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<br />Resources Investigations Report 87-4117 (Jarrett, 1988). The <br />selected stream-gage stations have ten or more years of reliable <br />data and record peak flows unaffected by regulation or diversion. <br />Omitted from the study are gages located at elevations above 8000 <br />feet and below' 3800 feet, urban qag'es, gages wit:h upstream <br />regulation, gages with less than 10 YE!arS of record, and gages <br />located on streams with topographic features markedly dissimilar to <br />those of the foothills. Table 1 shows the 26 stream gages selected <br />from Arkansas River tributaries and the 14 from the South Platte <br />River tributaries, as well as the drainage area of each gaged <br />basin, and the number of years of recorded annual peak data. The <br />drainage areas a.bove the stream gages vary from 6.79 square miles <br />to ::503 square miles, and the elevation of the gages range from <br />400e feet to 6500 feet. <br /> <br />REGIONAL FREQUENCY ANALYSIS. Flood flow frequency relationships <br />for each of the gaged streams on the l\rkansas River and 1:he South <br />Platte River were developed using the Corps of Engineers' <br />Hydrologic Engineering Center Computer Program 723-X6-L7550 "Flood <br />Flow Frequency Analysis", February 1982. IrcorporatE:cl in the <br />program is the Log-Pearson Type III distribution mE,thod in <br />accordance with USGS Bulletin l7B, "GuidelinE:s for det:ermining <br />Flood Flow Frequency", September 1981. The Corps of Engineers' <br />Report "Generalized Skew Coefficients of Annual Maximum St.reamflow <br />Loga:~ithms in Southwestern Division", March 1981, provided skew <br />coef~icients for the analysis of each basin. Corps of Engineers' <br />criterion was used to adjust generalized skew coefficients if the <br />standard deviation of the station rE!corded flows fron the <br />preL_minary portion of the frequency prosrram output exceeded 0.5. <br />TablE! 2 displays the computed dischar'Je'-frequency data for each <br />stream gage; the 07000000 series represent gages from the Arkansas <br />River basin and the 06000000 seriE!s represent the Sout:h Platte <br />River basin gages. <br /> <br />5 <br />