三盛公水库运用对下游河道输沙的影响

Influence of operation of Sanshenggong Reservoir on sediment transport in the downstream river

通过建立一维水沙数学模型,分析了不同下泄流量与含沙量条件下三盛公水库下游河道的水沙输移规律,统计了河道的含沙量、累计冲淤量和河段沿程冲淤量,并计算了河道单位长度冲淤量,定量分析了不同河段的冲淤特点。结果表明:流量相同的条件下,进口含沙量越大,河道沿程淤积量和累计淤积量越大,但水库下游100 km后水体含沙量逐渐趋于一致,与进口含沙量无关;水库的下泄流量和含沙量对下游河道的冲刷和淤积影响明显,下泄含沙量不大于3 kg/m^(3)时,下游河道以冲刷为主;水库至三湖河口河段冲淤变化受上游来水来沙条件影响明显,该河段冲淤平衡来沙系数在0.004 kg•s/m^(6)附近。

In this paper,a one-dimensional mathematical model is developed to study the sediment transportation law in the downstream reach of Sanshenggong Reservoir under different flow conditions and sediment concentrations.The sediment concentration,cumulative erosion and deposition,and erosion and deposition along the river section are counted,the erosion and deposition per length of the river is calculated,and the erosion and deposition characteristics of different river sections are quantitatively analyzed.The results show that under the same flow discharge,the larger the sediment concentration in entry,the larger the erosion and deposition along river and cumulative erosion and deposition.However,the sediment concentration after the 100 km downstream reach is prone to be consistent,having nothing to do with the entry sediment concentration.Meanwhile,the discharge flow and sediment content of the reservoir have a significant impact on the erosion and deposition of the downstream reach.When the sediment content of discharge is not more than 3 kg/m^(3),the downstream river is dominated by erosion.Finally,the erosion and deposition change of the reach from the reservoir to the Sanhu Estuary are significantly affected by the upstream inflow and sediment conditions,and the balanced inflow and sediment coefficient of erosion and deposition is around 0.004 kg•s/m^(6).