اثر سه نوع پوشش گیاهی بر تثبیت کنار‌‌ی رود ‌‌‌‌‌‌فریزی در استان خراسان رضوی

نوع مقاله : پژوهشی

نویسندگان

1 محقق بخش تحقیقات آبخیزداری مرکز تحقیقات کشاورزی خراسان رضوی

2 عضو هیئت علمی پژوهشکده حفاظت خاک و آبخیزداری

3 کارشناس بخش تحقیقات آبخیزداری، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی خراسان رضوی

چکیده

پژوهش حاضر با هدف ارزیابی عملکرد حفاظت زیستی پوشش گیاهی بر تثبیت کناره‌‌‌‌های رود‌‌‌‌‌‌‌‌‌‌‌‌ فریزی انجام شد. تیمارهای اصلی این پژوهش سه نوع پوشش گیاهیِ علفی و درختچه‌‌‌‌ای و درختی بود. یک تیمار بی‌پوشش هم برای شاهد انتخاب شد. میزان فرسایش در هر تیمار در یک بازه، با میخ‌‌‌‌‌کوبی در دو ردیف و سه مقطع عرضی اندازه‌‌‌‌گیری شد. در طول چهار سال، خصوصیات پوشش گیاهی ‌‌‌‌با کاربرد اندازه‌‌‌‌گیری ‌‌‌‌نواری و اطلاعات آب‌‌‌‌شناسی از داده‌‌‌‌‌‌‌‌‌‌‌‌های ایستگاه آب‌‌‌‌سنجی به‌‌‌‌دست آمد. نتایج نشان‌‌‌‌ داد که پوشش درختچه‌‌‌‌ایِ بید (Salix eleganos Scop.) با عمر متوسط پنج سال و پوشش درختیِ همین گونه بید (Salix alba L.) و نیز سنجد (Elaeagnus angustifolia L.)، با عمر متوسط 25 سال، عمل‌کرد مناسبی در تثبیت حاشیه‌ی رود دارند؛ زیرا فرسایش این دو تیمار در دوره‌‌‌‌ی طرح کمتر از 1% تیمار شاهد بود. بیشترین پوشش علفی در این منطقه، از گونه‌ها‌ی گندمیان (poaceae) بود که با 50% کاهش فرسایش نسبت به تیمار شاهد، ‌‌‌‌به‌‌‌‌رغم نصف‌شدن میزان فرسایش، انتظارات اولیه را در مقایسه با دو تیمار دیگر، درخصوص تثبیت کناره‌ی رود برآورده نکرد. دلیل آن را می‌‌‌‌توان به شرایط گونه‌‌‌‌های علفی و تطابق نداشتن دوره‌‌‌‌‌‌‌‌‌‌‌‌ی رشد آن‌ها با زمان وقوع سیل‌‌‌‌های رود مربوط دانست. بر این اساس می‌‌‌‌توان گفت که در شرایط مشابه، گونه‌‌‌‌های علفی یک‌ساله، در رود‌‌‌‌هایی که  روند سیل آن‌‌ها  در خارج از فصل رشد گیاه است، عملکرد مناسبی در تثبیت حاشیه‌ی رود ندارند. در دوره‌‌‌‌ی اجرای پژوهش، سیل‌‌‌‌های رخ‌‌‌‌‌‌‌‌‌‌‌‌داده در رود‌‌‌‌‌‌‌‌‌‌‌‌ فریزی در حد سیل‌های کوتاه‌مدت پنج‌ساله بودند.

کلیدواژه‌ها

عنوان مقاله [English]

Riverbank Stabilization Using Vegetation Cover in the Ferizi River, Khorasan Razavi Province

نویسندگان [English]

  • Seyed Hossein Rajaei 1
  • Masoud Sajedi Sabegh 2
  • Hossein Pejman 3
  • Ali Vahedy Toroghi 3
  • Zohre Sheybanizade 3
1 Researcher in Khorasan Agricaltur and Natural Resources Research center
2 Scientific member in Soil Conservation and Watershed Management Institute
3 Expert of Watershed Research Department, Khorasan Razavi Agricaltur and Natural Resources Research and Education center
چکیده [English]

The use of vegetation cover for the sustainable riverbank stabilization is not only economical in ‌most cases, but also ameliorates the landscape. The purpose of this research was to evaluate vegetatative stabilization of the Ferizi River, s erodible banks. Considering that each vegetative form offers a unique type of protection, 8 grass species, short shrub and a tree species were selected for this research. Salix eleganos Scop.,Salix alba L. Elaeagnos angustifolia L. were planted at suitable spacing on the banks. A plot without vegetative protection was established as the control steel pins with specific lengths were driven in to the banks at two rows and three cross sections. The depth of erosion was measured monthly for 4 years by an increase in the length of the pins outside of the river side on transects. The flow data were collected at the hydrometry station. The results indicated that shrub and tree cover performed satisfactorily in stabilizing the riverbank. The erosion depth for the shrub and tree cover was <1% of the control; this was 50% for the grass cover; therefore it was not as effective in erosion control as we had expected. The reason for this poor performance is due to the growth season of these grass species which is not ‌synchronized with flooding season of the Ferizi River. It is interesting to note that the study duration coincided with the 5-year flow regime of the river.

کلیدواژه‌ها [English]

  • Biological stabilization
  • Ferizi River
  • riverbank stabilization
  • riverbed Erosion
  • vegetative cover

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سابقه مقاله

  • تاریخ دریافت: 23 بهمن 1396
  • تاریخ بازنگری: 10 اردیبهشت 1397
  • تاریخ پذیرش: 02 مرداد 1397

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