مدل‌سازی شبه دوبعدی هیدرولیک جریان و بار بستررودخانه زارم‌رود

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی دکترای سازه های آبی گروه مهندسی آب دانشکده آب و خاک دانشگاه علوم کشاورزی و منابع طبیعی گرگان

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

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

چکیده

تعیین مقدار رسوب حمل شده توسط رودخانه­ها از جنبه­های متعددی حائز اهمیت است. این پارامتر در تعیین ابعاد و مشخصات هندسی سازه­های تنظیم و انحراف جریان، سدهای مخزنی و نیز ایستگاه­های پمپاژ موثر است. در این تحقیق محاسبه دبی جریان و بار بستر رودخانه زارم­رود (در استان مازندران) به کمک مدل ریاضی شبه­دوبعدی شیونو و نایت مورد بررسی قرار گرفته است. این مدل بر مبنای معادلات پیوستگی و مومنتوم ناویر-استوکس بوده و به صورت متوسط در عمق ساده شده است. برای این منظور با استفاده از روش اجزاء محدود، مدل ریاضی مذکور حل عددی شده و پروفیل­های عرضی سرعت جریان در رودخانه زارم­رود در محل ایستگاه هیدرومتری گرم­رود واسنجی شد. مقایسه نتایج مدل مذکور در دبی­های مختلف جریان با داده­های اندازه­گیری شده حاکی از دقت بالای مدل در برآورد توزیع عرضی سرعت جریان است. سپس با استفاده از توزیع عرضی سرعت محاسباتی، توزیع عرضی بار بستر شبیه­سازی شد. نتایج نشان داد که از میان 17 رابطه تجربی بار بستر مورد مطالعه، رابطه رسوبی دوبوی (1879) در هر دو حالت مدل­سازی یک­بعدی و شبه­دوبعدی دارای بهترین دقت است. این رابطه در حالت یک­بعدی با انحراف معیار نسبت ناجوری 34/0 درصد مطابقت بهتری با مقادیر بار بستر اندازه­گیری­شده داشته و نسبت به روابط رسوبی فرایلینک (1952) و میر-پیتر و مولر (1948) به ترتیب با انحراف معیار 46/3 و 33/7 درصد از دقت بالاتری برخوردار می­باشد. نتایج مدل­سازی شبه­دوبعدی بار بستر نشان داد که ریشه میانگین مربعات خطا (RMSE) برای سه رابطه دوبوی، فرایلینک و میر-پیتر و مولر به­ترتیب حدود 45/7، 8/98 و 9/173 است که فقط رابطه دوبوی دقت قابل قبولی داشته و دو رابطه فرایلینک و میر-پیتر و مولر دارای خطای زیادی می­باشند. همچنین مشخص شد که دقت مدل­سازی بار بستر حاصل از رابطه دوبوی در حالت شبه­دوبعدی از یک­بعدی بیشتر است.

کلیدواژه‌ها


عنوان مقاله [English]

Quasi Two-Dimensional Modeling of Flow Hydraulics and Bed Load Transport in Zaremrood River

نویسندگان [English]

  • morteza nabizadeh valukolaei 1
  • Abdolreza Zahiri 2
  • amirahmad dehghani 3
  • mehdi Meftah halaghi 3
1 PhD. Student of Water Structures Dep. of Water Engineering, water and soil college. Gorgan University of Agricultural Sciences and Natural Resources. iran
2 Associated Professor, Dep. of Water Engineering, Faculty of Water and Soil, Gorgan University of Agricultural Sciences and Natural Resources, Golestan.
3 Dep. of Water Engineering, water and soil college. Gorgan University of Agricultural Sciences and Natural Resources. iran
چکیده [English]

Determining the amount of sediment carried by rivers is important in several ways. This parameter is effective in design of dimensions and geometric characteristics of flow regulation and diversion structures, reservoir dams as well as pumping stations. In this study, the calculation of flow discharge and bed load of Zaremrood river located in Mazandaran province has been investigated using Shiono and Knight quasi-two-dimensional model. This model is based on the Navier-Stokes continuity and momentum equations and has been simplified by depth averaged concept. For this purpose, using the finite element method, this model was solved numerically and the lateral velocity distribution was calibrated at the Garmrood hydrometric station. Comparison of obtained results by Shiono and Knight model in different flow discharges against measured data indicates the high accuracy of the model for lateral velocity distribution. Then, by using the computed lateral velocity distribution, the distribution of bed load across the river was simulated. The results showed that among the 17 empirical bed load equations selected in this study, the Duboy formula (1879) has the best accuracy in both one and quasi-two-dimensional modeling cases. In 1D modeling case, this formula with standard deviation of the discrepancy ratio of 0.34 percent had better agreement with the measured bed load in comparison to the Frijlink (1952) and Meyer-Peter and Mueller (1948) equations with the standard deviation of 3.46 and 7.32 percent, respectively. In 2D modeling bed load transport, the root mean square error (RMSE) was obtained 7.45, 98.8 and 172.9 for three equations of Duboy, Frijlink and Meyer-Peter and Mueller, respectively which indicates that only Duboy formula has an acceptable accuracy while Frijlink and Meyer-Peter and Mueller equations have large errors. The results also showed that the bed load transport in quasi-two-dimensional model using Duboy equation is more accurate than one-dimensional case.

کلیدواژه‌ها [English]

  • Bed Load Experimental Relationships
  • Quasi two-dimensional Modeling
  • Shiono and Knight Model
  • Zaramrood river
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