New Equations for Energy Dissipation for Spillways with Slope of 30 Degrees and Height of 0.305m

Abstract

Stepped spillways are current method of choice for safe discharge of flood water due to their inherent ability to employ their stepping nature to safely dissipate substantial energy. Hence, the authors in this study aim to provide to design engineers new models for estimating energy dissipation in a stepped spillway with an equal step heights and widths of 0.3 m. Many researchers have investigated both the hydraulic and the geometric relationships of stepped spillways of varying sizes that resulted in significant energy dissipation, but quite a few of them has conducted researches on stepped spillways with equal heights and widths of 0.3 m, thereby leading to limited information at the disposal of design engineers involved in the design of stepped spillway with equal heights and widths of 0.3 m. The authors obtained more than 500 measured data from the Engineering Research Center Colorado State University Fort Collins, Colorado work published in April, 2002 and about 300 of them that had complete data were re-analyzed and used to develop energy dissipation model that govern nappe and skimming flows over a wide range of operating conditions. This energy dissipation model was formulated in terms of the number of the steps of the stepped spillway and the flow critical depth using multiple regression analysis and matrix method. This developed model was later calibrated and yielded very high coefficients of correlation that ranged from 0.8808 to 0.9982, which upon verification gave good predictions between the measured and estimated data. Results showed that the rate of energy dissipation along a stepped spillway increases with increasing numbers of steps, but decreases with increasing rate of discharge.