American Society of Civil Engineers

Selection of Empirical Formulae for Design of Stepped Spillways on RCC Dams

by M. Sarfaraz, (Graduate student, Civil Engineering Department, Sharif University of Technology, P.O. Box 11365-11155, Tehran, Iran. E-mail: and J. Attari, (Assistant Professor, Water Engineering Department, Power and water University of Technology, P.O. Box 16765-1719, Tehran, Iran. E-mail:
Section: Hydraulics and Waterways, pp. 2508-2517, (doi:

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Document type: Conference Proceeding Paper
Part of: World Environmental and Water Resources Congress 2011: Bearing Knowledge for Sustainability
Abstract: Stepped spillways have been widely used in Roller Compacted Concrete (RCC) dams in the recent decades. Considering complexity of hydraulics of stepped chutes, their initial design involves pre-selection of some empirical formulae for calculation of flow characteristics and design parameters. In this paper, accuracy of several empirical formulae, proposed for calculating locations of aeration inception (LI), uniform flow (Lu) and rate of energy dissipation (ΔH/Hmax), were compared in relation to results of physical model tests of four stepped spillways and the preferred formulae, providing least amounts of relative errors, were identified. Such a feedback will be helpful for improvement of initial design and subsequent physical modeling of similar stepped spillways in future.

ASCE Subject Headings:
Energy dissipation
Hydraulic structures