Author(s): J. Angus Webb; Geoff J. Vietz; Wayne M. Koster; Anna Lintern
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Abstract: Ecological responses to environmental flows are often evaluated by describing the relationship between flow and response. However, aquatic organisms experience the hydraulic environment in a river system, not its hydrology. Here we used 2D hydraulic modelling to evaluate spawning responses to high flow events in an iconic native Australian fish species. Probability of spawning was positively related to both discharge and average water velocity during high flow events, but water temperature was critical for allowing the flow response to be seen. Hydraulic metrics are often not linearly related to hydrology, and evaluating responses to hydraulics offers a more process-based analysis of ecological effects of environmental flows. Additionally, consideration of ecological response in terms of the hydraulics of environmental flow events offers improved opportunity to consider results across multiple rivers, including specific responses for rivers of different sizes. Collectively, these can improve the efficiency and effectiveness of environmental flow management decisions.
Year: 2018