Optimal transient network design: A multi-objective approach

This article formulates the optimal design of a water distribution system under transient conditions as a multi-objective optimization problem. Unlike most optimization models in which demands are set to their end-of-life levels, this approach more accurately models the demand loadings to vary throughout the design life of the system. The first objective was formulated as a least-cost optimization problem with the selection of pipe diameters as the decision variables. The second objective was to minimize the likelihood of a damaging transient event. For the dual objectives of minimizing pipe cost and the likelihood of a damaging transient event, a set of compromised Pareto-optimal solutions is provided to circumvent subjective decision-making. None of the solutions on the Pareto-optimal curve are dominated by any other solution. In going from one solution to another, it is not possible to improve on one objective without making another objective worse. This leads to a trade-off relationship between pipe cost and the likelihood of a damaging transient event in which a decision-maker can choose a preferred solution.