乌江流域水库拦沙及其减沙作用研究

Study on Sediment Retention and Reduction of Reservoirs in Wujiang River Basin

乌江作为三峡入库水沙的重要控制站,水库拦沙对其流域输沙的影响,直接关系到三峡入库水沙条件的变化。为了系统掌握乌江流域水库拦沙情况,基于1956年以来流域内水库及实测水沙资料,采用经验公式、典型调查以及输沙平衡原理相结合的方法,对近60年不同阶段乌江流域的水库拦沙情况以及水库建设对乌江流域减沙贡献权重进行了定量研究。结果表明:1956~2015年,乌江流域水库年均拦沙1347万t,大型水库拦沙量占总拦沙量的83%,其中1956~1990、1991~2005、2006~2015年水库拦沙对乌江武隆站的减沙权重分别为14%、45%和72%,可见水库拦沙作用逐步增强;1991~2005年对武隆站减沙造成影响的主要分布在乌江中游的乌江渡和东风水库,2006~2015年则主要分布在乌江中下游干流的构皮滩、思林、沙陀和彭水等水库。

As an important control station of flow and sediment into the Three Gorges Reservoir (TGR), the influ-ence of reservoir trapping in the Wujiang River has a great influence on the condition of the inflow and sediment of the TGR. To complete understanding of the situation of reservoir trapping in the Wujiang River basin, the reservoir silting situation in the recent 60 years and the contribution weight of reservoir trapping to sediment reduction were studied quantitatively based on the observed flow and sediment data from 1956, and the empirical formulas using typical investigations and the principle of sediment transport balance. The results indicated that the average annual sediment interception capacity of reservoirs was 13.47 million tons from 1956 to 2015, and the sediment interception capacity of large reservoirs accounted for 83% of the total sediment interception capacity. In which the contribution weight of reservoir trapping to the sediment reduction at Wulong station from 1956 to 1990, 1991 to 2005, and 2006 to 2015 was 14%, 45% and 72%, respectively, it is apparent that the effect of reservoir trapping increased gradually. The sediment reduction at Wulong station were mainly affected by the Wujiangdu and Dongfeng reservoirs from 1991 to 2005, and were mainly distributed in Goupitan, Silin, Shatuo and Pengshui reservoirs in the middle and lower reaches of Wujiang River from 2006 to 2015.