Around the world governments are making huge investments in environmental flows. However, much of the rationale for these releases is based on expert opinion, which is non transparent and can be challenged. Empirical studies that relate ecological responses to flow restoration are mostly case studies of limited generality. Radically different approaches are required to inform the development of general models of ecological response to flow alteration. Here, we describe the modelling process being used in a major study of ecological responses to environmental flows in the Australian state of Victoria. The process attempts to make best use of all the information available from the literature, experts, and monitoring data to inform the development of general quantitative response models. We illustrate the process using the example of terrestrial vegetation encroachment into regulated river channels. Environmental flow assessments frequently propose that flow releases can be used to remove this vegetation. However, the evidence for these predictions has not been rigorously tested. Our analysis found strong evidence that increased inundation duration reduces terrestrial vegetation within river channels. However, dividing the same total inundation period into several separate inundation events reduces its effectiveness. More importantly, it allows us to make quantitative predictions of vegetation cover under different inundation scenarios. Our project is focused on developing general flow-response models, and also demonstrating that the Victorian environmental flows program has been a sound investment of public funds. However, our results have the potential to be incorporated into planning and decision-making processes, helping to drive a transformation in evidence-based practice for environmental flow management.
flow-response modelling monitoring and assessment hierarchical Bayes Eco Evidence
J.A.Webb S.C.de Little K.A.Miller M.J.Stewardson I.D.Rutherfurd A.K.Sharpe L.Patulny N.L.Poff
Department of Resource Management and Geography, The University of Melbourne, Parkville 3010, Austra Department of Infrastructure Engineering, The University of Melbourne, Parkville 3010, Australia Sinclair Knight Merz, Level 11 452 Flinders Street, Melbourne 3000, Australia Department of Resource Management and Geography, The University of Melbourne, Parkville 3010, Austra Department of Biology, Colorado State University, Fort Collins 80523, United States of America