Application of new hybrid method in developing a new semicircular-weir discharge model

Circular weirs have been utilized as a flow-measuring device in open channel hydraulics. Since the corresponding theoretical equation for computing discharge is not adequately suited for practical purposes due to its complexity, empirical models are utilized as a preferable alternative. In this research, new improved simple formulas for semicircular weirs with sharp and semicircular crests were proposed in favor of achieving more accurate results. These relations were obtained using a new hybrid method for an experimental database. The proposed correlations were compared with the ones in the current literature. The comparison shows that the proposed models reduce the mean absolute relative errors, MARE, by about 32% and 46% for calculating discharge with sharp and semicircular crests, respectively. Finally, the obtained results demonstrate that not only the new hybrid method is capable of rigorous calibrating process, but also the proposed models facilitate computing discharge values with more accuracy. Keywords: Open channel flow measurement, Weirs, Semicircular opening, Sharp crest, Semicircular cres