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根据1953～2009年大通水文站水沙过程监测资料,分析了三峡水库2003年蓄水前后长江下游大通水文站泥沙变化过程。三峡水库蓄水前(1953～2002)的多年平均径流量为9011亿m3、多年平均输沙量为4.27亿t;蓄水后(2003～2009年)的多年平均径流量为8121亿m3、多年平均输沙量为1.14亿t;蓄水后与蓄水前相比,年平均输沙量减小了73.3%,多年平均径流量虽有减小,但减小的幅度相对要小,约为9.9%;从年内分配变化看,三峡水库蓄水后沙量大幅减少主要发生在汛期5～10月间,蓄水后5～10月多年平均输沙率减少约67%、多年平均含沙量减少约65%;从主汛期6～8月间变化看,平均含沙量较蓄水前总体呈下降趋势,蓄水前主汛期平均含沙量均值为0.632kg/m3,蓄水后主汛期平均含沙量均值为0.218kg/m3,与蓄水前相比主汛期含沙量均值减小了65.5%。
According to monitoring data of water and sediment from Datong Hydrographic Station from 1953 to 2009, the sediment change of Datong Hydrographic Station in the lower reaches of the Yangtze River before and after the impoundment of the Three Gorges Reservoir in 2003 was analyzed. The multi-year average runoff of the Three Gorges Reservoir (1953-2002) was 901.1 billion m3, with an average annual sediment transport of 427 million tons. After the impoundment (2003-2009), the average annual runoff was 812.1 billion m3 for many years The average amount of sediment transport was 114 million tons. Compared with that before water storage, the average annual sediment discharge decreased by 73.3%. Although the average annual runoff decreased, the decrease was relatively small, about 9.9%. According to the distribution change in the year, the drastic decrease of sediment after the impoundment of the Three Gorges Reservoir occurred mainly in the flood season from May to October. The average annual sediment transport rate decreased by 67% from May to October after impounding. The average sediment concentration A decrease of about 65%. According to the change of main flood season from June to August, the average sediment concentration showed a downward trend compared with that before impoundment. The mean value of average sediment concentration in main flood season before impounding was 0.632kg / m3, The mean sediment concentration is 0.218kg / m3, which is reduced by 65.5% compared with that before water storage.