三峡水库调节典型时段对鄱阳湖湿地水情特征的影响

Effect of the Three Gorge Reservoir on the water regime of the Lake Poyang wetlands during typical water-regulation period

三峡工程建成运行将改变下游的水文过程,影响通江湖泊湿地生态系统.本文选取水文情势变化大且可能对植被生长产生较大影响的汛末蓄水和汛前腾空两个时段,运用长江中游江湖耦合水动力模型计算了三峡水库不同调节流量下湖泊水位变化特征,并结合湖泊高程和面积关系曲线,分析了不同增减下泄流量对洲滩湿地淹没出露的影响.结果表明,三峡水库汛末蓄水减泄流量1000-7653m3/s可使大湖面(都昌站)水位降低0.09-1.11m;汛前腾空增泄1000-6500m3/s,可使水位抬高0.15-0.94m.水位影响格局呈现北高南低,在底水位较高的汛前腾空时段增泄引起水位变化范围较大,基本覆盖湖泊主要水面.

Operation of the Three Gorge Project will change the hydrological processes and affect the ecosystem of lake wetland.The two time periods,i.e.water storage after flood season and water emptying before flood season,with highly changed water regime are selected to evaluate the effects of the Three Gorge Reservoir regulation by using the hydrodynamic method.The lake water levels and discharge variations are computed under the different regulation of discharge values.Combined with lake level variations and the elevation-area curve,the wetland exposure area are also analyzed.Results show that lake level of the Lake Poyang（at Duchang Station） would decrease 0.09-1.11m for steady flow condition if the discharge of Yangtze river decreases 1000-7653m3/s after flood season,whereas lake level will increase 0.15-0.94m if the discharge increases 1000-6500m3/s before flood season.The effect of Three Gorge Reservoir on lake levels varies significantly from northern to southern part of the lake,which are depended on the hydrodynamic connectivity conditions.