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Show Permissible Drawdown: The permissible drawdown below 1982 levels was varied between 0 and 15 feet. For all these runs, the upper bound on well pumpage was maintained at three times the 1982 value for the well, and the water rights, water quality and water district demand constraints were maintained at their 1982 levels. Finally a run was performed with no limit on the permissible drawdown, and individual well pumpages restricted to 9 times the 1982 value at each well. The other constraints were maintained as i the other runs. Table 4.3 presents the results from these applications of the model. Table 4.3 Parametric Solutions with Permissible Drawdown varied Permissible Drawdown Optimal Solution ( ft. below 19821 HMO Ac- ff/ Yr) 0 47.05 3 52.84 6 58.64 9 64.43 12 69.71 15 75.25 no limit 148.55 The general trend is for the optimal yield to increase approximately linearly as the limit on drawdown is increased. The maximum point drawdown associated with the run with no limits was 328 feet at node ( 35,13). The drawdown at the other nodes varied between 12 and 294 feet. In general, the heads at each node decreased uniformly as the limit on permissible drawdown was increased. Heads at nodes ( 15,10), ( 15,12) and ( 15,13) were however lower for the run with maximum permissible drawdown of 15 feet, compared to the run with no limits. This is a consequence of a relaxation of the bounds on well pumpage for the latter case, leading to an increased exploitation of wells ( e. g. ( 34,13)) that were at their upper bounds for the constrained runs. Pumpage Bound: The upper bound on pumpage at each well was varied, while maintaining the permissible drawdown at 15 feet below 1982 levels, and all other constraints as specified at the 1982 levels. Table 4.4 presents the results from these applications. The optimal yield is seen to increase rapidly as the upper bound is increased from one to three times the 1982 pumping. Thereafter, the permissible drawdown constraint is critical and further increases in annual yield are minimal relative to a change in the pumpage upper bound. Table 4.4 Parametric Solutions with Pumpage upper bound varied Q upper bound Optimal Solution ( multiple of 19821 ( 1000 Ac- ft/ yr) 1 51.40 2 65.15 3 75.25 5 75.30 no limit 75.31 Water District Demand Variation: The lower limit on the water district demand constraint was varied to examine the effect of the spatial distribution of demand ( implicitly the water rights structure) on the development of the system yield. The upper bound on pumpage at each well was maintained at three times the 1982 value, and the permissible drawdown at 100 |