流量波动对黄河下游输沙效率的影响

Influence of fluctuating flow on sediment transport efficiency in the lower Yellow River

通过总结黄河下游输沙效率研究的相关成果,结合黄河下游流量和输沙过程的实测资料,对流量过程中的相对变差给出了波动比的量化指标,并分析了此指标对黄河下游输沙效率的影响,发现原型河道中流量波动比在0.6左右时,各站的输沙水量最小,说明适宜的流量波动比能提高黄河下游河道输沙效率。在原型数据及理论分析的基础上,对黄河下游进行了动床概化模型实验,发现波动比对输沙水量的影响规律与实测资料是一致的,都随波动比的增大先减小后增大。进一步研究了流量波动对输沙效率的影响,发现模型实验中流量标准差4.03L/s(即波动比为0.375)、周期1h的水沙过程输沙效率最高。

This paper summarizes the previous studies on sediment transport efficiency in the lower Yellow mainstream and analyzes the field data of this river to study the influence of flow fluctuations on the transport efficiency. An index of fluctuation ratio is adopted to quantify the flow fluctuations. The analysis reveals that the water volume demand for unit sediment transport is minimized at a fluctuation ratio of 0. 6, showing a trend that appropriate fluctuation ratio improves sediment transport rate. To verify this trend further, a physical model of movable bed generalization was designed and tested to carefully examine the dependence of sediment transport on fluctuation ratio. The test results show that as the fluctuation ratio increases, the water volume demand increases first and then decreases, the same phenomena as that derived from field data analysis. A further examination by using a comprehensive fluctuation index indicates that a peak transport efficiency can be achieved if the fluctuating flow has a standard deviation of 4.03L/s （ fluctuation ratio is 0. 375 ） and a fluctuation period of one hour.