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<br />2, Results <br /> <br />As shown in Tables 12 and 13, the artificial manufacturing of snow will not effect the peak runoff <br /> <br /> <br />expected due to snowmelt for most instances, The main effect ofmanmade snow is to extend the <br /> <br /> <br />runoff season by the period of time necessary to melt the additional snow, and it has a slightly <br /> <br /> <br />different water content. An instance when the manmade snow could effect runoff is if a major <br /> <br /> <br />storm took place on AspenMountain during the time that this additional manmade snow was still <br /> <br /> <br />melting, but the natural snow would have all disappeared, The likelihood of this event occurring <br /> <br /> <br />involves multiple probabilities and is beyond the scope of this study, <br /> <br />E. RAIN ON SNOW ANALYSIS <br /> <br />1. Introduction <br /> <br />During the spring and early summer, there is a possibility that a major rainfall event could occur <br />when there is still snow on the ground. If the snow is ripe (partial melting has already taken place <br />and the snow has little capacity to "absorb" water), rainfall can produce runoff that is much <br />greater than would be expected by rain alone or snowmelt alone, <br /> <br />2. Methodology and Input Data <br /> <br />For the purpose of this analysis, the rainfall event was assumed to occur in the afternoon (2:00 <br />PM to 4:00 PM) when the temperature was the warmest, Rainfall amount and distribution was <br />the same as was developed for CUHP/SWMM, The average monthly temperature was used for <br />this analysis (see Table 11). Since snowmelt was currently occurring, the uniform loss rate was <br />used with a hydraulic conductivity of 0.5 inches per hour and no initial losses. <br /> <br />Since the Degree-Day method of calculating snowmelt does not account for the melt created by <br />the heat transfer from the rain to the snow, a value of snowmelt created by the rain was estimated <br />and added to the hyetegraph, This snowmelt is estimated by the following equation (Chow, 1964): <br /> <br />21 <br />