Multi-Species Assessment of Injury, Mortality, and Physical Conditions during Downstream Passage through a Large Archimedes Hydrodynamic Screw (Albert Canal, Belgium)

Abstract

Fish passing downstream through hydraulic structures and turbines may be exposed to an elevated risk of injury and mortality. The majority of live fish studies are single-species laboratory investigations and field studies of Kaplan turbines, with a limited number of studies in Francis and screw turbines. In addition to these studies, the physical conditions during turbine passage can be directly measured using passive sensors. In this study, we investigate the multispecies risk of injury and mortality during downstream passage through a large Archimedes hydrodynamic screw for bream (Abramis brama), eel (Anguilla anguilla), and roach (Rutilus rutilus) in conjunction with passive sensors that record the pressure, acceleration, and rate of rotation. This work proposes several new metrics to assess downstream passage including the times and durations of impact events, the kinetic energies of translation and rotation, and the pressure gradient. The major findings of this work are three-fold: (1) Significant differences in injury and mortality were observed between the three investigated species with 37% mortality for bream, 19% for roach, and 3% for eel on average. (2) The operational scenario was found to be significant only for a limited number of species-specific injuries and mortality rates. (3) In contrast to studies in Kaplan turbines, the sensor data revealed highly chaotic physical conditions in the Archimedes hydrodynamic screw, showing little difference in the physical metrics between operational scenarios.