Experimental Investigation and Assessment of Turbidity Current Head Dynamic Over a Mobile Bed

Authors

1 Ph.D. student, Dept. of Water Struc., Faculty of Water Sciences Engin., Univ. of Shahid Chamran of Ahvaz, Iran

2 Prof., Dept. of Water Struc., Faculty of Water Sciences Engin., Univ. of Shahid Chamran of Ahvaz, Iran

Abstract

Turbidity current phenomenon is one of the most important factors in reservoir sedimentation and sediment distribution, which causes management and operational problems and decreases dam’s useful life. Study and investigation of progressive section (head of turbidity current), as the most significant and considerable section is essential for sustainable management of dam reservoirs. So far, most of the studies have been conducted under experimental conditions on rigid beds. But In this study, in order to achieve more realistic results regarding natural conditions in rivers and reservoirs, the experiments were carried out on an erodible and mobile bed. So dynamic of turbidity current head was analyzed on rigid and erodible beds for different effective hydraulic conditions. It was shown that erodible bed increased the head velocity of turbidity current and Keulegan coefficient up to about 20% and also, increased the relative forehead height up to about 40% with increasing flume bed slope. In addition, in order to estimate the averaged head velocity, an equation with correlation coefficient of 0.86, was developed using multivariate linear regression and effective dimensionless parameters. Finally sensitivity analysis of the equation’s dimensionless parameters showed that the most effective parameter in estimation of the head velocity average is Richardson number.

Keywords

References

Akiyama J and Stefan HG, 1985. Plunging flow into a reservoir: Theory. J. Hydraul. Eng 110(4): 484-499.
Altinakar MS, Graf WH and Hopfinger EJ, 1990. Weakly depositing turbidity current on a small slope. Hydraul Res 28(1): 55-80.
Bahrami H, 2009. study the effect of slope failure on turbidity current characteristics using a physical model. Phd thesis. Faculty of Water Engineering, Shahid Chamran University of Ahvaz (In Persion).
Daryaee M, Kashefipour SM and Ghomshi M, 2014. Study of Obstacle and Roughness Impacts on Controlling Sedimentary Density Current. Water and Soil Science-University of Tabriz 24(4): 1-9(In Persion).
Garcia MH, 2008. Sedimentation Engineering, Manual 110, Chapter 2, ASCE, Reston, Va.
Garcia MH and Parker G, 1993. Expriments on the entrainment of sediment into suspention by a dense bottom current. J. Geophys. Res 98(C3): 4793-4807.
Graf WH, 1971. Hydraulics of sediment transport. Mc Graw–Hill, New York.
Hosseini SA, Shamsai A and Ataie-Ashtiani B, 2006. Synchronous neasurements of the velocity and concentration in low density turbidity currents using an acoustic Doppler Velocimeter. Flow Measurement and Instrumentation 17(1): 59-68.
Huang H, Imran J and Pirmez C, 2012. The depositional characteristics of turbidity currents in submarine sinuous channels. J. Marine Geology, 329–331.
Kaheh M, 2012. Experimental  investigation of Gravity Current Dynamics on Rough Beds. PHD thesis, Chamran university. Ahwaz, 124p (In Persion).
Keulegan GH, 1957. An experimental study of the motion of saline water from locks into fresh water channels. U. S. Natl. Bur. Stand. Rept 5168.
Khavasi A, 2009. Experimental Study on Deposition Behavior of Turbidity Current. Master's thesis, Faculty of Mechanical Engineering. Sharif University of Technology. 122 pages (In Persion).
Kneller BC, Bennett SJ and McCaffrey WD, 1999. Velocitystructure, turbulence and fluid stresses in experimental gravity currents. J. Geophys. Res 104(C3), 5381–5391.
Kullenberg G, 1977. Entrainment velocity in natural stratified vertical shear flow. Est and Coast Mar Sci 5(3):329-338.
Little WC and Mayer PG, 1976. Stability of channel beds by armoring. J. Hydr. Div 102(11), 1647–1661.
Lu J, Liao X and Zhao G, 2013. Experimental study on effects of geometric distortion upon suspended sediments in bending channels. J. Sedimentary Geology 294:27–36.
Middleton GV, 1966. Experiments on density and turbidity currents, II. Uniform flow of density currents. Can. J. Earth Sci 3, 627–637.
Parker G and Sutherland AJ, 1990. Fluvial armor. J. Hydraul. Res 28(5): 529–544.
Parker G, García M, Fukushima Y and Yu W, 1987. Experiments on turbidity currents over an erodible bed.  J. Hydraul. Res 25(1):123–147.
Rastello M, Ancey C, Ousset F, Magnard R and Hopfinger EJ, 2002. An experimental study of particle-driven gravity currents on steep slopes with entraiment of particles. J. Natural Hazards and Earth System Sciences 2: 181-185.
Sequeiros O, Naruse H, Endo N, Garcia M and Parker G, 2009. Experimental study on self-accelerating turbidity currents, J. Geophys.Res 114, C05025.
Sequeiros O, Spinewine B, Beaubouef R, Sun T, García M and  Parker G, 2010a. Characteristics of Velocity and Excess Density Profiles of Saline Underflows and Turbidity Currents Flowing over a Mobile Bed. J. Hydraul. Eng 136(7):412-433.
Sequeiros O, Spinewine B, Beaubouef R, Sun T, García M and  Parker G, 2010b. Bedload transport and bed resistance associated with density and turbidity currents. Sedimentology 57: 1463–1490.
Shafaee bejestan M, 1999. Sediment hydraulic. Chamran University Press, 548p (In Persion).
Sheikhinejad B and Ghomeshi M, 2014. Providing an Empirical Relationship for Estimating Velocity of Density Current Head over the Bed with Cylindrical Roughness. Water and Soil Science-University of Tabriz. 25(1): 193-204 (In Persion).
Xu JP, Sequiros OE and  Noble MA, 2014. Sediment concentrations, flow condition and downstream evolution of two turbidity currents, Monterey canyon, USA. J. science Direct. Deep-Sea Research I 89:(11-34).
Water and Soil Science
Volume 28, Issue 3
November 2018
Pages 131-140

Files

Share

How to cite

Statistics