黄河下游河道巨大的输沙能力与平衡的趋向性——“黄河调水调沙的根据、效益和巨大潜力”之二

尽管黄河下游河道以堆积性著称,河底、水面不断抬高,但在长期水沙作用下,特别是河流的自动调整和反馈迅速,其平衡的趋向性也很明显。从上、下河段挟沙能力及典型资料看,当流量为1000~4000 m3/s时,上段(河南河段)挟沙能力与下段(山东河段)之比为1.049~0.915,即流量小于2000 m3/s时,上段挟沙能力大于下段;而当流量大于2500 m3/s时,下段挟沙能力则大于上段;流量为2300 m3/s时,上、下河段基本平衡。从多年平均过程看,如果不考虑高含沙洪水,不漫滩,流量沿程不变,下段输沙量为上段输沙量的1.01倍,也说明多年输沙量是平衡的。特别是从1960年9月至1996年10月的资料看,三门峡至利津河段淤积36.32亿t,其中20次高含沙量洪水淤积37.22亿t,若不计高含沙洪水,则全河冲刷0.90亿t,占来沙348亿t的0.26%。

Huge Sediment Transporting Capacity and Trend of Equilibrium of the Lower Yellow River

Although the lower channel of the Yellow River is well known as accumulation formation,the river bottom and water surface are continuously increasing,the speed of automatic regulation and feedback of the river and the trend of equilibrium are very obvious under the long-term action of silt-discharge.Viewing from sediment carrying capacity and typical data of the upper and lower sections,when discharge is 1 000-4 000 m3/s,the ratio of sediment carrying capacity of the upper(Henan) and lower(Shandong) sections is 1.049-0.915,i.e.when the discharge is smaller than 2 000 m3/s,the sediment carrying capacity of the upper section is greater than that of the lower section;when discharge is greater than 2 500 m3/s,the sediment carrying capacity of the lower section is greater than that of the upper section;and when discharge is 2 300 m3/s,the capacity of the upper and lower sections are basically equilibrium.Viewing from normal process,the sediment transport of the lower section is 1.01 times of the upper section,showing the long-term sediment transport is equilibrium if not considering hyper sediment concentrated flood,no overflow and no change of discharge along the channel.Specially viewing from the data from September 1960 to October 1996,the deposition of Sanmenxia-Lijin section is 3.632 billion tons,of which,the deposition is 3.722 billion tons in 20 hyper sediment concentrated floods;the whole river scour is 90 million tons,making up 0.26% of the 34.8 billion tons coming sediment if hyper sediment concentrated flood is not calculated.