Investigation on the Effect of Sediment Level on Pressurized Flushing Performance from Reservoirs using Physical Model

Document Type : Research Article


1 M.Sc. Student of Water Structures, Department of Water Structures, Faculty of Agricultural Engineering, Tarbiat

2 Associate Professor, Department of Water Structures, Tarbiat Modares University, Tehran, Iran.

3 Professor, Department of Water Structures, Tarbiat Modares University, Tehran, Iran.


In the Pressurized Flushing method, the previously settled sediments at the bottom of the reservoir will be cleaned up and flushed by the downstream water after opening dam’s bottom outlets. The volume of the flushed sediments can be affected by various factors such as the reservoir water surface elevation, flow rate, and sediment elevation at the dam. This study investigates the laboratory scale “Pressurized Flushing” method as well as the impacts of sediment elevation on the efficiency and the dimensions of scour funnel. A physical model was built in Tarbiat Modarres University in order to assess the effects of the aforementioned factors. All the tests were performed at 3 sediment levels and in each sediment level with 3 water depths and 3 flow rates. According to the measured data, there is a direct correlation between the flushing cone dimensions and the sediment elevations. Based on the measured cone dimensions; the greater the sediment discharge at the higher sediment elevations, the greater the dimensions of the flushing cone will be. Furthermore, increasing of the accumulated sediments elevations at the reservoir leads to a higher efficiency of the pressurized flushing. An average increase of 29 percent in sediment elevation leads to 2 percent increase in the efficiency .Moreover, it has been observed that the flushing cone shape in plan view closely resembles a semicircle. Finally, based on the experimental data, dimensionless equations were developed in order to determine the dimensions of the scour funnel. There was a good correlation between the equations and the experimental data.


امامقلی‌زاده، ص. و جهانی، ح. (1387). "بررسی هیدرولیک جریان در رسوب‌شویی تحت فشار با استفاده از نتایج آزمایشگاهی". چهارمین کنگره مهندسی عمران، دانشگاه تهران.
شهیرنیا، م. (1391). "بررسی وارزیابی تأثیر تراز رسوباب در رسوب‌شویی تحت فشار در سدهای مخزنی با استفاده از مدل فیزیکی"، پایان‌نامه کارشناسی ارشد، رشته سازه‌های آبی، دانشگاه تربیت مدرس.
مشکاتی شهمیرزادی، م. ا.، دهقانی، ا. ا.، ناصر، غ و امامقلی‌زاده، ص. (1388). "تأثیر ابعاد دریچه تحتانی بر حجم و ابعاد مخروط آبشستگی در رسوب­شویی تحت­فشار"، هشتمین سمینار بین المللی مهندسی رودخانه.
Atkinson, E. (1996). "The feasibility of flushing sediment from the reservoir". Report OD 137, p. 99.
Brandt, S. A. (2000). "A review of reserevior desiltation". International Journal of Sediment Research, Vol. 15, pp. 321-342.
Emamgholizadeh, S. (2005). Pressure flushing of sediment through storage reservoir: Laboratory testing. J. Inst. Eng. (India), CEDiv. 89(5), pp. 23-27.
Emamgholizadeh, S.,. Bateni, S.M. and Jeng D.S. (2013)."Artificial intelligence-based estimation of flushing half-cone geometry". Engineering Applications of Artificial Intelligence, Vol. 26 (10), pp. 2551-2558.
Fang, D. and Cao, S. (1996). "An experimental study on scour funnel in front of a sediment flushing outlet of a reservoir". Proceedings of the 6th Federal Interagency Sedimentation Conference, Las Vegas, March 10-14, pp. I.78-I.84.
Fathi-Moghadam, M., Emamgholizadeh, S., Bina, M. and Ghomeshi, M. (2010). "Physical modeling of pressure flushing for desilting of non-cohesive sediment". J. Hydraul. Res. 48(4), pp. 509-514.
Lai, J. S. and Shen, H. W., (1996). "Flushing sediment through reservoirs". Journal of Hydraulic Research, Vol. 34(2), pp. 237-255.
Meshkati Shahmirzadi, M. E., Dehghani, A. A., Sumi, T., Mosaedi, A. and Meftah, H. (2009). "Experimental investigation of pressure flushing technique in reservoir storages". Water and Geoscience, pp. 132-137.
Morris, G.L. and Fan, J. (2009). "Reservoir Sedimentation Handbook: Design and management of dams, reservoirs, and watersheds for sustainable use". McGraw-Hill, New York, p. 784.
Qian, N. (1982). "Reservoir sedimentation and slope stability, technical and environmental effects". Fourteenth International Congress on Large Dams, Transactions, Rio de Janeiro, Brazil, 3-7 May, Vol. 3, pp. 639-690.
Scheuerlein, H., Tritthart, M. and Nunez Gonzalez, F., (2004). "Numerical and physical modeling concerning the removal of sediment deposits from reservoirs". Conference Proceeding of Hydraulic of Dams and River Structures, Tehran, Iran, pp. 245-254.