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<br />. <br /> <br />. <br /> <br />. <br /> <br />structures, which store about 1 inch of runoff behind their emergency spillways, delay <br />tributary flows to Kiowa Creek. This storage decreases natural-flow peak discharges <br />and helps to reduce downstream property damage. Thus, even though retarding dams <br />are placed across numerous tributaries, unusually large floods still can result from <br />intense thunderstorms. <br /> <br />The largest probable flood is difficult to define, but comparison of the peak flow <br />observed from a given drainage area puts past floods into perspective. Crippen and <br />Bue (1977, fig. 14, p. 13) described maximum peak discharges observed for the region <br />which includes eastern Colorado. Crippen and Bue drew an envelope curve, part of <br />which has been reproduced in the graph below. Flood data for sites in and near Elbert <br />County are included in the table. McCain and Jarrett (1976) determined that the 100- <br />year flood values in eastern Colorado are a function of drainage area and basin slope. <br />A 100-year flood-discharge curve, computed using an average basin-slope value, has <br />been added for visual comparison with the envelope curve. Actual 1 OO-year discharge <br />values at a site may differ from those of the 1 OO-year curves shown. <br /> <br />The envelope curve does not represent a physical limit, but shows the magnitude of <br />some extremely rare events which have occurred. East Bijou Creek, which drains the <br />central part of Elbert County, produced a peak discharge in 1965 near the Arapahoe- <br />Elbert County line which approached the envelope curve (site 9). In 1935, a 50-year <br />flood was measured at the same site. <br /> <br />IWJ~ <br />bOO, <br />f- <br />, <br />i- <br />i <br />I <br /> <br />lTITrl:'" <br /> <br />I I" ,ill <br /> <br />illl' <br /> <br />: r Illl!1 <br /> <br />1.1196~1 DATA. POINT ANO SITE Nl.M8I::R- <br />1'11,,,..1...' III 1""."1",",,.. 'll Y".... <br />1_" flow O~L;urIoKl S.... Iftl,l.. <br /> <br />, <br />" <br /> <br />.911~1t., ..... <br />i <br />I <br />'1 <br /> <br />12.119Jfol <br />10. l.,:S!>1 <br />Il~G, <br /> <br /> <br />J <br />=1 <br /> <br />100 <br /> <br />E:nvelOlloo' c,..v..!Allttl <br />Ct'PPUIJ and b..m. 19171 <br /> <br />8 IY.,l!,.I. .'2t19tib: <br />".ll~!.>1 <br /> <br />-i <br />-' <br />-1 <br />"1 <br /> <br />bO <br /> <br />6.lnu~. <br />6 "1l965l <br /> <br />':~ <br />I <br />~ <br />,I <br /> <br />""-.lOO.y_r rIllCU'rll'~e '!\leNal <br />IAfte' McCam .,1(1 JaulItt. 1976l <br /> <br />211&651 1.(19661 <br /> <br />,..1 <br /> <br />. 401186&1 <br />I I J IllI <br />ObI <br /> <br />I I 111111 I 1111111 <br />b 10 fiO 100 <br />Of\A,INAGf AAEA IN 'OJAM UllES <br /> <br />01 <br /> <br />60u llXl(, <br /> <br />3 <br />