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<br />The steet girder truss bridge which waS in place from 1936 - 1976 <br />was never damaged or threatened by flood water. The 1965 flood <br />did not reach the bottom of the bridge anrl the house northwest of <br />the bridge was not flooded. <br /> <br />CIlAPTERV <br />HYDROLOGIC ANALYSIS <br /> <br />Flood ChatacteriHtics <br /> <br />Water has never overtopped the abandoned railroad embankment along <br />the "est bank of Running Creek. lIo\iever, the railroad embankment <br />was eroded during the 1935 flood from reference line stations 57+00 <br />to 65+00. <br /> <br />Flood flo"'s on Running Creek occur primarily during the ~y through <br />August period. lIi.torical account. indicate that floods are caused by cloud- <br />burst type thunderstorms ",hich produce heavy rainfall amounts over relatively <br />small areas. Floods are characterized by rapid rises, large peak flo"~, <br />short durations, and comparatively low volumes of total runoff. A typical <br />flood event would pass through the .tudy area and recede within .ix to eight <br />hours after the initial rise. <br /> <br />Water flowed in the .hallow cutoff chan~el between reference line <br />station. 35+00 and 50+00 during the 1935 flood. <br /> <br />Methods of Analysi. <br /> <br />n,e hydrologic analysis was performed co establish the 10- and InO-year <br />frequency fto<>d di~chare"" in the study rench. n,is analysis is based on <br />e"istingbasinconditionswhicharenotexpcctedtochanr,esimificantlyin <br />~hc h,t~rc. <br /> <br />Four indepanden~ methods were used ~o predict expected flood magnitudes <br />for Running Cr"ek. F.achmethodhasit.strangthssndweaknessesinits'ppli- <br />cation to the Running Creek drainage basin. The results of each method were <br />cQm?ared and final discharges were selected after the evsluatioo of the reli- <br />ability of each method. A brief descriptio" oi: each method follow;: <br /> <br />1. 0.5. Geolor,ical 5urvey RegionalAnalysi.-The Regio<".lAnaLysi3 is <br />?ubli.hed in u.s. Geological Survey Water Supply Paper No. 1680. It is baaed <br />on extensive statistical anaIy.is of actual floods which have occurred in the <br />South Platt~ bSSH1. For fl,,,,d pt"edictions. the over.1l South Platte bad" is <br />divided iflto re;;io,," witl, .i",ilar hydt"olollic characteristics. The re~ioI\ <br />",,!lioh e"comp~sse. RUClnng C,,'ck aloo il1cl\'des the Kiowa Cn'eil and Ch"ny C,,'~k <br /> <br />~20- <br /> <br />-21- <br />