Author(s): Desmond O. Anim; Tim D. Fletcher; Geoff J. Vietz; Gregory B. Pasternack; Matthew J. Burns
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Keywords: No Keywords
Abstract: Streams draining urban catchment are almost universally ecologically degraded due to the impact of urbanization. Addressing channel form or flow regime remains two key management components for restoration. Both components impact the stream hydraulic habitat, however, very little is known about the relative influence of the channel and flow alteration. This paper present the application of two-dimensional hydraulic model to investigate the relative role between the channel form and flow in impacting the in-stream habitat. The study examined different scenarios of urban and natural flow with urban and natural channel form in the context of benthic habitat disturbance which is important for a variety of ecological and geomorphic processes. The analysis used Shields stress, that quantifies the relative potential for bed mobilization, a phenomenon that is key to physical habitat degradation. Comparing the different scenarios, the results indicate that i) altered flow regime is not the only dominant control on bed disturbance frequency but also influenced by the channel form, ii) addressing just flow regimes is unlikely to restore and/or protect stream habitat from further adjustment if the channel is fundamentally degraded. This suggest that management strategies to address instream habitat degradation should consider opportunities for self-regeneration of the channel form that mitigate bed mobility or if required rehabilitate the channel.
Year: 2018