中文摘要：

洞庭湖与长江联系紧密,三峡工程运行将改变洞庭湖的水文过程,影响湖泊湿地生态系统。为了评估三峡工程运行对洞庭湖湿地的水文影响,选取水文情势变化大且可能对植被生长产生重大影响的汛末蓄水和汛前腾空两个时段,运用反映江湖水动力交互的水动力学方法计算了三峡水库不同调节流量下湖泊水位与流量的变化特征,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,洞庭湖吞吐长江,复杂的江湖水动力交互作用使得湿地水文过程变化有明显的非线性。在恒定流条件下,汛末蓄水减泄4 000m3/s流量可使城陵矶水位降低1m。同样抬高1m水位,汛前腾空约需增泄3 500m3/s。在空间分布上,三峡水库调节对洞庭湖水情影响具有明显的异质性,受江湖关系和湖盆地形的影响,与长江水力联系紧密的东洞庭湖、南洞庭湖东部和西洞庭湖北部受三峡水库调节影响大,而西洞庭湖南部影响较小。

英文摘要：

The Dongting Lake is closely linking with the Yangtze River.The operation of the Three-Gorge Project will change the hydrological Process 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 were selected to evaluate the effects of the Three-Gorge regulation by use of the hydrodynamic method.The lake stage and discharge variations were computed under different regulation discharge values.Combined with stage variation and lake elevation-area curve,the wetland exposure area was also analyzed.Results show that the Dongting Lake stage nonlinearly responded to different regulation discharge values of Three-Gorge reservoir because of complex lake-river interactions.For steady flow condition,stage variation with one meter might arise when the discharge reduction with 4 000 m3/s after flood season or the discharge increase with 3 500 m3/s before the flood season.Spatial pattern of stage variation was heterogeneous.The Eastern part and the east of the Southern part,the north of the Western part of the Dongting Lake had high response to the Three-Gorge reservoir regulation,but the south of the Western part had low response.