OPTIMAL DESIGN OF WATER DISTRIBUTION NETWORKS USING FUZZY OPTIMIZATION

A new heuristic approach for the design of water distribution networks involving a robust fuzzy linear program optimization in which the capital costs of the network are minimized while maintaining the nodal heads at demand nodes within a satisfactory region as defined by the customers at those nodes is presented. Iterative interaction between the fuzzy linear program and a network solver is used to ensure hydraulic consistency. Level of service is modelled by the residual nodal head available at demand nodes with the subjective nature of customers’ satisfaction with the nodal head being represented through fuzzy sets which reflect more realistically consumers’ attitudes toward pressure variations in the supply of water. Non-probabilistic uncertainty in the demand is modelled by a trapezoidal possibility distribution function. The model is demonstrated by application to an example network.