Experimental investigation of the effect of geometrical parameters on the equilibrium time of scour around the complex pier group

Document Type : Research Paper


1 M.Sc. student, Depratment of Water Engineering, University of Guilan, Rasht, Iran.

2 Associate Professor, Depratment of Water Engineering, Department of water and environmental engineering, Caspian Sea basin research center, University of Guilan, Rasht, Iran.(

3 Assistant Professor, Depratment of Water Engineering, University of Guilan, Rasht.

4 Associate Professor, Depratment of Civil and Environmental Engineering, Politecnico di Milano, Milan, Italy.


Scour around the bridge piers is a kind of erosion that occurs due to complex vortex flows and finally creates a hole around the bridge piers (Yang et al., 2019). The maximum scour depth, which called Equilibrium scour depth, can take a very long time to reach. Although many researches have been carried out to determine the equilibrium scour time, there is still no suitable criteria for determining the equilibrium scour time for the complex piers which consist of the pile group, pile cap and piers. In the present study, considering the importance of this fact that the local scour process is dependent on time, the effect of the complex pier geometrical parameters on the equilibrium scour time around the complex pier is investigated. In addition, a regression equation for the estimation of equilibrium scour time was presented which has suitable performance to estimate desired output in the range of the experimental data of the present study.


Main Subjects

  • Chabert, J. and Engeldinger, P., 1956. Study of the scour around the bridge piers. Laboratoire National d'Hydraulique. Chatou, October.
  • Coleman, S. E., Lauchlan, C.S. and Melville, B. W., 2003. Clear water scour development at bridge abutments. Journal of Hydraulic Research, 41(5): 521-531. Doi: 1080/00221680309499997.


  • Esmaeili Varaki, M., Tavazo, N. and Radice, A., 2022. Using a bed sill as a countermeasure for clear-water scour at a complex pier with inclined columns footed on capped piles. Hydrology, 9(65): 1-19. Doi: 3390/hydrology9040065.


  • Ferraro, D., Tafarojnoruz, A., Gaudio, R. and Cardoso, A. H., 2013. Effects of pile cap thickness on the maximum scour depth at a complex pier. Journal of Hydraulic Engineering, 139 (5): 482–491. Doi: 10.1061/(ASCE)HY .1943-7900.0000704.


  • Grimaldi, C., 2005. Non-conventional countermeasures against local scouring at bridge piers. D. Thesis, Hydraulic Engineering for Environment and Territory, Univ. of Calabria.


  • Krause, P., Boyle, D. and Bäse, F., 2005. Comparison of different efficiency criteria for hydrological model assessment. Advances in Geosciences, 5: 89-97.doi:10.5194/adgeo-5-89-2005.


  • Lagasse, P. F., Clopper, P.E., Pagan-Qrtiz, J. E., Zevenbergen,L. W., Arneson, L. A., Schall, J. D. and Girard. L. G., 2009. Bridge Scour and Stream Instability Countermeasures, Experience, Selection, and Design Guidance. FHWA, Hydraulic Engineering Cirular, No. 23.


  • Lança, R. M., Fael, C. S., Maia, R. J., Pêgo, J. P, and Cardoso. A. H., 2013. Clear-water scour at comparatively large cylindrical piers. Journal of Hydraulic Engineering, 139 (11): 1117–1125.


  • Lee, S. O., 2006. Physical modeling of local scour around complex bridge piers. Gooria Instiute of Technology.


  • Lu, J. Y., Shi, Z. Z., Hong, J. H., Lee, J. J. and Raikar, V. K., 2011. Temporal variation of scour depth at nonuniform cylindrical piers. Journal of Hydraulic Engineering, 137(1): 45–56.


  • Melville, B.W., Sutherland, A.J., 1988. Design method for local scour at bridge piers. . Journal of Hydraulic Engineering, 114(10): 1210-1226.


  • Melville, B. W. and Chiew, Y. M, 1999. Time scale for local scour at bridge piers. Journal of Hydraulic Engineering, 125 (1): 59–65.


  • Moreno, M. R. and Couto. L., 2015. Effects of relative column width and pile-cap elevation on local scour depth around complex piers. Journal of Hydraulic Engineering, 142 (2): 04015051.


  • Moreno, M. R. and, L., 2016. Prediction of equilibrium local scour depth at complex bridge piers. Journal of Hydraulic Engineering,142(11): 04016045.


  • Nash, J. E. and Sutcliffe, J. V., 1970. River flow forecasting through conceptual models part I—A discussion of principles. Journal of Hydrology, 10(3): 282-290. Doi:10.1016/0022-1694(70)90255-6.


  • Oliveto G. and Hager, W. H., 2002. Temporal evolution of clear-water pier and abutment scour. Journal of Hydraulic Engineering, 128(9): 811- Doi: 10.1061/(ASCE)0733-9429(2002)128:9(811).
  • Oliveto, G., and Hager. W. H., 2005. Further results to time-dependent local scour at bridge elements. Journal of Hydraulic Engineering, 131(2): 97-


  • Raudkivi, A. J. and Ettema. R., 1983. Clear-water scour at cylindrical piers. Journal of Hydraulic Engineering, 109(3): 339-350.


  • Richardson, E. V. and Davis, S. R., 2001. Evaluating scour at bridges. Hydraulic Engineering Circular No. 18 (HEC-18). Rep. No. FHWA NHI 01-001, Federal Highway Administration, Washington, D.C.


  • Sheppard, D. M. and Renna, R. 2005. Florida bridge scour manual. Tallahassee, FL: Published by Florida Department of Transportation.


  • Simarro, G., Fael, C. M. and Cardoso, A. H., 2011. Estimating equilibrium scour depth at cylindrical piers in experimental studies. Journal of Hydraulic Engineering, 137 (9): 1089–1093.


  • Yang, Y. Melville, B.W. Macky, G. H. and Shamseldin, A. Y., 2019. Local scour at complex bridge piers in close proximity under clear-water and live-bed flow regime. , 11: 1530. doi.org/10.3390/w11081530.


  • Yang, Y., Melville, B.W. Macky, G. H. and Shamseldin, A. Y., 2020. Temporal evolution of clear water local scour at aligned and skewed complex bridge piers. Journal of Hydraulic Engineering, 146(4): 04020026.
Volume 47, Issue 1
June 2024
Pages 99-117
  • Receive Date: 10 December 2022
  • Revise Date: 29 April 2023
  • Accept Date: 01 May 2023
  • Publish Date: 21 May 2024