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<br />rate corresponds to the change in elevation within the zone. The input <br />temperature data are those corresponding to the bottom of the lowest <br /> <br />elevation zone. Temperatures are reduced by the lapse rate in degrees <br /> <br />per increment of elevation zone. The base temperature at which melt will <br />o 0 <br />occur must be specified because variations from 32 F (0 C) might be <br /> <br />warranted considering both spatial and temporal fluctuations of temperature <br />within the zone. <br /> <br />Precipitation is assumed to fall as snow if the zone temperature is <br />less than the base temperature plus 2 degrees. Melt occurs when the <br /> <br />temperature is equal to or greater than the base temperature. Snowmelt <br /> <br />is subtracted and snowfall is added to the snowpack in each zone. Snow- <br />melt may be computed by the degree-day or energy-budget methods. <br />Precipitation Loss Rates. Loss rates can be computed using initial <br />and uniform losses or by a function which relates loss rates to rainfall <br />and snowmelt intensity and to accumulated loss (ground wetness). Figure 2 <br />shows the loss rate function for a snow-free basin. The loss rate function <br /> <br />is successively applied for each computational interval. <br /> <br />The loss rate parameters of figure 2 are: <br /> <br />DLTKR - Amount of initial accumulated rain loss during which <br />the loss rate coefficient is increased. This param- <br />eter is considered to be a function primarily of <br />antecedent soil moisture deficiency and is usually <br /> <br />different for different storms. <br /> <br />. <br /> <br />10 <br />