Laserfiche WebLink
<br />c:) <br />(:) <br />t~ <br />1'0 <br />tv <br />0) <br /> <br />195 <br /> <br />SP = 15 MAF (the notation of 0.0+ is used to indicate that no inci- <br />M <br /> <br />dents of failure were observed in a given, 200 year simulation). The <br /> <br />probability of failure to meet an annual Powell discharge of 7.5 MAF/yr <br /> <br />ranges from O.O~ to 7.5% for SPM = 15 (Figure 6.6(a) and from 0.0+ to 2% <br />for SPM = 27 (Figure 6.7(a)). <br /> <br />These differences, while not significant on the basis of the <br /> <br />Kolmogorov-Smirnov test, would have a great effect upon decisions of <br /> <br />design or operation of reservoirs. A simulation using one inflow <br /> <br />sequence indicates that a maximum Powell storage of one-half the design <br /> <br />value is sufficient to meet downstream demands with high reliability. <br /> <br />Another simulation, whose inflow sequence is derived from the same data <br /> <br />base as the first, indicates that such a reservoir operating policy will <br /> <br />cause Powell to fail on the average of one year in every 10. <br /> <br />The distributions of annual Lake Mead discharge are seen to vary <br /> <br />little from sequence to sequence (Figures 6.6(b) and 6.7(b)). Discrep- <br /> <br />ancies occur in the region of excess discharge. Again, the differences <br /> <br />are not statistically significant. <br /> <br />Cumulative distributions of the 10-year average discharge for <br /> <br />both reservoirs exhibit large differences. Figures 6.8(a,b) show the <br /> <br />distributions of the 10-year average discharge from both Powell and <br /> <br /> <br />Mead for the case with SPM = 15. The case with SPM = 27 is shown in <br /> <br /> <br />Figures 6.9(a,b). The graphs represent the percentage of simulated <br /> <br />years for which the average discharge over the previous ten years is <br /> <br />less or equal to some value, D. <br /> <br />For the case with SPM <br /> <br />15, large differences in probability <br /> <br />of Powell failure are observed (Figure 6.8(a)). Failure to maintain <br />