Integrated multi-objective optimization framework for urban water supply systems under alternative climates and future policy

Abstract

Abstract The sustainable implementation of an urban water supply system (UWSS) should achieve an optimum compromise among water ecosystem protection, climate change mitigation, and economic performance. This paper establishes an UWSS optimization framework by integrating a multi-objective optimization model with life cycle assessment and a water distribution system simulation model. The trade-offs among total cost, greenhouse gas (GHG) emission, and an extended water ecosystem impact (WII) objective are taken into consideration. The central area of Beijing City which is the main water-receiving area of the South-to-North Water Transfer Project (SNWTP), is chosen as a case study. A baseline scenario for 2012 and several future scenarios for 2020 and 2030 are implemented to investigate the influence of alternative climates and future policies on UWSS optimization. The outcome of this study indicates that the UWSS should be shifted towards an unconventional water-based supply system in the future. The share of contribution of the unconventional water supply is increased from 41% in 2012 to more than 70% in 2020 and 2030. This result can be drawn in all of the water-receiving areas of the middle route of the SNWTP. Moreover, alternative climates have influences on unconventional water utilization. Imported water through the middle route of the SNWTP is a preferable choice to augment the water supply in arid climates while reclaimed wastewater is more appropriate in moist climates. A decomposition analysis of the emissions reduction policies shows that the water demand control strategy is efficient in GHG emissions reduction while the water supply management strategy is efficient in WII reduction. Such a systematic analysis of an UWSS could provide sustainable and practical recommendations on water resource management in arid regions.