鄱阳湖水利枢纽工程对水质环境影响初步研究

鄱阳湖水利枢纽工程的建设，将改变湖内水动力特性，进而影响鄱阳湖的水环境质量。采用水深平均的二维水动力-水质模型对鄱阳湖现状水动力和水质进行模拟验证，水陆边界模拟采用动边界技术，摸拟“高水湖相,低水河相”的湖泊水域变化特征，水质特性为枯水期水质较差，丰水期水质较好，靠近入湖河口的湖区劣于湖心水质，北部出湖水质较好的现状。根据水利枢纽工程“控枯不控洪”的调度原则，模型模拟预测在现状外部入流边界和现状污染负荷条件下，三种不同运行方式下，鄱阳湖湖流的时空形态相应发生的变化和相应水质变化。计算结果表明，枯水期大部分区域的水质浓度下降，但尾闾等部分区域有所升高，开闸泄水期前后，水质较现状水质下降，敞泄期的大部分时间，较现状水质基本相似，蓄水期水质变化不大。水动力特性综合水质浓度的改变，增加了局部水体的富营养化风险。研究结果为枢纽的有效建设提供了科学依据。

Modeling the impacts of the hydraulic infrastructure in Poyang Lake on hydrodynamics and water quality

Poyang hydraulic infrastructure planned on the flow channel that connects the lake to Yangzi River will alter the hydrodynamics and consequently change the water quality. A 2D depth-averaged numerical model has been applied to improve the understanding of water environment of Poyang Lake and investigate the effects of the hydraulic construction. The model was validated against several series of measurements with satisfactory agreements on both hydrodynamics and water quality. According to the computational results, three different operation schemes of the gate have significant impacts on hydrodynamics in Poyang Lake especially in low flow period, as the result of the slow lake flow instead of rapid river stream in winter and autumn. Further analysis of the effects on water quality was carried out. Currently, water quality of Poyang Lake in low flow season is worse than that in high flow season under present pollution loads. After the gate is constructed, water quality at most part of lake of is improved in low flow season (Dec~Mar), while at the inlets of main inflow rivers it becomes worse. When the gate is open annually from Apr 1st, the water quality is worse than that at present. In the rest time of a year there is no obvious difference among those cases. The results indicate that the risk of lake eutrophication increases at curtain place in Poyang Lake due to the gate building.