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<br />C::J <br />.") <br />N <br />10 <br />r~ <br />o <br /> <br />189 <br /> <br />As the number of replications, n, is increased, the variability of ~ , <br />n <br /> <br />of the estimate of average discharge DCN)' is seen to decrease slowly <br /> <br />(Figure 6.3). The mean discharge, for the system control variables <br /> <br />prescribed, appears to stabilize after seven replications have been <br /> <br />included. <br /> <br />The same result would not necessarily be obtained from a single <br /> <br />simulation of 1400 years. The storage conditions at the end of the <br /> <br />first 200 years of simulation could affect reservoir behavior during <br /> <br />the following 150 years, as shown in the preceding section. The results <br /> <br />from treating seven independent 200 year simulations as replications <br /> <br />would be expected from a single simulation of 2450 years. In this <br /> <br />application, the advantage of using independent simulations is to insure <br /> <br />that independent estimates of average discharge are obtained. However, <br /> <br />since the values of the seven estimates are not significantly different, <br /> <br />replication is of no value in the determination of average discharge. <br /> <br />A single simulation of 200 years is found to provide a good esti- <br /> <br />mate of average reservoir discharge. <br /> <br />6.2.2 Examination of Mean Reservoir Storage <br /> <br />The sensitivity of estimates of average storage to different <br /> <br />inflow sequences was also examined to see if ,stable response is obtained <br /> <br />from one simulation of 200 years. <br /> <br />As stated in Section 6.2.1, storage variability increases with <br /> <br />maximum reservoir storage. For this analysis the maximum allowed Lake <br /> <br />Powell storage, SPM, was set to SPM = 27 MAF. Lake Powell storage ex- <br /> <br />hibits higher variability than Lake Mead storage due to the unregulated <br /> <br />