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<br />J.6 <br /> <br />ANALYSIS OF GAGING ;;Tl',TION RECORDS <br /> <br />Gaging station records were llsed in the analysio: to <br /> <br />predict. t;he design discharge :Eor DeBeque Canyor:. The Log <br /> <br />Pearson Type III procedure was used bJ determine the re- <br /> <br />currence interval curve for each 'o:tat;ion. ThE' observE,d <br /> <br />N+J. <br />discharges were plotted, usLnq tl""-vt recurrence int,eJ:val, <br /> <br />along with the Log Pearson Type -III curve.. See figures 7 <br /> <br />thru 11 in the appendix, <br /> <br />Two periods of time were studied; records before and <br /> <br />after 1934. The year 1934 was piCked for two reasons. <br /> <br />One, that was about the time tene first re-cention structure <br /> <br /> <br />(Williams Fork Reservoir) wa:3 built:. Secondly, that year <br /> <br />was the approximate time the:ce wa.s a break in the principal <br /> <br />gaging station records. Gage 9-1060 records stopped in <br /> <br />1933 and gage 9-0955 records start2d in 1934. <br /> <br />Gage 9-0725 at Glenwoo,) Sprj Iq,; lS the only qage on the <br /> <br />Colorado River near 'Iohe study ::ce,:.: <br /> <br />that had many years of <br /> <br />records in both periOds of tin~; 34 years before 1934 and <br /> <br />33 years after 1933. There was d difference of 11,500 cfs <br /> <br />(33%) between the 50 year floods calcula'ted for' the two time <br />periods. See figure 7 in tne dPFendix for the recurrence <br /> <br />interval plot. A graph of thE' peilk f.Lows for gage 9--0725, <br />:figure 12, readily illustrates a t.rend of lower annual peak <br /> <br />flo"<8 in recent year<3. <br />The two periods of gage records \,ere plot'led in figure <br /> <br />5 to form a Dischar9t~ vs. Drainage Area Curve. A st,ra.ight <br />