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Show Figures 3.12 and 3.13 and a comparison of Tables 3.7 through 3.10 show some rather interesting changes as the spatial distribution of demand changes from the historical average to the 1982 pumping. While the differences between the optimal solutions for the runs at 100% of the base for each case ( runs 2 and 5) are small, they are significant when 150% of the base demand is considered in each case ( runs 4 and 8). For 150% of the 1982 base demand, several nodes - ( 24,19), ( 24,22), ( 25,21), ( 26,20), ( 27,20), ( 27,21), ( 29,22), ( 34,13) - reached the maximum drawdown of 100 feet. While the solution for 150% of the historical average demand shows the same trends as the solution for 100% of the historical average demand, the solution for 150% of the 1982 demand as base is characterized by a marked increase in cost ( total and unit) and by all agencies except 1 and 8 ( Salt Lake County and White City) pumping in excess of their stated demands. For demand at 150% of the 1982 demand the flows for boundary segments 2 through 10 for water rights are at their bounds as well as the flow for the Vitro Tailings contaminated area ( boundary segment 16) with dual costs higher than the dual costs for the demand constraints. The specification of water rights and contaminant control constraints based on the historical average demand thus turns out to be rather restrictive as the spatial demand pattern changes and the demand level increases. 3.3.3 Linearly Increased Demand Only one run ( number 9) was made for this condition with the 1982 base demand and pumping going from 100% of the base to 145% of the base over 10 years. The results of this run are presented in Table 3.11. The characteristics of the results are essentially similar to those for the case with uniform demand over time. Once again, areas 2,4,7, and 10 pump in excess of their demands, and the same boundary flow constraints are active. The unit pumping cost is approximately at the same level as that for the run with 120% of the 1982 base demand. This suggests that the timing of pumping over the 10 year period is not as critical in determining system costs as the magnitude of pumping. The maximum drawdown ( 100 feet) ( see Fig 3.14) also occurred at nodes ( 24,19) and ( 26,20), and the second most extreme drawdown ( 90 feet) occurred at ( 27,20) and ( 28,22). 3.3.4 Simulated Drought Conditions Fifteen runs - 10 through 24 ( Table 3.6) - were made with various levels of base and peak demand to simulate drought effects. TTie drought demand pattern specified in all cases follows equation 3.28, with the base demand varying as 100%, 120% and 150% of the historical average demand ( with peak demand at year 5 ranging from 120 to 200%), and 100% of the 1982 base demand ( with a peak at year 5 of 140% of the 1982 demand). Tables 3.11 through 3.15 present the summary results from these runs. Fig 3.15 and 3.16 show some typical drawdown contours for the simulated drought conditions. The results from these runs are largely similar to those obtained for the uniform and linearly increasing demand cases, and exhibit the same trends, reinforcing the idea, that the quantity of pumping over the 10 year period, rather than its timing has the greatest effect on system costs and pumping patterns. Figures 3.17 and 3.18 provide a comparison of the total and unit pumping costs for the drought simulation with those for uniform demand, as a function of the total quantities pumped. The costs are lower for the drought situation than for the one with uniform high demand. This is to be expected since some of the years have lower pumping as well as lower pumping lifts compared to the uniform case. The maximum drawdowns are located at the same nodes as for the earlier runs, and the costs exhibit similar trends. The main differences are that ( 1) the excess pumping for the 70 |