The past year (2012-2013) has been hotter and drier than usual throughout the Basin (Figure 2). In the Southern Basin, some early flooding occurred along parts of the Murray, Murrumbidgee, Goulburn and Ovens Rivers but since September 2012 there have been few rainfall events. In the Northern Basin, some catchments in Queensland and Northern New South Wales received heavy rainfall and flooding from ex-tropical cyclone Oswald in late January 2013. However, other rivers throughout central-north New South Wales and the region of the Basin have experienced below average rainfall throughout the year. Figure 2. Rainfall throughout the Murray-Darling Basin, 1 June 2012- 31 May 2013 (Bureau of Meteorology) Despite low inflows and high water usage in response to hotter temperatures, dam storage levels throughout the Basin still generally remain above average. This provides confidence that reasonable environmental water allocations may become available in 2013-14, however volumes will vary between catchments according to inflows. The Bureau of Meteorology rainfall outlook for the next three months (June – August 2013) indicates a wetter than normal season is more likely throughout the Basin (Figure 3). Figure 3. Chance of exceeding the median rainfall, 1 June – 31 August 2013 (Bureau of Meteorology) Given the antecedent conditions, current climate forecasts and likely water availability, the Priorities for 2013-14 focus on the broad management outcomes aligned to the moderate to wet resource availability scenarios (Table 1). These are to maintain, and in some cases improve, ecological health and ecosystem resilience throughout the Basin. However, due to the highly variable nature of climate and river flow across the Basin, real-time management of environmental water will be undertaken according to specific conditions in each catchment. Each Priority is supported by a rationale that describes how its implementation may vary according to prevailing conditions throughout 2013-14. Table 1: Management outcomes for each resource availability scenario Resource availability scenario: Very Dry Resource availability scenario: Dry Resource availability scenario: Moderate Resource availability scenario: Wet – Very Wet western
Management outcomes Avoid irretrievable loss of or damage to, environmental assets: − Avoid critical loss of species, communities, and ecosystems. − Maintain critical refuges. − Avoid irretrievable damage or catastrophic events. − Allow drying to occur, where appropriate, but relieve severe unnaturally prolonged dry periods. Ensure environmental assets maintain their basic functions and resilience: − Support the survival and viability of threatened species and communities. − Maintain environmental assets and ecosystem functions, including by allowing drying to occur consistent with natural cycles. − Maintain refuges. Maintain ecological health and resilience: − Enable growth, reproduction and small-scale recruitment for a diverse range of flora and fauna. − Promote low-lying floodplain-river connectivity. − Support river and floodplain functions. Improve the health and resilience of water-dependent ecosystems: − Enable growth, reproduction and recruitment for a diverse range of flora and fauna. − Promote higher floodplain-river connectivity. − Support high-flow river and floodplain functions. Rationale and process In putting together the Priorities for 2013-14, the Authority has taken a Basin-scale approach which adds value to current environmental watering activities without duplicating them. This philosophy encompasses moving the concept of environmental watering, from just the delivery of a volume of water at specific sites towards the preferred concept of a flow regime as near natural as possible within river systems. The Priorities have been developed using both the conventional triage approach to environmental watering, whereby assets and functions are prioritised by their urgency of watering, as well as drawing on a restoration ecology approach. Restoration ecology emphasises providing environmental water to those assets and functions already in good condition where a significant positive response to environmental water is most likely. scale