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تحلیل منابع ماسههای بادی بر اساس تلفیق تحلیل باد و مورفومتری ذرات ماسه مطالعه موردی: دشت بورالان آذربایجان | ||
| پژوهش های جغرافیای طبیعی | ||
| دوره 57، شماره 3، آبان 1404، صفحه 63-85 اصل مقاله (1.54 M) | ||
| نوع مقاله: مقاله کامل | ||
| شناسه دیجیتال (DOI): 10.22059/jphgr.2025.395829.1007885 | ||
| نویسندگان | ||
| مهران مقصودی* 1؛ ابوالقاسم گورابی2؛ مجتبی یمانی1؛ آیلا قلی زاده1 | ||
| 1گروه جغرافیای طبیعی، دانشکده جغرافیا، دانشگاه تهران، تهران، ایران | ||
| 2گروه جغرافیای طبیعی، دانشکده جغرافیا، دانشگاه تهران، تهران، لیران | ||
| چکیده | ||
| این پژوهش با هدف شناسایی منابع ماسههای بادی دشت بورالان از طریق رویکرد تلفیقی شامل تحلیلهای بادی و مطالعات رسوبشناسی انجام شد. دادههای بادی 30 ساله (1990–2020) ایستگاه سینوپتیک ماکو، ایران، تحلیل شدند. نرمافزار WRPLOT View 8 و ابزار سفارشی ترسیم گلباد برای تولید گلباد، گل طوفان و گل حمل ماسه و همچنین محاسبه شاخصهای بادی شامل پتانسیل جابجایی (DP)، پتانسیل جابجایی نتیجهگیر (RDP)، جهت جابجایی نتیجهگیر (RDD) و شاخص یکجهته (UDI) استفاده شدند. برای شناسایی منشأ رسوبات بادی، نمونههای ماسهای سطحی از تپههای ماسهای جمعآوری و آزمایشهای گرانولومتری و مورفوسکوپی بر روی آنها انجام شدند و منحنیهای دانهبندی با استفاده از نرمافزار GRADISTAT و روش Folk و Ward (1957) ترسیم شدند. تحلیل گلباد نشان داد بادهای جنوب شرق (SE) و شرق (E) بیشترین فراوانی را دارند، درحالیکه گل طوفان، بادهای فرساینده شمال غرب (NW) و غرب (W) را مشخص کرد. پتانسیل حمل ماسه عمدتاً به سمت شرق است و بادهای دو جهته (E-W) در پاییز و زمستان نقش مهمی در جابجایی رسوبات بادی دارند. تحلیل دانهبندی نشان داد میانگین اندازه ذرات بین 125 تا 250 میکرون متغیر است، با جورشدی از جورشده تا ضعیف جورشده و توزیع عمدتاً متقارن. بررسیها نشان داد منابع اصلی ماسههای روان دشت بورالان شامل آبرفتهای رودهای قرهسو و ارس، هوازدگی روانههای بازالتی، مخروطافکنههای حاشیهای و سطوح فرسایش یافته ناشی از کاهش پوشش گیاهی به دلیل تغییرات کاربری اراضی هستند. بنابراین، منابع ماسههای بادی دشت بورالان ترکیبی از فرآیندهای آبی و بادی است که توسط ویژگیهای زمینشناسی و اقلیمی منطقه هدایت میشوند. | ||
| کلیدواژهها | ||
| بورالان؛ تپه های ماسه ای؛ فرسایش بادی؛ گرانولومتری؛ مورفوسکوپی | ||
| عنوان مقاله [English] | ||
| Investigating Aeolian Sand Sources through Integrated Wind Analysis and Grain Morphometry: A Case Study of Boralan Plain, West Azerbaijan Province, Iran | ||
| نویسندگان [English] | ||
| Mehran Maghsoudi1؛ Abolghasem Goorabi2؛ mojtaba yamani1؛ Ayla Gholizadeh1 | ||
| 1Department of Physical Geography, Faculty of Geography, University of Tehran,Tehran, Iran | ||
| 2Faculty of Geography, Department of Physical Geography, University of Tehran, Tehran, Iran | ||
| چکیده [English] | ||
| ABSTRACT This study aimed to identify the sources of aeolian sands in the Boralan Plain through an integrated approach combining wind analysis and sedimentological studies. Wind data spanning 20 years (2000–2020) from the Maku synoptic station, Iran, were analyzed. WRPLOT View 8 and a custom sand rose graphing tool were used to generate wind, storm, and sand transport roses, and to calculate wind indices, including drift potential (DP), resultant drift potential (RDP), resultant drift direction (RDD), and unidirectional index (UDI). To identify the origin of aeolian sediments, surface sand samples were collected from dunes, and grain-size and morphoscopic analyses were conducted, with distribution curves generated using GRADISTAT. Wind rose analysis showed that southeast (SE) and east (E) winds were most frequent, while storm rose analysis identified predominant erosive winds from the northwest (NW) and west (W). Sand transport potential was highest toward the east, with bidirectional winds (E-W) in autumn and winter significantly influencing aeolian sediment transport. Grain-size analysis revealed mean particle sizes ranging from 125 to 250 microns, with sorting ranging from well-sorted to poorly sorted, and distributions predominantly symmetrical. Sedimentological analyses identified the main sources of mobile sands in the Boralan Plain as alluvial deposits from the Qareh Su and Aras rivers, weathered basaltic flows, marginal alluvial fans, and eroded surfaces due to reduced vegetation from land-use changes. Overall, the aeolian sands originate from a combination of fluvial and aeolian processes driven by local geological and climatic conditions. Extended Abstract Introduction Wind erosion is a dominant geomorphic process in arid and semi-arid regions, forming landforms such as sand sheets and dunes. Iran, located within the global arid zone, has over two-thirds of its territory classified as arid or semi-arid. Low precipitation, climate change, and unsustainable land management have accelerated desertification nationwide. The Boralan Plain, in West Azerbaijan Province, northwest Iran, is highly vulnerable to sandstorms and dune migration, posing significant environmental challenges. This study investigates the impact of erosive winds, analyzes sand transport patterns, and employs granulometric and morphoscopic analyses to characterize sediment texture and provenance. The objective is to identify sediment sources and controlling factors, providing insights for sustainable environmental management in the region. Methodology This study examines the wind regime of the Boralan Plain using aeolian indices, including drift potential (DP), resultant drift potential (RDP), resultant drift direction (RDD), and unidirectional index (UDI). Wind data spanning 30 years (1990–2020) from the Maku synoptic station, Iran, were analyzed using WRPLOT View and a custom sand rose graphing tool to determine prevailing wind directions, assess sand transport capacity, and generate sand rose diagrams. To trace aeolian sediment provenance, sand samples were systematically collected and subjected to granulometric and morphoscopic analyses. For granulometric analysis, 100 g of each sample was processed via dry sieving with mesh sizes of 2000, 1000, 500, 250, 125, and 63 μm, including a collector for particles finer than 63 μm. Grain-size distributions were analyzed in GRADISTAT to calculate statistical parameters (mean size, sorting, skewness) following the Folk and Ward (1957) method, providing insights into transport distance and depositional environment. Morphoscopic analysis of 25 randomly selected grains per sample was conducted under a binocular microscope, documenting surface textures (e.g., matte texture, brilliance, speckling, and signs of physical or chemical weathering) to infer sedimentary processes and identify sediment sources. Results and discussion Wind rose and sand rose analyses revealed dominant annual winds from the southeast (SE) and east (E). Sand transport potential, calculated using a threshold wind speed of 6.7 m/s (13 knots), exceeded 65 vector units (Fryberger’s method) annually. Sand transport is primarily directed eastward, with sediments mobilized from the southwest (SW), west (W), and northwest (NW). The strongest winds, occurring in winter and spring, originate from the SW, W, and NW sectors. Granulometric analyses showed mean grain sizes ranging from 125 to 250 μm, with sorting (σφ) ranging from 0.465 to 1.309, indicating moderately well-sorted to poorly sorted sediments. Skewness ranged from -0.541 to 0.449, with most samples showing nearly symmetrical distributions. Kurtosis values (0.9–1.11) indicated mesokurtic distributions. Morphoscopic analysis identified surface textures, including matte texture (45% of grains), brilliance (43%), speckling, and signs of physical or chemical weathering. Grain shapes were categorized into four abrasion levels: unabraded/angular (over 45%), slightly abraded, abraded, and well-rounded. The high proportion of angular grains suggests significant physical weathering and limited transport-induced rounding. Conclusion This study indicates that alluvial deposits from the Aras and Qareh Su rivers are primary sources of aeolian sand in the Boralan Plain, alongside weathered basaltic flows and eroded surfaces. The predominantly angular grain shapes indicate physical weathering of local basaltic rocks. Overgrazing and land-use changes, leading to reduced vegetation cover, have increased the region’s susceptibility to wind erosion. Consequently, sand transport in the Boralan Plain is driven by the combined effects of fluvial and aeolian processes, highlighting the need for integrated environmental management strategies to mitigate desertification and promote sustainability in the region. Funding There is no funding support. Authors’ Contribution Authors contributed equally to the conceptualization and writing of the article. All of the authors approved thecontent of the manuscript and agreed on all aspects of the work declaration of competing interest none. Conflict of Interest Authors declared no conflict of interest. Acknowledgments We are grateful to all the scientific consultants of this paper | ||
| کلیدواژهها [English] | ||
| Boralan, Sand dunes, wind erosion, granulometry, morphoscopy | ||
| مراجع | ||
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