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<br />relat:ionship established by usinq these annual peak discha.rges <br /> <br />does not reflect intense rainfall produced flood. A more detailed <br /> <br />method was used for each gauging station to develop regional <br /> <br />relationships for 'this area. The procedures are described as follows: <br /> <br />(1) separating the rain and snowmelt dat:a at each gauging st:at:ion, <br /> <br />developing statistics for each type of event, and statistically <br /> <br />combining the two frequency curves (st.ream flow records were obt:ained <br /> <br />from the U.S. Geological Survey, Denver Federal Center) ,; (2) adjust- <br /> <br />ing short period statistics to reflect long per:iod valUE,s if they <br /> <br />are closely correlated; (3) outliers and historical dat:a were con- <br /> <br />sidered during the development of flood flow fr'equency rela1:ionships <br /> <br />for each gauging station; and (4) developing re'gional relationships <br /> <br />relating basin area to peak discharge for the 10-, '50-, 100-- and <br /> <br />SOO-year floods by regression analysis. <br /> <br />The procedures of combining rainfall and snowmelt f):equency curves <br /> <br />are described as follows: <br /> <br />(1) select a peak discharge <br /> <br />(2) read the probabilities for rainfall and snowmelt events from the <br /> <br />respective frequency curve at the selected peak discharge <br /> <br />(3) combine probabilities by the follolNing equation: <br /> <br />pet) = per) + pes) - per) pes) <br /> <br />Where <br /> <br />pet) = total probability of t~? selected peak discharge <br />per) - probability of the rain flood event at the selected <br /> <br />peak discharge <br /> <br />pes) - probability of the snowmelt flood event at 1:he <br /> <br />selected peak discharge, <br /> <br />RESUI.'rS <br /> <br />During the course of the study, the. re3ults of hydroloCfic analysis <br /> <br />-6- <br />