A Flexible Approach for the Reinforcement of Water Networks Using Multi-Criteria Decision Analysis

This work proposes a multi-criteria decision analysis (MCDA) as a useful tool for supporting interventions to overcome problems faced by water utilities due to inadequate network hydraulic capacity. Urban population growth and ageing infrastructure have brought new challenges at a time of mounting preoccupations with high consumer expectations of water services. The proposed MCDA approach uses four criteria to assess the performance of a set of alternative designs for the reinforcement of existing water networks. The traditional formulations that only consider a single-phase fixed plan are replaced with a flexible and robust design approach able to deal with uncertainty related to future demand changes. For this purpose, a phased planning horizon scheme is proposed that considers various possible future demands that the network might have to cope with during its lifespan. After implementing the solution for the first phase, the reinforcements foreseen for the next phases can be reassessed if new information becomes available. The procedure can be repeated up to the last phase. This means that the infrastructure is prepared from the outset to deal with circumstances to change as time unfolds. The results for a specific case study show that the value of MCDA lies in the insightful information that it provides for decision makers.