OPTIMAL CAPACITY-EXPANSION PLANNING IN MULTIAQUIFER SYSTEMS

Three models were developed and tested for the optimal capacity expans ion planning in a hypothetical multiaquifer system. The response of th e system was included in the models using response matrices. All model s are 0/1 mixed-integer programming models and enable the determinatio n of minimum capital investment and operation costs of well fields and associated pipeline facilities while satisfying a set of system const raints. The performances of the models are compared in terms of comput ational requirements and approximation to pumpage costs under three wa ter-demand schedules. Multiobjective analyses were conducted to develo p trade-off curves relating pumpage to drawdown. The sensitivity of th e capacity expansion policies to variations in demand requirements, in terest rates, and system parameters are analyzed. The first model prod uces minimum total drawdowns and requires lesser computation time whil e the remaining two models yield minimum total costs but require more computation time. The variations in demand requirements, interest rate s and system parameters causes variations in selection of the potentia l well fields, their completion time, resulting total costs and minimu m total drawdowns.