شبیه سازی هیدرولیک جریان و رسوب معلق در قوس رودخانه (مطالعه موردی: رودخانه کارون)

نوع مقاله : مقاله پژوهشی

نویسنده

دانشیار گروه مهندسی آب، دانشکده مهندسی آب و خاک، دانشگاه علوم کشاورزی و منابع طبیعی گرگان

چکیده

شبیه­سازی توزیع عرضی سرعت جریان و نیز غلظت رسوب معلق در قوس رودخانه­ها، دارای اهمیت زیادی بوده و در حفاظت سواحل رودخانه، الگوی انتقال و ته­نشست رسوبات، انتشار آلودگی و کنترل سیلاب کاربرد دارد. به­دلیل ساختار سه­بعدی جریان در قوس رودخانه­­ها، مدل­های ریاضی یک­بُعدی در این شرایط جواب­گو نبوده و باید از مدل­های ریاضی دو یا سه­بُعدی استفاده نمود. در این تحقیق، ابتدا با اندازه­گیری میدانی داده­های توزیع عرضی سرعت و غلظت بار معلق از سه قوس واقع در رودخانه کارون (قوس­های ملیحه، جنگیه و خبینه)، مدل شبه دوبعدی متوسط در عمق (Shiono and Knight, 1991) واسنجی شد. با استفاده از نتایج توزیع سرعت به­دست آمده از این مدل ریاضی، ظرفیت انتقال رسوب رودخانه محاسبه شد. نتایج نشان داد که در هر سه قوس انتخاب شده، از میان روابط رسوبی مورد مطالعه، رابطه رسوبی یانگ مطابقت بهتری با مقادیر غلظت رسوب اندازه­گیری شده در عرض رودخانه داشته و نسبت به روابط رسوبی اکرز-وایت و انگلوند-هانسن، از دقت بالاتری برخوردار می­باشد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Simulation of Flow Hydraulics and Sediment Load in River Bends (Case Study: Karoun river)

نویسنده [English]

  • Abdolreza Zahiri
Associate Professor, Water Engineering Department, College of Water and Soil Engineering, Gorgan University of Agricultural Sciences and Natural Resources
چکیده [English]

Simulation of lateral distributions of velocity and suspended sediment concentration in river bends is of great significance, and has many applications for river engineering projects. Due to secondary flow development, flow structure in river bends has 3-dimensional nature. As shown in Fig. 1, the secondary flow, coupled with the longitudinal primary movement, causes a helical flow that forms in the river bend (Perkins, 1970). In this case, 1-dimensional mathematical models (e.g. HEC-RAS, MIKE-11 and ISIS) are generally not satisfactory and 2 or 3-dimensional mathematical models should be used instead. However, the large amount of computational time needed to simulate flow field in rivers by 3D or 2D mathematical models, justifies the use of quasi 2D modes. Among the numerous quasi 2D models, the Shiono and Knight model has attracted great attention of river engineers. This mathematical model is based on the depth averaged integration of Navier-Stocks equations. Due to suitable form of in this study, at first with field measurement of lateral distributions of velocity and suspended sediment concentration in three bends located at the Karoun river (namely Maliheh, Jangieh and Khabineh), the Shiono and Knight quasi-two dimensional model (1991) has been calibrated. Using the lateral velocity profiles obtained by this mathematical model, sediment transport capacities were computed. The results showed that in all three river bends, among the empirical sediment equations selected for this study, the sediment transport equation of Yang has very well agreement with the measured lateral suspended sediment concentration, in comparison to the Ackers-White and Engelund-Hansen equations.

کلیدواژه‌ها [English]

  • Sediment transport equations
  • Karoun river
  • River Bend
  • Quasi-two dimensional mathematical model
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