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<br />VElOCITIES OF FLOW
<br />
<br />During a 100j.year flon,!, channel ,'c1ucit)'
<br />in theCotorado River would avera,.;e;,-f> feet
<br />I"'" second bdween :l2 JV,nrl Bridge nnd
<br />Oldham Hottoms. Ul'_-;tream from Oldham
<br />Rottoms,cbannclveloeitywouldincreaaetoi!-
<br />II) fect per ,;('c(Jod Narrow~et'tion' hdow the
<br />Grand Vall"y Canal di"craion anu near the
<br />uIIISl""amlimitoftne.t",lyreal'hcouldexpect
<br />ehannelvelocil.,\'nrI2.13f~"tperseeoodfor
<br />short distances. Overbank '-e!ocity would
<br />f1sera,.;e 2-4 reet per il€cond. ]" _-;neet flow'
<br />areas, avcra,.;e velocity of now would ranll'e
<br />
<br />FLOODED AREAS
<br />
<br />Tnearcas t.lmt would be inundatetlby tbe
<br />100-and;,OO-yearfhlll"areshownonPlat""Z
<br />- 26. Aa may be Sl'€n from thme platel, th<1
<br />lOO-year flood on tbe Colorado Riverwo\lldbe
<br />o\ll of banks for almost its entire study a"-'a
<br />len.':tb. but would clo",-"Iyparallel thech"nnel
<br />and remaLn mo;;t)y within ita natoml flood
<br />plain. Wider area;; of f1oodin" wuuld fan out
<br />,ponulirally on hnth sides of the river
<br />throughout. tlw "wdy nr,'a. Sevcnd area~ of
<br />L'ural""si(l",w~~and fal'tllbuildinK,w"ultlbe
<br />inum:lawd:o;pecifically.e"""tantlwuth,.""stof
<br />Palisade ",hae floodwate,", wO\ll<lal.nowr-
<br />
<br />FLOOD DAMAGES
<br />
<br />l!amagcsrcsultin>!:fromal()()-yearor:itJO.
<br />year flood would principally be a<sociawd
<br />with agricult.ural "nd rllral rl'sidenti..lar~&;.
<br />"rul public fa"ilitios. Residenti"llfl<"'~8 would
<br />include lhm"ge t<i fflund"tiol\8.lowerflDors.
<br />',V"ll<, furBishing-:;. appliances. and lawns and
<br />gard"n.. A!l'ric\lIturaldamal>:ewouldinvol\'e
<br />"r,,"ion "n<ilkl""iti"n "fsiltand d..brison
<br />crop and pa-~tur€ lands.P\lblic faeiHty 10."0.
<br />would compriH'dama.:eto,t,'ects.hij(hways.
<br />hridW',.andirrLJ<".<tion:\ndsewaJ<l'treatment
<br />~Y'lI'ms. ()th~r ".0,,1, attrihlltablt' tv f"",Kling
<br />
<br />1~",",1. ,h..Ik,~. ,m,d..,,, IIHW ~,'r"".,;I;..." th"" 2 ~""L ,1c,<p.
<br />
<br />f!"l,m 1-;j reet per .~c""d.
<br />Wawr flowinr: at a raw of 7 feet per aecond
<br />or greawr will ea\l"e """ere ~ro~ion of
<br />streambanh and is capable or tran~p<>rtin.:
<br />lar;rerOCK8. Streambanks and th,'fill around
<br />brid"e abutment, may h.> eroded and larw'
<br />amOllnl-" of Jl:ravel. sand. al,d ailt m:l.,\' b.
<br />transported by water flowing ata rateo{5.7
<br />ffftPfrse<:ond. Waterfl<Jwinll'atabout~feH
<br />perseeond or Ie" will deposit sancl. silt. and
<br />Qtber-dehri,.
<br />
<br />top portions "f U$. Jlighway 6.24 and State
<br />Highway340:th~northsideoftheriverinthe
<br />vidnLt.yofM Rl)ao: and north nfthe riVi'r in
<br />the vicinity of :l3-)f Road and D-Y; Iwad. The
<br />IOO-Yfar flood would inundate about LB50
<br />acr~_'.ofwhieh ahoutf,oaere,areurlwni".;'ll,
<br />1.4()O acres ar~ d"votRd t<1 aj{riclllture or are
<br />undeveloped, and 400 ""res are streamway.
<br />The500.yearfloodwollld>:enerallyfoUowthco
<br />same p;ltkrn aH lhe l00-Yl'l\.r flOCK!. but it
<br />would ,'xt.",d furth,'r from t1w ('hannpl and
<br />wO\llrl he r1e~]1('r in some areas.
<br />
<br />mjghrb€temporaryevacuat;onofsome"rea<.
<br />erode<:l st",amhanks, and flood fightin>:and
<br />postfloodcleanupandre"toration.
<br />Due to the wider flood plain. ll'reat"r deptb
<br />offloodinll",andhill"hervcloeityofflowduring
<br />"fiOO-year flood. damage would hf Il:feater
<br />!h"ndurinll:a lOO-year flood.
<br />The depth of flow inthc river channel and
<br />adjacent flocKled area, can Ilt'd<'terminl"(l
<br />from the w"ter ,urfacp profile. '5hnwn on
<br />Plate,n-:l1.
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