Charles Hin Joo Bong, Frederik Josep Putuhena, Tze Liang Lau, Aminuddin Ab. Ghani


There are evidences in existing literatures suggesting the incipient motion values for any particle size is substantially lower for rigid boundary condition as compared to loose boundary condition.  The objective of the current study is to determine the effect of sediment deposition thickness on the critical shear stress for incipient motion. Experimental works for incipient motion were carried out in a rectangular flume with varying sediment deposits thickness. Results showed that the sediment deposits thickness has effect on the critical shear stress at low sediment deposits thickness and the effect will slowly diminish as the sediment deposits thickness increases. Multiple linear regression analysis was performed on the experimental data to develop a new critical shear stress equation.  The best regression model has   value of 0.69;    value of 0.60;  value of 0.009 and Mallow’s  value of 3.00. The new equation appears to be more consistent as compared to existing incipient motion equations for rigid boundary condition by having 80% of the predicted data falls within the acceptable discrepancy ratio when tested with data from other authors. The new equation can be used to determine critical shear stress values for self-cleansing sewerage design and other related engineering applications


Critical shear stress; incipient motion; loose boundary; rigid boundary; sediment

Full Text:



Dey, S., and Papanicolaou, A. 2008. Sediment Threshold under Stream Flow: A State-of-the-Art Review. KSCE Journal of Civil Engineering. 12(1): 45-60.

Novak, P., and Nalluri, C. 1984. Incipient Motion of Sediment Particles over Fixed Beds. Journal of Hydraulic Research. 22(3): 181 - 197.

Mohammadi, M. 2005. The Initiation of Sediment Motion in Fixed Bed Channels. Iranian Journal of Science and Technology. 29(B3): 365-372.

Shields, A. 1936. Anwendung der ahnlichkeitsmechanik und der turbulentzforschung auf die geshiebebewegung. PhD, Mitt. Preuss. Versuchsanst. Wasserbau Schiffbau.

Vongvisessomjai, N., Tingsanchali, T., and Babel, M. S. 2010. Non-deposition Design Criteria for Sewers with Part-full Flow. Urban Water Journal. 7(1): 61-77.

Novak, P., and Nalluri, C. 1975. Sediment Transport in Smooth Fixed Bed Channels. Journal of the Hydraulics Division. 101(HY9): 1139 - 1154.

Salem, A. M. 2013. The Effects of the Sediment Bed Thickness on the Incipient Motion of Particles in a Rigid Rectangular Channel. Seventeenth International Water Technology Conference (IWTC17). Istanbul, Turkey. 5-7 November 2013.

Bong, C. H. J., Lau, T. L., and Ab. Ghani, A. 2013. Verification of Equations for Incipient Motion Studies for a Rigid Rectangular Channel. Water Science and Technology. 67(2): 395-403.

Ashley, R. M., Bertrand-Krajewski, J.-L., Hvitved-Jacobsen, T., and Verbanck, M. A. (Eds.). 2004. Solids in Sewers - Characteristics, Effects and Control of Sewer Solids and Associated Pollutants. London: IWA Publishing.

Verbanck, M. A., Ashley, R. M. and Bachoc, A. 1994. International Workshop on Origin, Occurrence and Behaviour of Sediments in Sewer Systems: Summary of Conclusions. Water Research. 28(1): 187-194.

Almedeij, J. 2012. Rectangular Storm Sewer Design under Equal Sediment Mobility. American Journal of Environmental Science. (4): 376-384.

Paphitis, D. 2001. Sediment Movement under Unidirectional Flows: An Assessment of Empirical Threshold Curves. Coastal Engineering, 43(3-4): 227-245.

El-Zaemey, A. K. S. 1991. Sediment Transport over Deposited Bed Sewers. PhD thesis. Department of Civil Engineering, University of Newcastle upon Tyne.

Lange R.-L., and Wichern, M. 2013. Sedimentation Dynamics in Combined Sewer Systems. Water Science and Technology. 68(4): 756-762.

Ashley, R. M., Wotherspoon, D. J. J., Goodison, M. J., McGregor, I., and Coghlan, B. P. 1992. The Deposition and Erosion of Sediments in Sewers. Water Science and Technology. 26(5-6):1283-1293.

Bong, C. H. J., Lau, T. L. and Ab. Ghani, A. 2014. Sediment Size and Deposition Characteristics in Malaysian Urban Concrete Drains – A Case Study of Kuching City. Urban Water Journal. 11(1): 74-89.

Yalin, M. S. 1977. Mechanics of Sediment Transport. 2nd edition. Great Britain: Pergamon Press.

Kramer, H. 1935. Sand Mixtures and Sand Movement in Fluvial Models. Transactions of the American Society of Civil Engineers. 100(1): 798-838.

Bong, C. H. J. 2013. Self-cleansing Urban Drain using Sediment Flushing Gate based on Incipient Motion. Ph.D thesis, Universiti Sains Malaysia.

Gaucher, J., Marche, C., and Mahdi, T.-F. 2010. Experimental Investigation of the Hydraulic Erosion of Noncohesive Compacted Soils. Journal of Hydraulic Engineering. 136(11): 901-913.

Yalin, M. S., and Karahan, E. 1979. Inception of Sediment Transport. Journal of Hydraulic Division. 105(11): 1433-1443.

Shvidchenko, A. B. 2000. Incipient Motion of Streambeds. Ph.D thesis, University of Glasgow.



  • There are currently no refbacks.

Copyright © 2012 Penerbit UTM Press, Universiti Teknologi Malaysia.
Disclaimer : This website has been updated to the best of our knowledge to be accurate. However, Universiti Teknologi Malaysia shall not be liable for any loss or damage caused by the usage of any information obtained from this web site.
Best viewed: Mozilla Firefox 4.0 & Google Chrome at 1024 × 768 resolution.