Effects of gravel mulch on aeolian transport: a field wind tunnel simulation
KeCun ZHANG*, WeiMin ZHANG, LiHai TAN, ZhiShan AN, Hao ZHANG
Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China
Effects of gravel mulch on aeolian transport: a field wind tunnel simulation
KeCun ZHANG*, WeiMin ZHANG, LiHai TAN, ZhiShan AN, Hao ZHANG
Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China
摘要 The shape, size and coverage of gravels have significant impacts on aeolian sand transport. This study provided an understanding of aeolian transport over the gravel mulching surfaces at different wind velocities by means of a mobile wind tunnel simulation. The tested gravel coverage increased from 5% to 80%, with a progressive increment of 5%. The gravels used in the experiments have three sizes in diameter. Wind velocities were measured using 10 sand-proof pitot-static probes, and mean velocity fields were obtained and discussed. The results showed that mean velocity fields obtained over different gravel mulches were similar. The analysis of wind speed patterns revealed an inherent link between gravel mulches and mean airflow characteristics on the gravel surfaces. The optimal gravel coverage is considered to be the critical level above or below which aeolian transport characteristics differ strongly. According to the present study, the optimal gravel coverage was found to be around 30% or 40%. Threshold velocity linearly increased with gravel coverage. Sand transport rate first increased with height above the wind tunnel floor (Hf), reaching a peak at some midpoint, and then decreased.
Abstract: The shape, size and coverage of gravels have significant impacts on aeolian sand transport. This study provided an understanding of aeolian transport over the gravel mulching surfaces at different wind velocities by means of a mobile wind tunnel simulation. The tested gravel coverage increased from 5% to 80%, with a progressive increment of 5%. The gravels used in the experiments have three sizes in diameter. Wind velocities were measured using 10 sand-proof pitot-static probes, and mean velocity fields were obtained and discussed. The results showed that mean velocity fields obtained over different gravel mulches were similar. The analysis of wind speed patterns revealed an inherent link between gravel mulches and mean airflow characteristics on the gravel surfaces. The optimal gravel coverage is considered to be the critical level above or below which aeolian transport characteristics differ strongly. According to the present study, the optimal gravel coverage was found to be around 30% or 40%. Threshold velocity linearly increased with gravel coverage. Sand transport rate first increased with height above the wind tunnel floor (Hf), reaching a peak at some midpoint, and then decreased.
This research was supported by the Key Program of Knowl-edge Innovation Project of the Chinese Academy of Sciences (KZCX2-EW-313), the National Basic Research Program of China (2012CB026105) and the National Natural Science Foundation of China (41371027).
引用本文:
KeCun ZHANG, WeiMin ZHANG, LiHai TAN, ZhiShan AN, Hao ZHANG. Effects of gravel mulch on aeolian transport: a field wind tunnel simulation[J]. 干旱区科学, 2015, 7(3): 296-303.
KeCun ZHANG, WeiMin ZHANG, LiHai TAN, ZhiShan AN, Hao ZHANG. Effects of gravel mulch on aeolian transport: a field wind tunnel simulation. Journal of Arid Land, 2015, 7(3): 296-303.
Bagnold R A. 1941. The Physics of Blown Sand and Desert Dunes. London: Methuen.Chepil W S, Siddoway F H. 1959. Strain-gauge anemometer for ana-lyzing various characteristics of wind turbulence. Journal of Mete-orology, 16: 411–418.Cook R, Warren A, Goudie A. 1993. Desert Geomorpholgoy. London: UCL Press Ltd.Dong Z B, Gao S Y, Fryrear D W. 2001. Drag coefficients, roughness length and zero-plane displacement height as disturbed by artificial standing vegetation. Journal of Arid Environments, 49: 485–505.Dong Z B, Liu X P, Wang X M. 2002. Aerodynamic roughness of gravel surfaces. Geomorphology, 43: 17–31.Dong Z B, Wang H T, Liu X P, et al. 2004a. A wind tunnel investigation of the influences of fetch length on the flux profile of a sand cloud blowing over a gravel surface. Earth Surface Processes and Land-forms, 29(13): 1613–1626.Dong Z B, Wang H T, Liu X P, et al. 2004b. The blown sand flux over a sandy surface: a wind tunnel investigation on the fetch effect. Geomorphology, 57: 117–127.Kaseke K F, Mills A J, Henschel J, et al. 2012. The effects of desert pavements (gravel mulch) on soil micro-hydrology. Pure and Ap-plied Geophysics, 169: 873–880.Liu B L, Zhang W M, Qu J J, et al. 2011. Controlling windblown sand problems by an arti?cial gravel surface: a case study over the gobi surface of the Mogao Grottoes. Geomorphology, 134: 461–469.Livingstone L, Warren A. 1996. Aeolian geomorphology: an introdu¬ction. Singapore: Longman Singapore Publisher Ltd. McEwan I K, Willetts B B, Rice M A. 1992. The grain/bed collision in sand transport by wind. Sedimentology, 39: 971–981.Mckenna Neuman C. 1998. Particle transport and adjustments of the boundary layer over rough surfaces with an unrestricted, upwind supply of sediment. Geomorphology, 25: 1–17.Nalpanis P, Hunt J C R, Barrett C F. 1993. Saltating particles over flat beds. Journal of Fluid Mechanics, 251: 661–685.Pye K. 1987. Aeolian Dust and Dust Deposits. London: Academic Press.Qu J J, Huang N, Dong G R, et al. 2001. The role and significance of the Gobi Desert pavement in controlling sand movement on the cliff top near the Dunhuang Magao Grottoes. Journal of Arid Environments, 48: 357–371.Qu J J, Huang N, Tuo W Q. 2005. Structural characteristics of Gobi sand-drift and its significance. Advances in Earth Science, 20(1): 19–23. (in Chinese)Remigius E O. 2003. Wind tunnel study on aeolian saltation dynamics and mass flow. Journal of Arid Environments, 53: 569–583.Schmiedle U, Jurgens N. 2004. Habitat ecology of southern African quartz fields: studies on the thermal properties near the ground. Plant Ecology, 170: 153–166.Stone R. 2008. Shielding a Buddhist shrine from the howling desert sands. Science, 321: 1035.Stout J E. 2007. Simultaneous observations of the critical aeolian threshold of two surfaces. Geomorphology, 85: 3–16.Stout J E, Arimoto R. 2010. Threshold wind velocities for sand move-ment in the Mescalero Sands of southeastern New Mexico. Journal of Arid Environments, 74: 1456–1460.Tan L H, Zhang W M, Qu J J, et al. 2013. Aeolian sand transport over gobi with different gravel coverages under limited sand supply: a mobile wind tunnel investigation. Aeolian Research, 11: 67–74.Wang X M, Hua T, Zhang C X, et al. 2012. Aeolian salts in Gobi deserts of the western region of Inner Mongolia: gone with the dust aerosols. Atmospheric Research, 118: 1–9.Wiggs G F S, Baird A J, Atherton R J. 2004. The dynamic effects of moisture on the entrainment and transport of sand by wind. Geo-morphology, 59: 13–30.Wu Z. 1987. Aeolian Geomorphology. Beijing: Science Press. (in Chinese)Yin Y S. 1989. Study on sand drift in strong wind region in gravel desert. Journal of Desert Research, 9(4): 27–36. (in Chinese)Zhang K C, Qu J J, Zu R P, et al. 2008. Characteristics of wind blown sand on Gobi and mobile sand surface. Environmental Geology, 54: 411–416.Zhang X Y, Arimoto R, An Z S, et al. 1993. Atmospheric trace elements over source regions for Chinese dust: concentrations, sources and atmospheric deposition on the Loess Plateau. Atmospheric Environ¬ment, 27: 2051–2067.Zheng X J, He L H, Wu J J. 2004. Vertical profiles of mass flux for windblown sand movement at steady state. Journal of Geophysical Research: Solid Earth, 109, B01106, doi:10.1029/2003JB002656.
2015, Vol. 7 
