Volume 16, No. 12, December 2016, Pages 3026-3036 PDF(806 KB)
The Horizontal and Vertical Characteristics of Aeolian Dust from Riverbed
Jin-Yuan Syu1, Yu-Chih Cheng1, Yuan-Yi Kao1, Chi-Sung Liang1, Yeou-Lih Yan2, Chane-Yu Lai3, Chang-Tang Chang4, Chih-Chieh Chen5, Chea-Yuan Young6, Yee-Lin Wu7, Wen-Yinn Lin1
1 Institute of Environmental Engineering and Management, National Taipei University of Technology, Taipei City 10608, Taiwan
2 Department of Safety, Health and Environmental Engineering, National United University, Miaoli 36003, Taiwan
3 Department of Occupational Safety & Health, College of Health Care & Management, Chung Shan Medical University, Taichung City 40201, Taiwan
4 Department of Environmental Engineering, National I-Lan University, I-Lan City 26047, Taiwan
5 Institute of Occupational Medicine and Industrial Hygiene, National Taiwan University, Taipei City 10055, Taiwan
6 Department of Natural Resource, Chinese Culture University, Taipei City 11114, Taiwan
7 Department of Environmental Engineering, National Cheng Kung University, Tainan City 70101, Taiwan
- The horizontal/vertical properties of Aeolian dust was analyzed in this study.
- The UAV imagery was discriminated the covering condition of riverbed.
- This study clued the spatial variability of river dust event.
- The shielding effect of particle motion affect the fine particle suspension.
Arid riverbed is an important source of Aeolian dust to influence the atmosphere of nearby village or downtown. In general, Aeolian dust pertains to wind activity in the study of geology, environment and meteorology on particle suspension. This field study set the horizontal/vertical sampling system up in order to investigate the Aeolian dust dimensional distribution properties from the riverbed of the Jhuoshuei River. In addition, the study utilized the unmanned aerial vehicle (UAV) imagery to discriminate the covering condition of riverbed. The results revealed that the percentage of riverbed covering conditions, including bare zone, wetlands, green covering and water covering was about 50.1, 15.7, 16.8 and 17.4%, respectively, on January 5th, 2011. Two Aeolian dust cases from riverbed were measured on November 26th, 2010 and January 15th, 2011. First sampling case was under slower wind speed, and the total particulate matter (PM) concentration in vertical sampling was almost decreased with increasing sampling height, however, the phenomena of second case (faster wind speed) was just on the contrary. Besides, Aeolian dust was distributed in a bimodal or a multimodal curve, and the main peak size was above 10 µm. Mode size of suspension particle diameter was increased as the wind speed increased (14.8 µm/ first case; 21.3 µm/ second case). The total mass concentration ratio of south site to source site (one meter height) was about 1:9 in first case and about 1:3 in second case. Comparing with those two cases, the faster the wind is, the shorter the surface roughness height is (3.08 mm/ first case; 1.07 mm/ second case). Besides, as the wind speed increasing, the friction velocity was also increased (0.33 m s–1/ first case; 0.68 m s–1/ second case). Consequently, this study clued the spatial variability of river dust events, which can further aid the site investigating, forecasting and preventing of dust influences.
Aeolian dust; UAV; Horizontal/vertical sampling; Roughness height.