مدل‌سازی تأثیر آب‌شکن‌های رودخانه‌ای در کنترل فرسایش ساحل با مدل دوبعدی CCHE2D

نویسندگان

چکیده

هدف از این مطالعه به‌کارگیری یک مدل هیدرودینامیک دوبعدی برای پیش‌بینی و پایش فرایند‌های حاکم بر جریان،‏ انتقال رسوب و حفاظت ساحل در یک پیچان‌رود طبیعی است. محدوده مورد مطالعه بخشی از رودخانه کارون با طول در حدود 5 کیلومتر در حد فاصل ایستگاه‌های آب‌سنجی اهواز و فارسیات است. حفاظت ساحل در پیچان‌رود موردنظر به‌دلیل همسایگی با اراضی کشاورزی و تأسیسات سازمان آب و برق خوزستان مهم است. در این پژوهش ابتدا با مدل CCHE-MESH شبکه محاسباتی تشکیل شد و در ادامه مدل دوبعدی CCHE2D پس از صحت‌سنجی برای شبیه‌سازی الگوی جریان،‏ پیش‌بینی تغییرات بستر و ساحل در یک دوره زمانی 20 ساله استفاده شد. نتایج نشان داد خط‌القعر پیچان‌رود بین 4 تا 8 و به‌طور متوسط 7‎/5 متر نسبت به شرایط اولیه عمیق‌تر شده و به‌دلیل حضور جریان حلزونی عمق بستر در محل قوس خارجی افزایش بیشتری دارد. از آنجا که یکی از سازه‌های مهم برای حفاظت دیواره‌های رودخانه آب‌شکن‌های رودخانه‌ای هستند،‏ برای پیچان‌رود مورد مطالعه 14 عدد آب‌شکن پس از طراحی در مدل CCHE2D جانمایی شد. حضور آب‌شکن‌ها در دوره 20 ساله سبب افزایش رقوم بستر در محل ساحل خارجی بین 1 تا 9 و به ‌طور متوسط 7‎/4 متر (در مقایسه با حالتی که آب‌شکن‌ها حضور ندارند) شد اما خط‌القعر را در برخی مقاطع تا حدود 4 متر عمیق‌تر کرد.

کلیدواژه‌ها


عنوان مقاله [English]

Modeling the effect of spur dikes on bank erosion control using CCHE2D )Case study: Karun river)

نویسندگان [English]

  • Mohammad Tajbakhsh
  • Habib Musavi Jahromi
چکیده [English]

The aim of this research was to apply a two-dimensional hydrodynamic model to predict and investigate governing phenomena on flow, sediment transport and bank erosion in a natural meandering river. The study area is a meander of Karun River with the length of approximately 5 km between Ahvaz and Farsiat hydrometric stations. Bank protection of the considered meander is so important because the Khuzestan Water and Energy company structures and agricultural farms are located in the vicinity. In this study, mesh generation was performed by CCHE-MESH model. The validated CCHE2D model was applied for flow pattern simulation, and bed and bank change prediction in a 20 years period of time. Results showed the meander Thalweg elevation was decreased between 4 to 8 m and 5.7 m in average (in compare with initial bed level) and secondary flow caused a higher decrease in outer bank elevation. Since the Spur dike is an important structure in the river bank protection, 14 number of Spure dikes were designed in the CCHE-2D model for studied meander. After 20 years of simulation, dikes caused to increase the elevation of outer bank between 1 to 9 m and 4.7 m in average (in compare with 20 years of simulation without dikes), But in some sections the Thalweg became approximately 4m deeper.
The aim of this research was to apply a two-dimensional hydrodynamic model to predict and investigate governing phenomena on flow, sediment transport and bank erosion in a natural meandering river. The study area is a meander of Karun River with the length of approximately 5 km between Ahvaz and Farsiat hydrometric stations. Bank protection of the considered meander is so important because the Khuzestan Water and Energy company structures and agricultural farms are located in the vicinity. In this study, mesh generation was performed by CCHE-MESH model. The validated CCHE2D model was applied for flow pattern simulation, and bed and bank change prediction in a 20 years period of time. Results showed the meander Thalweg elevation was decreased between 4 to 8 m and 5.7 m in average (in compare with initial bed level) and secondary flow caused a higher decrease in outer bank elevation. Since the Spur dike is an important structure in the river bank protection, 14 number of Spure dikes were designed in the CCHE-2D model for studied meander. After 20 years of simulation, dikes caused to increase the elevation of outer bank between 1 to 9 m and 4.7 m in average (in compare with 20 years of simulation without dikes), But in some sections the Thalweg became approximately 4m deeper.
The aim of this research was to apply a two-dimensional hydrodynamic model to predict and investigate governing phenomena on flow, sediment transport and bank erosion in a natural meandering river. The study area is a meander of Karun River with the length of approximately 5 km between Ahvaz and Farsiat hydrometric stations. Bank protection of the considered meander is so important because the Khuzestan Water and Energy company structures and agricultural farms are located in the vicinity. In this study, mesh generation was performed by CCHE-MESH model. The validated CCHE2D model was applied for flow pattern simulation, and bed and bank change prediction in a 20 years period of time. Results showed the meander Thalweg elevation was decreased between 4 to 8 m and 5.7 m in average (in compare with initial bed level) and secondary flow caused a higher decrease in outer bank elevation. Since the Spur dike is an important structure in the river bank protection, 14 number of Spure dikes were designed in the CCHE-2D model for studied meander. After 20 years of simulation, dikes caused to increase the elevation of outer bank between 1 to 9 m and 4.7 m in average (in compare with 20 years of simulation without dikes), But in some sections the Thalweg became approximately 4m deeper.
The aim of this research was to apply a two-dimensional hydrodynamic model to predict and investigate governing phenomena on flow, sediment transport and bank erosion in a natural meandering river. The study area is a meander of Karun River with the length of approximately 5 km between Ahvaz and Farsiat hydrometric stations. Bank protection of the considered meander is so important because the Khuzestan Water and Energy company structures and agricultural farms are located in the vicinity. In this study, mesh generation was performed by CCHE-MESH model. The validated CCHE2D model was applied for flow pattern simulation, and bed and bank change prediction in a 20 years period of time. Results showed the meander Thalweg elevation was decreased between 4 to 8 m and 5.7 m in average (in compare with initial bed level) and secondary flow caused a higher decrease in outer bank elevation. Since the Spur dike is an important structure in the river bank protection, 14 number of Spure dikes were designed in the CCHE-2D model for studied meander. After 20 years of simulation, dikes caused to increase the elevation of outer bank between 1 to 9 m and 4.7 m in average (in compare with 20 years of simulation without dikes), But in some sections the Thalweg became approximately 4m deeper.

کلیدواژه‌ها [English]

  • Numerical CCHE?D Model-Karun River-Spur Dike.-Meander-