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<br />Srr.all areas "v"iit:nin t~'le flood bou:::-lda:::-ies may lie abcve the flood <br />elevat_io~lS ano! thec..::,:urct hot :.be subject to floodingi owing to <br />limitations of th~"? ma..? scale, such areas are not shown. <br /> <br />4.2 Floodways <br /> <br />Encroacl>nent en flocc. pl3.insr suet; 0_S artificial fill, reduces the <br />flood-carrying capacity and incr0_ases flood heights f thus increasing <br />flood hazards in areas beyond tho- encroac:b...ment itself. One aspect <br />of flood plair, management'_ involvi?:s balancing the ~conomic gain from <br />flood pla=-n develop;:ne.nt against the resul t_ing increase in flood <br />ha~ard. roY" par'IJc.s'2~: of -1-118 ;<;c..d,:Lo(idl Flood Insurance Program, 'the <br />concept of a tlocdway is used as a tool to assist local communities <br />in this aspect of flood plain m2nagem'2nt~ Cnder this concept, the <br />area of the lOO-year flood is d.i'l.ided into a floodway and a floodway <br />fringe. The floo;l,."zL'j i~; -t.hs chi:J.Lnel or a strea!ll., plus any adjacent <br />flood plain ii.i'ea;-:: t -t,na-L muse :;:n,;< free of encroachment in order <br />that the lOO~Y8n:{ .t 1 C)"_xi .lY?- cdr:r'i,~d vii thout. subsi.:antial ir~creases in <br />flood :ieiglll:.c., ~ !\s :!i-LninrJ.lTl S t3:rK'.~:il'd.'::;, t:le Federal Insurance Adminis- <br />tration lImits sueL i:v::::r.cascs In floo:::1 heights to I~O ::oot, provided <br />tha.t haza:cdous ve::loci ties are not: prod~:,ced. <br /> <br />The floodways .I.~' chis :3tudy \-/CTC comput:C'd on the basis of <br />equal conveycmce 2:0(Cjuc..::Li.on rYo)~ [c,ach side of the flood plain. <br /> <br />The results 0_= tJ-_cs,~' Cor:lp',rt~l.t::..o.:.!.':; ;:J_n::. tabu.lated 0t selected cross <br />sections Tor each stream segmE:'nt fo:c v-mich a floodway is computed <br />(Table 2) . <br /> <br />As shoT;ln on the Flr)8G. Eoundary and F'loodvlay r~ap (:Exhibi t 2), the <br />floodway boundar is::; ""lEre :lE.-tJ:~rrn.i~(cc.. r-:' t ::: ross SEct ions; betvleen <br />cross sections, the b::q;T:J:J_ci.e3 we, E intcrr--:,ola-t-0(L In cases where <br />t:r~e flood",Tay and lCO--yeal" flood buundaries are ClOSE together" only <br />the floodway boundary has been show~~ <br /> <br />The area between tJ'-"~.;;: -:':'lcodv'!-r.:.y and -t~1e bo-cr-~aarl of the IOO-year <br />flood is termed t,ne flo,:::x1~,.,ray Erin,IJe. '1'11.0 floodv,ray fringe thus <br />encompasses th0 pCJrt ion _-;:r i:hc :f J(.od plain tha-t could be completely <br />obstructed './'1ithout i.n.creasing the \'later-surface elevation of the <br />lOO-year fl.ood morE:: i.:hal< l~O foot_ at any point. Typical relationships <br />betweon "the flood':o\7?Y and the floc\c.h.1,S!Y fri.nge and their significance <br />to flood plaj n dGvel\.)pms!.-,-t~ a_r[~ shoTo'lo in -Figure 2. <br /> <br />B <br />