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<br />" ~. <br /> <br />. riP <br />~""'il <br />1> /, i'" <br />,v" ~" <br />\' .p."v' <br />t: ,,/ <br />cPA" <br /> <br />I \ <br />lQ..-I' 1\' . <br />\i (IV <br />vJ~ <br />. / <br /> <br />. <br /> <br />. <br /> <br />discharge of 1,000 cfs (900 cfs at study site) was inferred from the <br /> <br /> <br />Corps' study on Fountain Creek: 15,000 cfs above Sutherland Creek and <br /> <br /> <br />16,000 cfs below Sutherland Creek. This inference ignored the time <br /> <br /> <br />lagging of the peaks from Fountain Creek and Sutherland Creek. It is <br /> <br /> <br />obvious that the peak discharge from Sutherland Creek would be higher <br /> <br /> <br />than 1,000 cfs. The second discharge of 660 cfs (575 cfs at study site) <br /> <br /> <br />was estimated based on the State Highway Department's 50-year discharge <br /> <br /> <br />of 550 cfs. The third discharge of 765 cfs at the study site (880 cfs <br /> <br /> <br />at the mouth) was determined by the S.C.S. method using a curve number <br /> <br /> <br />of 60. The 100-year discharge of 750 cfs, taken as the average of these <br /> <br /> <br />three sources, was used to determine the floodplain at the study site. <br /> <br /> <br />Present Study <br /> <br />ECI performed a frequency analysis on the Pueblo gage using flow 8~"f' <br /> <br />+,qSlc""-" <br /> <br />records of 1935, 1941-1965 and 1971-1977 (see Table 1) and the assump- <br /> <br /> <br />tion of log-Pearson Type III distribution. In lieu of the computed <br /> <br /> <br />skew, a regional skew of ..Q..4 ",as used in computations of peak discharges <br /> <br /> <br />and confidence limits. Computational results are presented in Table 2 <br /> <br /> <br />and Figure 4. It is noted that the Corps' frequency curve falls within <br /> <br /> <br />the 50% confidence interval of present study for recurrence intervals <br /> <br /> <br />greater than 30 years while the 10-year flood is only slightly larger <br /> <br /> <br />than the 0.25 limit. It was concluded that the Corps' discharges for <br /> <br /> <br />Fountain Creek in Manitou Springs (see Table 3) would be adopted in this- <br /> <br /> <br />flood insurance study. <br /> <br />For Fountain Creek tributaries: Ruxton Creek, Williams Canyon and <br /> <br /> <br />Sutherland Creek, the standard project floods were computed using drain- <br /> <br /> <br />age areas below 9,000 feet along with Figure 3. The standard project <br /> <br /> <br />floods were then assigned a recurrence interval of 350 years and the <br /> <br /> <br />frequency curves were drawn parallel to the frequency curve at Pueblo <br /> <br /> <br />gage. Table 4 and Figure 8 show the resulting discharges. <br /> <br />2- <br />