黄河下游低含沙洪水的冲淤特性兼论艾山-利津河段不淤临界流量

黄河下游上、下河段河道形态迥异,同流量输沙能力上段大,下段小。观测表明一定流量的低含沙洪水,就全下游来说可以产生冲刷,但对下段(艾山以下)来说往往发生淤积。本文通过实际资料分析了下游河段的排沙比关系及不同来沙条件下泥沙冲淤强度等规律,并利用下游低含沙水流挟沙力关系,深入分析了艾山—利津河段不淤临界流量。结果表明这段河道不淤流量不仅与来水含沙量有关,还与河口段淤积延伸对艾山—利津段水面比降有顶托作用有关。

Characteristics of sediment transport of low sediment floods in the lower Yellow River and nondeposit discharge for the lower reach

The river pattern of upper and lower reaches in the Lower Yellow River is quite different.The sediment carrying capacity of the lower reach is smaller than the upper reach for the same discharge. Observed data indicate that the low sediment-laden floods can cause erosion if the lower Yellow River is taken as a whole, but deposition occurs in the lower reach(Aishan to Lijin)of the lower Yellow River. By using the field data, the relation between sediment scour/siltation intensity and different flow condition is developed.Also,by using the sediment-carrying capacity in low sediment concentration flows, the nondeposit flow discharge for Aishan-Lijin reach is analyzed. The results show that the nondeposit flow discharge is related not only to the incoming sediment concentration, but to the water surface slope of Aishan-Lijin reach.