Multistate Reliability of Water-Distribution Systems: Comparison of Surrogate Measures

Reliability of a water-distribution system (WDS) can address mechanical, hydraulics, and water quality failure in the system. The research reported in this paper focused on mechanical reliability (subsequently referred to simply as reliability) assessment of a WDS. Existing techniques are restricted to lower states of reliability (one pipe failure at a time) and very little attention has been paid to higher states (simultaneous failure of several pipes). This is due to large computational workload associated with higher-states reliability assessment. Studying various reliability measures, the research reported in this paper revealed statistical flow entropy had stronger correlation with higher states of reliability and was a better surrogate measure. A multicriteria decision analysis (MCDA) was applied to rank a set of WDS layouts (alternatives) using various states of reliabilities (criteria). The MCDA considered the relative importance of each state of reliability in the process of finding the most reliable system (decision making). The MCDA revealed the higher-state reliabilities should have more contribution in the decision-making process. (C) 2015 American Society of Civil Engineers.