ALGORITHM FOR RELIABILITY-BASED OPTIMAL-DESIGN OF WATER NETWORKS

This paper proposes a heuristic method to obtain a least-cost water distribution network design with a given reliability. The method first attempts an optimal design using a model without the consideration of reliability. The reliability of the obtained network design is then assessed. Finally an iterative feedback procedure is employed, moving between two models, which improves the reliability with a small increase in cost. Reliability is measured as the complement of the ratio of the expected minimum total shortfall in flow to the total demand, and the maximum total flow supplied under a link failure is computed by a network flow analysis. The reliability is improved by increasing link flows (or link capacities) along a longest path from the source node, in such a way that reliability increment is achieved with a small cost increment. The new link flows are used to find the new optimal pipe sizes. The iterative procedure continues until a satisfactory reliability is obtained. © ASCE.