مقاومت جریان در یک رودخانۀ شنی- قلوه سنگی در حضور توده‌های گیاهی موضعی و شکل‌های بستر گوداب و خیزاب (مطالعۀ موردی: رودخانۀ ماربر پادنا) 

نوع مقاله : مقاله پژوهشی

نویسندگان

• حسین افضلی مهر
• کورش نصرتی
• مسعود کاظم

دانشکده مهندسی عمران دانشگاه علم و صنعت ایران

10.22067/jfcei.2021.69121.1027

چکیده

هدف از این پژوهش برآورد مقاومت جریان در یک رودخانۀ‌ شنی قلوه‌سنگی از طریق خصوصیات نیم‌رخ سرعت در حضور شکل‌های سه‌بعدی بستر گوداب و خیزاب و توده‌های گیاهی پراکندۀ انعطاف‌پذیر مستغرق است. برای نیل به این هدف 39 نیم‌رخ سرعت در نقاط مختلف چهار بازۀ‌ کاملاً مستقل رودخانۀ ماربر پادنا مورد بررسی قرار گرفته‌است. نتایج نشان می‌دهد که عمق اعتبار قانون لگاریتمی به موقعیت محل اندازه‌گیری‌ها شامل ورودی گوداب و خروجی از آن بستگی دارد. شکل غالب میزان انحراف از این قانون در ورودی گودآب به‌سمت بالا، در خروجی گوداب به‌سمت پایین و خیزاب غالباً به‌سمت پایین مشاهده شده‌است که اثر مستقیم در برآورد مقاومت جریان دارد. هم‌چنین نتایج حاصل از بررسی مقاومت جریان حاکی از آن است که ضریب مقاومت جریان با نسبت انسداد به‌صورت نمایی با ضریب هم‌بستگی بزرگ‌تر از 8/0 در ارتباط است و نسبت انسداد می‌تواند پارامتر مناسبی در برآورد مقاومت جریان در رودخانه‌های شنی با توده‌های گیاهی پراکنده و شکل بسترهای سه‌بعدی گوداب و خیزاب باشد.

کلیدواژه‌ها

• گوداب و خیزاب
• مقاومت جریان
• ماربر پادنا
• تودۀ گیاهی مستغرق
• قانون لگاریتمی
• نسبت انسداد

20.1001.1.27832805.1400.34.2.3.7

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عنوان مقاله [English]

Resistance to Flow in a Cobble-Gravel Bed River with Irregular Vegetation Patches and Pool-Riffle Bedforms (Case study: Padena Marbor River)

نویسندگان [English]

• Hossein Afzalimehr
• Kourosh Nosrati
• Masoud Kazem

Faculty of Civil Engineering, Iran University of Science and Technology, Tehran, Iran.

چکیده [English]

This study was intended to estimate resistance to flow through velocity profile characteristics in a cobble-gravel bed river with 3D-Pool-Riffle bedforms and irregular distribution of flexible-submerged vegetation patches. To this end, a total of 39 velocity profiles consisting of four independent sections of Padena Marbor River have been studied. The finding showed that the depth of validity logarithmic law depends on the location of measurements including both inlet and outlet of the Pool. The predominant form of deviation from this law is frequently observed upwards at the inlet of the Pool and downwards at the outlet of the Pool and Riffle, which has a direct effect on the estimation of resistance to flow. Moreover, the results of resistance to flow revealed that the coefficients of resistance to flow are exponentially related to blockage area with a correlation coefficient greater than 0.8. Therefore, blockage area can be a suitable parameter in estimating resistance to flow in cobble-gravel bed rivers with 3D bedforms and irregular vegetations patches.

کلیدواژه‌ها [English]

• Pool and Riffle
• Resistance to flow
• Padena Marbor River
• Submerged vegetation patches
• Logarithmic law
• Blockage area

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