An Evaluation System for Assessing the Operational Efficiency of Urban Combined Sewer Systems Using AHP-Fuzzy Comprehensive Evaluation: A Case Study in Shanghai, China

In recent years, China's urban smart water management has focused on enhancing the quality, efficiency, energy conservation, flood prevention, and control of combined sewer overflow (CSO) and urban waterlogging. To evaluate the combined sewer system's operation efficiency effectively, a comprehensive evaluation system was established. This system incorporated expert scoring and the coefficient of variation method, considering 31 specific indexes to assess six key aspects: CSO control, waterlogging control, stable wastewater transportation, pipeline management and maintenance, energy conservation, and smart water affairs. The AHP-Fuzzy comprehensive evaluation was employed for evaluation, combining AHP for index weighting and fuzzy comprehensive evaluation for quantitative scoring. The system was applied to assess the operation efficiency of a specific area in Shanghai from 2020 to 2022. Results showed progress in CSO control and energy conservation, with operation efficiency improving from low in 2020 to moderate in 2021 and good in 2022. However, waterlogging control and pipeline management still require improvement in the combined sewer area. Overall, the evaluation system provides valuable insights into the system's performance, identifying areas for targeted enhancement and emphasizing the need for further improvements to achieve optimal operation efficiency.