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<br />The Fl~od Profiles may be \l~ed in ar~as where contruv"tsy arises oVeT
<br />the lOO-y"dr fl(Nd boun~ary shown on the Flood~d Art"a plates. Since thc
<br />Flood P.ofile pLates ~ive the water surface elevation at a specitic point on
<br />the reference line, the high water elevations oan be surveyed on the ground
<br />to nlleviate any d1screonncles ~n the hase mao.
<br />C. nooded Areas
<br />The Flooded Area maps, plat~s I throuv,h 13, show the boundary of the
<br />IDO-year and 50a-year flood plains. The flood plain boundaries were plotted
<br />from the flood profiles by determlnin~ the channel stationini\ of flood
<br />contours at the game interval as thetopog.aphicmapg. Fl""dcontours,
<br />~hown as ",i~~ly l1nes, ext~nd perpendicular to the direction of flow and
<br />intersect the ground at the cd~e of the flood plain.
<br />The areas included within the flood line boundaries are about 0-246
<br />acre. for the lOO-ye"r freq"encyand 1,444 acre"f"r the SOO-year ,
<br />Upon "fficlal appNval "f this.ep".t by the Col".ado Water
<br />C"n~ervatl"n &>ard, the area uutlined by thc laO-year flood boundary may be
<br />re,!ulated acc"rdin~ly by thc local offldal!J.
<br />D. Floodway
<br />Enc.oachments on flood plains, such as artificial fill. can reduce the
<br />areale>ttentofafloodplaini[provlsionsaremadcforit\creasedfl""d
<br />hd;:hts. As an alter~ati"" to the o.e~cnt fl,,(><Iin~ situation a possible
<br />flood,my with encroachment dikes ",as a"alyzed in this study. This ",as
<br />dl'lply a hydraulic "n,,:Vsls i""hich the flood plain was theoretically
<br />.."d1ftedtocontalnfl"odinl'!"wlth1nse,c"tc.den"r""chmentbounJarles. The
<br />rcs"ltin~ cffcct~ on flo"d clcv,1t1on~ "r" "h()~.,.. in ,m Apoe.n,ji", scp,",","" fr"",
<br />
<br />~~is rep"rc.
<br />
<br />Hydr"logy
<br />Hydrologi"datauseJ In this study were provided by the Coloiado Wa ter
<br />Conservatlun eoatd (CW'CB) In accordance with the Plan of Work. The original
<br />Source of the dhcharfle~frequency value" ",as the Si"lOns. 1.i & A~soc1ates,
<br />ln~. <tudy "Cu"I"-'r Sluugh. B"xelder Cr~ek Maste! nralnag~way Pbnnlng Study
<br />- 19R 1", Th~. data was revlew~d ;>nd concurred In by the CWClI and ourselves.
<br />The methodQIQgy for developing the dischar~e data was the "S~Ot~ Water
<br />Hana~em~nt Model" (SWHM) , as revised by the ~issuuri River Division, U.S.
<br />Ar",yCorp8 uf Engineers, 1973.
<br />Hydrcotogic data was bllsed on ~_{)ndit1ons that reflected Hnal ccompletion
<br />of the Boxelder Creek Watershed project. Agene-ral assumptJon in the
<br />hydrolo~ic d~ta Is that 1rrigation ditches and canals that cruss the bastn
<br />do not intercept flood "'aters from the drainage$ they cross. Theloglc
<br />behind this assumption is that the di~ches and canalR CUTI'l" Int" the basin
<br />full fr"", upHrealll tuooff and th~rdore h"ve no capacHy to 1ntercept
<br />additional ",n"ff. ()n~ exception to this Msu"'ption is the \lind'or Ditch
<br />which c.usseB the b",.1n at th~ nurthern buundary "f the T""'" of Wellingt"n.
<br />A detafled hydraul1" study of ~hts ditch shoved it has the cap.clty to
<br />inte.cept abou" 200 cis. fro" Coal Creek flo,,". rhis 1l.dju"tm~llt .",. ",,,de in
<br />frequenc.y--dis~h/lrj(e data for the portion of study area "lon~ the noal r,r~ek
<br />fluod plain between the \ltnd~or D1tcb and Its "onfluenc~ with Box~ld~r
<br />Cce"k.
<br />The h~qll"nc1cs conc...ned with 1n this ,tudy an the lo-year, ~(1-year.
<br />IOO-ye"r and ~OO~year ~vents. Table i shulJS discharges ,,~ specific ~.r"s,
<br />"eclb>n l<>c,atle>na. The foll"wtn" tab\llati'>n sh"..s "a111ea at ,1 h~' selected
<br />["cations given in the ?redou.'ly referred to Si,wna. Ll ~ Assn~jate". tne.
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