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<br />17 <br /> <br />'" <br /> <br />FlnodedArea$ <br />The lOO-year frequency flood has been selected by the StateofColo rado <br />a, the flood event to be "sed for flGGdplain delineation and regulation, <br />Thus, the Flooded Area pi ates 5ho~' on IV the boundary of tll" 1 OO-y"'" flood- <br />pl,,;n. Since the case map for tll" FloOded Area pl~te' j S ~ 5-foot contour <br />O'ilp, the Out II nc, of the Clth"r f I cod event~, 10, 50. and 500-yea r. cannot <br />be, insomea;"as, readilypl,>ttedwslng the information in Table 3, <br />The area delineated on the Flooded Area plates as the IOO-year flood- <br />plainmcets tllerequlrementiofH.B.1041asan..reaof.tilteinterest, <br />Also, upon official approval of this report by the Colorado Water Con- <br />,ervatlonBoard, tile area owtlined by the 100-year flood bowndarycan be <br />de,lgnated a floodplain area and may be regulated accordingly by the local <br />off ic i a I ~. <br />AportionofthelOO-year floodplaln between Stations O+OOClnd <br />60+00, andStation5 123+00 and 145+00 I'subject to flooding due to up- <br />5tream cond it ion" ,u~h a, i rrigat jon di t~hes "nd topographi~a i character- <br />15tic~ whiCh divert flood "at~rs VJ ""Id I~nd$. The,e areas are d,,~jgnated <br />~'i th lIned ,had Ing <lnd repre~enl aced' uf sha Ilow oveciand flood Ing for <br />the 100-year flood. Because these waters are not hydr~u Ii ca Ily connected <br />to the channe I, tilt' d~tudl water surface "levat ion I n tile overbank drea~ <br />is genecally hiQhec than th",,, _hnwOl j<1 r~bl~ 3 For t~e ",,,j n c~"nne I. <br />Que to t~e 5-foot contour i ntcrval there may hI: areas in" luded wi thIn <br />the 100-year floodplain whiCh are above the 100-yeac water 5urface elevation. <br /> <br />Flood EleyatiQns <br />The FloQ~ Frequency-Elev~tion and DISCharge D~ta t~~le, Table 3, <br />I ins ,he 10, 50, 100, and 500~year flood e levJtion. at selected refer~ <br />ence"oint., The Flooded Area plates giv,-, the pian vle'oJof the flooded <br />b " ,., . ,'~- '.""r ~Ievat iens for the IOO".,ear <br />area on a contour ase map an~ " "~,, _~ _ <br />flood Can be interpolated from this, The Flood Profile "Iates Show the <br />stroac:bed elevation and the high wJter elevations fer all feurfrequcncy <br />floods. Also, the Cross-Section plates Show a graphical representation <br />, ' , ,.,'., "'__v ~_M'8.a_,I^n< throunhout <br />of the 1,lgh water e evat,ons a y~'~ v~ c, ~'v.o ~~~ v, ~ <br />thestudyreJch, <br />The FlOOd Profiles may be used in areas where controversy arises over <br />the IOO-year flood boundary on the Flooded Area plate~, Since the Flood <br />Profi Ie plates giw, the e)evation5 and distance or stationing from <l known <br />point, the high watec elevations Can be surveyed on the ground to alleviate <br />anydi"repdncie,,<;>ntneba,effidp. <br />Tooetermine the depth of flooding or the floodplain limits at an y <br />]oca,inn In the field, the following procedures should be used, <br />I. locate the ground point at which tl", depth of flondingnr the <br />floodpl" in I in'; t is to be cst~hl ished nn the I" '" 400' flo()d~d <br />nre~ m~p. <br />2. Deter.",jne the e lev"t ion of the w<lter .urfuce ~t t.he ~el eclcd ground <br />point fromTable3,andby interpolating between tnewatec surface <br />elevati<Msgiven for twoddjdcent cross.sectlonsand referring to <br />the pcofile drawin'ls. <br />3. Us ing the ~io'est monument for e levat ion controi. determine the 'Ndter <br />surface elevation at the qround point by standard ,urveying technique, <br />Th" fi""drlai~ II",it ;s e.ta~lished ~'he~ the "ater ~urf;,ce eleva:ion <br />i"t~r.~~~t, the yroullJ s~,-faee. <br /> <br />ground <br /> <br />An approximate ~epth of flood ing can be estJbl i shed by ,ubtr<!cti n~ the <br />~levJtl"n e,timJ:ed fro01 the contour map h"m the pc~,'lously dcter- <br /> <br />lli~"d ,",',]te r ,"dace ",1.-vJt ien. <br />r" Incate the edge of the rl OQ~pl" i n by simple "d I in~ methods, ,~eaSure <br />, ,." ".- 'h".'"nbei.;"n- <br />tne Ji,tane", on tn~ '"dP tlVl' t"" 0'. I,)()r.~ ~"y,;~o '~d,_~., u. <br />tT "ied both un the ,,,-,p and in th~ fie Id t<.> the c~ge of the floodp lal n, The <br />