<br />1'AllLE 3 - (ConL)
<br />
<br />III. FUTIJRE noons
<br />
<br />J.Oc.nlON
<br />
<br />E;l5t fiown Creek
<br />at Elbert
<br />
<br />28.6
<br />
<br />1%5
<br />
<br />41,500
<br />
<br />,
<br />I
<br />I
<br />I
<br />,
<br />
<br />II. De sc: ri p t 10)\ and ~!e thod
<br />As required, tr,e flood used for an;;llysi~ in this study is
<br />o;'",C) \,..hi.c:h ...ould occur on an avc,,,ge of cr,ce each 100 years, or
<br />whi ch might halfe " pTobah i 1 i ty a ~ QCCllrlince of one perce"-t in any
<br />given year. This is referred to as the "100 Year Flood".
<br />
<br />DRADlAGE AREA
<br />Squar" ~li~
<br />
<br />DATE OF FLOOD
<br />
<br />P!:.~K DISCIIARGE
<br />Second-Feet
<br />
<br />\'.'cH Kio"", CTeek
<br />~t El hert
<br />
<br />35.9
<br />
<br />1%5
<br />
<br />20,000
<br />
<br />I
<br />I
<br />I
<br />I
<br />!;
<br />I
<br />,
<br />,
<br />I
<br />
<br />1'h'o primary r\cthads of il',...estigation were nude>. The first
<br />of the~c is the USDA.SCS Synthetic hydrograph r.1ethod as descrIbed
<br />by their reference in a later sect inn. The second is a method based
<br />on historic records of the regi.onas analyzed by the liS Geological
<br />Survey. A complicating factor is thG 60 flood control reservoiTs
<br />installed by the SCS \"llich control the runoff of 60 percent of the
<br />basin <lrea.
<br />
<br />Kiowa Creek 21
<br />~.l il c s be 1 0',;
<br />Elbert
<br />
<br />100
<br />
<br />1935
<br />
<br />110,000
<br />
<br />Ki\)"", Creek
<br />at Ki.ow<J.
<br />
<br />III
<br />
<br />1965
<br />
<br />19,700
<br />
<br />C. Existing Flood ContnJl ~leasures
<br />
<br />I
<br />I;
<br />
<br />The effects of the~e flood control measures were carefully
<br />analy.ed on five typical structures for \\"hich complete data 1...as
<br />Dvailabl<,. The results shoh' that these structures provide signif-
<br />ic,tnt benefit on floods of a relatively small magnitude. However
<br />on the 100 yenr floo<1. their bcne:it is not as great as might be
<br />anticipated, .although there is not faIt to be any danger of the
<br />failure of thes" struct\lre~ hhi~h \iould create a hazard downstream.
<br />
<br />Most of these floods arc considered to be in exce~s of that
<br />which might be e,~pectcd to OC<.;UT on an aver;;lge of once each 100
<br />years.
<br />
<br />Falloh'ing the 1935 flood, the Corps of Engineecs in~talled
<br />embankments to protect the Towns of }:lbcTt and Kio.;r1 from the Creek.
<br />The embank:nent at Kioh'" i~ in evidence on pIa tC number 3, ext end in~
<br />:l1ong the South I'Icstprn City limits to th" Creek (lnd adjac"nt to
<br />lke Creck to State J-iiy,hHayS6.
<br />The ITSDA-Soil Conservation SCtTi~e completed a \"atershcd
<br />PTC'lTectio:l Program in 1961 [or the KiQ\"a Creek Watcrshed south of
<br />Kiohil reported the second such project in the ,btion. A ~cries uf
<br />gr<lde ~tabilization st ructurc5 and <.:hannal i.mprovements "ere instal-
<br />led along the Creeks, as well as 60 floodwater retarding structures
<br />shown on pl:ltos 1 and 2. :--:ulllerous seeding. furrowinp, and minor
<br />In\pl'ove~ent~ were installed as well, bringing to total cost to
<br />$780,766, excluding Technical assistance co~ts. The SCS estil"uted
<br />that these str\\cturc~ r<JdllCeU the peak discharges from the 1965
<br />flood by 6,000 CFS on West Kiowa Creek, 11,500 CFS on Dast Kio',,'a
<br />Creek, and 12,300 Cl'S on Kiowa Creek ~t Kiol;a. They fed the value
<br />of dmwge W<l~ reduced due tn these struct\lres by HOO,10S or about
<br />37~ of what dama~e could have been ~lJstaiJ\ed withn\lt theln. The l</Titer
<br />believes these estimates to be' some,,'hat ()ptimj~t;c.
<br />
<br />!;
<br />
<br />A substantial amount of Techni,_al infor:nation "'as proce;;sed
<br />in this study, and ,>"ill not be pre~"nt.ed in detail herein. The
<br />follol':ing is a summary of the 100 year desi,\:n runoff at Kio\~a.
<br />
<br />TABLE 4 - PROJECTED 100 YE,\R RU';OH AT K10l'.'.".
<br />
<br />Drainage Area
<br />
<br />I19. 57 ~qua re 'Iiles
<br />
<br />IOU Year Runorf
<br />
<br />21 , aoo Cubic ~eet per Second
<br />
<br />It may be not ic ed t hat this runo [f is s1 i y,ht 1y ~bove the
<br />19,7(lQ CFS recordnd in 1965 but 1'el1 belOh that computed at Flocrt
<br />in 1935 (43,500 CFS). Having h-o ~uch storms in the previous 40
<br />years 1,'ould cnst sam" logical doubt on the accuracy of such it pro-
<br />jection for a 100 year storm. A regional analy~is"considering the
<br />entire area-puts thi~ into perspeccive, and it can be said again
<br />that Ki.owa treckhas received f::rT:lore than i.ts fair share of sub-
<br />~tantia1 rainfall.
<br />
<br />B. FloodPlain Description
<br />
<br />Following thf' 1965 fl 0 0<\ , toe highway d<rp;'rtmer:t i~pl'ovcd
<br />the F.a~t abutment apprOadl to their bridge h'ith a piling 3nd rock
<br />wire pr<lte~t.ive structure ~o ~lS to prevent fl future l(ls~ of the
<br />1'0:<:h"ly .1t th(., ,tb\Jtllll"l't.
<br />
<br />The lil'!its of the flood plain are ~ho\,n on the thnw sheets
<br />of plate 3 in t.he appendix. The creek ;,'as dj,.i,!e(\ by J\Lll\1C'OUS
<br />"c ross - sect i (ln~" ut c r i t ieCtI locCl~ ions :ll()n~ its lengt h. The flood-
<br />\,':\l.el'~ an' well out of the banks, except at ~hc hi,:"';a,. hri.tlgt',
<br />\':hieh is mere than adequata to ca;;cain the rW:loff. The lollo\dng
<br />tabl~ will hricfly ~ummarilP the flDodplain of the 100 yr<lr storm.
<br />
<br />6
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