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<br />I <br />I <br />I <br />I <br />I <br />I},\ <br />1 <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />i~ HOl'maily dry, does not exceeri 8,600 feet .in ~~t:v utioa, d1J.U tL~I.,;UJ:J.iHg to lut,;tti <br /> <br />residents is more susceptible to flooding caused by thunderstorms during the lQ-te <br />. , -' -- -. <br /> <br />.SP!ing and Summer months. Thunderstorms in this area are typically of short <br /> <br />duration and high intensity and cause floods of high peak flo~s .but low vohlmes. <br /> <br />A synthetic hydrograph was developed for Sulphur Creek within the Town of _ <br /> <br />Meeker by the computational procedure for "Inflow Design Floods as Determined for <br /> <br />Design Thunderstorms West of 1050 Meridian" as outlined in "Design of Small Dams''-' <br /> <br />published by the Bureau of l:teclamation. U sing this procedure, 10, 5,0, 100, and 500 <br />, ,". '.- <br /> <br />year recurrent floods are based on runoff from one hour point rainfall values for the <br /> <br />same recurrence intervals \reduced according to basin size l soil group and ground <br />~ -' ' ..' . '.- .' - - --...-- <br /> <br />cover -( Design one hour rainfall)is then divided into 15-minute increments and the run- <br /> <br />off hydrographs computed for each increment and summed to give the final design storm <br /> <br />hydrograph. I!ata used in this procedure is given in Tables Z ,and peak runoff <br /> <br />quantities are shown in Table 3. <br />- . <br /> <br />The peak runoff quantities shown in Table 3 for Sulphur Creek are 50% less <br /> <br />'_:( <br /> <br />than peak flows calculated by the Soil Conservation Service in their report on Sulphur <br /> <br />v Creek published in 1969. The reasons for the larger values a!,pea!, to b.e that the <br /> <br />.. <br /> <br />6-hour point precipitation values where neither reduced according to basin size <br />- -", - <br /> <br />. <br />nor broken down into smaller time increments; _Local resident!> recall Sulphur Creek <br /> <br />overflowing its banks several times during the last 80 year~, and since the capacity <br /> <br />of the smallest culverts on Sulphur Creek are approximately equal to the 10 year <br /> <br />flood, the lower peak flow values presented i~ Table 3 se~ reasoEable.. In addition, <br /> <br />8 <br /> <br />--..... <br />