year 11, Issue 3 (Autumn 2021)                   E.E.R. 2021, 11(3): 64-81 | Back to browse issues page

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Soleimani Sardoo F, Karami S, Hoseinhamzeh N. Determining and analyzing the temporal and spatial trend of dust and its effect on vegetation and precipitation (Case study of Jazmourian Basin). E.E.R.. 2021; 11 (3) :64-81
URL: http://magazine.hormozgan.ac.ir/article-1-634-en.html
Department of Ecological Engineering, Faculty of Natural Resources, University of Jiroft, Iran , f.soleimani@ujiroft.ac.ir
Abstract:   (412 Views)
Extended abstract
1- Introduction                                                                                                                     
Jazmourian basin in southeastern Iran includes parts of Kerman and Sistan, and Baluchestan provinces. This region is one of the sources of dust production in southeastern Iran. The maximum dust emissions in the Sistan region occur in eastern Iran, southwestern Afghanistan, and Pakistan in the summer, and these storms load dust from local scales to regions. Vegetation and its type also play an important role in the severity of dust. There is positive feedback between precipitation and dust emission from the surface; This means that the dust from desert areas reduces rainfall and decreases rainfall, causes the soil to dry out, and further increases dust. In addition to the effect on rainfall, the presence of dust is also effective in its spatial distribution.
2- Methodology
  In this study, first, using the optical depth data of the MISR sensors of Terra satellite with a horizontal separation of 0.5 degrees, the monthly and seasonal average optical depth of the aerators in the Jazmourian basin is determined. In order to study the trend of AOD change, the average AOD regions of TODRA satellite MODIS sensor are shown annually in the period 2000 to 2020, and the regression line slope was calculated by age estimation method and Mann-Kendall method with 95% and 99% confidence levels. The amount of vegetation changes in the region has been studied using the annual average of the NDVI index in the Jazmourian region. Since precipitation is one of the factors affecting the occurrence of dust events, the average annual precipitation rates of the TRMM satellite have also been studied. Finally, to investigate the effect of vegetation change on dust, the correlation between the average annual data of AOD and NDVI data and the correlation between the average annual rainfall data and NDVI was calculated to investigate the effect of annual rainfall on vegetation.
3- Results 
   The monthly average values of the optical depth of air vents were in the period 2000 to 2020. In January, AOD values in the center of the Jazmourian Basin, located on the border of Sistan and Baluchestan and Kerman provinces, are slightly higher than in other parts. From February to July, an increase in AOD is observed in the region so that in large parts of the Jazmourian Basin, the average optical depth of air vents in this month has reached about 0.6. Since August, AOD values have gradually decreased until December; only in the central areas of the basin, small amounts of AOD are observed. As expected, the maximum AOD in this region is observed in summer, and then in spring is in second place. The amount of AOD has decreased significantly in autumn and winter. According to the results, NDVI values were low in years when the mean optical depth of the particles was high. For example, in 2008 and 2012, when AOD values were higher than in other years, the average annual NDVI values decreased. Interestingly, the average annual values of optical particle depth in 2020 and 2017 were lower than in other years, but in the same years, the average annual NDVI values are higher than in neighboring years. The results show that in the years when there is an increase in rainfall in the region, an increase in vegetation and a relative decrease in AOD compared to previous years are also observed. It should be noted that in some years, with increasing rainfall and vegetation, the amount of AOD has not decreased much that it can be said that the amount of AOD, in addition to the activity of local dust sources, is due to dust particles from other areas to the study area and AOD changes only Not due to changes in rainfall and vegetation in the area.
 4- Discussion & Conclusions
The average monthly light depth values of air vents in the period from 2000 to 2020 show that in January, the AOD values in the center of Jazmourian Basin, located on the border of Sistan and Baluchestan and Kerman provinces, are slightly higher than other sectors. From February to July, an increase in AOD is observed in the region so that in large parts of the Jazmourian Basin, the average optical depth of air vents in this month has reached about 0.6. From August, when small amounts of AOD were observed only in the central areas of the basin, AOD values gradually decreased until December. Also, the average monthly AOD values in the region in the period 2000 to 2020 show that the highest AOD values in July are related to 2003 and 2001, and in June are related to 2008, which is significantly different from other years. Examination of the seasonal average values of the optical depth of air vents in the period under study shows that the maximum amount of AOD in this region is observed in summer and then spring, and AOD values in the autumn and winter seasons have decreased significantly.
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Type of Study: Research |
Received: 2021/05/30 | Published: 2021/09/23

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