Applied Analysis of Piano Key Weir (PKW) Structures as a Diversion Dam

Document Type : Research Article


1 Department of Water Structure, Faculty of Water Science Engineering, Shahid Chamran University of Ahvaz, Iran.

2 Department of Water Structure, Faculty of Water Science Engineering, Shahid Chamran University, Ahvaz, Iran.


In the present study, the hydraulic capability of piano key weir (PKW) was investigated utilizing the physical model. Because of decrease in water surface at dry seasons, these structure increases upstream head water. In addition, they have an appropriate discharge coefficient at the flood. To achieve the purposes of this research, two models of PKW were built with the ratio of height to a cycle width (P/Wu) equal to 1.33 (model 1) and 0.5 (model 2). The positive and negative slopes of parapet walls were considered with slopes 3, 5.5 and 8o rather than direction of flow. The results showed that model 2 has a more capability at the increased water surface in the low discharges. Moreover, model 1 has a suitable discharge coefficient at the higher discharge. Results obtained from analysis showed that H/R parameters have a significantly influence on the discharge coefficient when this weir is not submersible or there is a low head after fully submergence. The correlation of discharge coefficient equation after and before fully submergence of weir was 0.976 and 0.973, respectively.


Main Subjects

[1] M.H. Vali-Samani, Design of Hydraulic structures, Dezab, Ahwaz, 2008 (in Persian).
[2] F. Laugier, A. Lochu, C. Gille, M. Leite Ribeiro, J.-L. Boillat, Design and construction of a labyrinth PKW spillway at Saint-Marc dam, France, Hydropower & Dams, 16(LCH-ARTICLE-2009-023) (2009) 100-107.
[3] T.C. Hien, H. Son, M. Khanh, Results of some piano keys weir hydraulic model tests in Vietnam, in: Proc. 22nd ICOLD Congress, Barcelona Q, 2006, pp. 581-596.
[4] R. Anderson, B. Tullis, Influence of Piano Key Weir geometry on discharge, in: Proc. Int. Conf. Labyrinth and Piano Key Weirs Liège B, 2011, pp. 75-80.
[5] R. Anderson, B. Tullis, Comparison of piano key and rectangular labyrinth weir hydraulics, Journal of Hydraulic Engineering, 138(4) (2011) 358-361.
[6] A. Kabiri-Samani, A. Javaheri, Discharge coefficients for free and submerged flow over Piano Key weirs, Journal of Hydraulic Research, 50(1) (2012) 114-120.
[7] F. Lempérière, A. Ouamane, The Piano Keys weir: a new cost-effective solution for spillways, International Journal on Hydropower & Dams, 10(5) (2003) 144-149.
[8] F. Lempérière, J. Vigny, A. Ouamane, General comments on Labyrinth and Piano Key Weirs: The past and present, in: Proc. Intl. Conf. Labyrinth and Piano Key Weirs, Liège B, 2011, pp. 17-24.
[9] M. Barcouda, O. Cazaillet, P. Cochet, B. Jones, S. Lacroix, F. Laugier, C. Odeyer, J. Vigny, Cost effective increase in storage and safety of most dams using fusegates or PK Weirs, in: Transactions of the International Congress on Large Dams, 2006, pp. 1289.
[10] J. Pralong, J. Vermeulen, B. Blancher, F. Laugier, S. Erpicum, O. Machiels, M. Pirotton, J.-L. Boillat, M. Leite Ribeiro, A. Schleiss, A naming convention for the piano key weirs geometrical parameters, Labyrinth and piano key weirs, (2011) 271-278.
[11] M.L. Ribeiro, M. Pfister, A.J. Schleiss, J.-L. Boillat, Hydraulic design of A-type piano key weirs, Journal of Hydraulic Research, 50(4) (2012) 400-408.
[12] M. Leite Ribeiro, M. Pfister, J.-L. Boillat, A. Schleiss, F. Laugier, Piano Key Weirs as efficient spillway structure, in: Proceedings (on CD) of the 24th Congress of CIGB–ICOLD, 2012, pp. 176-186.
[13] O. Machiels, Experimental study of the hydraulic behaviour of Piano Key Weirs, Université de Liège, Belgium, 2012.
[14] G. Cicero, J. Menon, M. Luck, T. Pinchard, Experimental study of side and scale effects on hydraulic performances of a Piano Key Weir, in: Proc. Int. Conf. Labyrinth and Piano Key Weirs Liège B, 2011, pp. 167-172.
[15] A. Javaheri, Hydraulic flow of piano key weirs, Industry University of Isfahan, 2012 (in Persian).
[16] V. Te Chow, Open channel hydraulics, McGraw-Hill Book Company, Inc; New York, 1959.
[17] N.S.L. Rao, Theory of weirs, in: Advances in hydroscience, Elsevier, 1975, pp. 309-406.
[18] O. Machiels, S. Erpicum, P. Archambeau, B. Dewals, M. Pirotton, Parapet wall effect on piano key weir efficiency, Journal of Irrigation and Drainage Engineering, 139(6) (2012) 506-511.