Review Study on the Effect of the End Sill Geometry on the Downstream Scour
DOI:
https://doi.org/10.59746/rz64s549Keywords:
End Sill Geometry, Froude Number, Scour, Sediment Size, Stilling BasinAbstract
Excessive downstream scour and inefficient energy dissipation in hydraulic structures remain critical challenges that can compromise structural stability and channel safety. The aim of this study is to evaluate the performance of various end sill geometries in reducing scour depth and improving energy dissipation efficiency. In terms of methodology, a comprehensive review was conducted based on 52 peer-reviewed studies published between 2000 and 2025, covering five primary end sill geometries: rectangular, inclined (sloped), semi-circular, convex, and perforated. The collected data were systematically analyzed to compare hydraulic performance under a wide range of flow conditions. The results indicate that inclined end sills with slopes between 45° and 60° provide significant scour reduction, typically ranging from 50% to 95%. Perforated end sills with porosity ratios of 40–50% demonstrate the highest energy dissipation efficiency, reaching 74% to 94%. Convex geometries are more effective in protecting the channel centerline, whereas concave configurations offer improved bank protection. Additionally, recent studies incorporating computational fluid dynamics (CFD) and machine learning models report high predictive accuracy, with coefficients of determination exceeding 0.98. In conclusion, despite these advancements, several research gaps remain, particularly regarding long-term scour evolution, the effects of sediment gradation, and the interaction between multiple energy dissipation devices. Addressing these gaps is essential for optimizing end sill design under varying hydraulic conditions, including different Froude numbers, sediment characteristics, and structural configurations.
References
[1] W. H. Hager and R. Bremen, “Classical hydraulic jump: sequent depths,” Journal of Hydraulic Research, vol. 27, no. 5, pp. 565–585, 1989, doi: https://doi.org/10.1080/00221688909499111.
[2] A. J. Peterka, Hydraulic design of stilling basins and energy dissipators, no. 25. in Engineering Monograph 25. Denver, CO, USA: Bureau of Reclamation, 1964.
[3] E. A. Elevatorski, Hydraulic Energy Dissipators. in Engineering societies monographs. New York, NY, USA: McGraw-Hill, 1959.
[4] D. V. S. Verma and A. Goel, “Stilling Basins for Pipe Outlets Using Wedge-Shaped Splitter Block,” Journal of Irrigation and Drainage Engineering, vol. 126, no. 3, pp. 179–184, 2000, doi: https://doi.org/10.1061/(ASCE)0733-9437(2000)126:3(179).
[5] J. N. Bradley and A. J. Peterka, “Hydraulic Design of Stilling Basins: Hydraulic Jumps on a Horizontal Apron (Basin I),” Journal of the Hydraulics Division, vol. 83, no. 5, pp. 1401–1424, 1957, doi: https://doi.org/10.1061/JYCEAJ.0000126.
[6] F. S. F. Abdelhaleem, “Effect of semi-circular baffle blocks on local scour downstream clear-overfall weirs,” Ain Shams Engineering Journal, vol. 4, no. 4, pp. 675–684, 2013, doi: https://doi.org/10.1016/j.asej.2013.03.003.
[7] A. Keshavarzi and L. Khaje Noori, “Environmental protection stability of river bed and banks using convex, concave, and linear bed sills,” Environmental Monitoring and Assessment, vol. 171, no. 1, pp. 621–631, 2010, doi: https://doi.org/10.1007/s10661-010-1306-x.
[8] R. Gaudio, A. Marion, and V. Bovolin, “Morphological effects of bed sills in degrading rivers,” Journal of Hydraulic Research, vol. 38, no. 2, pp. 89–96, 2000, doi: https://doi.org/10.1080/00221680009498344.
[9] M. Ben Meftah and M. Mossa, “Scour holes downstream of bed sills in low-gradient channels,” Journal of Hydraulic Research, vol. 44, no. 4, pp. 497–509, 2006, doi: https://doi.org/10.1080/00221686.2006.9521701.
[10] R. Gaudio and A. Marion, “Time evolution of scouring downstream of bed sills,” Journal of Hydraulic Research, vol. 41, no. 3, pp. 271–284, 2003, doi: https://doi.org/10.1080/00221680309499972.
[11] W. H. Hager and D. Li, “Sill-controlled energy dissipator,” Journal of Hydraulic Research, vol. 30, no. 2, pp. 165–181, 1992, doi: https://doi.org/10.1080/00221689209498932.
[12] A. Alikhani, R. Behrozi-Rad, and M. Fathi-Moghadam, “Hydraulic jump in stilling basin with vertical end sill,” International journal of physical sciences, vol. 5, no. 1, pp. 25–29, 2010, doi: https://doi.org/10.5897/IJPS.9000293.
[13] H. L. Tiwari and A. Goel, “Effect of End Sill in the Performance of Stilling Basin Models,” American Journal of Civil Engineering and Architecture, vol. 2, no. 2, pp. 60–63, 2014, doi: https://doi.org/10.12691/ajcea-2-2-1.
[14] H. Hamidifar, M. Nasrabadi, and M. H. Omid, “Using a bed sill as a scour countermeasure downstream of an apron,” Ain Shams Engineering Journal, vol. 9, no. 4, pp. 1663–1669, 2018, doi: https://doi.org/10.1016/j.asej.2016.08.016.
[15] M. E. Emiroglu and M. C. Tuna, “The effect of tailwater depth on the local scour downstream of stepped-chutes,” KSCE Journal of Civil Engineering, vol. 15, no. 5, pp. 907–915, 2011, doi: https://doi.org/10.1007/s12205-011-0921-6.
[16] M. C. Tuna and M. E. Emiroglu, “Effect of Step Geometry on Local Scour Downstream of Stepped Chutes,” Arabian Journal for Science and Engineering, vol. 38, no. 3, pp. 579–588, 2013, doi: https://doi.org/10.1007/s13369-012-0335-x.
[17] E. Eghlidi, G.-A. Barani, and K. Qaderi, “Laboratory Investigation of Stilling Basin Slope Effect on Bed Scour at Downstream of Stepped Spillway: Physical Modeling of Javeh RCC Dam,” Water Resources Management, vol. 34, no. 1, pp. 87–100, 2020, doi: https://doi.org/10.1007/s11269-019-02395-5.
[18] G. Oliveto and V. Comuniello, “Local Scour Downstream of Positive-Step Stilling Basins,” Journal of Hydraulic Engineering, vol. 135, no. 10, pp. 846–851, 2009, doi: https://doi.org/10.1061/(ASCE)HY.1943-7900.0000078.
[19] Y. Aminpour and J. Farhoudi, “Similarity of Local Scour Profiles Downstream of Stepped Spillways,” International Journal of Civil Engineering, vol. 15, no. 5, pp. 763–774, 2017, doi: https://doi.org/10.1007/s40999-017-0168-9.
[20] F. Tajabadi, E. Jabbari, and H. Sarkardeh, “Effect of the end sill angle on the hydrodynamic parameters of a stilling basin,” The European Physical Journal Plus, vol. 133, no. 1, p. 10, 2018, doi: https://doi.org/10.1140/epjp/i2018-11837-y.
[21] M. E.-S. El-Mahdy, “Experimental method to predict scour characteristics downstream of stepped spillway equipped with V-Notch end sill,” Alexandria Engineering Journal, vol. 60, no. 5, pp. 4337–4346, 2021, doi: https://doi.org/10.1016/j.aej.2021.03.018.
[22] L. Jiang, M. Diao, and C. Wang, “Investigation of a Negative Step Effect on Stilling Basin by Using CFD,” Entropy, vol. 24, no. 11, p. 1523, 2022, doi: https://doi.org/10.3390/e24111523.
[23] M. A. Lenzi, A. Marion, F. Comiti, and R. Gaudio, “Local scouring in low and high gradient streams at bed sills,” Journal of Hydraulic Research, vol. 40, no. 6, pp. 731–739, 2002, doi: https://doi.org/10.1080/00221680209499919.
[24] R. Rashed, A. El-Masry, and H. AbdelGawad, “Effect of hollow semi-circular baffles arrangement on local scour downstream hydraulic structures,” Mansoura Engineering Journal, vol. 47, no. 3, pp. 22–31, 2022, doi: https://doi.org/10.21608/bfemu.2022.246315.
[25] N. J. H. Al-Mansori, T. J. M. Alfatlawi, K. S. Hashim, and L. S. Al-Zubaidi, “The Effects of Different Shaped Baffle Blocks on the Energy Dissipation,” Civ Eng J, vol. 6, no. 5, pp. 961–973, 2020, doi: https://doi.org/10.28991/cej-2020-03091521.
[26] R. Daneshfaraz, R. Norouzi, P. Ebadzadeh, S. Di Francesco, and J. P. Abraham, “Experimental Study of Geometric Shape and Size of Sill Effects on the Hydraulic Performance of Sluice Gates,” Water, vol. 15, no. 2, p. 314, 2023, doi: https://doi.org/10.3390/w15020314.
[27] M. Sohrabi, A. Keshavarzi, and M. Javan, “Impact of bed sill shapes on scour protection in river bed and banks,” International Journal of River Basin Management, vol. 17, no. 3, pp. 277–287, 2019, doi: https://doi.org/10.1080/15715124.2018.1498855.
[28] A. Keshavarzi, R. Gazni, and S. R. Homayoon, “Prediction of scouring around an arch-shaped bed sill using Neuro-Fuzzy model,” Applied Soft Computing, vol. 12, no. 1, pp. 486–493, 2012, doi: https://doi.org/10.1016/j.asoc.2011.08.019.
[29] E. Asadi, A. Gholizad, N. Mirzaei, A. Hosseinzadeh Dalir, and A. Seyedzadeh, “Geometric characteristics of a cylindrical deflector above the end-sill of a stilling basin,” ISH Journal of Hydraulic Engineering, vol. 29, no. sup1, pp. 104–111, 2023, doi: https://doi.org/10.1080/09715010.2023.2180329.
[30] U. A. Jahad et al., “Flow characteristics and energy dissipation over stepped spillway with various step geometries: case study (steps with curve end sill),” Applied Water Science, vol. 14, no. 3, p. 60, 2024, doi: https://doi.org/10.1007/s13201-024-02110-9.
[31] M. Bagherzadeh and M. Mohammadi, “Impact of gabion sill on scouring depth downstream grade control structures,” Results in Engineering, vol. 27, p. 105717, 2025, doi: https://doi.org/10.1016/j.rineng.2025.105717.
[32] E. A. Elnikhely, “Investigation and analysis of scour downstream of a spillway,” Ain Shams Engineering Journal, vol. 9, no. 4, pp. 2275–2282, 2018, doi: https://doi.org/10.1016/j.asej.2017.03.008.
[33] U. K. Singh and P. Roy, “Energy dissipation in hydraulic jumps using triple screen layers,” Applied Water Science, vol. 13, no. 1, p. 17, 2022, doi: https://doi.org/10.1007/s13201-022-01824-y.
[34] A. Abbaspour, T. Taghavianpour, and H. Arvanaghi, “Experimental study of the hydraulic jump on reverse bed with porous screens,” Applied Water Science, vol. 9, no. 7, p. 155, 2019, doi: https://doi.org/10.1007/s13201-019-1032-7.
[35] E. M. Elshahat, G. M. AbdelAal, S. Hassan, and E. Eltohamy, “Effect of Perforated Sills on Maximum Scour Depth Downstream From a Sluice Gate,” The Open Civil Engineering Journal, vol. 17, p. e187414952308310, 2023, doi: http://dx.doi.org/10.2174/18741495-v17-e230906-2023-21.
[36] R. K. Zorab and S. M. Kashefipour, “A Laboratory Study on the Effect of One and Two Perforated Sills from the Beginning of the Stilling Basin on Head Loss and Hydraulic Jump Characteristics,” vol. 42, no. 3, pp. 47–60, 2019, doi: https://doi.org/10.22055/jise.2019.14812.
[37] N. Torkamanzad, A. Hosseinzadeh Dalir, F. Salmasi, and A. Abbaspour, “Hydraulic Jump below Abrupt Asymmetric Expanding Stilling Basin on Rough Bed,” Water, vol. 11, no. 9, p. 1756, 2019, doi: https://doi.org/10.3390/w11091756.
[38] S. Pagliara and M. Palermo, “Scour Control Downstream of Block Ramps,” Journal of Hydraulic Engineering, vol. 134, no. 9, pp. 1376–1382, 2008, doi: https://doi.org/10.1061/(ASCE)0733-9429(2008)134:9(1376).
[39] R. Padulano, O. Fecarotta, G. Del Giudice, and A. Carravetta, “Hydraulic Design of a USBR Type II Stilling Basin,” Journal of Irrigation and Drainage Engineering, vol. 143, no. 5, p. 04017001, 2017, doi: https://doi.org/10.1061/(ASCE)IR.1943-4774.0001150.
[40] F. Fatima, M. K. Sarwar, F. U. Haq, and A. Raza, “CFD Simulation of hydraulic jump in the USBR type-III stilling basin with converged walls,” AQUA - Water Infrastructure, Ecosystems and Society, vol. 73, no. 5, pp. 888–901, 2024, doi: https://doi.org/10.2166/aqua.2024.317.
[41] M. W. Zaffar, I. Hassan, U. Latif, S. Jahan, and Z. Ullah, “Numerical Investigation of Scour Downstream of Diversion Barrage for Different Stilling Basins at Flood Discharge,” Sustainability, vol. 15, no. 14, p. 11032, 2023, doi: https://doi.org/10.3390/su151411032.
[42] S. Y. Kumcu and K. Ispir, “Experimental and numerical modeling of various energy dissipater designs in chute channels,” Applied Water Science, vol. 12, no. 12, p. 266, 2022, doi: https://doi.org/10.1007/s13201-022-01792-3.
[43] M. W. Zaffar and I. Hassan, “Hydraulic investigation of stilling basins of the barrage before and after remodelling using FLOW-3D,” Water Supply, vol. 23, no. 2, pp. 796–820, 2023, doi: https://doi.org/10.2166/ws.2023.032.
[44] M. W. Zaffar and I. Hassan, “Numerical investigation of hydraulic jump for different stilling basins using FLOW-3D,” AQUA - Water Infrastructure, Ecosystems and Society, vol. 72, no. 7, pp. 1320–1343, 2023, doi: https://doi.org/10.2166/aqua.2023.290.
[45] A. Bayon-Barrachina and P. A. Lopez-Jimenez, “Numerical analysis of hydraulic jumps using OpenFOAM,” Journal of Hydroinformatics, vol. 17, no. 4, pp. 662–678, 2015, doi: https://doi.org/10.2166/hydro.2015.041.
[46] J. F. Macián-Pérez, F. J. Vallés-Morán, and R. García-Bartual, “Assessment of the Performance of a Modified USBR Type II Stilling Basin by a Validated CFD Model,” Journal of Irrigation and Drainage Engineering, vol. 147, no. 11, p. 04021052, 21 AD, doi: https://doi.org/10.1061/(ASCE)IR.1943-4774.0001623.
[47] M. W. Zaffar, I. Haasan, and A. R. Ghumman, “Performance Evaluation of Different Stilling Basins Downstream of Barrage Using FLOW-3D Scour Models,” Hydrology, vol. 10, no. 12, p. 223, 2023, doi: https://doi.org/10.3390/hydrology10120223.
[48] C. Abdi Chooplou, E. Kahrizi, A. Fathi, M. Ghodsian, and M. Latifi, “Baffle-Enhanced Scour Mitigation in Rectangular and Trapezoidal Piano Key Weirs: An Experimental and Machine Learning Investigation,” Water, vol. 16, no. 15, p. 2133, 2024, doi: https://doi.org/10.3390/w16152133.
