با همکاری انجمن آبخیزداری ایران

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دکتری علوم و مهندسی آبخیزداری،‌ دانشکده منابع طبیعی و علوم دریایی، دانشگاه تربیت مدرس

2 استاد، دانشکده منابع طبیعی و علوم دریایی، دانشگاه تربیت مدرس

3 دانشیار، دانشکده منابع طبیعی و علوم دریایی، دانشگاه تربیت مدرس

چکیده

فرسایش خاک به­‌عنوان یک موضوع مهم در پژوهش‌­های حفاظت آب و خاک است که تحت تأثیر عوامل انسانی و طبیعی است. بنابراین، آگاهی از میزان فرسایش خاک، امکان شناسایی نواحی بحرانی و اولویت­‌بندی اقدامات اجرایی را فراهم می‌کند. یکی از عوامل مؤثر در ارزیابی فرسایش خاک، طول و درجه شیب است که محاسبه آن با استفاده از روش‌های محاسباتی مختلف امکان­‌پذیر بوده و در عین‌حال انتخاب مناسب‌­ترین رابطه برای تخمین آن از اهمیت زیادی برخوردار است. حال آن‌که تا کنون مقایسه کارایی روش‌های مختلف در تخمین آن‌ها مورد توجه کافی قرار نگرفته است. بنابراین، در پژوهش حاضر با هدف محاسبه عامل توپوگرافی و بررسی تأثیر آن بر میزان هدررفت خاک در حوزه آبخیز شازند از چهار روش‌ محاسباتی متداول مورد استفاده در سامانه اطلاعات جغرافیایی شامل Renard و همکاران (1997)، Desmet و Govers (1996)، Moore و همکاران (1991) و Böhner و Selige (2006) انجام شده است. برای ارزیابی نتایج حاصل از محاسبه فرسایش خاک با استفاده از روش‌های محاسباتی مذکور، از نتایج حاصل از اندازه‌گیری مستقیم طول شیب روی نقشه توپوگرافی استفاده شد. نتایج به­دست آمده از این پژوهش، ضمن تائید اختلاف حدود 15 برابری نشان داد که متوسط میزان هدررفت خاک در حوزه آبخیز شازند، با استفاده از روش‌های محاسباتی Renard و همکاران (1997)، Desmet و Govers (1996)، Moore و همکاران (1991) و Böhner  و Selige  (2006) در صورت ثبات سایر عوامل در رابطه جهانی فرسایش خاک تجدیدنظر شده، به‌ترتیب 4.95، 19.47، 1.73 و 1.34 تن بر هکتار بر سال بوده است. با توجه به محاسبه طول شیب به‌عنوان کوتاه‌ترین پاره‌خط بین خط‌الرأس تا خط‌القعر از روی نقشه توپوگرافی و نیز عامل شیب، عملکرد روش Desmet و Govers (1996)، در محاسبه عامل توپوگرافی بهتر از سایر مدل‌ها ارزیابی شد. یافته‌های پژوهش حاضر مشخصاً بر ضرورت انتخاب شیوه مناسب برآورد عوامل ورودی در تخمین فرسایش خاک تأکید دارد.

کلیدواژه‌ها

عنوان مقاله [English]

Comparative analysis of the effect of different algorithms for calculating the topographic factor on the amount and spatial distribution of soil erosion in the Shazand Watershed, Iran

نویسندگان [English]

  • Fahimeh Mirchooli 1
  • Seyed Hamidreza Sadeghi 2
  • Abdulvahed Khaledi Darvishan 3

1 PhD,, Faculty of Natural Resources and Marine Science, Tarbiat Modares University, Iran

2 Professor, Department of Watershed Management Engineering, Faculty of Natural Resources and Marine Science, Tarbiat Modares University, Iran

3 Associate Professor, Department of Watershed Management Engineering, Faculty of Natural Resources and Marine Science, Tarbiat Modares University

چکیده [English]

Soil erosion is an important subject in water and soil conservation researches which is influenced by natural and anthropogenic factors. Hence, knowledge on soil erosion amount enables the identification of critical areas and prioritization of measures. One of the effective factors in the evaluation of soil erosion is slope and length (LS) which could be calculated using different methods and algorithms, so the selection of the best method to provide proper estimation is important. However, the comparison of the performance of the different estimation methods has not been sufficiently considered. Therefore, the present study was conducted to calculate the LS factor and evaluate its effect on estimations of soil erosion in the Shazand Watershed using four common algorithms viz. Renard et al. (1997); Desmet and Govers (1996); Moore et al., 1991, and Böhner and Selige (2006) in geographical information system. The results of this study while confirming the difference of about 15 times among performances of various algorithms, indicated that the mean soil erosion using the algorithm of Renard et al. (1997); Desmet and Govers (1996); Moore et al. (1991), and Böhner and Selige (2006) were 4.95, 19.47, 1.73, 1.34 t ha-1 yr-1 in case of the stability of other factors of RUSLE model. Considering the calculated amounts of slope length on the topographic map, the Desmet and Govers (1996) algorithm performed better than other algorithms in LS calculation for the study watershed. It clearly verified the necessity of selecting pertinent procedures for the calculation of input factors for the precise estimation of soil erosion.

کلیدواژه‌ها [English]

  • Makazi Province
  • Water and soil conservation
  • Sensitivity analysis
  • Soil erosion estimation
  • Soil erosion modeling
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