城市通江泵站排水对长江干流水质的影响——以武汉市江南泵站为例

Influence of Dainage Pumping Station on Water Quality of the Yangtze River Main Stream:Take Jiangnan Pumping Station in Wuhan as An Example

长江中下游通江泵站数量众多,是城市雨污水入江的主要通道。以武汉市江南泵站为例,基于MIKE21构建江段二维水动力水质模型,模拟预测了正常、事故排放污水处理厂尾水以及排涝3种工况条件下江段COD、NH_(3)-N、TP的迁移扩散特征。与正常排放污水处理厂尾水相比,江南泵站排涝时所在江段各水质指标影响范围均显著扩大,尤其超Ⅱ类水质标准的TP污染带长度、宽度分别增加了2.66、0.64倍,且下游杨泗港国控断面TP超标0.16倍,与事故排放污水处理厂尾水的影响相当,泵站排涝已成为所在水域汛期水质超标的潜在风险源。泵站排涝的水环境影响主要受排涝水质及流量控制,制定基于防洪安全、水环境保护等多目标的泵站运行调度方案是未来研究的重点,同时建议将通江泵站纳入入河排污口监督管理,倒逼沿江城市水环境提升,有效降低长江干流水环境风险。

There are numerous pumping stations in the middle and lower reaches of Yangtze River,which are main channels for urban rainwater and sewage to the River.Jiangnan pumping station in the Great Tangxun Lake basin in Wuhan was taken as an example in this study.A two-dimensional hydrodynamic water quality model of the river section based on MIKE21 was built.The migration and diffusion characteristics of COD,NH_(3)-N,TP in the river section was simulated under three conditions,including normal discharge of sewage treatment plant tail water(ND),accident discharge of sewage treatment plant tail water(AD),and waterlogging drainage(WD).Compared with ND,the influence range and degree of WD on the concentration of water quality index in river reach increased significantly.The length and width of TP pollution zone exceeding Class II water quality standard increased by 2.66 times and 0.64 times,respectively.In addition,the TP concentration of the downstream Yangsigang national control section exceeded the standard by 0.16 times,which was equivalent to the impact of AD.Pumping station drainage was becoming a potential risk source of water quality exceeding the standard in flood seasons.The impact of pumping station drainage on the water environment was mainly controlled by the quality and flow of drainage.Developing a multi-objective operation and scheduling plan for pumping stations based on flood control safety,water environment protection,and other objectives was proposed for future research.It was suggested drainage pumping station in supervision and management of the river discharge outlet be considered,to force the improvement of water environment quality of cities along the River and to effectively reduce environmental risks of the main stream.