三峡工程蓄水对鄱阳湖水情的影响格局及作用机制分析

Water storage effects of Three Gorges project on water regime of Poyang lake

鄱阳湖近年多次出现罕见的枯水水情,且恰逢三峡工程开始试验性蓄水,三峡工程对鄱阳湖的影响因此广受关注和议论。为明确三峡蓄水对鄱阳湖的影响及其作用机制,本文运用长江中游江湖耦合水动力学模型,以2006年三峡蓄水试验为例,计算了汛末蓄水对鄱阳湖水情的影响分量。结果表明:受蓄水影响,鄱阳湖湖口、星子、都昌和康山水位平均下降0.94m、0.74m、0.50m和0.03m。水位影响格局呈北高南低。湖泊内部的洲滩湿地受水位下降影响,提前出露,受影响最大的是中部的开敞水域。干流水位快速下降,加速湖水下泄是三峡工程蓄水对鄱阳湖水位的主要影响方式。

Extreme drought happened several times in the Poyang lake region recent years when Three Gorges project（TGP） began to store water.The impacts of this reservoirs impoundment on the lakes water regime attract great attention.To understand and identify these impacts and their acting mechanism,this paper presents a quantitative analysis on the Poyang water regime with a river-lake coupling hydrodynamic model for the middle Yangtze,focusing on the reservoir′s test impoundment in 2006.Results show that during the impoundment,the lake stage was higher in the north than in the south showing a spatially uneven effect and that the average lake stage was lowered by 0.94m,0.74m,0.50m and 0.03m at Hukou（the lakes outlet）,Xingzi,Duchang and Kangshan,respectively.As a result of water stage falling,grasslands in the lake region were exposed relatively earlier,particularly those in the central region where bed elevation was slightly changed.The water stage drop-off in the Yangtze main stream leaded to a rapid increase in hydraulic slope and thus a speed-up in lake drainage.