نوع مقاله : مقاله پژوهشی
موضوعات
عنوان مقاله English
نویسندگان English
Aim: This study aims to analyze the wind regime and estimate sand drift potential in the ergs along the southern margin of Qom Salt Lake. It also investigates how erosive wind direction and strength influence the formation of aeolian geomorphological features, improving the understanding of morphodynamic processes in the region.
Materials and Methods: To achieve the research objectives, 20 years of meteorological data from five synoptic stations around the study area were used. WRPLOT View 7 and Sand Rose software were employed to plot wind rose and sand rose diagrams and to analyze the DP, RDP, RDD, and UDI indices. A geomorphological map of the area was also prepared, and sand transport pathways were interpreted.
Findings: At Qom and Aran & Bidgol stations, dominant winds blow from the north and northwest, producing the highest sand transport potential along the northeast–southwest axis. Kashan, Garmsar, and Ardestan stations experience winds primarily from the east and southeast, with Garmsar and Ardestan showing multidirectional patterns at obtuse angles, significantly influencing sediment displacement and dune dynamics.
Conclusion: The findings indicate that the directional variability and intensity of winds in the study area directly affect sand displacement and accumulation. The prevailing pattern of sand movement corresponds to the orientation of the region’s sand dunes, which are primarily directed toward the east and southeast. It was also determined that much of the transported sediment originates from surrounding alluvial fans with diverse lithological compositions. These results confirm the crucial role of climatic factors, topography, and sediment sources in the dynamism of aeolian landforms and geomorphic processes in the region.
Innovation: This study applies a vector-based, quantitative approach to sand drift analysis using wind indices, helping explain dune formation patterns and predict future morphological changes. These results support better resource management and planning in arid environments.
کلیدواژهها English
Wind is one of the main causes of erosion and degradation on the surface of the Earth. The amount of wind energy and its variability play an important role in the formation of erosive faces, the development and movement of wind sediments, especially sand dunes. This phenomenon is highly dynamic and has time changes and at the same time acts on a large scale. The achievement of easy and practical methods of wind data analysis has been the focus of experts from the past to the present, so that by analyzing the wind data of a station, the type of sand dunes that can be formed, the amount and direction of movement of sediments can be predicted. Typically, the direction of the prevailing wind determines the direction of the displacement of the largest amount of sediment particles. One of these methods, first proposed and used by Freiberger and Dean, was statistical analysis of winds exceeding the threshold velocity of wind erosion. In this method, different wind speeds in different directions, which have a speed exceeding the rate of erosion threshold, are converted into identical vector units and are formed Sand rose by drawing them in the corresponding directions. Using this method, in addition to analyzing wind abundance and determining the direction of eroding winds, the amount of wind power in transporting sand sediments, the amount of sediment discharge and the final direction of transporting wind sediments can be achieved. The main objective and hypothesis of this research is to analyze the abundance of eroding winds and estimate the potential and final direction of the sand transport flow at the surface of the Ergs on the southern edge of the Salt Lake and examine its relationship with the geomorphology of existing wind shapes using time series data of the side and wind speed recorded at the synoptic stations located around these Ergs.
The study used meteorological data from five stations at different intervals around these Ergs to analyze the wind situation and examine the eroding winds at the level of the study area. WRPLOT VIEW 7 was used to perform wind statistics and draw Wind rose. Wind rose is the simplest method to comply with Statistical wind data shows the abundance of the direction and speed of the winds in each direction. Sand Rose Graph 3 software was also used to draw the Sand rose of the stations around the Ergs due to the high volume of calculations. The software can well show the power and direction of carrying sand by wind. Sand Rose is a graph of the amount of wind energy used to transport sand and represents the erosion power of the wind and the relative amount of sand in different directions. Unlike Sand rose, where the unit of arm size is based on wind speed, the unit of arms in Sand rose is based on a vector unit (v.u) defined.
The results of the analysis of the Wind rose of the stations in the study area for the seasons of the year show that in Qom station, western winds are dominant with a percentage of occurrence of about 20 to 25 percent in all seasons, and other winds blow from the eastern and Northwestern directions and between the East and Southeast. For the summer season in addition to the westerly direction, winds with an easterly direction of about 20-25% also prevail. The results of annual Storms Rose indicate that winds with westerly directions prevail in the Stations of Qom and Kashan and Garmsar. At Arran and biddegal stations, there is a wide variety of wind directions.these winds also blow from the Northeast, East, West and northwest directions in addition to the northern directions. But unlike other stations, wind does not blow from the North and West, and most winds blow from the south and East. Analysis of the net direction of sand movement (RDD) of the stations studied shows that the direction of sand movement at Qom station is southward at Aran and Bidgul station to the East and southeast, at Kashan station to the east-northeast, at Ardestan station to the Northeast, and at Garmsar station to the East and Southeast. The analysis of the direction of movement of the Sand rose shows full compliance with the Storms rose of the study stations, which indicates the systematization of the trend of changes in wind direction, as well as the acceptability of the results of the Storm rose of the storm.
The study shows that on a regional scale, natural changes in the area, ranging from expansion and contraction, are mainly the result of wind regimes, the supply of sand and its transport, especially from prone areas and geological resources, as well as the Ergs of this area in the eastern part are fed by sand-sized particles obtained from alluvial fan systems at the periphery of eroding heights with a variety of substrate rocks including granite, limestone, basalt and andesite. In conclusion, the use of the results of this study enables us to understand the speed and direction of eroding winds, the ability to drift sediments by wind, the amount of discharge and the direction of movement of sediments, as well as the type of morphology of wind sediments.
