Author(s): H. R. Kammanankada; J. C. Martino; I. M. Suthers; R. T. Kingsford; S. Felder
Linked Author(s): Stefan Felder
Keywords: Closed conduit fishway; Fishway hydraulics; Hydraulic structures; Low-head weirs; Unsteady surge
Abstract: Hydraulic structures, such as dams and weirs, impede the natural flow of rivers which fragments fish movement and migration routes. The consequent loss of connectivity has caused freshwater fish populations to significantly decline worldwide. Enabling upstream fish passage over these structures can be established with fishways. However, only a few large hydraulic structures have functioning fishways and often these fishways are expensive to build and maintain. The closed conduit Tube Fishway is a promising option to achieve upstream passage over barriers. This fishway uses gravitationally charged water sourced from upstream of the barrier to create an unsteady surge that can lift fish from the base of the structure over its crest. The surge is prompted by the operation of two control valves and requires no additional energy input beyond the pneumatic operations of the two valves. So far, the Tube Fishway has only been operated under laboratory conditions and its field operation remains to be resolved. As such, the Tube Fishway was installed and operated for the first time in the field at three low-head weirs in NSW, Australia. The weirs varied in type and location to assess varied operation of the fishway. Across these sites, the hydrodynamic properties of the fishway were measured to validate a numerically model. Hydrodynamic tests conducted with Lagrangian sensors recorded acceleration and pressures of the surge along the delivery pipe, and recorded values were found to be within ranges that have lifted fish safely during previous laboratory investigations. Manual measurements of the surge volume were conducted and compared to a numerical model and were found to complement each other. Slight discrepancies between modelled and measured results indicate that further refinement of the numerical model is required to enable better predictions for future field installations. Finally, some preliminary lifting experiments were performed with native, Australian fish (Retropinna semoni and Hypseleotris klunzingeri), indicating that these two fish species can be safely lifted by the Tube Fishway in the field. Outcomes from these tests pave the way for upcoming field trials that will focus on the combined attraction and lifting of fish using the Tube Fishway.
Year: 2024