Environmental Erosion Research

fa بررسی روند تغییرات عمق نوری گرد و غبار استان البرز در بازه‌ی زمانی 20 ساله (2020-2001) Analyzing the Trends in Aerosol Optical Depth (AOD) Changes Over a 20-Year Period (2001–2020): A Case Study of Alborz Province مدلسازی و تحلیل زمانی و مکانی رخداد انواع مختلف فرسایش محیطی پژوهشي Research <div style="text-align: justify;">توفان گرد و غبار، فرآیند پیچیدهای است که تحت تأثیر فعل و انفعالات سامانههای جوی بوده و شرایطی مانند سرعت زیاد باد، خاک خشک و بدون پوشش یا با پوشش سطحی کم و هوای خشک باعث ایجاد آن میشود. این توفان ها میتواند روی تغییرات آب و هوایی اثر گذاشته و سبب آسیبهای جدی برای مردم شود. در این پژوهش برای بررسی تغییرات مکانی و زمانی گرد و غبار در استان البرز از دادههای سنجش از دوری سنجنده مودیس با قدرت تفکیک مکانی 1 کیلومتر در بازه زمانی 2001 تا 2020 از ماهواره ترامودیس استفاده گردید. میزان شاخص عمق نوری در یک بازه 20 ساله در 5 درجه، خیلی‌کم، کم، متوسط، شدید و خیلی شدید با استفاده از روش Natural Breaks Classification طبقه‌بندی گردید. بررسی روند تغییرات AOD استان البرز در این بازه زمانی 20 ساله نشان داد، میزان شاخص عمق نوری در جنوب و جنوب غرب استان افزایش یافته است. همچنین بررسی میزان حداقل، حداکثر و متوسط سالانه شاخص عمق نوری نشان داد که در این دوره 20ساله  این شاخص افزایشی بوده به طوریکه میزان حداقل آن از 06/0 در سال 2001 به 13/0 در سال 2018،  میزان حداکثر از 18/0 در سال 2001 به 41/0 در سال 2009 و مقادیر متوسط نیز در سال‌های 2008، 2009 و 2011 به بالاترین مقدار یعنی 19/0 رسیده‌اند. بررسی تغییرات کلاس‌های مختلف با استفاده از روش مد نظر در بازه‌های 5 ساله، نشان داد که کلاس‌های خیلی کم و شدید، کاهشی و دیگر کلاس‌ها بخصوص کلاس خیلی شدید، افزایشی بوده است به طوریکه از میزان 01/3 درصد در سال 2001 به میزان 02/8 درصد در سال 2020 رسیده است.</div>   1- Introduction Dust storms are complex atmospheric phenomena that result from the interaction of various dynamic and physical processes within the atmosphere. These storms primarily occur in regions where conditions such as high wind speed, dry soil surfaces, and minimal or absent vegetation cover prevail. Dust storms can significantly impact local and global climates, as they contribute to the transport of suspended particles in the atmosphere, potentially leading to climatic changes, air quality degradation, and increased health risks for humans. This phenomenon is fundamental in arid and semi-arid regions, such as Alborz province, which faces specific climatic and geographical challenges. Alborz is characterized by its unique topography and climate, which create conditions that are conducive to the formation of dust storms. The province's location, altitude, and land cover play a crucial role in how dust storms develop and spread. In recent decades, the frequency and intensity of dust storms have been reported to increase across many parts of the Middle East and Central Asia. These changes are often linked to anthropogenic factors such as land degradation, deforestation, and excessive groundwater withdrawal. In Iran, particularly in Alborz province, growing urbanization and changing land-use patterns have exacerbated environmental sensitivity, making it more vulnerable to dust generation and transport. The rapid expansion of urban areas has led to the destruction of natural landscapes, thus diminishing the land's ability to retain moisture and vegetation, which is essential for mitigating dust storm formation. Furthermore, agricultural practices, including overgrazing and improper irrigation, contribute to soil erosion and degradation, making the region even more susceptible to dust storms. Given the regional implications for air quality, agriculture, and human health, it is essential to assess dust storm trends using reliable atmospheric data. By doing so, we can better understand the patterns and causes of dust storms and develop effective strategies to mitigate their impact. Collaborative efforts combining scientific research, policy-making, and community engagement are necessary to address these challenges comprehensively and protect the environment and public health. 2- Methodology To analyze dust storm trends and their spatial distribution in Alborz province, satellite-derived Aerosol Optical Depth (AOD) data were employed as a primary indicator of atmospheric dust concentration. AOD measures the extinction of solar radiation caused by aerosol particles in a column of the atmosphere and is a reliable proxy for assessing dust intensity and transport patterns. Data from 2001 to 2020 were collected, processed, and analyzed using remote sensing techniques and geographic information systems (GIS). This approach facilitated classifying AOD values into discrete classes representing varying dust concentrations, mapping their spatial coverage across the study area period. 3- Results The temporal analysis of AOD data revealed a clear upward trend in atmospheric dust levels in Alborz province over the two-decade study period. In particular, the southern and southwestern regions of the province experienced a noticeable increase in AOD values. The annual analysis showed that between 2008 and 2011, AOD levels exhibited significant fluctuations, with the highest value recorded in 2009 at 0.4. In other years, values remained relatively elevated at 0.29 in 2008, 0.34 in 2010, and 0.29 in 2011, indicating persistent dust activity. Furthermore, the spatial distribution of AOD classes demonstrated dynamic shifts over time. While the areas covered by very low and moderately high AOD classes decreased, those in the very high AOD class expanded markedly. Specifically, the AOD class area grew from 3.01% of the province's surface in 2001 to 8.02% in 2020. This shift underscores a substantial intensification in the region's frequency and severity of dust storm events. 4- Discussion & Conclusions: This study's findings indicate a concerning trend of rising dust storm activity in Alborz province, especially in the southern and southwestern regions. Multiple interconnected factors may contribute to this increase. Climate change has caused elevated temperatures and decreased precipitation, leading to drier soils and less vegetation cover, which heightens wind erosion potential. Rapid urban growth and unsustainable land use practices, including overgrazing and unregulated agricultural expansion, have intensified land degradation and desertification, creating favorable conditions for dust storm formation. The surge in very high AOD levels showcases the growing frequency of dust events and underscores a heightened environmental health risk for the province’s residents. Increased particulate matter levels worsen respiratory issues, lower life expectancy, and burden public health systems. Additionally, these trends pose challenges to infrastructure, agriculture, and water resources, calling for urgent policy action intervention. To tackle these challenges, it is crucial to implement integrated land management approaches that support vegetation restoration, soil conservation, and sustainable agriculture. Moreover, urban planning should include measures to mitigate dust, particularly in areas at risk. Continued long-term satellite remote sensing monitoring ought to be enhanced with ground-based observations for improved accuracy in assessments. In summary, the rising trend in AOD values and the expansion of high-dust zones in Alborz province clearly signify increasing risks of dust storms. This study offers valuable insights for environmental planners, policymakers, and researchers focused on air quality and public health. It emphasizes the necessity for further research into the underlying causes of dust activity and the creation of predictive models to anticipate future dust storm patterns amid changing climate and land-use scenarios.   استان البرز, تصاویر ماهواره‌ای, سنجش از دور, عمق نوری, گرد و غبار Dust storms, Aerosol Optical Depth (AOD), Alborz province, remote sensing, satellite imagery 110 126 http://magazine.hormozgan.ac.ir/browse.php?a_code=A-10-66-8&slc_lang=fa&sid=1 Mahdiyeh Shaker مهدیه شاکر mahdiye.shaker@yahoo.com 10031947532846009459 10031947532846009459 No Department of Reclamation of Arid and Mountainous Regions, Faculty of Natural Resource, University of Tehran, Karaj, Iran گروه احیاء مناطق خشک و کوهستانی، دانشکدگان کشاورزی و منابع طبیعی ، دانشگاه تهران، ایران Hadi Eskandari Damaneh هادی اسکندری دامنه hadi.eskandari71@gmail.com 10031947532846009460 10031947532846009460 No Desert Research Division, Research Institute of Forests and Rangelands, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran مؤسسه تحقیقات جنگل‌ها و مراتع کشور، سازمان تحقیقات،آموزش و ترویج کشاورزی،تهران، ایران Hassan Khosravi حسن خسروی hakhosravi@ut.ac.ir 10031947532846009461 10031947532846009461 Yes Department of Reclamation of Arid and Mountainous Regions, Faculty of Natural Resource, University of Tehran, Karaj, Iran گروه احیای مناطق خشک و کوهستانی، دانشکده منابع طبیعی، دانشگاه تهران، ایران