k near Boulder <br />4 Boulder Creek near Orodell <br />5 South Boulder Creek near Eldorado Spnnp <br />6 Cle.ar Creek near Golden <br />7 Clear Creek at Forb Creek <br /> <br />1118 <br />20 25 35 SO <br />RECURRENCE INTERVAL IN 'fEARS <br /> <br />FIGURE 3 -FREOUENCY OF FLOODS ABOVE ELEVA <br />TION 1118 FEET AT SIXTH STREET CREST STAGE <br />GAGING SITE ON BOULDER CREEK AT BOULDER <br />COLORADO <br /> <br />'00 <br /> <br />FIGURE Z -LOCATION OF GAGING STATIONS USED <br />TO DETERMINE FREOUENCY OF FLOODS ON BOUL <br />DER CREEK AT BOULDER COLORADO <br /> <br />FLOODS AT BOULDER, COLORADO <br /> <br />500 <br /> <br />o <br /> <br />SCALE I 6000 <br />500 1000 <br />I <br /> <br />2000 FEEt <br />I <br /> <br />1500 <br /> <br />CONTOUR INTERVAL 5 FEET <br />ELEVATIONS SHOWN "RE REFER REO 10 BOULDER City O"rUM <br />TO CONVERT TO ELEV"TlONS "eOVE ME"N SE" LEVEL ADD 42480 FEET <br /> <br />1961 <br /> <br />'NTEIl OR_GEgLOG'CM. "UIl\lE'" W_S"'NGTCN " e_'O~tt <br /> <br />For sale by U S Geolog,cal Survey Price 50 ~nts <br />