风滚植物高立式沙障防风效应研究

Study on Windproof Effect of Wind-Rolled Plant High Vertical Sand Barrier

“风滚”扩散是植物种子传播与个体扩张的重要形式,具有重要生态学意义。草地、沙地均存在大量的风滚植物,冬春季在气流作用下运动并堆停在各种障碍物周围,其中,网围栏拦截形成风滚植物障体较为常见,此类障体对过境风沙也会产生明显的阻挡作用。为探究风滚植物障体的防风效应,本研究模拟了网围栏拦截不同数量的风滚植物,设计了具有密、中、疏3种疏透度的风滚植物高立式沙障(障高H为1 m),通过野外试验研究了防风效能、风沙动力学粗糙度及风速流场特征,并探索了高度、疏透度等沙障工程参数对防风效益的影响,为防沙治沙新方法与新技术应用提供参考。结果表明(:1)风滚植物高立式沙障能够影响周边风场特征,可影响至障后7 H距离、0~90 cm高度范围(;2)密、中、疏3种沙障均能够显著降低过境风速强度,具有较好的防风效能。3种沙障风速最小值均出现在障后3 H距离处,但随着疏透度的减小,沙障防风效能呈现增加的趋势,防风效能最高值出现在密型沙障后10 cm处,可达到50%。(3)密、中、疏3种沙障均能够增加地表粗糙度,3种沙障整体上呈现密型>中型>疏型的趋势,粗糙度最大值出现在密型沙障,可达2.97 cm。风滚植物高立式沙障能有效对过境风速产生影响,具有很好的防风效应,能够为防沙治沙应用提供参考。

Wind-rolling dispersal is an important form of plant seed dispersal and individual expansion,which has important ecological significance.Many wind-rolled plants exist in both grassland and sandy land,which move under the action of air flow in winter and spring and pile up around various obstacles.Among them,the wind-rolled barriers formed by net fences are more common,and such barriers also have obvious blocking effect on the transit wind sand.To investigate the windbreak effect of wind-rolled plant barrier,this study simulated the interception of different quantities of wind-rolled plants by net fences,and designed three kinds of sparse,medium,and dense wind-rolled plant vertical sand barriers(barriers with a height of 1 m),and studied the windbreak efficiency,windbreak sand dynamic roughness and wind speed flow field characteristics through field tests.The influence of sand barrier engineering parameters such as height and permeability on wind control efficiency was explored,which was intended to provide reference for new methods and technologies of sand control.The results showed that:(1)the vertical sand barrier of wind-rolling plants could affect the characteristics of the surrounding wind field up to the distance of 7 H and the height range of 0−90 cm behind the barriers.(2)Dense,medium and sparse sand barriers were able to significantly reduce the intensity of transit wind speed,with good wind prevention efficiency.The minimum wind speed of the three sand barriers appeared at the distance of 3 H behind the barrier,but with the increase of thinning permeability,the wind protection efficiency of the sand barriers showed an increasing trend,and the maximum wind protection efficiency appeared at the distance of 10 cm behind the dense thinning permeability barrier,which could be up to 50%(.3)Dense,medium and sparse sand barriers could all increase the surface roughness,and the three sand barriers all showed a trend of dense>medium>sparse,and the maximum value of roughness appeared in the dense and sparse permeability,which could reach 2.97 cm.The high vertical sand barrier of wind-rolling plant could effectively affect the transit wind speed and had a good windproof effect,which can provide reference for the application of sand control.