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Abstract:  
Introduction: Sand and dust storm (SDS) is one of the most important challenges in arid areas. In addition, drought and water limitation strengthens the intensity of SDS. The Sitan plain, in the east of Iran was affected intensively by the negative effects of sands and dusts storms. In this paper, changes in the climate variables and dust storms in the Sistan plain were investigated and compared. This is important for decision makers to plan the management measurements against the sand and dust storms.
Method: Precipitation and mean monthly temperature were selected as climate variables. These data were analyzed in 1977-2014 period. To examine the trends of the selected variables, the Mann-Kendall (M–K) test was used. The change in sand and dust storm frequency in Sistan plain was investigated using the Present weather data (WW). Also, the wind speed data were applied to investigate the changes in this parameter. The brightness temperature degree index was calculated to determine the affected sand and dust storm extent. This extent was determined for 2000, 2004, 2013 and 2018 to determine the changes in the affected extent of sand and dust storm.
Results: The results of this paper showed that the number of dusty days was increased during the research period. Besides, the affected extent of sand and dust storm was extended in recent years especially when the precipitation is low. But the wind speed over the study period was not changed significantly. On the other hand, MK test of precipitation and mean annual temperature, shows a significant trend in both variables. Results of MK test shows a decreasing trend in precipitation over the study area and an increasing trend in annual mean temperature. These trends indicate the climate is getting drier and warmer in Sistan plain. In addition, the number of dusty days is increasing and the extent of affected area is developing while the wind speed is constant.
Conclusion: The results of this paper showed that the number of sand and dust storms was increased during the research period. This can be because of the change in two groups of variables; the wind speed or mean annual temperature and precipitation of region which make this area drier than before. The results of wind storm change detection, showed the changes in the wind speed is not significance. But the changes in the second group were significance. Based on the Man-Kendal test, the precipitation has a decreasing trend and the temperature experienced an increasing trend during the study period. These trends indicate the climate is getting drier and warmer. These changes make this region drier than before which increase the potential of rise the sands and dusts in each storm. By drying up the weather the soil wetness will be decreased which provides the conditions for a dusty day by blowing each wind. Since the extent of affected area by sand and dust storm was also developed, this paper demonstrates the importance of planning to deal with these storms to protect the local life.
     
Type of Study: Research | Subject: Desert
Received: 2020/03/16 | Accepted: 2020/11/11

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