Joint layout, pipe size and hydraulic reliability optimization of water distribution systems

Abstract

A multicriteria maximum-entropy approach to the joint layout, pipe size and reliability optimization of water distribution systems is presented. The capital cost of the system is taken as the principal criterion, and so the trade-offs between cost, entropy, reliability and redundancy are examined sequentially in a large population of optimal solutions. The novelty of the method stems from the use of the maximum-entropy value as a preliminary filter, which screens out a large proportion of the candidate layouts at an early stage of the process before the designs and their reliability values are actually obtained. This technique, which is based on the notion that the entropy is potentially a robust hydraulic reliability measure, contributes greatly to the efficiency of the proposed method. The use of head-dependent modelling for simulating pipe failure conditions in the reliability calculations also complements the method in locating the Pareto-optimal front. The computational efficiency, robustness, accuracy and other advantages of the proposed method are demonstrated by application to a sample network.

Keywords:

• entropy
• head-dependent modelling
• multicriteria optimization
• reliability
• water distribution system

Acknowledgements

The authors are grateful for the financial support of the UK EPSRC for the PRAAWDS HDA research (GR/NO2672); and the ORS scheme and the University of Liverpool for the second author. The investigation in this article is one of several studies that were conceived (while both authors were at the University of Liverpool) to help assess PRAAWDS in a productive way in an HDA intensive environment.