为科学定量评价三峡水库运行过程对洞庭湖径流及生态特征的影响,收集城陵矶、石龟山、南咀、小河咀4个水文站1988—2020年逐日流量数据,应用IHA-RVA法和Shannon指数法对三峡水库试运行阶段(2003—2008年)和三峡试运行后阶段(2009—2020年)流量演变和生态效应进行定量分析。结果表明:①三峡水库运行过程中汇入洞庭湖流量占比方面,湘、资、沅、澧四水占比持续提高,荆江三口占比持续下降;②三峡水库蓄水试运行阶段洞庭湖区水文站整体流量改变度和IHA高度改变指标个数高于三峡水库试运行后阶段,且城陵矶和石龟山整体改变度分别达到67.27%和69.55%,形成高度改变;③三峡水库试运行阶段,三峡水库蓄水下游流量上涨次数及上涨幅度减少,连续日流量正差异值R_rate减少,洞庭湖Shannon指数均有下降趋势;三峡水库试运行后阶段按“枝城调度”规则运行保证三峡次数下游有中小洪水过程并增加下游枯水补给,R_rate增加、Shannon指数有所回升。研究成果可为洞庭湖水安全和水生态健康提供科学依据。

To scientifically and quantitatively evaluate the impact of Three Gorges Reservoir operations on the runoff and ecological characteristics of Dongting Lake, we analyzed daily flow data from four hydrological stations—Chenglingji, Shiguishan, Nanzui, and Xiaohezui—spanning 1988 to 2020. We employed the IHA-RVA method and Shannon index method to assess flow evolution and its ecological effects during the trial operation phase (2003-2008) and the post-trial operation phase (2009-2020) of the Three Gorges Reservoir. Our findings indicate that: (1) During the operation of the Three Gorges Reservoir, the proportions of water flowing into Dongting Lake from the Xiangshui River, Zishui River, Yuanjiang River, and Lishui River increased, while the proportions from the three outlets of Jingjiang River decreased.(2) In the trial operation phase, the overall changes in flow rate and IHA were greater than those in the post-trial phase, with Chenglingji and Shiguishan exhibiting overall changes of 67.27% and 69.55%, respectively.(3) During the trial operation phase, a reduction in the magnitude of downstream flow increases led to a decrease in both the daily flow rate positive difference (R_rate) and the Shannon index. However, in the post-trial phase, adherence to the “Zhicheng Dispatch” rules, which aimed to ensure small and medium-sized floods downstream and increase dry-season water supply, led to an increase in R_rate and a rebound in the Shannon index. These results provide a scientific basis for ensuring water safety and ecological health in Dongting Lake.