Seasonal and Spatial Variability of Airborne Dust Loading Rate over the Sistan plain cities and its Relationship with some Climatic Parameters

Sistan plain has a high erodibility potential because of fine grain size alluvial deposits and these fine particles can be easily moved due to 120-day wind blow in this arid region and cause numerous dust storms. Therefore, this study aimed to investigate seasonal changes of dust loading rate in Sistan plain and its relationship with some climatic parameters from March 2015 to March2016.
25 Siphon dust trap samplers were installed in the 5 cities of Sistan plain including Zabol (7), Zahak (4), Nimrouz (4), Hirmand (5) and Hamoun (5) and the dust was collected and measured seasonally. Seasonal climate data including wind speed, air temperature, relative humidity, precipitation, evapotranspiration and average soil temperature at depth of 5 cm were used from Zabol and Zahak meteorological stations. Suitable statistical analyses were used to investigate seasonal and spatial variations of dust loading rate and its relationship with climatic parameters.
The results showed average and total annual dust loading rate in Sistan plain were 338.85 (g/m2) and 6777.03 (g/m2), respectively. Hirmand city had the highest dust loading rate in the spring and summer and Nimrouz city had the highest rate in the autumn and winter. Hamoun city had the lowest dust loading rate in the all periods. The average of dust loading rate in the summer (566.23 g/m2) was greater than the average rates in the autumn and winter, significantly. The average dust loading rate showed significant positive correlation with wind speed, air temperature, soil temperature at a depth of 5cm and evapotranspiration and also showed a significant negative correlation with relative humidity. The correlation between precipitation and dust loading rates were negative but not significant.
According to the results, the most important factors on spatial and temporal variations of dust loading rate in Sistan plain are the distance from source of dust origin (Hamoun wetlands), the erodible area in the direction of prevailing wind and climatic factors that directly affected on soil erosion and degradation, and hydrologic and ecologic conditions (presence of water in Hamoun wetlands and vegetation cover) in the region.