水库拦沙对长江水沙态势变化的影响

Influence of sediment trapping in reservoirs on runoff and sediment discharge variations in Yangtze River

为探讨水库建设对水沙变化态势的影响,通过引入来沙系数、输沙模数和流域水库调控系数,深入分析了长江水库拦沙对水沙态势变异的作用。长江干支流水沙参数与流域水库库容参数之间有重要关系,主要水文站年输沙量随流域累积库容增加而逐渐减少,来沙系数和输沙模数随流域水库调控系数成指数关系衰减,表明水库蓄水拦沙是长江水沙态势变异的主要因素。长江干支流输沙量衰减规律有一定差异,支流来沙系数和输沙模数衰减规律相对独立,而干流上游站衰减幅度大于下游水文站,且干流各站输沙模数的衰减规律比较接近。

In order to understand the influence of reservoir construction on the runoff and sediment discharge varia- tions, relationships between water and sediment parameters and reservoir capacity parameters in the trunk stream and tributaries of the Yangtze River were deeply studied through using the incoming sediment coefficient （ISC） , the sediment transport modulus （STM） and the reservoir regulation coefficient in the basin （RCB）. Annual sediment discharge in the typical hydrologic stations gradually reduces with increase of the cumulative reservoir capacity in the basin, and the ISC and the STM of the rivers decrease in an exponential form with the RCB, which shows that water storage and sediment trapping of the reservoir is a main influence factor on the runoff and sediment discharge variations. The attenuation laws of the sediment discharge in the trunk stream are some differences from that in tributaries. For the tributaries, the ISC and STM attenuation laws are relatively independent with each other. For the trunk stream, the ISC and STM attenuating ranges in the upper stations are greater than that in the lower stations, and it is near same for the STM attenuation laws in all typical hydrologic stations.