Cost-effectiveness-based multi-criteria optimization for sustainable rainwater utilization: A case study in Shanghai

Shanghai, the economic centre of China, is under increasing pressures of potable water shortage, urban flooding and surface water pollution by urbanization. As one of the best countermeasures, rainwater utilization plays a considerably important role in the alleviation of these issues. A four-step method of cost-effectiveness-based multi-criteria optimization (CEMCO), which integrates the advantages of monitoring data, monetary-based techniques and stakeholder preferences, was proposed for sustainable rainwater utilization. The first rainwater utilization system in the urban residential area of Shanghai was taken as a case study, and eight alternatives to the existing system were proposed. The results of the study showed that the net present value and the dynamic payback period of the optimized system during the 15-year life cycle were 407.4 thousand CNY (ChiNa Yuan) and 8.26 years, respectively. The results also indicated that rainwater utilization can improve the sustainability of cities when different stakeholder preferences and multiple criteria were considered.