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<br />The magnitude of flood at any exceedance probability or recurrence <br />interval may be computed for each type of event by the equation <br /> <br />log QT = M + KT(S) <br /> <br />(1) <br /> <br />Where: <br /> <br />QT <br /> <br />Floodflow with recurrence interval of T years (in cfs) <br /> <br />M <br /> <br />Mean of the logarithms of annual floods <br /> <br />S <br /> <br />Standard deviation of the logarithms of annual floods <br /> <br />KT <br /> <br />Frequency factor, which is a function of skew, for <br />recurrence interval T. <br /> <br />Constants in the above equation that were derived for Bear Creek <br />and its major tributaries are: <br /> <br />S = 0.553 <br /> <br />KIO 1.3285 <br /> <br />K50 2.359 <br /> <br />KIOO 2.775 <br /> <br />K500 = 3.609. <br /> <br />The composite probability for the flood event if the rain event <br />and snowmelt event are statistically independent is <br /> <br />P(C) <br /> <br />PIR) + peS) - PIR) PIS) <br /> <br />(2) <br /> <br />Where: <br /> <br />peR) Exceedance probability of rain event <br /> <br />peS) Exceedance probability of snowmelt event <br /> <br />P(C) Composite exceedance probability of both rain and <br />snowmelt events. <br /> <br />9 <br />