برآورد پتانسيل فرسايش بادي و رسوبدهي با استفاده از روش IRIFR در منطقه مياندشت اسفراين

Estimation of the Potential of Wind Erosion and Deposition Using IRIFR Method in Miandasht Esfarayen Region

فرسايش بادي در مناطقي با بارندگي كمتر از 150 ميلي متر اهميت ويژه اي دارد. فرسايش بادي به عنوان يكي از عوامل مهم بيابان زايي، همواره مورد توجه قرار گرفته است .در اين تحقيق بعد از جمع آوري اطلاعات و مطالعات پايه در منطقه و تهيه نقشه­ هاي لازم از قبيل توپوگرافي، زمين ­شناسي، ژئومرفولوژي، قابليت اراضي، پوشش گياهي و آگاهي از مطالعات هواشناسي و جهت بادهاي غالب در منطقه به بازديد صحرايي پرداخته و فرم­ هاي بياباني و پرسشنامه مردمي در منطقه تكميل شد و سپس واحدهاي كاري به روش احمدي- اختصاصي تهيه، سپس مقدار فرسايش بادي براساس مدل تجربي اريفردرهريك از واحدهاي كاري تعيين شد. همچنين نقشه حساسيت اراضي به فرسايش بادي با استفاده از اريفر تهيه شد و پتانسيل رسوبدهي نيز با استفاده از رابطه بين درجه رسوبدهي و توليد رسوب به دست آمد. نتايج نشان داد كلاس فرسايشي I (فرسايش خيلي كم) با مساحتي در حدود 11287/21 هكتار بيشترين مساحت وكلاس فرسايشي IV (فرسايش زياد) با مساحت6682/45 هكتار در رتبه دوم از نظر مساحت مي باشد. دربين رخساره هاي ژئومرفولوژي رخساره هاي مسيل (5-3-2) و اراضي زراعي (2-3-2) داراي بيشترين مقاديررسوبدهي مي باشند. وجود توپوگرافي مسطح و اراضي با شيب كم در بخشهاي شرقي وشمالي حوزه كه مستقيماً تحت تاثير بادهاي غالب منطقه مي باشند، باعث شده تا باد از قدرت تخريبي بالاتري برخوردار باشد. يكي از راهكارهاي مناسب به منظور مقابله با فرسايش بادي در حوزه مياندشت احداث بادشكن در اطراف مزارع داخل و خارج منطقه با توجه به گسترش اراضي كشاورزي در اطراف منطقه مورد مطالعه و در مسير بادهاي غالب محدوده در بخشهاي شرق، شمال شرق مي باشد.

Wind erosion is important in areas with less than 150 mm of rainfall Measuring the extent and severity of wind erosion in many countries, including Iran, there is no station to measure wind erosion sediments and so the deposition estimation methods rely on empirical models so that in many cases there are measurement errors. With estimates wind and water erosion and deposition potential compared using IRIFR EA and MPSIAC models in semi-arid Nematabad Bijar watershed concluded that the IRIFR model quantitatively and qualitatively accuracy and, due to a 22.6% wind erosion and 77.4 percent water erosion effective in reducing the fertility of soil (Ahmadi et al, 2006). This study estimates deposition and wind erosion potential using IRIFR method in esfarayen Miandasht region. In this study, the data collection and basic research in the area uses of maps such as topography, geology, geomorphology, land capability, vegetation, and include information and meteorological studies, field visits, and the prevailing wind direction in the form of desert and question naires were completed and work units to people in another way - specific preparation, IRIFR experimental model of wind erosion in each of the work units were defined the land to wind erosion susceptibility map was prepared using IRIFR and deposition potential temperature using the relationship between precipitation and sediment yield were obtained. After scoring each of the factors affecting wind erosion facies geomorphology (erosion) and the sum of given annual sediment production rates, the rate of erosion severity maps were produced in ArcGIS environment. Soil erosion severity and sedimentation of the area, were obtained nine factors affecting wind erosion scores are considered in five classes. The results showed erosion class I (very little) with an area of ​​about 11287.21 acres more land erosion. This erosion class is includes geomorphological facies 1-1-2 (water erosion on the erosion piedmont) and 1-2-2 (water erosion on the apandajz piedmont). and class IV (erosion) with an area of ​​6682.45 acres, is the second largest in the area. This erosional class also includes geomorphological facies detachement region - farm lands – fine desert pavement and the stream. Among stream geomorphologic facies (5-3-2) and arable land (2.3.2) have the most the highest amounts of precipitation. Wind erosion in the miandasht region, include 8 erosional form and severity of erosion stream facies, etachement region, farm lands and fine desert pavement have high erosion rates. Topography is flat and low-slope land in the north eastern parts of the area where directly affected by the prevailing winds, led to the destructive power of wind improve. One of the best ways to combat wind erosion in the area around the farm and out carminative Miandasht construction area of agricultural land around the study area and the direction of the prevailing winds in parts of the east, the north east is. The study area of wind erosion control perspective is a set of constraints and capabilities. Fine tissue silt abundant salts in the soil and reduces adhesion of soil particle aggregate structure fragmentation and reduce the threshold velocity of wind erosion in the region and the area are prone to erosion. Existence drought resistant species such as Haloxylon prsicum Artimisia sp. in the region can be developed that will help to control wind erosion.