洞庭湖与长江水体交换能力演变及对三峡水库运行的响应

运用洞庭湖区与长江干流相关控制站1951-2010 年实测水文数据, 在分析江湖水力关系的基础上, 从不同时间尺度分析江湖水体交换能力的演变特征及其对三峡水库运行的响应。结果表明:① 7-9 月长江荆南三口对洞庭湖的补给能力较强, 1-3 月洞庭湖对长江的补给能力较强;② 江湖水体交换系数具有明显的年代际波动, 其中1951-1958 年、1959-1968 年荆南三口对湖泊的补给能力较强, 而2003-2010 年湖泊对长江的补给能力增强;③ 三峡水库运行后无论是典型年还是在水库不同调度方式运行期, 三口分泄能力减弱, 入湖水量减少, 而因四水入湖水量占绝对优势, 湖泊对长江的补给能力明显增强;④ 尽管影响江湖水体交换能力的因素极为复杂, 但从总体上讲, 除受流域降水波动影响外, 江湖水体交换能力在不同时间尺度上的演变特征及其过程均随着江湖水体交换量的变化而变化, 说明江湖水体交换能力强度与江湖水体交换量之间存在着彼此消长的关系。

Evolution of water exchange ability between Dongting Lake and Yangtze River and its response to the operation of the Three Gorges Reservoir

By using the hydrological data of the related control stations in the Dongting Lake region and the Yangtze River mainstream in 1951-2010, this study analyzed the evolution of water exchange ability between Dongting Lake and the Yangtze River and its response to the operation of the Three Gorges Reservoir (TGR) from different time scales based on their hydraulic relationships. The results are shown as follows. Firstly, from July to September, the compensation ability of the Three Outlets into Dongting Lake is stronger, and from January to March, the compensation ability of Dongting Lake into the Yangtze River tends to be stronger. Secondly, there has been an obvious inter-decadal wave on the water exchange coefficient between Dongting Lake and the Yangtze River, namely, in the periods of 1951-1958 and 1959-1968, the compensation ability of the Three Outlets into Dongting Lake tends to be stronger, but in 2003-2010, the compensation ability of Dongting Lake into the Yangtze River are strengthened. Besides, the spill-division ability of the Three Outlets is weakening, and the water of the lake coming from the Three Outlets decreases. As a result, the water of the lake which comes from the Four Rivers in Hunan takes the dominate position, which obviously enhances the compensation ability of Dongting Lake into the Yangtze River in either typical years after the operation of the TGR or under different dispatching modes of the TGR.