沙柳方格沙障对库布齐沙漠防风固沙效应的影响

Effect of Salix psammophila Checkerboard Sand Barrier on Wind Prevention and Sand Resistance in Kubuqi Desert

以流沙为对照,设置年限为2,4,7年规格为1.5m×1.5m的沙柳方格沙障沙丘为研究对象,测定各沙丘丘间地、迎风坡底部、迎风坡中部、迎风坡中上部、沙丘顶部、背风坡中部和背风坡底部7个部位的风速、输沙量及蚀积状况,探讨沙障对防风固沙效应的影响。结果表明:沙柳沙障对风速的降低作用随设障年限的延长呈增强趋势,设障沙丘在0.2m处较2m处风速显著降低,3种设障沙丘的防风效果以设障4年为最好,2年最差;设障沙丘不同部位的防风效应由沙丘两侧坡脚向沙丘顶部减弱,迎风坡的防风效果大于背风坡,且以丘间低地防风效应最大。沙障具有增大地表粗糙度、减小输沙量与减弱蚀积强度的作用,输沙量、风蚀强度与设障年限成反比,随设障年限增长,输沙量与蚀积强度呈不同程度地减小,设障年限与沙障中心风蚀深度间遵循一元二次方程的变化趋势,沙丘不同部位的输沙量与蚀积强度自沙丘两侧向丘顶呈增大变化趋势。

With mobile dune as control,the Salix psammophilacheckerboard sand barrier which specification was 1.5m×1.5m,with period of 2a,4aand 7awas studied.The wind velocity,sediment discharge and the erosion-deposition status at seven locations（the low land,the lower part of windward slope,the middle part of windward slope,the upper part of windward slope,the top part,the middle part of leeward slope,the lower part of leeward slope）of dune were analyzed.The result showed that：The effect of the Salix psammophila checkerboard sand barrier on reducing the wind velocity tended better along with the period longer.As to the height of 2m,that of 0.2mhad a significant decrease on wind velocity.Relation to the effect of the windbreak,the 4-year sand barrier was the best while the 2-year was the worst.The windbreak effect of dune with the sand barrier at different locations,that was the effect decreased from foots of slope to the top,and that of windward was better than leeward.The low land had the best effect of windbreak.Barrier could increase surface roughness,reduce sediment discharge and weaken the intensity of the corrosion product.The sediment discharge and wind erosion intensity was inversely proportional with the barrier period tends longer.With the period of the barrier longer,sediment discharge and erosion intensity reduced in different degrees.The period of barrier year was unary quadratic equation of wind erosion depth at center of checkerboard sand barrier.The sediment discharge and the intensity of the wind erosion showed a trend of increase from foots of slope to the top.