中文摘要：

河渠中植被可以增大水流阻力、雍高水位并改变水流的横纵向流速分布。应用先进的PIV技术,在野外大型试验场,开展了沙棘柔性植物对水流特性影响的野外试验。根据实验数据,本文分析与讨论了沙棘柔性植物对水流表面流速沿横向分布的影响。分析表明,在恒定非淹没流作用下,无沙棘植物的对比段表面流速横向分布符合对数型顺＂流舌＂的光滑型态,沙棘柔性植物丛内的表面流速沿横向则呈现出反＂流舌＂型态,并沿整个断面的分布并不光滑,表现出沙棘植物对水流明显的阻力效应。在流出柔性植物后的对比段中,流速沿程增大,沿横向分布也开始逐渐恢复到无植物时的状态。这些对于研究河道植被阻力及滞流拦沙能力都有重要意义。

英文摘要：

Vegetation in rivers and open channels can increase flow resistance,raise water level and change the transverse and vertical distributions of water flow velocity.In this work,a field experiment on the effects of seabuckthorn flexible vegetation on water flow features was conducted with advanced PIV technique in a large-scale field test base.Based on the experimental data,the vegetation effects on the transverse distribution of surface water flow velocity are analyzed and discussed in this paper.Comparison of the no-vegetation bed case with the vegetation bed case indicates that under the condition of non-submerged steady flow,the velocity distribution in the contrast zone of the former case takes a logarithmic ＂flow tongue＂ of smooth form,while it takes a reverse ＂flow tongue＂ that is not transversely smooth in the latter case.This shows that seabuckthorn vegetation obviously produces extra resistance on the water flow.In the section downstream the flexible vegetation zone,a gradual increase of the mean surface velocity along the streamwise direction can be observed as the transverse distribution is gradually restored to the no-vegetation one.These results would be significant to the studies of river flow resistance,flow retarding and sediment deposition caused by vegetation.