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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />'. <br />I <br />I <br />. <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />DISCHARGE -FREQUENCY CURVES FOR MEEKER, COLORADO <br /> <br />10,000 <br /> <br />8,000 <br /> <br /> <br />6,000 <br /> <br />4,000 <br /> <br />2,000 <br /> <br />o <br />z <br />o <br />u <br />.... <br />VI <br />lr <br />.... <br />0- <br />I- <br />.... <br />.... <br />IL <br />~ <br />ID <br />::l <br />U <br /> <br />Z <br /> <br />1,000 <br /> <br />800 <br /> <br />600 <br /> <br />400 <br /> <br />.... <br />C) <br />lr <br /><( <br />:I: <br />U <br />VI <br />o <br /> <br />200 <br /> <br />100 <br /> <br />80 <br /> <br />40 <br /> <br />2 5 10 50 100 500 <br />EXcEEDANcE INTERVAL IN YEARS <br /> <br />FIGURE 7 <br /> <br />-11- <br /> <br />Hydraulic Analysis <br />Analyses of the hydraulic characteristics of the White River and Sulphur Creek <br /> <br />within the study area were carried out to provide estimates of the water . surface <br /> <br />elevations of floods of the selected recurrence intervals along each stream, The water <br /> <br />surface elevations were computed through use of the U,S. Army Corps of Engineers' HEC- <br />2 step-backwater computer program (Reference 6). Cross sections for the backwater <br /> <br />analyses of the White River and Sulphur Creek were field-surveyed at close intervals <br /> <br />above and below bridges and culverts in order to compute the significant backwater <br /> <br />effects of these structures. Additional digitized cross sections were secured when the <br /> <br />topographic maps were compiled. The locations of the cross sections are shown by <br /> <br />reference points on the flooded area maps and the flood profiles. The reference points, <br /> <br />100-year flood elevations and discharges are also listed in Table lA. <br />Channel roughness factors (Manning's 'n' values) for these computations were <br />assigned on the basis of field inspection of the floodplain areas. The values for Manning's <br /> <br />'n' range as follows: <br />Main Channel - White River <br /> <br />.04 to,05 <br /> <br />Main Channel - Sulphur Creek <br /> <br />.047 to .085 <br /> <br />Clear OVerbank Areas <br /> <br />.04 to .06 <br /> <br />Obstructed Overbank Areas <br /> <br />.06 to .1 <br /> <br />Hydraulic losses through the culverts on Sulphur Creek were computed with the use <br />of nomographs available from the Bureau of Public Roads (Reference 7) and input into the <br /> <br />HEC-2 computer program. <br /> <br />Because d'ainage from the Sanderson Heights area presently flows through Meeker <br />as shallow surface flow, no hydraulic calculations were necessary. The path of the <br /> <br />overland flow. estimated from the topographic mapping and site investigations, is shown <br /> <br />on the topographic maps by arrows. <br /> <br />A detailed description of the hydraulic analysis is included in the Technical <br /> <br />Addendum, <br />