团洲垸溃决险情发生后,三峡水库紧急调度减小出库流量,洞庭湖水位快速下降,为险情应急处置创造了有利的条件。定量评估调度效果有助于深入认识和不断优化三峡水库调度。构建荆江河段一维和东洞庭湖二维耦合水动力模型,利用实测资料对模型进行验证。设计并模拟了三峡水库不同调度场景下的江湖水情,定量分析了三峡水库调度对江湖流量、水位的影响。分析了团洲垸溃决前后洞庭湖区(含团洲垸)的险情发展与七里山水位的变化情况,探讨了三峡水库调度对减轻洞庭湖区防洪压力的效果。结果表明:三峡水库调度减小了7月6—9日期间荆江干流的流量,加快了洞庭湖水位下降过程,使东洞庭湖区水位最多降低了0.34 m,七里山站水位下降至警戒水位以下的时间提前了18 h。洞庭湖区堤防险情主要发生在水位超警后的高水位及其退水期间,三峡水库调度降低了湖区堤防险情发生的概率。研究成果科学、定量地评估了三峡水库调度效果,可为其优化调度提供基础。

[Objective] This study aims to quantitatively evaluate the effects of the emergency regulation of the Three Gorges Reservoir in response to the Tuanzhou polder breach emergency, thereby improving the understanding of flood control regulation of the Three Gorges Reservoir and laying a foundation for further optimization of its operation in the future. [Methods] A one-dimensional and two-dimensional coupled hydrodynamic model for the Jingjiang River reach and east Dongting Lake was established and validated with field-measured data. Hydrological conditions of the river-lake system under different regulation scenarios of the Three Gorges Reservoir were designed and simulated, and the effects of reservoir regulation on river-lake discharge and water levels were quantitatively analyzed. The development of emergencies in the Dongting Lake area (including Tuanzhou polder) before and after the breach, as well as the variation of water level at Qilishan, were analyzed. The effects of the Three Gorges Reservoir regulation on alleviating the flood-control pressure in the Dongting Lake area were discussed. [Results] Compared with the original regulation plan before the Tuanzhou polder emergency, the actual regulation of the Three Gorges Reservoir reduced the water level in east Dongting Lake by up to approximately 0.34 m, and advanced the time for the water level at Qilishan station to fall below the warning level by 18 hours. Flood-control emergencies in the Dongting Lake area mainly occurred during the high-water period after the water level exceeded the warning level and during the water recession period, and the regulation of the Three Gorges Reservoir reduced the probability of emergencies in the Dongting Lake area. [Conclusion] The emergency regulation of the Three Gorges Reservoir shortens the duration of the Qilishan water level exceeding the warning level and alleviates flood-control pressure in the Dongting Lake area. This study provides a scientific and quantitative evaluation of the regulation effects of the Three Gorges Reservoir, which provides a basis for further optimization of its operation.