System-Dynamics Modeling for Exploring the Impact of Industrial-Structure Adjustment on the Water Quality of the River Network in the Yangtze Delta Area

The coordinated development of the environment and economy is the core of sustainable development. This research investigated sustainable water-quality management by exploring the impact of socioeconomic activities on water quality associated with a major global city. To achieve this goal, a system dynamics (SD) model was developed to capture the feedback processes and interactions between the water quality; population; water resource; and the primary, secondary, and tertiary sectors of the Yangtze Delta area, especially Jiaxing City. More importantly, we further subdivided and identified the nine key subindustries within three sectors as high-polluting factors. Using this model, five scenarios based on different industrial restructurings were investigated. The simulation results suggested that Jiaxing City’s water quality would conform to a steadily increasing trend over 2021–2035. Changes in the farming industry have the most significant impact on water quality, followed by those in the paper and paper production (PPP) industry and the livestock and poultry breeding (LPB) industry. In terms of individual pollutant concentrations, the concentrations of COD and TN were most sensitive to changes in the farming industry, while PPP and LPB were identified as having the most influence on the concentrations of NH3-N and TP, respectively. It is feasible for Jiaxing City to improve its water quality through collaborative optimization of three industries. However, the effect of industrial structure adjustment is limited. Strategies comprising cleaner production should be undertaken to reduce pollution generation