三峡水库运行以来洞庭湖水文条件变化与对策

为了解三峡水库运行以来洞庭湖区的水文条件变化和影响,利用实测水文地形资料对三口水沙、城陵矶水位变化与湖泊萎缩、三口河系水源不确定性及洞庭湖变化趋势等进行了分析。结果表明:在三峡水库及其上游梯级水库调节下,清水下泄及径流过程的进一步坦化,出现了洪水在城陵矶附近进一步集中、三口河系水资源与水环境的水源缺失的不利影响;未来水情趋势下三口仅松滋口具备不断流条件,洞庭湖主要以西、南、东洞庭湖内深水河道转化为河流形态。为缓解这些变化的影响,可通过湖区防洪工程体系提质改造和区域再划分,以适应城陵矶附近防洪蓄洪的水情变化;通过稳流拓浚,维持三口河系中下游水源条件,以改善该区域水资源水环境;通过城陵矶出口控制调节水位,以维护洞庭湖湖泊水域条件,保障湖泊湿地的生态安全。

Variation of hydrological conditions of Dongting Lake and corresponding countermeasure analysis after operation of the Three Gorges Reservoir

The variation of the hydrological conditions of Dongting Lake and its influenceafter the operation of the Three Gorges Reservoir was studied in the present paper. Based on the actual measured hydrological and topographic data, the variations of Dongting Lake were analyzed, including the change of sediment at the three inlets, the relationship between water levels at Chenglingji and the shrinking of lake area, the uncertainty of water source of the three inlets river network. Under the regulation of the Three Gorges Reservoir and the cascade reservoirs in the upstream, clear water discharge and the smooth of runoff process result in flood accumulation in Chenglingji. The water resources of the three inlets has also been damaged. In the future, only Songzi estuary can maintain constant runoff to avoid river blanking. The deepwater region of the west, south and east Dongting Lake will transform into rivers. To alleviate the impact of these changes and adapt to the flood control near Chenglingji, improving and regional optimizing of the flood control engineering systems in the lake area should be implemented. Dredging in the downstream can improve water environment at the three inlets area. The water level in the outlet of Chenglingji can be adjusted so that to protect the water condition of Dongting Lake and to ensure the ecological security of the wet land.