洞庭湖和鄱阳湖泥沙冲淤特征及三峡水库对其影响

长江中游江湖关系复杂，分布有中国第一、二大淡水湖泊，江湖关系演变对防洪、生态等影响重大。通过分析反应长江中游洞庭湖和鄱阳湖泥沙冲淤的实测水沙和地形资料，初步掌握了湖区泥沙冲淤特征及主要影响因素，并着重探讨了三峡水库蓄水对两湖泥沙冲淤的影响。结果表明，近10年洞庭湖和鄱阳湖湖区泥沙淤积速度明显减缓，部分年份出现冲刷，其中洞庭湖湖区泥沙沉积率下降主要由来沙减少引起，三峡水库拦沙作用的影响明显；鄱阳湖区冲刷主要集中在入江水道，采砂活动影响显著，三峡水库蓄水影响尚不明显。

Sediment erosion and deposition in two lakes connected with the middle Yangtze River and the impact of Three Gorges Reservoir

As the largest freshwater lakes in China, the Poyang and Dongting Lakes enter a complicate coupling with the middle reach of Yangtze River, which plays a significant role in flood control and eco-environment protection. Based on the field flow-sediment and topography data, the leading factors to the characteristics of sediment erosion and deposition in both Lakes have been studied, of which the Three Gorges Reservoir is highlighted. The results indicate that the rate of siltation in both Lakes shows visibly slowdown to occasional erosion in the recent decade. The decrease of sedimentation rate in Dongting Lake is basically induced by the reduction of incoming sediment due to the operation of Three Gorges Reservoir, while the erosion dominated in Hukou reach of Poyang Lake is mainly caused by excessive sand mining rather than the Three Gorges Reservoir which still remains uncertain.