This research paper investigates the effect of the longitudinal channel slope on the discharge coefficient of cylindrical weirs. The methodology applied is by adopting three different diameters of the cylindrical weir and at three different slopes of the channel. In addition, various five flow rates values were used for each case.
The study showed that the discharge coefficient increases when the dimensionless value of (Hw/R) [which represents the ratio of the net hydraulic head in upstream to the radius of cylindrical weir] is high. Furthermore, the discharge coefficient increases as the channel slope increase, for the same (Hw/R) ratio. As a result, the discharge coefficient increases with the increment of cylindrical weir diameter. Finally, an empirical non-dimensional relationship was obtained between the discharge coefficient with a channel slope and dimensionless value (Hw/R) with a good correlation coefficient.