|
<br />Hydrol~Ri~ Analysis
<br />
<br />A statistical analysis of gage records and historical data waS
<br />employed to obtain the hydrology for ;,'il10w Creek at Creede. Gage
<br />records were obtained fromUSGSgage082l65oo, "\"illowCreekatCreede".
<br />This gage, located at the entrance to the Corps of Engineers flood
<br />control channel in Creede, has records for 32 water years (l951 tn1982;
<br />discuntinued in 1982). Historical data WaS obtained from Corps of
<br />EnRineers design documents (Refs. 8 and 11) for the flume.
<br />
<br />Because there are two distinct causes of high water in \/illow Creek
<br />at Creede (see Flood Characteristics section of this report), a
<br />statistical analysis waS performed on each of the two types of runoff.
<br />Strip charts from the USGS gage W<!re exarnined by C;,'CB in order to obtain
<br />the annual rainfall runoff peaks. A log Pearson Type 3 distribution was
<br />employed in the statistical analysis of the peak flows. The historical
<br />period used in this analysis was 1911 to 1986 since it was believed that
<br />the largest events far this period were known. The freq,uency curves
<br />resulting from the two types af runoff were then statistically combined
<br />into the "adopted" results.
<br />
<br />Results of the hydrolagicanalysis lead ta the follawing results :
<br />
<br />Recurrence Interval
<br />(yesrs)
<br />10
<br />50
<br />WO
<br />500
<br />
<br />Peak Flow
<br />(Cf~
<br />510
<br />910
<br />1120
<br />l600
<br />
<br />These values are plotted in Figure 1.
<br />
<br />Hydraulic Analysis
<br />
<br />An analysis of the hydraulic characteristics of willow Creek and
<br />ths Corps of Engineers flood control channel through town was performed
<br />in order to determine water surface elevations for the 100-year flood.
<br />The Corps of Engineers built a flood control channel in the late t940's
<br />consisting of grouted rip rap for its entire 5527 foot Length. The
<br />channel extends through all but the upperlllOst 100 feet of the creek's
<br />length through Creede. The channel was designed to carry a rnaxirnlL'n flow
<br />of 1800 cfs. Plan and sections of this channel are shown in Plate 2.
<br />
<br />A f1.eld"urveyw8s conducted by the CoLorado Vater Cans"rvation
<br />Board on July 22 and 23,1986. The primary purpose of the fie1dvislt
<br />was to determine if the 100-year flow wau1d iMeed all enter the Carps
<br />ch~nn..l. l1: i" known thflt the Corp" ch,mnel "1M designed to carry L800
<br />cfs. Cross-s"ctianswere surveyed upstre"m from the up'.ltream end of the
<br />CorjJs channel in order to determine if it was phvsicallvp()ssi"le for all
<br />of the loo-year flow to enter the channel. The locations of the
<br />field-surveyed cross-s...ctions are sho"-n on Figure 2. A ?lot of the
<br />field_surveyed cross-sections is given in Plate 5.
<br />
<br />9
<br />
<br />.
<br />
<br />,,-,, '"
<br />
<br />.,
<br />
<br />"'_.
<br />
<br />; ,-I
<br />: =--:--~:::::~-:=-~ u_c~_~_.;.:,==--~"'" 'C_ -- -- :"-:!':::: i;:.~~:t-:::t~~::-(,:::::,;:-:::=-+-:::-~::~.~:
<br />'" ;_.!-=:.._~....:___ "";'_--'---, __:~__ ____-!___L~__j_J ___:_ _~.I; -!....i.-,;-~,---,,--,-,- -- _,_
<br />, , ',,-0 _,
<br />:',:: 'i ,i~, J-T!' L:J:.:....'.I..._=-l.~J:::::~~,:_~;t I
<br />,-, " '" .!...'
<br />, ...-t--I .t--+-'--'-"'-~-'" :'__..I_.,......J.
<br />;---,-~i:-:..":{ .. _< ._ ..-........-.--1-.." I ..,__.: -..0,. .~ -,-
<br />,2:-,--,- _--;..,- _ _~:~;::j._ __:--~::-!:=: '::C"_y'::::~-::~:""::___:o~I'-
<br />~ - <'-{::J;;f:_~J~t;: ""~::F"~J :_,~; ~c::, l::-: --_::
<br />,
<br />
<br />ol~ ,
<br />1--+-;--
<br />.-,,_: -,-
<br />"'r-i---'--
<br />
<br />III
<br />! i ~
<br />
<br />--"
<br />,
<br />Uj
<br />
<br />,
<br />:,';'
<br />
<br />a
<br />
<br />
<br />"
<br />
<br />
<br />"I
<br />c
<br />
<br />I
<br />~.
<br />
<br /> , ,
<br /> , , ,
<br /> , ,
<br /> ,
<br />,
<br /> , , ,
<br /> ,
<br />
<br />s
<br />
<br />; -'+ ~ ,-; ,;-
<br />-<--, .~.!~: '1,::1" . ~,,', _":"H=.t=-----,------.-i
<br />r-.L~: .=: _>- ,,_,._~,. ~:1
<br />-'~~-i------='-' ~:.:~ _ o<:,-'~.- _::r."' ==;:.--~---~
<br />_ . _.= _""r__. _"." _~_ ____..,._1
<br />-iOC'.-, '=, ' ' '",<,++:;=... g' . =t=I'
<br />'-'---"-"~""""
<br />, . + .. I ' , ",." ."', . .
<br />..-, ---.--c, I ""'--::;~I;" ,
<br />,...-., ., ,.....,
<br />....$l~
<br />:...J.....+-. ,:!:=tL='"
<br />-'~4-- .."-I---:--''-'--'-...!.-.--;.
<br />~u _~,=-;: ,
<br />L-,._ ~ ;
<br />r-r--+.,--.--. '
<br />',-' ' .
<br />... -..,.'
<br />
<br />"
<br />e
<br />
<br />u
<br />
<br />.~
<br />,
<br />,
<br />
<br />~.
<br />
<br />~
<br />
<br />-~
<br />
<br />-)
<br />
<br />~
<br />
<br />,
<br />
<br />-,-~,-
<br />
<br />_' "___I
<br />I
<br />,
<br />,
<br />
<br />-
<br />
<br />~-
<br />,
<br />
<br />, .
<br />,~ ~
<br />,
<br />.
<br />
<br />.
<br />,,'
<br />'.
<br />,.,
<br />"
<br />, ,
<br />..
<br />,.
<br />gl
<br />..
<br />
<br />.::~.,.'"
<br />,i, +-,-,~;t_
<br />'<1:8:.:+,.:' -::L,-: ; -',}.: ';:~'f-'-'~; c:IL: ' - --
<br />,,,,' :;,-, ' ",,,., !:._""""':....;:.,.,',.,c:::::I[!:~_ r~:-LI
<br />,~ ,," , '"'''''' " ", ,,; , ,. ,,"'" "iiti ,', '.. .. ".." "'" , ,
<br />'lli' , , I',,' . , , , 'I,' I I I II I I' I
<br />'1'-.,0'" _' I' III II '11,1 I, I _ ~--=tuJ.:l_L_;...:.L' ',I;;; 1,1' ..L.._::-~
<br />"I'I""!,, ""1""'11 '. 'II I,,',~, ~,
<br />~ __ 'I" . , " " ' .J
<br />."~3~C:-,fEliE1'TcV;--~C--U"'--~'u~ .C["1c~===f" .-:-'. U""~~:
<br />"I:':: -~
<br />. ~-:;rOl---O::;;-C_ ~--=;::::::;---f=='-" .--.--- ,--'--" , ---- --.- . -,_.. -- --=';-~~"I
<br />-,._- -.-,.-,....,. . - 'I-'~'-~ ~ ~ -~ -:.:.-:-.-.-r-::'-'----:-:: I .
<br />---,-c';" ..._ __,_~_ I ~,_._--,
<br />1--.-r~I--r~.~-" II., I ' I ' .:' " ,; , : J
<br />"ffit-TiTW'" i:l1"n:'TII-~ 1 I"'-C~~; i":'T':"I:; 1 II
<br />$_ '-5-.]-,"1' 1_1" , L--..:_'_ .~~.._"~,--,-----..l'.:.i_,'_:,!:
<br />:: '_----!--'.~"I I " , I I I, "! I, I I "'I' I"~
<br /><;, - 1 --::, e.- to -~'-::t'~ ~-."-= -'-E-"=-" --".'n":'::::"-":"':;:'-' .,,-"'--_._;:;....:'c,=-.'---~,,'" _._,.,,-~;..;-=c_,
<br />;rl~:ll-~;~C-gIi:=g=g~~=~=;[~~~~=
<br />o 0 '" 0>... ~ II)
<br />"
<br />
<br />1,-',j
<br />"
<br />'",'
<br />
<br />,;,
<br />
<br />'.
<br />
<br />"
<br />
<br />"
<br />
<br />.,
<br />
<br />0'."'",
<br />
<br />"
<br />
<br />"
<br />
<br />.,
<br />
<br />.,
<br />
<br />(',oj ,5a~"!p ~"d
<br />
<br />,
<br />
|