نوع مقاله : مقاله پژوهشی
1 دانشیار گروه جغرافیای طبیعی، دانشکده جغرافیا، دانشگاه خوارزمی تهران.
2 استادیارگروه جغرافیای طبیعی، دانشکده جغرافیا، دانشگاه خوارزمی تهران.
3 دانشجوی دکترای ژئومورفولوژی، دانشگاه خوارزمی تهران.
عنوان مقاله [English]
A dust storm is an atmospheric event that is usually associated with deserts. Due to its physical, chemical and biological properties, dust in the atmosphere has harmful consequences for human health, and this issue has caused special attention to this hazard in recent years. Knowledge of the main sources of dust emissions and their relative importance is essential for policymakers to determine effective pollution reduction strategies. The risks associated with the dust phenomenon can be considered from both health and socio-economic consequences. Dust phenomenon is one of the atmospheric-climatic disasters, the occurrence of which causes environmental damage and the occurrence or exacerbation of respiratory and heart diseases, air and ground traffic, tourism, agriculture, etc. Given the great damage of this phenomenon and the possibility of increasing its occurrence in the coming years, it is necessary for the government to pay attention to it and implement appropriate solutions in this regard. Obviously, before implementing operational plans, with sufficient information and knowledge of this phenomenon and how and why it occurs, appropriate ways can be found to deal with it. For this purpose, it is necessary to use the experiences and findings of other countries in this field in order to take a fundamental step in this direction by using correct and principled methods. Due to the importance of the issue, in this study, dust centers in Qom province have been identified.
Materials and methods
In this research, in order to achieve the desired goals, climatic information of Saveh, Tafresh, Salafchegan, Kahak, Kashan and Garmsar stations, Landsat satellite images and also a digital elevation model-30m of the region have been used as research data. Important research tools include ArcGIS (in order to output and prepare the desired maps), WRPLOT and SandRose, which have been used to prepare the wind-rose and sand-rose maps. In this study, IDW interpolation method (for preparing maps related to wind characteristics in Qom province) has been used. This research has been done in 3 general steps. In the first step, in order to prepare the land cover map, the Landsat satellite image of 2020 has been used. In the second step, in order to study the wind characteristics and analyze its effect on creating dust centers, first the information of Kahak, Salafchegan, Kashan, Saveh, Tafresh and Garmsar meteorological stations was prepared and then the wind-rose and sand-rose diagrams of the stations were prepared. These stations are covered. In the third step, in order to identify areas prone to dust production, land cover information as well as wind characteristics of the area have been used.
According to the results, a large part of Qom province is covered by sand fields and salt marshes, which has made Qom province prone to dust production in terms of land cover. In general, the results of the study of land cover in Qom province indicate that the eastern parts of the province, due to the presence of sand fields and salt marshes, has a high potential to create dust hotspots. In this study, after evaluating the land cover condition, the status of wind characteristics in stations of Qom province and adjacent areas was investigated and then based on it the general status of wind characteristics in this province was described. According to the results, a large part of Qom province is covered by winds with a speed of more than 6.2m/s (erosion threshold speed). In a general trend, wind speed from east to west and also from north to south has an increasing trend, and thus in terms of wind speed, western and southern regions have a high potential for dust generation. Also, the results of DPt coefficient (sand carrying capacity in different directions) indicate that the western and southwestern regions of Qom province have the highest sand carrying capacity, which indicates the sensitivity of land cover in these areas. Due to the fact that the prevailing wind direction in the region is from the south to the north, so the presence of salt marshes and sand fields in the southern regions of the province can be a danger to the north and northwest of the province.
The importance of the dust concern in arid and semi-arid regions has led to various studies in this regard. In this study, unlike many previous studies, in addition to examining the state of winds in the region, the state of land cover was also examined and erosion-prone areas were identified in relation to land cover and wind characteristics of the region. The sum of the results of the research indicates that the central and northern regions of Qom province are prone to dust production due to the salt marsh and sand filed type of land cover, high DPt coefficient and also high average wind speed, so based on the DPt coefficient and wind speed index, these areas are considered as dust production centers in Qom province. According to the aforementioned, a large part of Qom province is exposed to wind erosion as well as the creation of dust hotspots, so it is necessary to make the necessary control programs to stabilize the type of land cover and control wind erosion.