ارزیابی خطر بیابان زایی با استفاده از مدل جدید مدالوس پیشنهادی

شیرگیر, سمیه; مسعودی, مسعود

doi:10.22092/wmej.2021.352966.1381

ارزیابی خطر بیابان زایی با استفاده از مدل جدید مدالوس پیشنهادی

نوع مقاله : پژوهشی

نویسندگان

¹ دانش آموخته کارشناسی ارشد، گروه مهندسی منابع طبیعی و محیط زیست، دانشکده کشاورزی، دانشگاه شیراز، شیراز

² دانشیار گروه مهندسی منابع طبیعی و محیط زیست، دانشکده کشاورزی، دانشگاه شیراز، شیراز

10.22092/wmej.2021.352966.1381

چکیده

افزایش روند تخریب منابع طبیعی زندگی جامعه‌ی بشر را به‌طور نگران کننده یی تهدید می‌کند. فرآیند بیابان زایی نمونه‌ی اصلی این گونه تخریب ها است. هدف اصلی این پژوهش ارزیابی امکان خطر بیابان زایی با مدل مدالوس در منطقه ی گلسرای تربت حیدریه در استان خراسان رضوی است. بر پایه‌ی این مدل پنج معیار کلیدی کیفیت خاک، اقلیم، پوشش گیاهی، مدیریت و روند (معیار پیشنهادی) ارزیابی ‌شد. کیفیت هر معیار از میانگین هندسی شاخص های آن، و از میانگین هندسی معیارها نقشه ی نهایی شدت بیابان زایی به‌دست آمد. در منطقه ی گلسرا سه طبقه‌ی خطر حساس ((F1,F2,F3 و دو طبقه‌ی احتمال خطر (P) و بی تاثیر (N) به دست آمد. مدل مدالوس علاوه بر افزودن معیار روند در سه مرحله ی دیگر نیز اصلاح شد. در مرحله ی اول پس از تهیه ی نقشه ی شدت بیابان زایی در چهارچوب مدل مدالوس، نقشه ی جدید شدت بیابان زایی بر پایه‌ی طبقه بندی چهار طبقه‌یی (کم تا خیلی شدید) به دست آمد، که نشان داد در 66 % از منطقه احتمال بیابان زایی متوسط هست. در مرحله ی دوم، با تهیه ی نقشه ی تولید فعلی به تولید بالقوه‌ی منطقه به نوعی وضعیت فعلی بیابان زایی که در مدل اصلی در نظر گرفته نشده‌بود وارد محاسبه‌ها شد، که نشان داد 60 % از منطقه در وضعیت فعلی بیابان زایی شدید است. در مرحله ی سوم بر پایه‌ی نقشه ی تولید فعلی به تولید بالقوه ی به دست آمده، طبقه بندی جدید شامل طبقه های اصلی خطر فعلی و خطر بالقوه برای نقشه ی شدت بیابان زایی اصلاح‌شده ی مدل مدالوس تعریف شد. بر پایه‌ی نقشه ی نهایی اصلاح‌شده ی مدالوس، 93/4 % از مساحت منطقه‌ی بررسی‌شده در طبقه ی اصلی خطر فعلی و 6/60 % در طبقه ی اصلی خطر بالقوه بود. این نتیجه‌ نشان‌دهنده‌ی کارآ نبودن مدل مدالوس فعلی در منطقه ی گلسرا بی‌درنظرگرفتن ویژگی وضعیت فعلی تخریب است. به‌کاربردن روش پیشنهادشده توصیه می‌شود.

کلیدواژه‌ها

عنوان مقاله [English]

Hazard Assessment of Desertification Using the New Model of Proposed MEDALUS

نویسندگان [English]

Somayeh Shirghir ¹
Masoud Masoudi ²

¹ Former M.Sc. Student, Department of Natural Resources and Environmental Engineering, Faculty of Agriculture, University of Shiraz, Shiraz

² Associate Prof., Department of Natural Resources and Environmental Engineering, Faculty of Agriculture, University of Shiraz, Shiraz

چکیده [English]

An increasing trend of natural resources degradation threatens human life dramatically. Desertification process is the main sign of land degradation. The principal aim of this research was an assessment of potential hazard of desertification using the MEDALUS model in the study of Golsara Torbat Heydarieh area in the province of Khorasan Razavi. The MEDALUS model was evaluated based on 5 key factors, namely: soil quality, climate quality, vegetation quality, management quality and trend of desertification (suggested factors). The quality of each factor was evaluated using the geometric mean of its indices. The desertification intensity map was prepared based on the geometric mean of all 5 key factors. In the Golsara region, 3 fragile classes (F1, F2, F3) and 1 potential class (P) and 1 non affected class (N) were evaluated. The MEDALUS model was modified by of adding a trend factor in which 3 other steps were revised. 1. After preparation the desertification intensity map based on the MEDALUS model, a new map of desertification intensity of the study area was prepared based on 4 classes of low to very severe situations showing 66% of the study area was under a moderate potential of desertification. 2. By upgrading the map of current productivity to potential productivity the current state of desertification that wasn’t considered in the MEDALUS model was run showing 60% of the study area was under a severe state of desertification. 3. Based on the map of current productivity to potential productivity, a new classification involving two main classes of potential risk and actual risk were defined for the desertification intensity map of revised the MEDALUS model. According to the final revised map of desertification in the Golsara region, 93.4% of the area was classified as the main class of actual risk and 6.6% as the main class of potential risk. These results point to the inefficiency of the current the MEDALUS model in the study area without considering the current degradation status parameter; therefore, we recommend the use of the modified model.

کلیدواژه‌ها [English]

Actual risk
desertification
GIS
MEDALUS
potential risk
rate
state

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