Experimentally determination of discharge coefficients of Ogee spillway under axial arc condition with convergent lateral walls

Document Type: Research Paper


1 Faculty of Civil Engineering, University of Sistan & Baluchestan, Zahedan, Iran

2 Soil Conservation Watershed Management Research Institute (SCWMRI), Tehran, Iran

3 Faculty of Civil Engineering., University of Sistan & Baluchestan, Zahedan, Iran


A dam spillway is a hydraulic structure that appropriately and safely diverts the outflow to downstream, so that the dam stability and passing of flood flows can be guaranteed. Compared to straight crest spillway, an Ogee spillway with curvature in plan in a fixed-width can pass more flow. Therefore under the low hydraulic heads and the need for a smaller place in plane, they are considered as an economical structure so that their application from several aspects are under developed. An experimental model of the Garmi-Chay Miane dam spillway was made in 1:50 scale. The water head over spillway crest was measured in the eight discharges values and consequently the efficiency of spillway were determined. For Q/Qd ranging from 0.63-1.13, discharge coefficient had ascendant trend with acceptable agreement against the diagram of USBR, while for Q/Qd between 1.13-1.51, due to the submergence of spillway, the discharge coefficient decreased.


  1. Bahmani, T., Rostami ravari, A., and Tayari, A., (2010), “The determination of discharge coefficient the Roodbal dam spillway by using a physical model”, second global conference on integrated water resources management.
  2. Bradley, J. N., (1945), “Studies of flow characteristics, discharge and pressures relative to submerged dams”, Hydraulic Laboratory Rep, U.S. Dept. of the Interior, Bureau of Reclamation, No. 182, Denver.
  3. Cassidy, J. J., (1965), “Irrational flow over spillways of finite height”, J Mech Eng Div, ASCE; 91(6):155–173.
  4. Chatila, J., Tabbara, M., (2004), “Computational Modeling of Flow over an OgeeSpillway”, Computers and Structures 82, p.p.1805–1812.
  5. Crookston, B. M., (2010), “Labyrinth Weirs”, All Graduate Thesis and Dissertations, Utah State University, paper 802.
  6. Dargahi, B., (2006), “Experimental study and 3D numerical simulations for a free-Overflow Spillway”, Journal of Hydraulic Engineering, ASCE, Vol. 132, No. 9.
  7. Ghodsian, M., (1998), “Viscosity and Surface tension Effects on Rectangular Weir Flow”, International Journal of Engineering Science, Iran University of Science & Technology, Vol.9, No.4, pp. 111-117.
  8. Hunt, S.L., Kadavy, K.C., Abt S.R, and Temple, D.M., (2008), “Impact of Converging Chute Walls for Roller Compacted Concrete Stepped Spillways”, Journal of Hydraulic Engineering, ASCE, Vol. 134, No.7.
  9. Johnson, M.C., and Savage, B.M, (2006), “Physical and Numerical Comparison of Flow over Ogee Spillway in the Presence of Tail water”, Journal of Hydraulic Engineering, Vol.132, No.12.
  10. Khosrojerdi, A., “Study of discharge coefficient with a weir broad crest centered arches using hydraulic model”, (1997), M.Sc thesis, Islamic Azad University Branch of Tehran Science and Research.
  11. Khosrojerdi, A., Mehrjerdi, M., (2007), “Hydraulic checking ogee spillway in arc axis conditions”, 9th Seminar on Irrigation and reduce evaporation.
  12. Savage, B. M., and Johnson, C. M., (2001), “Flow over ogee spillway physical and numerical model case study”, Journal of Hydraulic Engineering. ASCE, Vol.127, No.8, 640-649.
  13. Tullis, B. P., and Neilson, J., (2008), “Performance of Submerged Ogee-Crest Weir Head-Discharge Relationships”, journal of Hydraulic Engineering, ASCE, Vol. 134, No. 4.