三峡工程运行后长江中游溶解气体过饱和演变研究

为了分析三峡工程运行后泄洪对长江中游溶解气体过饱和的影响，本文建立了长江中游溶解氧数学模型，对不同流量下长江中游的溶解氧过饱和演变进行了模拟预测。模拟结果表明，三峡和葛洲坝过坝水流的溶解氧饱和度在40000m3/s～50000m3/s和100000m3/s附近存在两个峰值，长江中游河道天然情况下溶解氧过饱和恢复速度较为缓慢，平均每100km降低5%，洞庭湖水的汇入能显著降低长江干流的溶解氧过饱和度。当三峡出库流量超过40000 m3/s时，其影响范围可达400km以上。本文讨论了溶解气体过饱和的不同指标间的关系，对气体过饱和可能造成的影响以及对长江中游鱼类目前的影响进行了阐述，认为通过三峡水库的调度减小出库高流量次数和历时是减缓下游溶解气体过饱和的有效手段。

The Evolvement Study on Supersaturation of Dissolved Gas in the Middle Reaches of Yangtze River during the Three Gorges Project Operation

In order to analyze the ecological effects of gas supersaturation by the Three Gorges Dam in the middle reaches of Yangtze River, this paper established a mathematical model of dissolved oxygen(DO) in the middle reaches of the Yangtze River. Using this model, the evolvement of supersaturation of dissolved oxygen under different discharges in the middle reaches of the Yangtze River was simulated and predicted. The results show that there are two peaks of DO, one of which is at the discharge between 40000m3/s and 50000m3/s, the other is near the discharge of 100000m3/s.The reduction of DO is very slow in the natural river and the rate is 5% per 100km in the middle reaches of Yangtze River. The inflow of Dongting Lake can reduce the supersaturation of DO in Yangtze River. When the outflow of Three Gorges Reservoir is 40000 m3/s, the harmful range is more than 400km. This paper also discussed the relationship among different indexes of gas supersaturation and briefly analyzed the effects of gas supersaturation on fishes in the middle reaches of Yangtze River. Reducing the times and duration of high outflow of Three Gorges Reservoir through the operation is considered the best mitigation measures.