In this research, we studied the optimum positions of fishways through a few inquiries into existing fishways and related positive investigation. Then, we made a laboratory reproduction of data concerning the shape of channels near headworks. In Japan, these are widened so as not to impede the descent of flood flow. We also checked for the characteristics of the compound cross-section channel, which is locally strongly affected by the widened part, as a structure necessary to assure a gut and grasped its basic flow regime pattern
