草本植被覆盖结构对径流侵蚀动力的作用机制

 为了解植被与坡面径流侵蚀动力的关系,通过野外模拟冲刷试验,研究不同处理条件下草类植被坡面径流的水动力学特性和侵蚀产沙规律。结果表明:植被完整程度的差异,对坡面径流的流速有显著影响。试验小区上坡面径流流速的大小顺序依次为:裸地小区(0.27m/s)>铲草小区(0.24 m/s)>剪草小区(0.16 m/s)>原状坡面小区(0.1 m/s)>除草剂小区(0.08m/s),径流雷诺数也有相似的变化趋势。在相同的试验条件下,植被越完整,径流运动所遇到的阻力也就越大;相应的坡面径流深也表现出增加的趋势。径流含沙量的分析结果表明,各小区的径流含沙量都随试验进行而逐渐降低,植被结构越完整,径流含沙率降低的趋势也就越明显,相应地径流输沙率也从最大裸地小区的400 g/min降低到3 g/min。

Effects of vegetative cover on runoff hydraulic characteristics and erosion

Relationship between vegetation and runoff hydrodynamic characteristic was probed into based on field simulate experimentation under different vegetative cover on pasture slope.Results indicated that the difference in vegetation integrality had influence clearly on runoff velocity,and the order of runoff velocity on vegetative plots was following,bare plot(0.27m/s)>shaved plot(0.24m/s)>clipped plot(0.16m/s)>original plot(0.1m/s)>herbicide plot(0.08m/s).Changes of Reynolds number showed the similar trends.Analysis of Darcy-weisbach friction indicated that runoff friction increased with the integrality of vegetative cover,while runoff depth increased with the integrality of vegetative cover.Sediment decreased with the integrality of vegetative cover,and consequently sediment transportation rate decreased from 400?g/min to 3?g/min.