Examination of the Effect of Cubic Artificial Roughness Density inInclined Channel on Downstream Scour Depth

Document Type : Research Paper


1 Master Student, Department of Hydraulic Structures, Shahid Chamran University of Ahvaz.

2 Assistant Professor in Hydraulic Structure of Shahid Chamran University of ahvaz


Water passage from  steep slopes in river engineering issues and the design of water transfer structures is inevitable. Because of the steep slope of the surface, the surface velocity and surface erosion rates are high. Energy control in high-speed flows is one of the challenges of designing hydraulic structures. These flows, for example, occur in places such as dam overhead structures, drainage systems of urban areas and Mountain Rivers with a steep slope. One of the ways to reduce dimensions or eliminate energy depreciating structures is to use methods to reduce the kinetic energy of flow over the weir, including using of stairs or blocks on the overflow. The use of large-sized stairs or blocks will cause the passing jets of flow to be separated and as a result turbulent, which can effectively deplete the kinetic energy of the current. The problem with using a staircase or block is a huge cost of built and a high risk of cavitation. Another method of energy depreciation is to apply roughness at the overflow bed, which may be an efficient way to reduce energy. Roughness can dramatically reduce the flow turbulence, and thus reduces the risk of cavitation. Also, roughness can reduce the flow power over the overflow and reduce the depth of the lower erosion pit by removing or reducing the dimensions of the relaxation basin. Most studies in this field have investigated the effect of these roughs on the amount of energy depletion, which in addition to energy depletion is also important for lowering the erosion of the structure. However, for the economic design of hydraulic structures, designers need to have full knowledge of the particle mechanics and the dimensions of the scour hole, so that they can consider the requirements for the stability of the structure, which has so far been  investigated insufficiently. Therefore, the present study aimed to investigate the effect of roughness density on sloped bed surface on its downstream scour depth.


Main Subjects

1-    Adduce, C. and Sciortino, G., 2006. Scour due to a horizontal turbulent jet: Numerical and experimental investigation. Journal of hydraulic research, 44(5), pp.663-673.
2-    Dey, S. and Sarkar, A., 2006. Scour downstream of an apron due to submerged horizontal jets. Journal of hydraulic engineering, 132(3), pp.246-257.
3-    Farhoudi, J. and Smith, K.V., 1985. Local scour profiles downstream of hydraulic jump. Journal of Hydraulic Research, 23(4), pp.343-358.
4-    Hamidi Far, H., Omid, H.A., 2010, No cohesive Sediment Scour Downstream of an Apron”, Journal of Agricultural Engineering Research, 11(2):17-28, (In Persian).
5-    Hosseini, M., Abrishami, J., 2015, Open Channel Hydraulics, Astan Ghods Razavi, pp 613, (In Persian).
6-    Kazemi Nasaban, G., 1996, Study of the Depth of Scour Downstream of Gabion's Stepping Smash, 4th Conference of River Engineering, Shahid Chamran Ahvaz University, (In Persian).
7-    Khalili, S., Farhoudi, J., 2013, Scour Profiles and Variation of Shear Stresses in Scour Holes Downstream of Adverse Stilling Basins, Journal of Hydraulics, 7(4), pp. 85-99, (In Persian).
8-    Mousavi, S. 2004, Study of Depth of Scour Downstream of Stepping Smash, Master Thesis, Shahid Chamran Ahvaz University, (In Persian).
9-    Novak P, 1961. Influence of Bed Load Passage on Scour and Turbulence Downstream of Stilling Basin. Proceeding of 19th IAHR Conf. Dubrovnik: 66-75.
10- Omidi, S., Shafaie Bajestan, M., 2014, “Investigation of Scour Depth Downstream of Stilling Basin for the Case of B-Jump” Journal of Irrigation Sciences and Engineering, 38(4), pp 125-136, (In Persian).
11- Pagliara, S, and Chiavaccini, P. (2006). Energy Dissipation on Block Ramps. Journal of Hydraulic Engineering. ASCE. 132(1): 41-48.
12- Pagliara, 2007. Influence of Sediment Gradation on Scour Downstream of Block Ramps. Journal of Hydraulic Engineering. ASCE. 133(11): 1241-1248.
13- Pagliara, M.Palermo, (2008) .Score Control Downstream of Block Ramps in Basins With Continuous and Denated Sill. 16th IAHR-APD Congress and 3rd Symposium of IAHR-ISHS.
14-  PAGLIARA, S. and PALERMO, M., 2008. Scour downstream of a block ramp in asymmetric stilling basins. In Fourth International Conference on Scour and Erosion ICSE-4 (pp. 240-245).
15- Rahmanshahi, M., Shafai Bajestan, M., 2012, Experimental Investigation of the Effect of Chute Bed Roughness Height on Energy Dissipation, Water and Soil Science, 22(2), pp. 95-106, (In Persian).
16- Sayahi, A., 1993, Review and Forecast of Maximum Depth of Local Scour Downstream of Saint Anthony Falls Stilling Basin, Master Thesis, Shahid Chamran University, (In Persian).
17- Ahmad, Z., Petappa, N.M. and Westrich, B., 2009. Energy dissipation on block ramps with staggered boulders. Journal of Hydraulic Engineering, 135(6), pp.522-526.
Volume 41, Issue 4
January 2019
Pages 147-159
  • Receive Date: 12 December 2016
  • Revise Date: 02 May 2017
  • Accept Date: 03 May 2017
  • Publish Date: 22 December 2018