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<br />18 <br /> <br />greater) flood than a low frequency (2 to 5 year) flood. <br />A complicated model basin study would be required to relate <br />the effect of diversion and controls on a particular fre- <br />quency flood. For lack of more data, the 25% reduction of <br />floods due to controls was applied to the 50 year flood <br />frequency. The small difference in final design discharge <br />would not warrant a more detailed study. <br />The period of records before 1934 are relatively un- <br />affected by diversions or controls. Using this as a base <br />for unaffected flood peaks, a 25% reduction was made from <br />the Discharge vs. Drainage Area Curve (figure 5) to predict <br />the 50 year flood. This discharge read from figure 5 is <br />54,000 cfs. Therefore the 50 year design flood for DeBeque <br />Canyon would be 25% less than 54,000 cfs or 41,000 cfs. <br />A design recurrence interval curve, figure 6, was con- <br />structed using figures 12 thru 16. The design mean annual <br />flow is 22,000 cfs. <br />The flood records used in analysis did not reflect any <br />reduction that the most recent reservoirs may have on peak <br />discharges. By the same token, neither was increased runoff <br />due to weather modification included. Since both of these <br />factors are difficult to predict and could be offsetting, <br />they were neglected in the final analysis. <br />