Iterative Multistage Method for a Large Water Network Sectorization into DMAs under Multiple Design Objectives

This paper considers the sectorization of a large water distribution network into district metered areas (DMAs) and simultaneously optimizes rehabilitation of the network with new pipes, control valves, and storage tanks. Since the available water resources are much smaller in the dry season, both the design and operational settings are optimized to satisfy water demand, water quality and pressure constraints, and efficiency indices under stringent conditions. Because of the heterogeneity of the multiple decision variables and the complicated way they interact through the multiple objectives (some complimentary and some conflicting), it is not possible to fully automize the simultaneous sectorization, rehabilitation and operational optimization. Therefore, we employ a multi-stage approach where engineering judgement and network graph simplification and visualization tools are employed to find a good feasible solution that is used as a first guess for further optimization of sectors and operational settings, to achieve feasible solutions with better cost of implementation, demand similarity among DMAs and better pressure uniformity in operations. A multi-objective Agent Swarm Optimization framework is used to iteratively change the sectors at the boundaries. For the final configuration, sequential linear programming is used to find optimal valve and pump settings.Water Resource