QUAL2Kw-based source identification and remediation strategy assessment for black and odorous water in urban river

Remediation of black and odorous water in urban rivers is a key priority for urban water governance, but identifying pollution sources and optimizing strategies remain challenging. This study targeted the 3.2-km Qianjin Canal (Tianjin), integrating the QUAL2Kw model with a self-developed pollution source contribution module (two-step method) to simulate pollutant migration and assess the effectiveness of multiengineering remediation measures. Results showed that the integrated model successfully quantified the contribution of major pollution sources, including point sources (domestic sewage), nonpoint sources (farmland runoff), and source water (rainfall runoff combined with reservoir discharge). Under the combined measures including aeration (20% oxygenation efficiency), water supplementation (0.1 m³/s), and source control, the removal rates of COD, NH₃-N, TN, and TP were 44.0%, 47.5%, 54.1%, and 70.0%, respectively; after treatment, most water quality indicators met GB 3838-2002 Category V. The integrated model effectively supports pollution source identification and remediation strategy optimization for urban black and odorous rivers similar to the Qianjin Canal, providing a targeted scientific framework.