Rock-weir fishway II: design evaluation and considerations

The flow characteristics of a rock-weir type nature-like fishway are determined by the configuration of the stream channel and passage structures. For a fishway to be effective, the rock-weir hydraulics must be compatible with the swimming capabilities of the target fish species. This study optimized the design characteristics of rock-weir fishways by simulating the water depth and velocity for different channel characteristics and geometries, which govern the fish resting zones, volumetric dissipated power and ultimately upstream fish passage performance. This study provided recommendations on effective pool spacing, bed slope, weir height, weir angle and weir arrangements for designing rock-weir fishways. These design recommendations are based on fishway hydraulics and should provide suitable hydraulics for fish migration and sufficient slow velocity areas for fish resting in rock-weir fishways for specific structure geometries and channel characteristics.