Prioritizing Pipe Replacement: From Multiobjective Genetic Algorithms to Operational Decision Support

Abstract

Deterioration of water distribution systems and the optimal allocation of limited funds for their rehabilitation represent crucial challenges for water utility managers. Decision makers should be provided with a set of “informed” solutions to select the best rehabilitation plan with regard to available resources and management strategies. In a risk-based scenario, such an approach should result in an element-wise prioritization scheme based on individual pipe rehabilitation/replacement effectiveness. This manuscript describes a framework for devising a short-term decision support tool for pipe replacement. The approach allows for the introduction of economic, technical, and management rationales as separate objectives to produce a pipe-wise prioritization scheme which is achieved by ranking pipes selected during a multiobjective (MO) evolutionary optimization of replacement scenarios. Such a procedure helps overcome the doubts in choosing among the solutions obtained by MO evolutionary optimization due to the diverse sets of pipes selected for replacement even when they are economically comparable. The effectiveness of the entire framework is demonstrated on a real U.K. water distribution system.