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<br />, <br /> <br />, <br /> <br />7~OO <br /> <br />. <br /> <br />f;~CO <br /> <br />50.1,,1"-100fo.1 <br /> <br /> <br /> <br />N <br /> <br />)11": /,\'''', <br />i II \~,6';;JV/ii~ <br />I I! I~.IJ '~'.::. '= <br />\ \\[ ~I.i { <br />( ~I ~;,II If <br />"I,! \ %l~ ,,,,-__.100: <br />) I \\ ~ -- -=1~"" "'<;1'3<3 <br />/~ /.~I ~\~' ,,~~~''''''s\ ~ \~ <br />" ,-.,~:, .,.,\ ".' <br />(., ,--,' , <br />"\">~~':',~;~;\ ~<,,:' \'~\~' <br />\. ,'/;::;._ I! ,\ ~\." ',' , <br />'<.~ /-" -< " _,I "~ '0- ,\, <br />,---... r,\ 1/''';''' "I \. ,', '\ 1 <br />'~~~:!~,1'< r. x<;:\\ \, <br />, _ - "7----V ,I I "\ I <br />' " .-::::~~ "1.' :',' -, '. "' :!c.,1 <br />i .__;:.._-,/_ ':0- , ' ~ \';';-J~:- <br />~~., _~,,- ~ ~ :,1 ,~-' I" I.eatl" ,fUSGS lag. <br />~=<"~. ,-",. ~~/, II,,'" ," ~,. <br />::=Jr:?''''--~-~-=--:-;'- ,,', xY'"""'\ I ',' , '~;~':';~~~ 'I"'~,~~ <br />=:=....-...\ \....- _ >', ", \ I ""':'-~"'1"'~';;:' " <br />:;:~ ,~". . I, \ ' ili?' "~A ,~~,~;" .",:]" <br />,. -~ . ", I' ""' _~-' I,"""', <br />.~~~:::\ ,.--'..~~~;~~..\ 1\' \ 'I 'J!' \' 'I' \~~ "'~~'"\_>:'\\\\:~\ '\ ' ,~~.'."'''Ol chun.1 <br />~: "-'-;:----:::1"\-,-.:>-,- ". <,'''\' \1):; \. j .. \. \\',"'\-,,,\ . <br />\, ~___""-;-:;".\ '"'--, \._~,.. : \ ',\\::-' \: \, -"". .. \\ \ \, I <br /> <br /> <br />FIGURE 2 - LOCATION OF SURVEYED CROSS-SECTIONS <br /> <br />, <br /> <br />The second v~iIDary purpose <br />determine the causes and history of <br />upstream from the Corps channel. <br /> <br />field <br />of the <br /> <br />.'as to <br />material <br /> <br />investigation <br />loose rock <br /> <br />of the <br />erosion <br /> <br />Other purposes of the field trip we~c to inspect the condition of <br />the Corps channel and to dete~mine roughness coefficient,. (M"nn1-ng',. "n" <br />values) Roughness coefficient for Willo,,;Creek upstream from the Corps <br />channel was determined to be 0.040; for the Corps chann~l itself it was <br />0.025. <br /> <br />Field work yielded the following findings: <br /> <br />1. The debris upstream from the channel is indeed migrating <br />doW'nstred[ll; hoW'ever, th" debris is coming down gradually but may erode <br />suddenly with high flows. It should be noted that the Public Works crew <br />from the To"n of Creede annually clears debris upstream from the Corps <br />channel. This practice must be continued in the future. In addition, <br />d<Jring high spring runoff of snowmelt, there is a person put On 24 hour <br />duty at the mines uvstream of to,,;n to insure that debris is cleared from <br />cUlverts,eu. (per conversation Io'ith Charles Steele, Mineral County Land <br />Use Administr~tor). <br /> <br />2. The <br />of the channel <br />channel. <br /> <br />Corps cha<lnelwas <br />"as very good Io'ith <br /> <br />insp.,cted horn end to end. <br />no vegetation ar cracks in <br /> <br />Theconditian <br />the masonry <br /> <br />Ii <br />I <br />" <br />I, <br />I <br />I <br />. <br />, <br /> <br />Findings of the field investigation were combined "ith hydrolagic <br />findings and cross-section data from Carps flood control channel plans <br />(see Ref. 12). 1U1 of the crc",~_section data vas inp\ltted into in the <br />U.S. Army Corps of Engineers HEC-2 step-backlo'ater computer program. A <br />starting water surface elevation of criticsl depth "as used at the <br />entranco to the Corps channel since "ater in the Corps channel itself <br />floW's in supercritical Ho",; this type of flow regime could not be <br />maintained upstream from the masonry channel d<Jeto the erodible type of <br />streamlllaterial. <br /> <br />I <br />, <br /> <br />The hydraulic analysis usingtheHB:-2 cowputer model showed that, <br />assuming a rigid (i.e. fixed) streambed, ALL of the floodwaters "ould <br />enter the Corps channel, even at t.'",Corpschanne1 design flo"of 1800 <br />efa. None of the flo" would bypass the channel and flo" do"n Creede <br />Avenue tOlo'ard tOlo'n. Thus at the lOO_yearpeakdisehargeof1l20cfa, <br />none of the to"n W'ould be flooded if the channel "ere kept clear of <br />debris. <br /> <br />, <br />Ii <br />, <br />, <br />,. <br /> <br />Flooded Areas <br /> <br />As determined by the hvdraulic:analysis of the atudy, none of the <br />land in the town itself "QuId be flooded with the lOO-year discharge. <br />W,,~er ",,,.old pnt..r ann rf!matn in th.. rorl'~ of Engineers noce!. control <br />channel through tOIo'n. The lOO-year flood "'<luld, how,"ver flood a small <br />are" just IJp:!tream from the Cor?:! chann"l. Figur..'3showOlthtaar"". <br />Inform"-tinn "i.th. re;;srds to water surface e1evacion~ at various locations <br />is ~ho~'n On the Pbtos in Uli" r~po~t. <br /> <br />, <br />