Abstract: The influence of vegetation density and vegetation height at different beaches on the velocity distribution in compound channels is discussed through the flume experiment. ADV is used to measure the instantaneous velocity at different vertical line and different measuring points; and bamboo sticks are chosen instead of arbores to participate in the simulation. The experiment results indicate that the velocity distribution follows a logarithmic distribution for non-vegetated floodplain, and obey S-shaped distribution for vegetated floodplain. The S-shaped distribution divides the flow into three regions. The range of every region is related to the flow depth, lateral location and vegetation character istics, such as vegetation density and height. For different density of vegetation, the S-shaped distribution is different. Meanwhile, it is found that the velocity in the main channel increases and that in the floodplain decreases after the floodplain is vegetated. Furthermore, the influences of vegetation density on local velocity distribution are distinctive for the same types of vege tation.

Key words: compound channel;velocity distribution, vegetation density, vegetation height

摘要： 通过水槽试验,探讨了不同滩地植被密度、植被高度对复式河槽流速分布的影响。试验时,借助声学多普勒测速仪(ADV)观测不同垂线、不同测点的瞬时流速,选竹签模拟乔木。试验结果表明,在滩地无植被情况下,流速分布满足对数分布;滩地种树后,主槽流速明显增大,滩地流速减小,流速呈S型分布,不同植物密度,S型的分布是不同的。这种S型分布将水流划分为3个区的复杂行为,S型分布的形状与水深、垂线位置和植物特性(植被高度, 植被密度)有关。植被密度对流速分布的影响非常明显。

关键词: 复式河道, 流速分布, 植被疏密度, 植被高度