Transient-Aware Multi-Objective Optimization of Water Distribution Systems for Cost and Fire Flow Reliability

Urban water distribution systems, as integral parts of underground pipeline networks, face challenges from aging infrastructure, operational demands, and transient pressure surges that can compromise structural integrity and service reliability. This work introduces a cost-oriented multi-objective design framework that explicitly accounts for both the likelihood of fire flow failure and the risks posed by transient pressures. The approach links a probabilistic reliability model with a transient pressure evaluation module, and couples both within a non-dominated sorting genetic algorithm to generate Pareto-optimal design solutions. Design solutions are constrained to maintain transient pressures within permissible limits, ensuring enhanced pipeline safety while optimizing capital costs. Case studies show that adopting a minimum 150 mm distribution main improves fire flow capacity and reduces transient-induced failure risks. The proposed method provides a predictive, computational tool that can be integrated into digital twin environments, supporting sustainable infrastructure planning, long-term monitoring, and proactive maintenance for resilient urban water supply systems.