三峡水库蓄水期洞庭湖区水文情势变化研究

洞庭湖湖区的水文情势变化直接影响到区域洪水灾害防治、水资源利用、水环境保护和水生态安全维护,意义重大。基于实测资料分析了三峡水库运行前后洞庭湖区水文情势变化,受三口分流量减少和来水偏枯等综合因素影响,2003～2016年8～11月洞庭湖入、出湖水量较1981～2002年分别减少26%和23. 7%,湖区水位下降0. 76～1. 27 m。建立了长江与洞庭湖一、二维耦合水动力模型,模拟计算了三峡水库蓄水期初设调度方案、优化调度方案和规程调度方案下长江干流及洞庭湖区的水文过程,3种方案对应的城陵矶站蓄水期多年旬平均流量分别减少1 220,928,900 m~3/s,湖区鹿角站蓄水期多年旬平均水位分别降低1. 47,1. 23,1. 20 m。实际调度流量减小812 m~3/s,水位降低1. 14 m,表明实际调度最优。从不同调度方案比较来看,实际调度提前了起蓄时间,减缓了对洞庭湖区水文情势的不利影响。

Study on hydrological regime variation in Dongting Lake during water storage period of Three Gorges Reservoir

The variation of hydrological regime in Dongting Lake would directly affect regional flood prevention, water resources utilization, water environment protection and water ecology protection, which is of great significance. Based on the measured data, the variation of the hydrological situation in Dongting Lake area before and after the Three Gorges Reservoir operation was analyzed. The results showed that the inflowing and outflowing water volume of Dongting Lake from 2003 to 2016 had decreased by 26% and 23.7% respectively and the water level in lake area dropped 0.76~1.27m from August to November, compared with the period from 1981 to 2002, due to the combined factors, such as the diversion decrease of three distributaries from Jinjiang River and the decrease of incoming water, etc. A 1D and 2D coupled hydrodynamic model of the Yangtze River and Dongting Lake was established to simulate the hydrological processes of the study area during the water storage period of Three Gorges Reservoir under the initial-designed scheduling scheme, optimal scheduling scheme and protocol scheduling scheme. The corresponding average annual flow of Chenglingji station decreased 1 220,928 m3/s and 900 m3/s respectively, and the average annual water level of the Lujiao Station in the lake area decreased 1.47,1.23 m and 1.20 m respectively; however, the average flow decreased 812 m3/s and the water level decreased by 1.14 m under the actual scheduling practice, indicating that the actual scheduling is optimal. From the comparison of different scheduling schemes, the actual dispatching advanced the storage starting time and slowed down the adverse impact on the hydrological situation in Dongting Lake area.