Research on hydrodynamic regulation schemes for water environment improvement in plain urban river networks

To address the challenges of water environment management in urban river networks, this study systematically analyzes the impact of hydrodynamic regulation on water quality improvement. Focusing on the ancient urban river network in Suzhou's plain region, the study aims to enhance water quality based on field observations of the current conditions. A one-dimensional hydrodynamic-water quality coupled model was employed to examine the effects of three water diversion conditions and four regulation strategies on improving water quality. The results indicate that under current conditions, the dissolved oxygen (DO), ammonia nitrogen (NH₃-N), and chemical oxygen demand (COD) concentrations in the main river channels of Suzhou's ancient city river network remain at Grade IV water quality standards. As the duration of hydrodynamic regulation increases, the water quality improvements in the river network become more pronounced and eventually stabilize. Under two designed hydrodynamic regulation schemes, the water quality of most river sections meets the required standards, with a compliance rate of approximately 90%. The findings provide technical guidance for improving the water quality of river networks in Suzhou and other similar plain urban areas.