Based on PIV technique, in order to explore the feasibility of using PIV technique in large-scale field flow test, a field experiment on the effects of the seabuckthorn plant flexible dam on stream-wise surface velocity field was conductted in the field test base. And the effects of the seabuckthorn vegetation on lengthwise surface velocity variation in water flow through the seabuckthorn flexible dam were analyzed and discussed to test the retarding effect of the seabuckthorn plant on flow. The results showed that: (1) it was feasible for PIV technique to be used in large-scale field flow test; (2) the plant had a very strong retarding and dissipating water energy effect on flow compared to the dam without seabuckthorn plant, and the flow surface velocity in front of flexible dam was the higher while the surface velocity rapidly slow down after the water flow into flexible dam and the water level was sharply raised; (3) it was easily subject to plant row that the surface velocity variation form in the plant flexible dam presented slow wavy or "zigzag” shape; (4) the surface velocity gradually restored and tended to form the same distribution like that in front of the seabuckthorn flexible dam since the stream water flow out the seabuckthorn flexible dam. This study provides the theoretic proof for developing the soil and water conservation and ecological projects for retarding flow and depositing sediment in montane gully.%基于PIV技术,在野外试验基地,开展了沙棘植物柔性坝对水流表面流速场影响的野外试验.探索在大型野外水流试验中应用PIV技术的可行性.主要分析与讨论了沙棘植物柔性坝作用下水流表面流速的沿程变化特性,以反映沙棘植物对水流的阻滞效应.结果表明:将PIV技术应用于大型野外水流试验研究中是可行的;与无植物的对比段对比表明,植物对水流具有很强的阻滞消能作用,坝前表面流速最大,水流进入沙棘柔性坝后,表面流速迅速减小,水化雍高;受植物排的影响,沙棘柔性坝水流表面流速变化表现出缓慢的波浪型态或曲折的"之"字变化型态;水流流出沙棘柔性坝后,表面流速沿程开始逐渐恢复,并趋向于坝前对比段表面流速分布.本研究可为山区沟道开展以植物为主体的滞流拦沙水土保持生态工程提供理论依据.
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