通过野外调查及风场观测，研究了在主导风向为NW-SE时，榆靖高速公路K404处上风向植被防护体系的地面流场变化特征。结果表明:（1）风速和地形存在较好的相关性。在流动沙丘和固定沙丘迎风坡，风速放大率均为正，背风坡为负，背风坡没有产生回流，风速整体减小。风速放大率计算结果表明，愈接近地面风速的变化程度越大，风速放大率绝对值与垂直高度呈指数函数关系，风速放大率的大小与沙丘类型无关。（2）接近公路的贴地面风速显著下降，现有植被防护体系能够缓解流沙危害，植被的防风效果较好。（3）流动、半固定、固定沙丘的迎风坡地表风速廓线基本符合对数律，丘顶和背风坡风速廓线偏离对数曲线，固定沙丘粗糙度高于流动沙丘。

Through the field observation and the wind velocity measurement, we studied the flow field characteristics at the protection system of vegetation, which was located at K404 of Yulin-Jingbian Expressway, where the wind direction was NW-SE. There is a significant correlation between wind velocity and the topography. The magnification ratio of wind velocity is positive at the windward slope of the moving sand dune and fixed sand dune; the magnification ratio of wind velocity is negative at the leeward slope, which doesnt produce backflow and the wind velocity is reduced as a whole. The characteristics of magnification ratio of wind velocity show that more close to the land, the bigger the wind velocity changes. There is an index function relation between absolute value of wind velocity magnification ratio and vertical height. There is no relation between wind velocity magnification ratio and the types of dunes. The wind velocity closed to the highway decreases significantly, which means that the vegetation protection system can remit the damage of drift sand. The wind velocity profiles over windward slope of the moving, semi-fixed and fixed dunes conform to logarithm law basically, but the wind velocity profiles over the summit and the leeward slope deviates from the logarithmic curves. The aerodynamic roughness of the fixed dunes is higher than that of the moving dunes.