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<br />KO = loss coefficient at start of storm <br /> <br />C = empirical constant <br />rL = accumulated loss during storm <br /> <br />e = natural log base 2.718 <br /> <br />Losses computed with this equation should be constrained between 0.0 <br />and some reasonable upper limit such as 50 mm/hr. In order to compare <br />initial loss coefficients for different storms, it is necessary to <br />derive each one using the same empirical constants E and C. This loss <br />function is one of the methods used in the computer pragram described <br />in Appendix 1. A simpler function also contained in that program <br />may be preferable in some applications. This simply consists of an <br />initial loss such as 10 to 20 .. followed by a unifol'lll loss rate rang- <br />ing from 2 to 10 IIII/hr. Another procedure widely used by hydrologists <br />consists of an exponential decay of a starting loss rate until a spe- <br />cified minimum is reached and then continuing at a constant rate. Some <br />lI1I!thods also include a specified recovery rate during periods of no <br />rainfall excess. <br /> <br />Section 3.04. Standard pro~ect snowPlck <br /> <br />Where the standard project flood is prilllarl1y a snowmelt flood, <br />standard project snowpack should envelope Maximum observed snowpack and <br />a percentage should be added as a safety factor, depending on the <br />length of snowpack record and history of snowmelt floods. If the <br />record is long or the greatest snowmelt flood in a long tillle occurred <br />during the period of snowpack record, a slllall or 110 factor may be added <br />to the largest observed snowpack. A better alternative procedure would <br />be to construct frequency curves of snowpack and select values of about <br />100 to 200-year exceedence interval. This would be the best procedure <br />where only short records are available. If no snowpack records are <br /> <br />3-08 <br />