Discharge Coefficients for Radial-Gated Ogee Spillways by Laboratory Data and by Design of Small Dams

Using the measured data on 15 laboratory models in USA, six models and one prototype in Turkey, the discharge coefficients ( C ’s) of radial-gated ogee spillways for various gate opennings and lake water surface elevations are computed. Comparison of these C ’s for 22 spillways with the ones given by Figure 9-31 of Design of Small Dams does not show close agreements. It is determined that C depends on both the angle Ɵ and the ratio d/H 1 , rather than Ɵ only where d and H 1 are the gate opening and the upstream head, and statistically significant regression equations are computed individually for each dam.