三峡工程运用后洞庭湖水沙情势变化及其影响初步分析

PRELIMINARY STUDY ON FLOW AND SEDIMENT CHANGING AND INFLUENCE ON DONGTING LAKE AFTER THE THREE GORGES PROJECT OPERATION

采用原型资料分析、长河段一维数学模型计算等手段,分析和预测了三峡工程运用对洞庭湖水沙与冲淤影响,研究了三峡工程运用对洞庭湖出口水位的影响,在此基础上初步分析了三峡工程运用对湖区防洪与生态环境影响。研究成果表明:三峡水库运用后30a末,荆江三口年均分流量和分沙量比多年平均值分别减少43%和73%,三口分流道的河床相应发生冲淤变化;三峡工程运用后,受荆江三口分流比减少影响,洞庭湖区泥沙淤积显著减少,对增强洞庭湖区调蓄功能、延长洞庭湖寿命有利;受三峡水库调度运用与长江干流河道冲刷影响,洞庭湖出口水位以下降为主,汛期水位的下降将对湖区防洪有利,而枯期水位的下降将对湖区水资源利用及生态环境带来一定不利影响。

By the methods of field data analysis and numerical model computation for the river network of the Jingjiang River and Dongting Lake,this paper analyzed the water-sediment transportation and erosion-deposition changing in Dongting Lake after the Three Gorges Project（TGP）,and predicted the impact on the water level in Dongting Lake.The main results show that at the end of the fifty year＇s operation of the Three Georges Project,the annual average runoff and the annual average sediment discharge of three diversions in the Jingjiang River will be less 43 percent and 73 percent than long term average value;after the operation of TGP,the flow and sediment diversion from Jingjiang reach of the Changjiang River to Dongting Lake will continue to decrease and the deposition in Dongting Lake will reduce greatly,which is much useful to prolong the lake＇s life.Because of the influence of the scheduling of TGP and the erosion of Jingjiang river reach,the water level decreasing in flood season is useful to flood prevention,but is harmful to the ecological environment in dry season,especially in storage period of TGP.