不同水沙条件下黄河下游二级悬河的发展过程

The Process of Secondary Suspended Channel in the Lower YellowRiver under Different Conditions of Runoff and Sediment Load

以大量实测横断面资料为基础,研究了1973￣1997年不同水沙过程对黄河下游二级悬河形成过程的影响。发现花园口至高村河段二级悬河集中形成于1985￣1997年的枯水阶段。高村以下河段二级悬河的形成可分两个阶段,1973￣1985年大水条件下是冲刷主槽和淤积滩地的时期,但是由于泥沙主要堆积在靠近滩唇的部位,造成河床横比降增大;1985￣1997年枯水条件下泥沙在主槽中大量淤积,导致二级悬河的形势更加严重。生产堤限制了泥沙的堆积范围,导致生产堤内滩地平均高程增长速度明显快于生产堤外滩地平均高程增长速度,生产堤距较窄的河段生产堤内滩地平均高程增长速度较快,显示了生产堤对二级悬河的发展有促进作用。

Based on data of cross-section measurements obtained during the period 1973-1997, the development of the secondary suspended channel in the lower Yellow River has been studied. It has been found that the period 1973-1985 was the main period in which the secondary suspended channel was formed in the reach above Gaocun station; but in the reach below, the process can be divided into two periods of time. In the period 1973-1985 with high water discharges, large quantities of sediment deposited on the floodplain near the natural levee, resulting in a larger lateral slope of the flood-plain. In the period 1985-1997 with low water discharges, large quantities of sediment deposited within the main channel, and as a result, the channel shrank and the situation of the secondary suspended channel became even more serious.