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<br />Hydraulics <br /> <br />..kcordinll to the ';a.t1onill Oceanl.: ~nrl At"'o~pheri.: Arlmlnhtration <br /> <br />The U.S. Army Enrrineers HEG-2 comD"t~r nrOfram ,"',. """rl to p~cform <br /> <br />.precipit"Uon-Frequency "tlas for Colorado." the follo"lngam ountsof <br /> <br />"~ter ~urface profit" computations. ';urncrous brid"e~ ~nd cul.,ert~ exist <br /> <br />r~infAll (rOlnt v~luea) could be uxpected for the frequencies shown: <br /> <br />along the channel" throu~h the study r~4ch. Those that cre~terl .irrnlfic~nt <br /> <br /> 6 flour " Hour <br /> Dur~t1on Duration <br />10 year 2.37 ,". 2.90 ,". <br />50y",,,r 3.22 ,". 1.95 '". <br />WOyear 3.M ,". 4.41 ,". <br />;00 year 4.53 h. 'i.55 ,". <br /> <br />back"'at~r "ffe~t w"re handled in th.. "lEC-2 analysts "Hh "pp!""p!"il'lte ~rl,jf(e <br /> <br />routines. A few brid~es arld culvects are ""ly ltl[nor .eO;""'rlt" uf the total <br /> <br />nn<><J plAin and therefore were conddered in the Karlrlirlgs reta!"da"c~ fa"tut <br /> <br />rAthe!" than in separate hridy,~ analyses. <br /> <br />A number of references "ere used to cherI< th~ reasonahleness of the <br /> <br />Cross se~tion dat~, "rld reach leo"th information ~ere obtalned fro~ <br /> <br />dlscharge-draiM~e area Curve. Some of t!l.ese include data fram T~chn1cal <br /> <br />photogrammetric",""pspreparedespeeiatlyforthisscudy. llyd!"aul1crou!,:h- <br />nesseoefHcients("n"values)weredeter:ntnedholtlfield lrlspection. arld <br /> <br />Kan"aINo.l(previouslyreferredto), SoilConservationServiceCu!"ve <br /> <br />~ulllber Method. U.S. Geological Survey Water Supply Paper 1681 _ Regional <br /> <br />docullentedwith photographs ([n technical addendum). FollowinKare a tahu- <br /> <br />Curves, Historical Peak Discharges, and DischarKe-Frequency data fr~ other <br /> <br />lation of these roughness coeffitients for various locations along the study <br /> <br />av~itabl~ studies. <br /> <br />a!"ea. <br /> <br />Reservoir constru.:tion on the three tributaries to Big Sandy Creek. <br /> <br />Water surface 'P!"ofiles, typical cross "~cttorla ,~nd ""'os ,~ho"tn!,: the 100 <br /> <br />significancly ",odified flows downstream fro", the dams. The uneontroLled <br /> <br />year and SOO year flood lines a!"e shown On exhibits A. ~, ~nd Flood HAzard <br /> <br />drainage area helow the dams was used to d~velop discha!"!,:e-frequcncy valu~B <br /> <br />Area ~~ps. Tahlp. l ~ho~~ co~puted flood elevations at specific ~ross <br /> <br />for thO! tribut<lries. Aba"" flo" re"..rvoir release rat~ was added in "-S a <br /> <br />$"cLiunB. <br /> <br />cont!"ibutnr to the pe~k discharge. This !"ele~se rate ~as detc!"mined by <br /> <br />Hydraulic Ro"ghness Coefficients (rl-value) <br /> <br />developin~ and routirl~ inflo~ hydro~raphs th!"ou~h the reaervoirs for various <br /> <br />" <br /> <br /> Section Left Rt~ht <br /> ,," " Ove!"bank Ovc!"bank Chann~t <br /> , " .0'0 .040 .060 <br /> C , .100 .110 .075 <br /> , , .'00 .110 .070 <br /> , "" .050 .050 .060 <br /> "" " .0)0 .0'i0 .055 <br /> "' "" .0'0 .0'0 .O'S <br /> , " .050 .050 .060 <br /> " " .100 .100 .060 <br /> " '" .050 .1)50 .061) <br /> on CP .040 .040 ,<'14'; <br /> , "' .110 .110 .%0 <br /> " '" .080 .011b .OSO <br /> 00 00 .0'0 .04'1 .050 <br /> 00 "' .040 .040 .045 <br /> "" E~ .050 .050 .045 <br />Note: llocu"'''ntin~ photof:raphic~ can "" fou"d '" ", t~chn:Lcal ~"ppl..m~nt . <br /> " <br /> <br />storm frequencies used trl this study. The inflow hydro~r8phs arld ro"tings <br /> <br />"..ce accQroplhhed u~ing the Soil Conservation Service [lAI1S-2 computer <br /> <br />progra.m. <br /> <br />The f!"eqtlenc1es cOrlcerned "ith irl this study are the 10vear. 50ve ar. <br /> <br />100 Y"'H IInd SOO y~ar e.,ents. Tnhle I sho~" dlscha!"l':es at specific cross <br /> <br />section Inc.~tlons. <br />