Hydraulics of free overfall in smooth triangular channels

Abstract

Abstract The present study deals with the hydraulic behavior of smooth triangular channels with free overfall in order to obtain useful relationships for the estimation of end depth discharge (EDD) in terms of brink depth (yb), channel side slopes (m) and channel bed slope (So). For this purpose, twelve triangular channel models have been built and tested having 3.6 m length and 19 cm drop at brink with different values of side slopes (m = 0.75, 1.0 and 1.25) and different channel bed slopes (So = 0.0, 0.0033, 0.0067 and 0.02). Experimental results of all models showed straight line relationships for the end depth ratio (EDR) for different values of (So) and (m) with high determination coefficients and low values of root mean square error. A quadratic equation is obtained for the variation of EDR with (So). An empirical expression is obtained for a dimensionless discharge in terms of (So) for all channel models tested for both subcritical and supercritical flow conditions with the range of Froude number in the approach channel between 0.64 and 4.15. Two methods (direct and indirect) are proposed for the estimation of EDD in which the outcome results compared quite well with the available data of previous studies.