تحليل پتانسيل فرآيند فرسايش بادي و گرد‌و‌غبار با تطبيق سيستم الگوي چرخندي بادها در چاله دامغان

Potential Analysis of Wind Erosion Processes and Dust by Adaptation of Wind Circular Pattern System in Damghan Hole

نواحي بياباني، گسترده­ ترين زيست بوم كره­ ي زمين، بيش از يك سوم سطح آن را فراگرفته ­است و بخش عمده­ اي از ايران، متأثر از شرايط اقليمي در اين قلمرو قرار دارد. فرسايش بادي به دليل تداوم و وسعت عمل فرسايندگي در زمان و مكان به ويژه در مناطق خشك، پتانسيل تخريب بالايي دارد. اين پژوهش در حوضه­ ي دامغان ـ كه پلاياي حاج­ علي­قلي در آن متأثر از فرسايش بادي مي­ باشد ـ انجام شده ­است. داده ­هاي مورد استفاده در آن عبارتند از: داده­ هاي كتابخانه­ اي، آمار سازمان هواشناسي، نقشه ­ها، تصاوير ماهواره­اي، داده­ هاي ميداني و آزمايشگاهي. در ابتدا براساس اطلاعات نقشه­ هاي ژئومورفولوژي، زمين ­شناسي، خاك، پوشش­ گياهي، شيب، كاربري اراضي و ... رخساره­ هاي ژئومورفولوژي منطقه مشخص و با استفاده از مدل تعيين پتانسيل فرسايش بادي (اريفر)، 9 عامل مؤثر در اين فرآيند بررسي و كلاس فرسايشي هر رخساره (ميزان رسوب­دهي) تعيين شد. همچنين باد منطقه به عنوان عامل محرك فرسايش بادي، با استفاده از داده­هاي ساعتي 4 ايستگاه­ سينوپتيك سازمان هواشناسي كشور در محدوده ­ي حوضه ­ي دامغان در بازه زماني (2003-2019) بررسي و گلباد سالانه براي تعيين سمت و سرعت آن رسم شد. پس از شناخت نسبي از وضعيت فرآيند باد براي تعيين سيستم الگوي چرخندي و محلي آن، از ويژگي ­هاي شواهد لندفرم ­هاي فرسايش بادي (جهت و توزيع پراكندگي) مانند برخان­ها، ريگ­ها، پيكان­هاي ماسه ­اي و ... در بازديد­هاي ميداني استفاده شد. سپس براي تشخيص تأثير اندازه ذرات در عملكرد فرسايش بادي و مخاطره­ ي گرد­و­غبار در اين چاله، 38 نمونه از رسوبات كواترنري از مناطق حاشيه ­اي پلايا براي آزمايش ­هاي رسوبي برداشت شد. نتايج حاكي از آن است كه يك سيستم سيكلوني ترمال به توزيع ماسه ­هاي بادي در حاشيه­ ي پلايا منجر شده­ است. همچنين براساس داده ­هاي باد و اندازه ذرات، حركت رسوبات در منطقه به صورت جهشي، سپس معلق و خزشي (غلطان) بوده­ است. همچنين فرسايش بادي به ايجاد لندفرم ­ها منجر شده­ است و مخاطره ­ي گرد­ و غبار در منطقه، عملكرد ضعيف ­تري نسبت به آن دارد.

1- Introduction The desert area, the world's widest ecosystem, covers more than one-third of its surface, and much of Iran is affected by climatic conditions. Wind erosion due to the persistence and extent of erosion in time and space, especially in arid areas with high damage potential. In fact, the morphodynamic boundaries affected by climate change have changed from past to present, leading to the expansion of the territory of wind erosion, and in recent years the dust hazard has also become an environmental issue in these areas. One of the natural occurrences and challenges for sustainable development and management in arid and semiarid areas is wind erosion .Also, wind erosion is one of the causes of soil loss and due to its wide range of activities it usually has less destructive performance than other erosions. This study was in Damghan basin. Haj Ali Gholi Playa is affected by wind erosion. 2- Methodology The data used are library data, meteorological statistics, maps, satellite imagery, field and laboratory data. Initially based on geomorphological, geological, soil, vegetation, slope, land use information, geomorphologic facies of the identified area and using 9 effective erosion potential determination models. This process was studied and the erosion class of each facies (sedimentation rate) was determined. Also, the wind as a motiving factor for wind erosion was studied using the hourly data of synoptic stations over the period (2003-2019) of the Meteorological Organization of the four stations in the basin and the annual windrose was plotted to determine its direction and velocity. After partial understanding of the wind process status to determine its rotational and local pattern system, the features of the evidence of wind erosion landforms (orientation and dispersion distribution) such as barchan, Erg, sand arrows, etc. used in field visits. Then, to determine the influence of particle size on wind erosion and dust erosion performance in this hole, 38 samples from Playa marginal areas were taken from Quaternary sediments for sedimentary experiments. 3- Results According to the results of implementation of the Erifer model for determining wind erosion potential in Damghan basin, seasonal lake bed facies, lakes and sand masses in high erosion class and seasonal mud facies and alluvial plain in middle erosion class and the coniferous facies and rough mountain slopes are in a low erosion class. This indicates that the lakeside facies have the highest potential for wind erosion due to the sediment type and the environment. This indicates that the lakeside facies have the highest potential for wind erosion due to the sediment type and the environment. In the study of wind erosion potential, it is the motiving factor of wind erosion that was intercepted and analyzed. The existence of a convective cyclone corresponding to the lowest and hottest point of the plain in the region was found to be counterclockwise in the cyclone, with converging motion toward the center. The wind cyclonic swirl pattern to the ground screw and removal of sediments in the west and southwest prevail hole. This moves eastward from the surface of the Earth, causing sand to be deposited in the southeastern half of the hole as we observe the wells of the Damghan Basin in the southeast of Playa, and in the eastern part of the wind deposits. We don't have. In fact, the movement of wind particles is a function of wind strength and erosion, surface resistance to erosion and erosion. The analysis of 38 sediment samples showed that sediments above 63 microns in the southwestern range of 66.18%, southeast of 76.33%, northwest of 93.62% and north of 97.85%. 4- Discussion & Conclusions The major causes of erosion on the surface, especially in arid and semi-arid wind erosion, to prevent damage is necessary to study their properties. As the Quaternary lakes declined in volume and volume and groundwater levels declined, large areas of the older lakes, including Playa Damghan, were exposed to wind and wind erosion .The results show that a thermal cyclonic system causes the distribution of wind sands along the playa border. Also based on wind data and particle size the sediment movement in the region was then mutated and suspended in creep and wind erosion has led to the creation of landforms, and the dust hazard in the area is poorer than that. The results show that in the Damghan Playa area, due to studies of wind erosion and various forms over time, more dust has been created than the landform evidence we see today in the Playa border.