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<br />[:a,.ards <:! r.~rge Plooes
<br />The hazards to lif~ and ex~cnt of darong~ c~~sed by a~y
<br />flo:d dCFcnd on the topograFhy of ~he ~re~ flooeeO, dnpth and dur3-
<br />tion of !~ooding, vnlocity of flow, rat" of ri"c, and develcrme"cg
<br />on tr.e Hood .?lab~. l'\lture floods of Int"rI1t>d~3te R<>qional oX"
<br />Star.dare project ,",,,qnit'.lde 0:"\ fount...in Creek and trib'~t~ries would
<br />inundate rcsidential, co~~ercia", and ind~stria1 developme~ts in
<br />J4a~itou Springs and west Colorado Sprioqs.
<br />Vel~cities greater tha" three f~"t per ~econc combi"ec
<br />witt dept~~ of three fcet Or mo~e are generally considcr~d ha~ardous
<br />to life ane proFerty. Water flowinq in exc~ss cf four feet per
<br />s~co~d is capabl~ of transporting .eei~e~t and ca~sing Severe ero~
<br />sion of ~tr~~rnbanks and fill aro~nd bridge abutnents. ~~er~ veloci-
<br />ties droF below t~~ feet Fer s~cor.d, debris and silt deposits can
<br />b~ild ~p, cxt~oding th~ floo~ darraqes a~d creati~g advp.rsn ~ealth
<br />concitio~s. The saturatio~ effects of prolonq~d flooding ca~ weake~
<br />bridge abut~~nt3, l~ve~s, ana ot~er errba~kment wor~s so they fail
<br />'" t~.e Hood",,,ter. ".e(""d~.
<br />rrorer~y da~~?e from fl()C1~ i~ developed areas c~n ~e
<br />overwhelmir.g. ~'he entire cc",.rn~nity ""H"-re wher. str~et", bridq"~,
<br />s"""rs, and oth~r p"blic utilities ar~ d;rr.L;\ged or J~~tr<ly"d. Adcing
<br />to th" phy~i"<ll ha2;Olr<;!,;. " Hood '"'<In unle""i1 dC<I<ily ",pldc",ic di~casc~.
<br />Sanitary '~"'erg b""o,"" pr"~s"re lir.~., 1010,,,bg manhole cove:<c, dnd
<br />spewing ra..... S<1w<lge into the flood,,-."t~rs, se"'.ag~ tr"at..e"t pl"~ts
<br />and feeCcr lines can Ioe washed C'ut, stockyard wast" ",an add to the
<br />pollution and b~zard of an apid~mic disaacc. Nc.....cpapers s~.cti~c
<br />report" "ligc.ter side 0: tl'.e r.ews" in picturing childr~n at play
<br />i~ the mud and water left by a receding fie"';. Unfortunately, th~
<br />eot}ca"'~nat~on t.~r"at to domes,t~c ".ater s'-,p~iies "tor-not "" ~llus-
<br />tr~toc witt si~ilar e~se.
<br />
<br />FlocxiedAreas and flood Dam<lge
<br />?latc 2 i$an i"de" "'ap for Plates 3 through 8 which
<br />show the areas along rountai~ Creek that ~ill be flooced by the
<br />Intermediate Regional Flood and the Standard Project ,100d. Depths
<br />of flo~ for any location on the stro~~s can be esti~~ted fron the
<br />high water profiles shown on Plates 9 thro~gh 14. rloodwater ele-
<br />vations determined in any particular area are not always indicative
<br />of the depths actually attained. Often floodwaters becon~ isolated
<br />and entrapped in overbank areas resulting in depths greater t~an
<br />those shown on the high water profiles. Plates 15 and 16 show
<br />se1ect~d cross sections that are typical of the sections surveyed in
<br />the stuey reaches, all c:<oss section locations are sho"-n on the pro-
<br />file plates. Stream c~aracteristics determined fron topographic
<br />~ps, aerial photograph$, and valley cross sections were used to
<br />comput~ ~nd defin~ the flood situation.
<br />
<br />Velocities, ~ates of Rise, and Duration
<br />The oceurr"nce of t~e Intermediate Regio~al or otandard
<br />Project flo"", would t"c.ult in the floC'c char"ct"risti= ~"0\"1'_ iL
<br />Table 4. This data reflect. t,,~ aVQr"ged ~~ximum conditions wit~
<br />heights of rise, rates of rise, and durations of floodioq ~ca~urcd
<br />dDc",,,t,,"y.[ullstag".
<br />1100dflo..... v~locities depend upon th~ g~ncr~l watcrw4Y
<br />configuration, and the si7.~, shape, and slope of streambed and Over~
<br />bank flow ar~as. Velocities may range from th~ maximum~ app.~ring
<br />in Table 4 to less than 50 percent of these values.
<br />
<br />Obstructioos
<br />
<br />or '""j,,': <:"'""~"H i" "",i"L"",,,",", ",r c:jJ",o'J""l ~'Jol ~V"'D"JLY.
<br />
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<br />
<br />capacity of a "tre~m to con~~y floodwat~rs without c~u"ing ~erious
<br />flood da~y~. Reducing wdter~~y openings by approach emb~n~.e"t~ at
<br />bri<:!gesandchangi"-gchar.nelar.doverbankeapaeiti"s",i.llL..pc<leflcca
<br />~lo'"'~ ar.d c/l.u.c gre~ter backwater deptts with co"-Se"lu"'~t i"crei>~" in
<br />flood~d areas.
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