نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشجوی دکترای آبخیزداری، دانشکده منابع طبیعی و علوم زمین، دانشگاه کاشان
2 استادیار گروه مرتع و آبخیزداری، دانشکده منابع طبیعی و علوم زمین، دانشگاه کاشان
چکیده
فرسایش خندقی موقت، یکی از انواع فرسایش آبی بوده که سهم زیادی در تخریب اراضی دارد. به‌منظور، ارزیابی میزان هدررفت خاک ناشی از آن و اجرای اقدامات حفاظتی مناسب، پیش‌بینی این پدیده امری ضروری است. این پژوهش، با هدف بررسی کارایی مدل EGEM در پیش‌بینی فرسایش خندقی موقت در حوزه آبخیز قوری‌چای استان اردبیل انجام پذیرفته است. بدین‌منظور، تعداد 17 خندق موقتی در حوضه شناسایی شد و از اردیبهشت ماه 1393 تا اردیبهشت ماه 1395 به پایش و ثبت خصوصیات مورفولوژیکی و حجم فرسایش آن‌ها پس از هفت واقعه بارشی مؤثر پرداخته شد. برای تخمین فرسایش خندقی موقت ناشی از تک واقعه بارش، مدل EGEM به چهار گروه ورودی شامل اطلاعات شناسایی، داده‌های حوضه، خاک و بارش در هر خندق نیاز دارد. این مدل شامل دو مولفه هیدرولوژی و فرسایش بوده که رواناب ناشی از بارش‌های رخ داده در هر یک از زیرحوضه‌های مشرف به خندق‌ها بر اساس روش شماره منحنی NRCS برآورد می‌کند. نتایج ارزیابی کارایی مدل EGEM نشان داد که مدل حجم خاک و سطع مقطع فرسایش یافته را به‌ترتیب با ضریب تبیین 0.96 و 0.89 پیش‌بینی کرده است. همچنین، نتایج تحلیل حساسیت مدل نیز نشان داد که مدل نسبت به پارامتر CN بیشترین حساسیت را داشته است، به‌طوری که با افزایش و کاهش 10 درصدی CN، میزان تغییرات حجم خاک فرسایش یافته به‌ترتیب 22.98 و 18.92- درصد تغییر پیدا کرد. لذا، می‌توان گفت که مدل EGEM برای برآورد میزان فرسایش خندقی موقت ناشی از وقایع منفرد بارندگی در حوزه آبخیز قوری چای مناسب بوده، می‌توان آن را برای مطالعه و برنامه‌ریزی روی خندق‌های موقتی در حوضه‌های مشابه توصیه کرد.
کلیدواژه‌ها
عنوان مقاله [English]
Evaluation of EGEM model performance in predicting ephemeral gully erosion, case study: Ghoorichay Watershed, Ardabil Province
نویسندگان [English]
- Behnam Farid Gigloo 1
- Ebrahim Omidvar 2
1 PhD Student,, Faculty of Natural Resources and Earth sciences, University of Kashan, Iran
2 Assistant Professor, Faculty of Natural resource and earth sciences, University of Kashan, Iran
چکیده [English]
Ephemeral Gully (EG) erosion is one of the most destructive types of water erosion, which contributes significantly to land degradation. EG erosion prediction is necessary to assess the magnitude of soil loss and to implement the appropriate conservation measures. The aim of current study was to evaluate the efficiency of EGEM model for EG erosion prediction in Ghoorichay Watershed, Ardabil Province, Iran. For this purpose, a number of 17 EG erosion was identified and monitored between the years 2014 to 2016. The morphological characteristics and erosion rate of EGs were measured and recorded after seven effective rainfall events. In order to calculate the EG erosion, EGEM model requires four major categories of input data, including identification information, watershed data, soil data, and rainfall data. The model has two major components: hydrology and erosion. The runoff induced by a rainfall event in each gully catchment was determined by the Natural Recourses Conservation service (NRCS) Curve Number (CN). The result of EGEM model performance evaluation showed that the eroded soil volume and cross-section were predicted with a determination coefficient of 0.96 and 0.89, respectively. Sensitivity analysis revealed that the curve number was the most sensitive parameter, so that, with a 10% increasing and decreasing in CN, the volume of soil loss varied 22.98 and -18.92%, respectively. It can be concluded that EGEM model was suitable for event-based EG erosion prediction in Ghoorichay Watershed and it can be recommended for studying and planning on EGs in similar watersheds.
کلیدواژه‌ها [English]
- Curve number
- Ephemeral gully
- Moghan Plain
- Sensitivity analysis
- Simulation
- Soil loss
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