• Ali Qasim Rdhaiwi Department of Civil Engineering, Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan, Iran https://orcid.org/0000-0002-6608-9429
  • Ali Khoshfetrat Department of Civil Engineering, Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan, Iran
  • Amirhossein Fathi Faculty of Civil and Environmental Engineering, Tarbiat Modares University, Tehran, Iran




Piano key weir (PKW), scour, scour index, stilling basin


In recent years, engineers have focused on finding a solution to reduce scouring downstream of piano key weirs. Piano key weirs have high efficiency in flood flow and a higher discharge coefficient. In this research, a type C trapezoidal piano key weir with a type 1 stilling basin was used. Three discharges and three water depths were also used. The results showed that the existence of the stilling basin reduces scour. In the weir with the stilling basin, the maximum scour depth is reduced and the scouring hole becomes more elongated. The maximum distance of the scouring depth increases compared to the toe of the weir. The maximum scour depth and the maximum scour depth distance in the weirs with the stilling basin are about 63.4% less and 20.4% more, respectively than in the weirs without the stilling basin. Additionally, by increasing the flow rate and decreasing the depth of the downstream flow, the amount of scour increases.


Kabiri-Samani, A. and Javaheri, A., 2012. Discharge coefficients for free and submerged flow over Piano Key weirs. Journal of hydraulic research, 50(1), pp.114-120. https://doi.org/10.1080/00221686.2011.647888

Sajadi, S.M., 2017. Effect of baffled outlet keys at Piano Key Weir on dissipating energy. Irrigation and Drainage Structures Engineering Research, Vol. 18, Issue 69, pp.77-92. https://doi.org/10.22092/aridse.2017.108456.1165

Al-Shukur, A.H.K. and Al-Khafaji, G.H., 2018. Experimental study of the hydraulic performance of piano key weir. International Journal of Energy and Environment, Vol. 9, Issue 1, pp.63-70.

Naghibzadeh, S.M., Heidarnezhad, M., Masjedi, A. and Bordbar, A., 2020. Experimental and Numerical Analysis of Energy Dissipation in Piano Key Weirs with Stepped and Baffled Barriers at Downstream Slop. Iranian Journal of Soil and Water Research, Vol. 51, Issue 10, pp.2431-2442. https://doi.org/10.22059/ijswr.2020.295541.668467

Eslinger, R. K. and Crookston, B.M., 2020. Energy dissipation of type a piano key weir. Water, Vol. 12, Issue 5, p.1253. https://doi.org/10.3390/w12051253

Singh, D. and Kumar, M., 2022. Gene expression programming for computing energy dissipation over type-B Piano Key Weir. Renewable Energy Focus, Vol. 41, pp.230-235. https://doi.org/10.1016/j.ref.2022.03.005

Fathi, A., Abdi Chooplou, Ch. and Ghodsian, M.G., 2023. An experimental study of flow energy loss in trapezoidal stepped Piano Key Weirs (PKWs). Modares Civil Engineering journal, Vol. 23, Issue 4.

Elyass, S.S., 2012. Effect of Channel Slope on Energy Dissipation of Flow for Single Step Broad–Crested Weirs. Journal of Engineering and Sustainable Development, 16(3), pp.91-103.

Hassan, S.N., 2013. The Effect of Total Solids on the Discharge Coefficient of Spillway, Broad crested weir and Crump weir. Journal of Engineering and Sustainable Development, 17(2), pp.233-242.

Jüstrich, S., Pfister, M. & Schleiss, A.J., 2016. Mobile riverbed scouring downstream of a piano key weir. Journal of Hydraulic Engineering, Vol. 142, Issue 11, p.04016043. https://doi.org/10.1061/ASCE HY.1943-7900.0001189

Gohari, S. & Ahmadi, F., 2019. Experimental study of downstream scour of piano keys weirs. Journal of Water and Soil Conservation, Vol. 26, Issue 1, pp.91-109. https://doi.org/10.22069/JWSC.2019.14680.2961

Ghafouri, A., Ghodsian., M. & Abdi, Ch., 2020. Experimental study on the effect of discharge and tailwater depth on bed topography downstream of a piano key weir. Journal of Hydraulics, Vol. 15, Issue 3, pp.107-122. https://doi.org/10.30482/JHYD.2020.236770.1465

Kumar, B. & Ahmad, Z., 2022. Scour downstream of a piano key weir with and without a solid apron. Journal of Irrigation and Drainage Engineering, Vol. 148, Issue 1, p.04021066. https://doi.org/10.1061/(ASCE)IR.1943-4774.0001647

Yazdi Mosalman, A., Hosseini, S.A., Nazari, S. & Amanian, N., 2020. Comparison of downstream scour of the rectangular and trapezoidal piano key weirs. Journal of Hydraulics, Vol. 15, Issue 2, pp.95-112. https://doi.org/10.30482/JHYD.2020.227522.1453

Ghodsian, M., Abdi, Ch. & Ghafouri, A., 2021. Scouring of triangular and trapezoidal pianos key weir. Journal of Hydraulics, Vol. 16, Issue 2, pp.43-58. https://doi.org/10.30482/JHYD.2021.261439.1497

Jamal, A.A.R., Tahaa, K.Y. & Hayawi, G.A.A.M., 2022. Experimental study of scour downstream Piano Key Weir type C with changing height of weir width of keys and apron. Al-Rafidain Engineering Journal (AREJ). Vol. 127, Issue 1, pp93-204. https://doi.org/10.33899/rengj.2021.130402.1101

Lantz, W., Crookston, B.M. & Palermo, M., 2021. Apron and cutoff wall scour protection for piano key weirs. Water. Vol. 13, Issue 17, p.2332. https://doi.org/10.3390/w13172332

Chooplou Abdi, Ch., Bodaghi, E., Ghodsian, M. and Vaghefi, M., 2022. Temporal evolution of scouring downstream of a trapezoidal piano key weir. International Journal of River Basin Management, pp.1-14. https://doi.org/10.1080/15715124.2022.2143513

Chooplou Abdi, Ch., Kazerooni, S., Ghodsian, M., & Vaghefi, M. 2022b. Experimental study of scouring downstream of type-A piano key weirs. Arabian Journal of Geosciences, Vol. 15, Issue 23, pp1702. https://doi.org/10.1007/s12517-022-11001-9

Bodaghi, E., Ghodsian, M. and Abdi, C., 2023. The experimental study of downstream scouring of trapezoidal Piano key weir type A under free and submerged flow. Journal of Hydraulics, Vol. 18, Issue 1. https://doi.org/10.30482/JHYD.2022.330389.1590

Chooplou Abdi Ch., Ghodsian, M., Abediakbar, D., & Ghafouri, A. 2023. An experimental and numerical study on the flow field and scour downstream of rectangular piano key weirs with crest indentations. Innovative Infrastructure Solutions, Vol. 8, Issue 5, 140. https://doi.org/10.1007/s41062-023-01108-7

Sumer, B.M. and Fredsoe, J., 1991, August. Onset of scour below a pipeline exposed to waves. In The First International Offshore and Polar Engineering Conference. OnePetro.

Novák, P. and Čabelka, J., 1981. Models in hydraulic engineering: Physical principles and design applications. Monographs & surveys in water resources engineering. Pitman, USA.

Chiew, Y.M., 1992. Scour protection at bridge piers. Journal of Hydraulic Engineering, Vol. 118, Issue 9, pp.1260-1269. https://doi.org/10.1061/ASCE0733-94291992118:91260




Submission Dates

Received 17/07/2023

Revised 24/09/2023

Accepted 16/10/2023

How to Cite

Qasim Rdhaiwi, A., Khoshfetrat, A. ., & Fathi, A. . (2023). EXPERIMENTAL INVESTIGATION OF SCOUR DOWNSTREAM OF A C-TYPE TRAPEZOIDAL PIANO KEY WEIR WITH STILLING BASIN. Journal of Engineering and Sustainable Development, 27(6), 688–697. https://doi.org/10.31272/jeasd.27.6.2