Vertical slot fishway design for fluctuating water-level reservoir

To match the fluctuation of the headwater level at a vertical slot fishway exit, a new fishway design method is proposed in this paper. The proposed new fishway consists of three sections, namely deep-water, overflow and shallow-water sections. This paper presents the results of a hydrodynamic experimental study on the hydraulic characteristics of flow in these three sections. The water depth and velocity profiles at the shallow section were uniform regardless of the water level at the fishway exit. Nevertheless, the hydrodynamic profiles at the deep-water section were non-uniform owing to the backwater profile, which decreases the velocity in the slot. Excess water outflow at the overflow section balanced the discharge between the exit and entrance. Although non-uniform conditions were present in the deep-water section, hydrodynamic profiles were suitable for migrating fish to pass through. This indicates that the new fishway design is fish friendly.