Abstract
This paper reports on an experimental study of the effect of tailwater depth on local scour downstream of stepped-chutes. Different tailwater conditions were tested to study the form of the scour for two gradations of non-cohesive bed material, various flow rates, chute angles, sill heights and step heights. Measurements were taken to obtain the scour hole profile in the equilibrium state of scour, the value of the maximum depth of scour, the location of the maximum scour depth, and the length of the scour hole. The present results indicate that maximum depth and area of scour are highly dependent on tailwater depth. Moreover, the maximum scour depth increases with increases in the discharge and the tailwater depth. It was also found that step geometry, stepped chute angle and the sill types of the stilling basin are very important parameters for scour hole and geometry. A comparison was made between the scour characteristics produced by different tailwater depths. Empirical correlations predicting maximum scour depth were developed. Hence, accurate equations for the maximum scour depth are introduced.
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References
Balachandar, R. and Kells, J. A. (1998). “Instantaneous water surface and bed scour profiles using video image analysis.” Canadian J. of Civil Engineering, Vol. 25, No. 4, pp. 662–667.
Balachandar, R., Kells, J. A., and Thiessen, R. J. (2000). “The effect of tailwater depth on the dynamics of local scour.” Canadian J. of Civil Engineering, Vol. 27, pp. 138–150.
Baylar, A., Bagatur, T., and Emiroglu, M. E. (2007). “Prediction of oxygen content of nappe, transition and skimming flow regimes in stepped-channel chutes.” J. of Environmental Engineering and Science, Vol. 6, No.2, pp. 201–208.
Boes, R. and Hager, W. H. (2003). “Two-phase flow characteristics of stepped spillways.” J. of Hydraulic Engineering, ASCE, Vol. 129, No. 9, pp. 661–670.
Breusers, H. N. C. and Raudkivi A. J. (1966). “Conformity and time scale in two-dimensional local scour.” Proc. Symp. On Model and Prototype Conformity, Hydr. Res. Lab., Poona, India, pp. 1–8.
Chanson, H. (2001). The hydraulics of stepped chutes and spillways, A. A. Balkema Publishers, Lisse.
Chatterjee, S. S. and Ghosh S. N. (1980). “Submerged horizontal jet over erodible bed.” J. Hydraulics Div., Vol. 106, No. 11, pp. 1765–1782.
Chatterjee, S. S., Ghosh, S. N., and Chatterjee, M. (1994). “Local scour due to submerged horizontal jets.” J. Hydraul. Eng., Vol. 120, No. 8, pp. 973–992.
Dey, S. and Raikar, R. V. (2005). “Scour in long contractions.” J. Hydraul. Eng., Vol. 128, No. 8, pp. 778–791.
Dey, S. and Raikar, R. V. (2007). “Scour below a high vertical drop.” J. Hydraul. Eng., Vol. 133, No. 5, pp. 564–568.
Dey, S. and Westrich, B. (2003). “Hydraulics of submerged jet subject to change in cohesive bed geometry.” J. Hydraul. Eng., Vol. 129, No. 1, pp. 44–53.
Farhoudi, J. and Smith, K. V. H. (1982). “Time scale for scour downstream of hydraulic jump.” J. Hydraul. Div., Vol. 108, No. 10, pp. 1147–1162.
Farhoudi, J. and Smith, K. V. H. (1985). “Local scour profiles downstream of hydraulic jump.” J. Hydraul. Res., Vol. 23, No. 4, pp. 343–358.
Hassan, N. M. K. and Narayanan, R. (1985). “Local scour downstream of an apron.” J. Hydraul. Eng., Vol. 111, No. 11, pp. 1371–1385.
Hoffmans, G. J. C. M. and Pilarczyk, K. W. (1995). “Local scour downstream of hydraulic structures.” J. of Hydraul. Eng., Vol. 121, No. 4, pp. 326–340.
Johnston, A. J. (1990). “Scour hole developments in shallow tailwater.” J. of Hydraulic Research, Vol. 28, No. 3, pp. 341–354.
Mohamed, M. S. and McCorquodale, J. A. (1992). “Short-term local scour.” J. of Hydraulic Research, Vol. 30, No. 5, pp. 685–699.
Rajaratnam, N. (1981). “Erosion by plane turbulent jets.” J. of Hydraulic Research, Vol. 19, No. 4, pp. 339–358.
Sarkar, A. and Dey, S. (2004). “Review on local scour due to jets.” Int. J. Sediment Res., Vol. 19, No. 3, pp. 210–238.
Sarkar, A. and Dey, S. (2005). “Scour hole downstream of aprons caused by sluices.” Proc. Inst. Civ. Eng., Water Management, Vol. 158, No. 2, pp. 55–64.
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Emin Emiroglu, M., Cihat Tuna, M. The effect of tailwater depth on the local scour downstream of stepped-chutes. KSCE J Civ Eng 15, 907–915 (2011). https://doi.org/10.1007/s12205-011-0921-6
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DOI: https://doi.org/10.1007/s12205-011-0921-6