Investigating Aeolian Sand Sources through Integrated Wind Analysis and Grain Morphometry: A Case Study of Boralan Plain, West Azerbaijan Province, Iran

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