1 Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; 2 Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China, Ningxia University, Yinchuan 750021, China; 3 Dunhuang Gobi and Desert Ecology and Environment Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Dunhuang 736200, China; 4 University of Chinese Academy of Sciences, Beijing 100049, China
Abstract The Lanzhou-Xinjiang High-speed Railway runs through an expansive windy area in a Gobi Desert, and sand-blocking fences were built to protect the railway from destruction by wind-blown sand. However, the shielding effect of the sand-blocking fence is below the expectation. In this study, effects of metal net fences with porosities of 0.5 and 0.7 were tested in a wind tunnel to determine the effectiveness of the employed two kinds of fences in reducing wind velocity and restraining wind-blown sand. Specifically, the horizontal wind velocities and sediment flux densities above the gravel surface were measured under different free-stream wind velocities for the following conditions: no fence at all, single fence with a porosity of 0.5, single fence with a porosity of 0.7, double fences with a porosity of 0.5, and double fences with a porosity of 0.7. Experimental results showed that the horizontal wind velocity was more significantly decreased by the fence with a porosity of 0.5, especially for the double fences. The horizontal wind velocity decreased approximately 65% at a distance of 3.25 m (i.e., 13H, where H denotes the fence height) downwind the double fences, and no reverse flow or vortex was observed on the leeward side. The sediment flux density decreased exponentially with height above the gravel surface downwind in all tested fences. The reduction percentage of total sediment flux density was higher for the fence with a porosity of 0.5 than for the fence with a porosity of 0.7, especially for the double fences. Furthermore, the decreasing percentage of total sediment flux density decreased with increasing free-stream wind velocity. The results suggest that compared with metal net fence with a porosity of 0.7, the metal net fence with a porosity of 0.5 is more effective for controlling wind-blown sand in the expansive windy area where the Lanzhou-Xinjiang High-speed Railway runs through.
Fund: This research was financially supported by the Scientific and Technological Services Network Planning Project of Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (HHS-TSS-STS-1504), the Technological Research and Developmental Planning Projects of China Railway Corporation (2015G005-B), and the National Natural Science Foundation of China (41501010, 41401611).
WANG Tao,QU Jianjun,LING Yuquan et al. Wind tunnel test on the effect of metal net fences on sand flux in a Gobi Desert, China[J]. Journal of Arid Land, 2017, 9(6): 888-899.
2017, Vol. 9 
