Water pollution is a globally significant issue. Water environment simulation is an important tool to study water pollution. In order to investigate the impact of hydrological periods, water quality indicators and cross-sections on the water environment capacity, we took the Luo River in Luoyang City as an example, and used MIKE21-coupled hydrodynamic and water quality model and the segmentation method to calculate the water environment capacity of COD, TP, and NH3-N in wet, normal, and dry periods under L1 (Gao Yazhai-Lilou), L2 (Li Lou-Baimasi), and L3 (Baimasi-G207 Highway Bridge) section. The results of the study showed that from the hydrological period, the water environmental capacity was the largest in the wet period due to the dilution effect caused by higher precipitation; from the water quality indexes, the COD concentration was the largest due to industrial pollution, but the higher degradation coefficients result in the largest water environment capacity for COD; from the cross-section, L1 has the longest channel, thus the highest capacity of the water environment was L1. This result can broaden new ideas for the application of the MIKE21 model, provide a basis for the calculation of the dynamic water environment capacity and water pollution control in river.

  • Innovative hydrodynamic water quality model evaluates Luo River pollution across diverse flow scenarios.

  • Dry periods exhibit poorest water quality, while wet periods showcase the best.

  • Identified sections exceeding capacity emphasize pollution management during distinct hydrological conditions.

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