三峡蓄水后开县城区污水排放对小江水质影响

Analysis of the Effect to the Water Quality of Xiao River for Kaixian County Sewage Discharge After the Sluice of the Three Gorges Reservoir

三峡水库蓄水至175m后,开县城区江段将成为三峡库区内为数不多的湖泊型水库,水质污染存在严重恶化趋势。文章运用二维水动力学水质模型和均匀混合型湖泊COD水质模型,模拟计算了开县城区污水处理前后排放对小江的水质影响。分析表明:污水不处理直排会导致小江水质严重污染;污水达标处理后,在丰、平水期小江水质有明显改善,可控制在水功能区划的标准范围内;但枯水期,则无有效改善,小江水质仍超过水域功能的控制标准。为确保小江总体水质良好,必须保证污水处理厂的正常运行,同时在枯水期必须采取其它措施控制污水排放。

Once the water level of the reservoir of the Three Gorges rises above 175 m, Yangtz River in Kaixian County will be changed into a lake-like reservoir which will be rare in the Three Gorges areas, and water pollution would be seriously deteriorated. In order to testify whether water quality meets the requirements of the function divisions, two-dimension water dynamics quality model and homogeneous-mixed water quality model are used to simulate polluted water disposal of Kaixian County before and after sewage purification. The analysis indicates that sewage disposal without any pretreatment will cause serious and continuous pollution; while sewage disposal after purificaiton up to standard, there are two kinds of results: in abundant and normal period , the water quality improves obviously, the water quality can meet the function of river area, but in dry seasons, the water quality improvement is not so effective, and still exceeds the control standard of the water function. To guarantee water quality of Xiaojiang River, it is proposed that, first, sewage treatment plant should run normally and continuously; second, other measures must be added to control sewage discharges in dry season.