Multiobjective Optimization of Rehabilitation and Leakage Detection Scheduling in Water Distribution Systems

Abstract

This paper presents a procedure for optimal medium-term scheduling (e.g., over a time window of 5 years) of rehabilitation and leakage detection interventions in a water distribution system given predetermined budget constraints. The decisional variables are the interventions to be scheduled, that is, which pipes to replace and when (in which year), and where and when (in which zone and year) to carry out leakage detection surveys, while the objectives are to minimize the volumes of water lost and break repair costs. The optimizer used is the NSGA II multiobjective genetic algorithm. It is assumed that the budget allocated for leakage detection and pipe rehabilitation (proactive interventions) represents a separate expenditure item from that for the repair of breaks (reactive interventions). In particular, whereas repair costs are subject to minimization, the budget for proactive interventions is allocated on a yearly basis during the scheduling period and a constraint is determined by the fact that the a...