نشریه علمی - پژوهشی مرتع و آبخیزداری

نوع مقاله : مقاله پژوهشی

نویسندگان

استادیار مرکز تحقیقات کشاورزی و منابع طبیعی کرمانشاه، کرمانشاه

چکیده

مدل فیزیکی WEPP رواناب و فرسایش خاک را به کمک مفاهیم فیزیکی فرسایش و هیدرولیک جریان و ملاحظة متغیرهای رشد گیاه، تجزیة بقایا، و فرایندهای زمستانه به صورت پویا شبیه‌سازی می‌کند. هدف این مقاله تعیین قابلیت این مدل در تخمین فرسایش و رواناب در چند تیپ مرتعی و بررسی اثر مدیریت در آن است. این طرح در محدودة کبوده علیا در حوضة آبخیز قره‌سو با نصب پلات‌های فرسایش به ابعاد 3×10 متر با 3 تکرار در سه تیپ مرتعی در شیب‌های 25، 35، و 45 درصد اجرا شد. داده‌های اقلیمی بارندگی و دما در داخل ایستگاه ثبت شد و سایر اطلاعات اقلیمی نظیر سرعت و جهت باد، تشعشع، و حرارت نقطة شبنم از ایستگاه سینوپتیک کرمانشاه تهیه گردید. شبیه‌سازی فرسایش و رواناب به صورت تک‌واقعه با استفاده از نسخة v2008.9 مدل در هر پلات انجام شد. ارزیابی نتایج مدل در برآورد روانابْ بیشترین دقت مدل را در شیب 45 درصد نشان داد. همچنین، در شیب 25 و 35 درصد مدل با خطای نسبی متوسط 61/0 لیتر رواناب را برآورد می‌نمود. در مجموع، کارایی مدل در برآورد رواناب در هر سه شیب خوب بود و ضریب کارایی ناش- ساتکلیف بین 69/0 تا 73/0 متغیر بود. کمترین و بیشترین خطای برآورد فرسایش خاک به‌ترتیب در شیب‌های 35 و 45 درصد بود. مدل در برآورد فرسایش در همة شیب‌ها کم‌برآوردی از خود نشان داد. همچنین، مقادیر منفی شاخص ناش- ساتکلیف مؤید کارایی پایین مدل در برآورد فرسایش به‌ویژه در شرایط حاکم بر دو شیب 25 و 35 درصد بود.

کلیدواژه‌ها

عنوان مقاله [English]

Capability of hillslope version of WEPP model in prediction of runoff and soil erosion dynamic in different type of semi-arid rangeland

نویسندگان [English]

  • yahya Parvizi
  • mohammad gheitury
  • Mosieb Heshmati

چکیده [English]

The WEPP physically model is able to dynamically simulate runoff and soil erosion using physical concepts of erosion and hydraulic of overland flow science considering plant growth, residue decomposition, winter process. Determination of the capability of this model in runoff and erosion estimation in different range type with investigation the effects of management were the main objectives of this research. This research was conducted in the Kabode placed across the Gharasoo watershed by installing erosion plot with dimension of 10×3 meter and three replications in three range types at the slopes of 25, 35 and 45%. Climate data including rainfall and air temperature was recorded in the site and additional data including wind velocity and direction, solar radiation and dew point temperature was prepared from Kermanshah synoptic climate station. Event based erosion and runoff was simulated in each plot by the v2008.9 version of the model. Results from model assessment for prediction of runoff indicated that the maximum model accuracy was in 45% slope. Also, mode relative error in runoff in 25 and 35% slope was about 0.61 liter. Overall, model performance in runoff estimation was sought in all three slopes, so that Nash-Sutcliff index was 0.96 to 0.73. Minimum and maximum estimation error in erosion prediction was occurred in 35 and 45% slope, respectively. Model prediction results indicated under-estimation in all the slopes. Negative amounts of Nash-Sutcliff index indicated confirms the low efficiency model especially in conditions prevailing in two slopes of 25 and 35%.

کلیدواژه‌ها [English]

  • WEPP
  • erosion
  • Runoff
  • model efficiency
  • Rangeland
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