Oral Presentation Australian Society for Fish Biology Conference 2024

Pre-Screen Viewing: Understanding Influences of Pump Driven Water Diversion on River Hydraulics (111363)

Patrick McSweeney 1 2 , Simon Mitrovic 1 , Laura Michie 3 , Fraser Torpy 1 , Craig Boys 3
  1. University of Technology Sydney, Glebe, NEW SOUTH WALES, Australia
  2. NSW Department of Primary Industries, New South Wales Fisheries, Port Stephens, New South Wales, Australia
  3. Department of Primary Industries , Department of Primary Industries and Environment, Sydney, New South Wales, Australia

Water diversion practices negatively impact native fish populations by altering hydraulic conditions near diversions. Fish protection screens mitigate these effects by modifying the flow dynamics in front of pumps. However, the hydraulic conditions before screen installation remain largely unknown. This study used an Acoustic Doppler Current Profiler to measure flow velocities near multiple water diversions of varying sizes, both during active and inactive pumping, under different flow conditions. By calculating velocities directed towards the pump, the study observed the extent of a pump's influence and the associated velocities. Larger pumps significantly impacted river hydraulics, with influence extending up to 10 meters and velocities reaching over 0.7 m/s. Velocity variation indicative of potential turbulence around pumps were also noted, especially within 0-3 meters of the pump, where peak velocities were highest. Differences in pump influence were observed across sites, with lower pump-driven velocities in areas of higher river velocity. These findings provide a framework for assessing the impact of water diversions on river systems and align with laboratory studies showing high velocities and turbulence near intakes. The results can guide the targeted application of fish screens to the most impactful pumps and improve fish screen designs to better protect native fish.