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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />3.2.4 <br /> <br />Precipitation Intensity Within storms <br /> <br />The distribution of precipitation intensity during the <br />storm periods was examined for each of the seven gauge sites <br />during the 11 storm periods. Because of the uncertainty of <br />whether all of the indicated precipitation was real in the <br />cases where very light precipitation was indicated, only the <br />hours where 0.01 inch or more was recorded were used in the <br />data-set. This should largely eliminate false observations <br />caused by temperature variations affecting the gauge mechanism, <br />the gauge still responding to precipitation from the previous <br />hour because of hysteresis, etc. This amounted to only a <br />5.5 percent reduction in precipitation from that shown in <br />Table 3-4, but it represented 468 hours, or 32 percent of <br />all the hours that precipitation was recorded during the storm <br />periods. Assuming most of these hours with rates less than <br />0.01 inch represented real precipitation, it is apparent that <br />many hours of very light precipitation did occur over the <br />watershed during the winter storms. On the average, these <br />very light rates occurred at each gauge site for about 67 <br />hours (6 hours per storm) during the field season. If, on <br />the average, a storm lasted one day, the suggestion is that <br />about one-quarter of the storm period had these very light <br />precipitation rates. <br /> <br />Figure 3.1 presents a plot of both the cumulative frequency <br />of occurrence and total precipitation at increments of 0.01 <br />inch. This analysis and some others presented subsequently <br />was patterned after that done by Super et ale (1986), so that <br />comparisons could be made with their work done on the Grand <br />Mesa of western Colorado. Their study used a two winter 10 <br />month period (November-March, inclusive) to develop precipi- <br /> <br />3-32 <br />