Abstract:

he 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 m3/s after flood season or the discharge increase with 3 500 m3/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.〖