برآورد فرسایش خندقی بر پایة معادلات REGEM و اصلاح ضرایب آن‌ در استان اردبیل

شهاب, حسین; اصغری, شکراله

برآورد فرسایش خندقی بر پایة معادلات REGEM و اصلاح ضرایب آن‌ در استان اردبیل

نوع مقاله : مقاله پژوهشی

نویسندگان

¹ فیزیک و فرسایش اردبیل

² گروه علوم و مهندسی خاک، دانشکده کشاورزی و منابع طبیعی دانشگاه محقق اردبیلی

چکیده

خندقهای کوچک به دلیل تراکم زیاد در واحد سطح، یکی از مهمترین عوامل تلفات خاک و آب به ویژه در اراضی کشاورزی است. در این پژوهش با انتخاب 81 خندق کوچک در سه حوزه آبخیز از منطقه اُرتاداغ، ملااحمد و سرچم در استان اردبیل، ابعاد خندقها با فاصله یک سال تعیین و تغییر طول، عرض متوسط، عمق و حجم آنها ثبت گردید. همچنین ابعاد خندقها با استفاده از مدل REGEM با فاصله زمانی یک سال برآورد شد و همبستگی بین مقادیر مشاهده شده و برآورد شده بررسی گردید. به منظور اصلاح و بهینهسازی مدل برای مناطق مورد مطالعه، با استفاده از مدلهای رگرسیونی، روابط مدل اصلاح شد و مجددا برای برآورد ابعاد خندقها و تغییرات آن در طول یک سال مورد ارزیابی قرار گرفت. برای اصلاح مدل از پارامترهای تنش برشی بحرانی و عامل فرسایش خاک مدل REGEM برای برآورد ابعاد خندق شامل طول، عرض متوسط و عمق متوسط استفاده شد. نتایج نشان داد مدل REGEM تنها در منطقه سرچم کارایی لازم را در برآورد فرسایش خندقی داشت و میزان ضریب همبستگی برآورد آن با تغییر حجم اندازهگیری شده خندقها برابر با 66/0 به دست آمد. در حالی که برآورد ابعاد خندقها با مدل REGEM اصلاح شده، در هر سه منطقه همبستگی معنیدار با مقادیر اندازهگیری شده داشت. همبستگی تغییر حجم خندقها بین مقادیر اندازهگیری شده و برآورد شده با مدل اصلاح شده برای اُرتاداغ، ملا احمد و سرچم به ترتیب 76/0، 67/0 و 78/0 تعیین گردید. بنابراین برای کاربرد مدل در مناطق دیگر نیاز به تصحیح مدل متناسب با شرایط منطقه میباشد.

کلیدواژه‌ها

عنوان مقاله [English]

Estimating of gully erosion based on REGEM model equations and modification of it’s for Ardebil province

نویسنده [English]

shokrollah asghari ²

² Department of soil science and engineering, faculty of agriculture and natural resources, University of Mohaghegh Ardabili

چکیده [English]

Small gully due to high density per unit area is one of the most important causes of soil and water losses in watersheds that have gully erosion. In this research, with the selection of 81 small gullies in three watersheds from Ordadagh, Mulla Ahmad and Sarcham in Ardebil province, the size of gullies was determined with a one-year interval and the change in length, average width, depth and volume of them were recorded. Also, gullies size was estimated using the REGEM model with a one-year interval and the correlation between observed and estimated values was investigated. In order to modify and optimize the model for the studied areas, the model was corrected using regression models and again evaluated for estimating the gullies size and its variations over one year. To correct the model, the regressive shear stress parameters and soil erosion parameters of the REGEM model were used to estimate the dimensions of the gully including length, average width and moderate depth. The results show that the REGEM model only in Sarcham area had the useful efficiency in estimating gully erosion and its estimation correlation coefficient with measured gullies volume changes was 0.66. While estimating the size of the gullies with the modified model, in all three regions, showed a significant correlation with the measured values. The correlation between the measured and estimated values by modified model for gullies volume change was determined to be 0.76, 0.67, and 0.78, for Ordadagh, Mulla Ahmad and Sarcham respectively. Therefore, in order to apply the model in other regions, it is necessary to correct the model according the conditions of the region.

کلیدواژه‌ها [English]

Small gullies
Modification of REGEM model
Estimation of erosion

مراجع

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