The effect of roughness density of gobi beds on the entrainment of sediment by wind: A wind tunnel study. Issue 190 (July 2019)

• Record Type: Journal Article
• Authors: Tan, Lihai; Zhang, Weimin; An, Zhishan; Xiao, Jianhua; Qu, Jianjun
• Is Part Of: Journal of wind engineering and industrial aerodynamics. Issue 190(2019)
• Page Start: 183
• Page End: 189
• Publication Date: 2019-07
• Subjects: Gobi -- Aeolian entrainment -- Entrainment threshold -- Entrainment rate -- Roughness density -- Wind tunnel; Wind-pressure -- Periodicals; Buildings -- Aerodynamics -- Periodicals; Pression du vent -- Périodiques; Constructions -- Aérodynamique -- Périodiques; Buildings -- Aerodynamics; Wind-pressure; Periodicals
• DOI: 10.1016/j.jweia.2019.05.002
• Languages: English
• ISSNs: 0167-6105

Abstract

Abstract: Although gobi is a major source of dust storms in northern China, few studies have investigated the effect of roughness density ( λ ) of gobi beds on aeolian sediment entrainment. This wind tunnel study quantitatively evaluated the effect of λ on aeolian entrainment from gobi beds with λ of 0.05–0.51 using R t and R Q . R t referred to the ratio of the entrainment threshold for a bare sand bed to those of gobi beds; R Q was the entrainment rate ratio, whose calculation was just reversed with R t . The results indicated that a two-to five-fold increase in entrainment threshold and 41.4–100% of entrainment rate was attenuated within an experimental friction velocity ( u * ) range of 0.40–0.63 m s −1 . Moreover, the variation of R Q with λ was almost negligible, as λ reached 0.176, 0.203, 0.313, and 0.375 for u * values of 0.40, 0.49, 0.54, and 0.63 m s −1, respectively, which were specific for the Gobi Desert with their typical gravel beds. This study also indicated that for higher u * of 0.54 and 0.63 m s −1, aerodynamic entrainment plays a significant role in aeolian entrainment, whereas at lower u * of 0.40 and 0.49 m s −1, splash entrainment exerts a greater impact. Highlights: Roughness density effect on aeolian sediment entrainment from gobi was studied. 41.4–100% of entrainment rate is attenuated in roughness density range of 0.05–0.51 Sediment entrainment threshold is accordingly increased by factors of two-five. For lower experimental speed, splash entrainment from gobi exerts a greater impact. For higher experimental speed, aerodynamic entrainment plays a significant role.