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<br />VElOCITIES OF FLOW
<br />
<br />During a 1(0).year flon(!, channel ,'c1oeity
<br />in theCotorado River would avera,.;e;,-f> feet
<br />I"'" ~cond bdween :l2 JV,nrl Bridge and
<br />Oldham Bottoms. Ul'"tream from Oldham
<br />Rottoms,cbanndvelocitywouldincreasetoi!-
<br />II) feet per ,;('cond Narr<Jw~cction' lIdow the
<br />Grand Vall"y Canal di"crsion anJ near the
<br />uIIIS!l"\eamlimitofthe.tudyreal'hcouldexped
<br />channel velocil,\'of 12.13 fe"t perseeood for
<br />short distances. Overbank '-e!ocity would
<br />f1sera,.;e 2.4 feet per ""cond, ]n ,~hcct flow'
<br />areas, average velocity of now would ranll'e
<br />
<br />FLOODED AREAS
<br />
<br />The areas t.batwO<Ildbe inundated by tbe
<br />100-and5llO-yrarfhlll"areshownonPlat""Z
<br />- 26. As may be ~l"n from thme platel, th<1
<br />lOO-year II"od on tbe Colorado Riverwouldbe
<br />oul<:>fba"ks for almost its entire study arc'a
<br />le".':tb, but would clo""lyparallel the channel
<br />and fernaLn rno;;tly witbin it, natuml i100d
<br />plain, Wider area;; of f1ood;n" wuuld fan out
<br />,ponulieally on hoth sides of the river
<br />throu.':nout, tlw "wdy ar,'a, Seve,'al area~ 01
<br />L'~ral "~si(l",w~~ and f,,!'m buildinK' w"uid be
<br />inundated: o;pccilieally. e"""t and wuth,.."stol
<br />I'ali,,,de wher" fluodwatc", woulclal."owr-
<br />
<br />FLOOD DAMAGES
<br />
<br />lJamagesrcsultin>!:lromalQO-yearof:itJO.
<br />year flood would principally b~ aS8oc;awd
<br />with axr;<:ult.ural and rllralr..,identi..larea,,;.
<br />"t\d pllblie faeilitios, Residentiall(l<"'~8 would
<br />include d~mal(e t<I IO<Iod'ltiol\8, lower flDors.
<br />'",,,lIs,furBishinll",appliances.andlawnsand
<br />f\"~rd"n". A.':ric\i1tural damai>:ewoulrl invol,'e
<br />"c"sion "n<ilkl""iti"" of silt and d..brison
<br />crop and pa.~tur€ landg. Public raeiHty Io."os
<br />would compriH' dama>:e to st,'ect.~, hi>:bways,
<br />hridW'"andirrLJ<".<tion:\ndsewaJ<l'tre"tment
<br />sY'1<'m". Other ,..o"j, attrihutabl~ to rh><xlin~
<br />
<br />1~",",1. ,h..Ik,~' ,m.'d",,, 11,,-.-- ~,'r"".,;I;..." th"" 2 ~""L ,1,,,,p,
<br />
<br />ft'om 1-;j feet per .~c""d.
<br />Water flowinr: at a raw of 7 fect per ,econd
<br />or grcawr will Cause """ere erosion 01
<br />streambanh and is capable or tran~porting
<br />lar;rerock~, StrcambanksMdth,'fill around
<br />briJ~e abutments may h.> eroded and Jar!/<'
<br />amount." of .':ra"~l. sand. alld ,ilt ma,\' be
<br />transported by water flowinx ata rale of 5.7
<br />ffctPfrse<:ond. Waterfl<Jwinll'atabout~I""'t
<br />per second or Ie," will deposit ~and, silt. and
<br />"tber-dellris.
<br />
<br />top portion. "f U$. Jlighway 6.24 anJ State
<br />Hi.':hway340: thf north side of the river intbe
<br />vidnit,yofM Rl)arl; and north nftl1e riwr in
<br />the vicinity of :l3')f Road and D-Y; Iwad. The
<br />lOll-year flood would inundate about l.B50
<br />acre,_.ofwhicb ahoutf,oaer",areurlwni".;'ll,
<br />1.4()O acres are d€voted W aj{riClllture ur are
<br />undeveloped, and 400 acres are streamwa.\',
<br />ThcSOO-yearfloodwonldi,(enenllylollowthl'
<br />same p;ltkrn aH lhe lOQ-yc'l\.r flOCK!. bUl it
<br />would ,'xt.",d furth,'r from t1w ('hann"l and
<br />would he r1e~]1('r in wnw areas,
<br />
<br />mi>rhthctemporaryevacuationofsome"reas,
<br />crOOe<:l st",ambanks, and flood fiRhtini,(and
<br />postfloodcleanupandre"wration.
<br />Due to the wider flood plain. ll'reatHr depth
<br />offlood;n~,andhiRhervclocityofflowduring
<br />"fiO(l-Yf'~r flood. damagc would he Kreatef
<br />th""durinll:a LOO-year flood.
<br />The depth or flow inthc river channd and
<br />adjacent nocKled areas can 'It'd<'terminl''(l
<br />from thc water 'urface profiles ,how" on
<br />Plate"2j-:l1.
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