Simulating and Analyzing the Effects on Concentration of Airborne Particulates derived from Unvegetated Riverbanks
Date Issued
2014
Date
2014
Author(s)
Lin, Kun-Ming
Abstract
Landslides frequently occur during large earthquakes and storms in Taiwan, supplying large volumes of sediment to downslope areas. When coupled with the intense northeast monsoon over Taiwan in the dry winter season, this can lead to high concentrations of airborne particulates that are hazardous to human health. Air quality monitoring stations near unvegetated riverbanks recorded high concentrations of particulate matter less than 10 microns (PM10) after Typhoon Morakot in 2009. The objective of this study was, therefore, to analyze the effects on air quality of sediment caused by the typhoon. A deflation model was simulated, and the resulting estimates were compared with observed data from the Taitung monitoring station for 2004 and 2005. The relationship of dust flux to average atmospheric dust concentration was analyzed for October to December 2001 ~ 2010. Analysis showed that the 2001 ~ 2008 data are highly correlated (0.78) with the average concentration. The intercept of 28.7 represented the background concentration with no dust emission, from October to December of 2001 to 2008. Based on the dust potential in 2009, the average PM10 concentration would be 37.98 μg/m3; however, the measured concentration was 61.67 μg/m3 from October to December. This suggests the strong influence of dust re-suspended from unvegetated riverbanks by Typhoon Morakot.
Also, this model was very ideal when applying the transportation mechanism in the complex terrain. The pollution air mass could move alone the East Rift Valley. In the deflation module, due to lack the vertical velocity of the dust emission, the influence height of dust pollution is only the affected by the mechanism of vertical diffusion in the mixing height. In general, influence height of dust pollution is about 200-800 meters.
From the contour maps of high density air quality stations near Jhuoshuei River, main influence area is from Lunbei station to Mailiao and Baozhong Station. Under high-speed winds, besides bare lands of the river, there were also other PM10 emission sources, such as pile storage, blocks yards and bare or abandoned farmlands. Even the monitoring stations are not closed the Jhuoshuei River, sometimes they read high PM10 concentration.
Subjects
土石流
PM10
莫拉克颱風
揚塵模式
揚塵潛勢
Type
thesis
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