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Effect of Step Geometry on Local Scour Downstream of Stepped Chutes

  • Research Article - Civil Engineering
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Abstract

A chute is characterized by a steep bed slope associated with torrential flow. The chute flow may be either smooth or stepped. Stepped spillways (or chutes) have become a popular method for handling flood releases. Scour hole formed downstream of a chute may affect the safety and stability of the hydraulic structure. In this study, the effect of step geometry on the dynamics of local scour processes is analyzed in the context of the scour that takes place downstream from a stepped chute. Three different step heights have been used to study the scour process for various chute angles, stilling basin sill heights, tailwater depths and flow rate conditions. A total of 216 laboratory tests have been conducted and the findings have been analyzed to determine the influence of step geometry on the scouring at the downstream of the stepped chute. The results show that the equilibrium depth of scour is highly dependent on the step geometry. In addition, the equilibrium depth of scour decreases while the step height increases. Also, the equilibrium depth of scour also increases with an increase in the discharge and the chute angle.

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Abbreviations

DH1:

Stilling basin without sill

DH2:

Stilling basin sill height with 0.02 m

DH3:

Stilling basin sill height with 0.04 m

M1:

Material 1, thin sediment, d 50 = 3.17 mm

M2:

Material 2, thick sediment, d 50 = 9.94 mm

b :

Step length [L]

b̃:

b/h [M0L0T0]

C u :

Coefficient of uniformity [M0L0T0]

d 16 :

Grain size for which 16 % of material is finer [L]

d 50 :

Mean diameter of bed material [L]

d 84 :

Grain size for which 84 % of material is finer [L]

d̃:

d 50 /h [M0L0T0]

d smax :

Maximum scour depth [L]

h :

Step height [L]

h g :

Control gate height [L]

h s :

Stilling basin sill height [L]

h̃s :

h s /h [M0L0T0]

h t :

Tailwater depth [L]

h̃t :

h t /h [M0L0T0]

H :

Total height of stepped-channel chute [L]

e :

Void ratio [M0L0T0]

G s :

Specific gravity (s.g) [M0L0T0]

g :

Acceleration of gravity [LT−2]

F d :

Densimetric Froude number [M0L0T0]

h c :

Critical flow depth [L]

J :

Slope of the water [M0L0T0]

L o :

Scour hole length [L]

L :

Length of stepped-channel chute [L]

L a :

Aerated flow region length [L]

L i :

Length of non-aerated flow region [L]

L d :

Length of stilling basin [L]

n :

Porosity [M0L0T0]

q :

Unit discharge [L3 T−1L−1]

Δ:

s − 1 [M0L0T0]

α :

Chute angle [M0L0T0]

γ d :

Dry unit weight of the particles [M L−2T−2]

γ s :

Unit weight of the particles [M L−2T−2]

γ w :

Unit weight of the water [M L−2T−2]

v :

Kinematic viscosity of water [L2T−1]

ρ :

Mass density of the water [ML−3]

ρ s :

Mass density of the bed material [ML−3]

β :

Upstream slope of scour hole [M0L0T0]

δ :

Horizontal location of the maximum scour depth reckoned from the end of the non-erodible bed [L]

σ g :

Geometric standard deviation [M0L0T0]

References

  1. Chatila J.G., Jurdi B.: Stepped spillway as an energy dissipater. Can. Water Resour. J. 29(3), 147–158 (2004)

    Article  Google Scholar 

  2. Cheng X., Chen Y., Luo L.: Numerical simulation of air–water two phase flow over stepped spillways. Sci. China Ser. E Technol. Sci. 49(6), 674–684 (2006)

    Article  MATH  Google Scholar 

  3. Qian Z.D., Hu X.Q., Huani W.X., Amador A.: Numerical simulation and analysis of water flow over stepped spillways. Sci. China Ser. E Technol. Sci. 52(7), 1958–1965 (2009)

    Article  MATH  Google Scholar 

  4. Khatsuria R.M.: Hydraulics of Spillways and Energy Dissipators. Marcel Dekker, New York (2005)

    Google Scholar 

  5. Breusers, H.N.C.; Raudkivi, A.J.: Scouring Hydraulic Structures Design Manual. A. A. Balkema, Rotterdam (1991)

  6. Dey S., Westrich B.: Hydraulics of submerged jet subject to change in cohesive bed geometry. J. Hydraul. Eng. ASCE 129(1), 44–53 (2003)

    Article  Google Scholar 

  7. Hassan M.K., Narayanan R.: Local scour downstream of an apron. J. Hydraul. Eng. ASCE 111(11), 1371–1385 (1985)

    Article  Google Scholar 

  8. Sarkar A., Dey S.: Scour hole downstream of aprons caused by sluices. Water Manag. 158(2), 55–64 (2005)

    Google Scholar 

  9. Dargahi B.: Controlling mechanism of local scour. J. Hydraul. Eng. ASCE 116(10), 1197–1214 (1990)

    Article  Google Scholar 

  10. Novak, P.: Study of stilling basins with special regard to their end sill. In: Proceedings of the 6th IAHR Conference, The Hague, paper C15 (1955)

  11. Schoklitsch, A.: Kolkbildung unter Überfallstrahlen. Wasserwirtschaft (1932)

  12. Jaeger, C.H.: Über die Ähnlichkeit bei flussbaulichenModellversuchen. Wasserwirtschaft und Wassertecknik 34 No 32/27, 269 (1939)

  13. Eggenberger, W.; Muller, R.: Experimentelle und theoretische Untersuchungen über das Kolkproblem. Mitteil., Versuchsanstalt f. Wasserbau, N0 5, Zurich (1944)

  14. Breusers, H.N.C.: Conformity and time scale in two-dimensional local scour. In: Proceedings of the Symposium on Model and prototype Conformity Hydraulics Research Laboratory, Poona, India, pp. 1–8 (1966)

  15. Kotoulas, D.: Das Kolkproblem unter Berüchsichtigung der Faktoren Zeit und Geschiebemischung im Rahmen derWildbachverbauung. Diss. T.U. Braunschweig (1967)

  16. Chatterjee S.S., Ghosh S.N.: Submerged horizontal jet over erodible bed. J. Hydraul. Div. 106(11), 1765–1782 (1980)

    Google Scholar 

  17. Chatterjee S.S., Ghosh S.N., Chatterjee M.: Local scour due to submerged horizontal jets. J. Hydraul. Eng. ASCE 120(8), 973–992 (1994)

    Article  Google Scholar 

  18. Sarkar A., Dey S.: Review on local scour due to jets. Int. J. Sediment Res. 19(3), 210–238 (2004)

    Google Scholar 

  19. Ghobadian R., Bajestan M.S.: Investigation of sediment patterns at river confluence. J. Appl. Sci. 7(10), 1372–1380 (2007)

    Article  Google Scholar 

  20. Dey S., Raikar R.V.: Scour below a high vertical drop. J. Hydraul. Eng. ASCE 133(5), 564–568 (2007)

    Article  Google Scholar 

  21. Farhoudi J., Smith K.V.H.: Local scour profiles downstream of hydraulic jump. J. Hydraul. Res. 23(4), 343–358 (1985)

    Article  Google Scholar 

  22. Simons D.B., Senturk F.: Sediment Transport Technology. Water Resources Publications, Fort Collins (1977)

    Google Scholar 

  23. Oliveto G., Comuniello V.: Local scour downstream of positive-step stilling basins. J. Hydraul. Eng. 135(10), 846–851 (2009)

    Article  Google Scholar 

  24. Comiti F., Andreoli A., Lenzi A.: Morphological effects of local scouring in step-pool streams. Earth Surf. Process. Landf. 30(12), 1567–1581 (2005)

    Article  Google Scholar 

  25. Emiroglu M.E., Tuna M.C.: The effect of tailwater depth on the local scour downstream of stepped-chutes. KSCE J. Civ. Eng. 15(5), 907–915 (2011)

    Article  Google Scholar 

  26. Ohtsu, I.; Yasuda, Y.: Characteristics of flow conditions on stepped channels. In: Proceedings of 27th IAHR Congress, San Francisco, USA, pp. 583–588 (1997)

  27. Ohtsu I., Yasuda Y., Takahashi M.: Discussion of ‘Onset of skimming flow on stepped spillways’. J. Hydraul. Eng. ASCE 127(6), 522–524 (2001)

    Article  Google Scholar 

  28. Chanson, H.: The hydraulics of stepped chutes and spillways. Balkema, Lisse (2002)

  29. Boes R., Hager W.H.: Two-phase flow characteristics of stepped spillways. J. Hydraul. Eng. ASCE 129(9), 661–670 (2003)

    Article  Google Scholar 

  30. Baylar A., Emiroglu M.E., Bagatur T.: An experimental investigation of aeration performance in stepped spillways. Water Environ. J. 20(1), 35–42 (2006)

    Article  Google Scholar 

  31. Chanson H.: Hydraulic design of stepped spillways and downstream energy dissipators. Dam Eng. 11(4), 205–242 (2001)

    Google Scholar 

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Authors and Affiliations

  1. Civil Engineering Department, Firat University, Elazig, 23119, Turkey

    M. Cihat Tuna & M. Emin Emiroglu

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  1. M. Cihat Tuna
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  2. M. Emin Emiroglu
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Correspondence to M. Cihat Tuna.

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Tuna, M.C., Emiroglu, M.E. Effect of Step Geometry on Local Scour Downstream of Stepped Chutes. Arab J Sci Eng 38, 579–588 (2013). https://doi.org/10.1007/s13369-012-0335-x

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