Abstract: In order to understand the dynamic properties of Gobi surface, some wind tunnel experiments were conducted on the Gobi surface with different gravel coverage on the top of the Mogao Grottoes in Dunhuang, Gansu Province, China. The study results showed that gravel coverage of Gobi surface affected directly the amount and distribution of roughness elements, such as the wind speed profile, friction velocity, roughness degree and shear stress. Friction velocity was increased in a linear way with the increase of wind speed in the wind tunnel, but the dynamic roughness was decreased in a fluctuation way. Wind speed near Gobi surface was gradually decreased with the increase of gravel coverage, but the friction velocity, dynamic roughness and shear stress were increased in a linear way. When the gravel coverage was increased to 35%, the dynamic roughness, friction velocity and shear stress on the Gobi surface were 0.30 cm, 0.93 cm/s and 1.11 N/cm respectively. The results in this paper can be used to guide the design of sandcontrol structures both in our study area and other Gobi regions where it suffers from windblown sand.

Key words: Gobi, gravel coverage, wind speed profile, friction velocity, Mogao Grottoes