DISCHARGE COEFFICIENTS OF ORIFICE AND NOTCH IN ICE-HARBOR FISHWAY

Abstract

 In recent years, Ice-Harbor fishways have been adopted in many rivers due to their high adaptability to flow fluctuations. Ice-Harbor fishway has two flow routes such as orifice and notch. Discharge coefficients of orifice and notch are not so clarified, because both coefficients were obtained from the fishway with only either orifice or notch. Both coefficients affect each other due to the three-dimensional nature of flow. When orifice and notch coexist, a shear layer forms at their boundary due to differences in flow velocity and direction, resulting in momentum exchange. In this study, discharge coefficients of orifice and notch in Ice-Harbor fishway were obtained by varying geometry and hydraulic conditions. It was found that those coefficients are controlled strongly by the ratio between weir thickness and approach flow depth. The equations of discharge coefficients of orifice and notch were suggested.