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<br />~ <br /> <br />. <br /> <br />. <br /> <br />2 <br /> <br />Analysis <br /> <br />The geometrIc mean of an annual peak flow series (pgm) repre- <br />sents the relative magnitude of all peaks in the series and <br />approximates Pb (Lowham 1982). In this analysis, pgm was <br />calculated for data from U.S. Geological Survey (USr.S) gage 9- <br />1635 for the Walker site, USGS gage 9-2610 for the Ouray Refuge <br />site, USGS gage 9-2510 for the Maybel! site and a report <br />prepared for the U.S. Fish and Wfldlffe Service by J. O'Brfen <br />(1984) for the Cleopatra's Couch sfte. For the relatfvely short <br />gage histories at gages 9-1635 and 9-2610, the annual <br />fnstantaneous peak flow for the 1977 water year was omitted from <br />the calculatfons because of the extreme drought condftions that <br />exfsted that year. For the longer gage hfstory of the Yampa <br />River, omftting the 1977 peak dfd not substantially affect Pgm. <br />Next, Log Pearson Type III flood frequency analyses were <br />computed for the flood series. The recurrence fnterval for each <br />sites Pgm was fnterpolated from the respective frequency <br />analysis. The duration of the Pgm was calculated from mean <br />dafly flow data for each gage. <br /> <br />The data from O'Brfen's report used for the Cleopatra's Couch <br />site did not fnclude instantaneous peak flows. Instead, O'Brfen <br />computed peak mean dafly flow for the sfte by summing mean daily <br />flow data for USGS gages 9-2510 and 9-2600. The geometrfc mean <br />of the peak mean dafly flow series was calculated to approximate <br />Pb. The duration analysis for this site was completed from data <br />for gage 9-2510. The duratfon Df mean daily flows in excess of <br />the Pgm was summed over the avaflable perfod of recDrd and <br />divided by the total available period of record. Appendices A-D <br />contafn the flow data used in thfs analysis. <br /> <br />....~. '-'.,. .. ~ - - - .. <br />