نقش فرسایندگی باد و حمل ماسه بر تحرک‌پذیری ماسه در حاشیه دریاچه ارومیه

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشیار، گروه احیاء مناطق خشک و کوهستانی، دانشکده منابع طبیعی، دانشگاه تهران، کرج، ایران

2 دانشجوی کارشناسی ارشد بیابانزدایی، گروه احیاء مناطق خشک و کوهستانی، دانشکده منابع طبیعی، دانشگاه تهران، کرج، ایران

3 مربی پژوهشی، بخش تحقیقات بیابان، مؤسسه تحقیقات جنگلها و مراتع کشور، سازمان تحقیقات، آموزش و ترویج کشاورزی، تهران، ایران

4 استادیار، گروه احیاء مناطق خشک و کوهستانی، دانشکده منابع طبیعی، دانشگاه تهران، کرج، ایران

چکیده

باد به عنوان عامل اصلی در تخریب و فرسایش مناطق خشک و نیمه‌خشک می باشد که برای جلوگیری از اثرات تخریبی آن باید شناخت کافی از ویژگی بادهای منطقه حاصل گردد. هدف اصلی این تحقیق، وضعیت فرسایندگی باد و میزان حمل‌ماسه در منطقه مورد مطالعه می‏‌‏باشد. جهت بررسی از داده‏‌‏های بادسنجی 8 ایستگاه سینوپتیک حاشیه دریاچه ارومیه با دوره آماری موجود مورد تجزیه و تحلیل قرار گرفت. گلبادهای سالانه منطقه نشان داد که  به­رغم تغییرات زمانی و مکانی بسیار‌زیاد باد در حاشیه این دریاچه، عمده بادهای غالب از سمت شرق و سپس از غرب می‏‌‏وزد. گل­توفان‏‌‏های سالانه نشان داد که بادهای فرساینده عمدتاً دارای جهات جنوب و جنوب غربی است که این بادها در فصول تابستان و بهار به صورت یک­طرفه و در فصول پاییز و زمستان به صورت چند­جهته می‏‌‏وزند. به منظور محاسبه توان حمل ماسه با استفاده از رابطه فرای‌برگر و دین، منطقه مورد مطالعه از نظر قدرت فرسایش باد در کلاس کم تا متوسط قرار گرفته است و جهت نهایی حمل ماسه عمدتاً به‌سمت شمال‌شرقی است که براساس معادله لتو-لتو دبی (شار) حمل ماسه بین 05/0 تا 73/2 تن بر متر درسال محاسبه شد. همچنین با استفاده از معادله تسوار، شاخص تحرک تپه‏‌‏های ماسه‏‌‏ای برای تمام ایستگاه­ها کمتر از 1 شد که نشان‌دهندة غیر فعال بودن اشکال تراکمی ماسه است. ولی چون پوشش گیاهی بسیار کمی بر روی آنها مستقر شده است میتوان نقش عامل انسانی (بویژه چرای دام و لگد کوبی احشام) و شوری بیش از حد تپه ها را در آن مهم دانست.

کلیدواژه‌ها


عنوان مقاله [English]

Effects of wind erosivity and sand drift on the littoral area of Urmia Lake and sand mobility

نویسندگان [English]

  • Ali Akbar Nazari Samani 1
  • leila Biabani 2
  • Hamidreza Abbasi 3
  • Hasan Khosravi 4
1 Associated Professor, Department of Reclamation of Arid and Mountainous Regions, Natural Resources Faculty, University of Tehran, Karaj, Iran
2 M.Sc. Student in Combat, Department of Reclamation of Arid and Mountainous Regions, Natural Resources Faculty, University of Tehran, Karaj, Iran
3 Research Instructor, Research Desert Division, Research Institute of Forests and Rangelands, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran
4 Assistant Professor, Department of Reclamation of Arid and Mountainous Regions, Natural Resources Faculty, University of Tehran, Karaj, Iran
چکیده [English]

   Wind, as a major driving factor on soil erosion in arid and semi-arid areas, needs to be investigated precisely to prevent its undesirable effects. The main purpose of this research was to determine the spatial variability of wind erosivity and sand drift around Urmia Lake. For this aim, the anemometry data of eight synoptic stations adjusted to the Lake were analyzed for the whole period time. Annual wind-roses showed that despite the very high spatial and temporal changes of wind variables (speed and direction), major prevailing winds were blown from the East and West, respectively. Also, annual storm-roses depicted that the erosive winds blew mainly from South and Southwest direction. These winds had a unidirectional regime in summer and spring, while in fall and winter, a multi directional regime was observed. The results of calculated sand drift power by Fryberger and Dean Formula indicated a low to moderate class of wind erosion potential and the final direction of sediment transport was mainly to northeast. According to the Letu-Letu equation, sand transport flux is varied between 0.05 to 0.76 Ton/m/year. Although the windiness of study area is moderate, the Tsoar sand mobility index is less than one, indicating inactive sand dunes. However, due to the low vegetation established on the sand dunes surface, it can be drawn that the role of human factors (especially cattle grazing and trampling) as well as the salinity caused by the drying of the Lake are responsible for this situation.

کلیدواژه‌ها [English]

  • Sand drift potential
  • wind erosivity
  • anemometer data analysis
  • Urmia Lake
  • wind regime
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