Author(s): Lisa Besser; Xiaoyang Shen; Mario Oertel
Keywords: Piano Key Weir; Fishway; Vertical Slot Fish Pass; River Continuity; Numerical Simulation
Abstract: Piano key weirs (PKW) are non-linear hydraulic structures developed from traditional labyrinth weirs with improved hydraulic efficiency and reduced space requirements. Compared to regular linear weirs, its folded planform enables a significantly longer total crest length which contributes to an increased discharge capacity. Thanks to its smaller footprint, this type of weir not only can be applicated as a replacement of outdated regular weirs but also is able to be constructed on the top of existing dams for flood release purposes. However, weir structures as PKWs also bring huge negative impact into river systems by disconnecting its natural biological continuity and blocking the migration path of the aquatic organisms. To overcome these disadvantages, the present study estimates the feasibility of a new solution to restore the river continuity and to guarantee fish migration by integrating a vertical slot fish pass (VSP) in a piano key weir structure. Numerical 3D CFD simulations were performed to preliminarily investigate geometrical aspects of such combined structure. Results show that for low discharges guiding flow currents will be produced. But with increasing discharge amounts, the PKW flow may affect the VSP entrance area.