沙颍河下泄污水的降解与稀释特性对西淝河取水口水质的影响

为了更有效地控制沙颍河污水的排放，保证西淝河线引水工程的正常运行，基于MIKE11建立了一维水动力-水质耦合模型，以氨氮为水质指标，分析了污水下泄过程中污染物的降解与稀释特性对西淝河取水口水质的影响机制。结果表明：汛前随着支干流量比增加，污染团从主要受降解作用为主过渡到稀释作用为主；汛初下泄的污水主要依靠干流的稀释作用降低质量浓度；当沙颍河在汛前和汛初的下泄污水流量分别大于淮干流量的10%和7%时，取水口水质有超Ⅲ类水的风险；取水口氨氮质量浓度与支干流量比之间存在幂函数关系，二者的拟合效果与污染团受干流稀释程度有关。

Impact of degradation and dilution characteristics of effluent discharged from Shaying River on the water quality of water-intake of Xifei River

In order to control the effluent discharge of the Shaying River more effectively and to ensure the normal operation on the water diversion project on the Xifei River line, a one-dimensional hydrodynamic-water quality coupling model was established from MIKE11, and the degradation and dilution characteristics of pollutants in the process of sewage effluent discharge were analyzed in terms of the mechanism of the influence on the water quality of the water-intake of Xifei River, using ammonia nitrogen as the water quality index. The results show that before flood, with the increase in the ratio of feeder flow, the pollution mass transitions from being mainly subject to degradation to dilution and the effluent discharged at the beginning of the flood mainly relies on the dilution effect of the main stream to reduce the concentration. When the sewage flow of the Shaying River before and at the beginning of the flood is greater than that of the main stream by 10% and 7%, respectively, the water quality at the water intake is at risk of exceeding Class III of surface water standard. There is a power function relationship between the concentration of ammonia nitrogen at the intake and the branch to trunk flow ratio, and the fitting effect of the two is related to the degree of dilution of the polluted mass by the main stream.