三峡水库蓄水期洞庭湖水力要素变化初步分析

Preliminary analysis of changes in hydraulic elements of Dongting lake in storage period of Three Gorges reservoir

为了研究长江-洞庭湖关系对三峡水库径流调蓄作用的响应,本研究基于近期数据,对三峡水库蓄水期长江干流及洞庭湖水力要素进行比较研究。结果表明:长江入湖流量和出口顶托关系是影响洞庭湖调蓄过程的主要因素;三峡水库蓄水后,受蓄水影响三口10月流量减少,11月变化不大,城陵矶10、11月份水位略有降低,而流量有增加趋势;通过类比分析法提出了洞庭湖水量平衡时的临界水位,建立了该临界水位和入湖流量及监利流量量化关系,可量化洞庭湖水量受三峡水库调蓄作用的影响程度。

The hydraulic elements of the Yangtze River and the Dongting lake are analyzed for the storage period of the Three Gorges reservoir based on the recent data to study the responses of the Yangtze-Dongting relationship to the reservoir＇s behaviors in flow regulation and retardation. The results show that the lake inflow and the river＇s pushing to the lake＇s outflow are two key factors that have caused flow regulation and retardation in the lake. After the reservoir＇s impoundment, the average flows at the three diversion outlets were decreasing in October but changed little in November, while the flow at Chenglingji was increasing in these two months and the corresponding water level was dropping. By using analogy analysis, a threshold water level was determined for the water balance condition of the Dongting and a quantitative relationship of this threshold versus the lake inflow and the river flow at Jianli was established. This work would provide a quantitative basis for estimation of the degree of influences on the Dongting＇s water quantity by the Three Gorges reservoir.