Science to support the management of riverine flows

The last two decades has seen introduction or reform of water legislation in many river basins of the world, and river managers are under increasing pressure to make effective and efficient flow management decisions. To support those decisions, the roles that freshwater scientists must fulfil are rapidly evolving, and now is a good time to ask: What roles must scientists fulfil to best support those decisions? What are the major barriers to seeing those roles fulfilled? How can those barriers be removed? We offer potential answers to these questions. To ensure our arguments are grounded within real policy and decision problems, they are framed within the context of Australia's Murray-Darling Basin Planlegislation to guide the management of environmental flowsand its associated Watering Strategy. These problems are not unique, so the challenges and solutions we identify have broader applicability to flow management. Indeed, many of the policy and decision problems we present are common to all ecosystem types, so our arguments will likely be applicable beyond freshwater ecosystems. We argue that scientists must fulfil four roles to support flows management: (1) Monitoring and evaluation of ecosystems to support scientifically defensible reporting of outcomes, and to reduce uncertainty through adaptive management. (2) Modelling to support spatial and temporal projections of ecosystem change under different flow scenarios, resulting in more effective management decisions; improved causal inference about flow effects; identification of threats to the efficacy of flow management; and scaling flow-response dynamics to broader spatial extents. (3) Fundamental research, resulting in improved outcomes through the identification of non-flow management interventions that work in synergy with environmental flows and improved understanding of the ecological limitations of current policy. (4) Decision science, leading to more defensible environmental flow decisions and more efficient use of resources. We identify key barriers specific to each role and offer possible remedies. We argue that a major impediment to seeing these roles fulfilled is the ad hoc nature of much of the current research effort. Investment in research must (1) be developed at the basin scale, to ensure science supports decision problems that span multiple scales; (2) be developed as a collaboration between all stakeholders to ensure that science investments remain aligned with decision problems; (3) recognise the need to build and maintain technical capacity within the four roles.