Abstract:

The Nanshu River plays a crucial role as an urban river in the Huai River Basin. Researching its water quality and quantity, along with implementing strategic water management practices, holds paramount importance in safeguarding the ecological health of the water system and enhancing the well-being of the local community. The study area chosen was the Nanshu River Basin. The evaluation of water environment quality focused on the key pollutants COD and NH₃-N. A one-dimensional water quantity-quality coupled model was developed using the MIKE11 software. Analysis was conducted to observe the fluctuations in water environment capacity during flood and non-flood seasons, alongside examining water quality responses to various scheduling scenarios within the Nanshu River, aiming to derive the most effective scheduling strategy. The findings highlight that the concentrations of key pollutants COD and NH₃-N in the Nanshu River fluctuate within water quality categories I to V, with pronounced deterioration during the flood season. The maximum water environmental capacity for COD and NH₃-N is observed at peak levels during floods, approximately 400g/s and 18.9g/s respectively, factoring in safety margins. Seven scheduling strategies have been proposed, encompassing measures such as regulating tributary sewage inflow and enhancing the flow of the main river to enhance water quality. Comparative analysis identifies the Oupu Gou tributary as the primary source of main river water quality degradation. The recommended optimal scheduling approach to enhance water quality involves augmenting the main river flow, closing the gate valves of the Oupu Gou tributary, and implementing preventative measures against pollutant intrusion. The one-dimensional water quantity-quality coupled model developed in this research aligns with the specific characteristics of the Nanshu River, making it suitable for conducting water environment studies in this region. The suggested operational strategies are capable of significantly enhancing the water quality of the Nanshu River, thereby safeguarding the integrity of its aquatic ecosystem.

Key words: water quality and quantity, MIKE11, Nansu River, water environmental capacity, ecological dispatch