Page 15 - VEWH Seasonal Watering Plan 2020-21
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Action 3.5 also reaffirms commitments to recover water
for the environment in the Thomson, Barwon, Moorabool, Werribee and Maribyrnong systems. Extra water was added to the Thomson environmental entitlement in 2017 and a new environmental entitlement was created for the upper Barwon River in 2019. Work continues to investigate water-recovery options in the other systems. All water recovered under these commitments will be managed by the VEWH and its partners to optimise future environmental outcomes in the face of climate change.
The VEWH and its program partners are addressing the challenges of climate change in the following ways.
Setting environmental watering objectives that describe the environmental outcomes that can be achieved under future climatic conditions
Environmental flow studies and environmental water management plans are revised periodically to update environmental watering objectives and their required
water regimes. These reviews consider how climate change will affect current environmental values and the types of outcomes that can be achieved in the future. Waterway managers also alter environmental watering objectives for individual systems to include the latest scientific information, as it becomes available. The seasonal watering plan presents the most up-to-date environmental watering objectives and the watering actions required to achieve them.
Strengthening decisions about where and how water for the environment is used
During prolonged dry periods (which are more likely in
the future), there is not enough water available to meet
the needs of all waterways. Rigorous decisions must be made about where and how to use the available water,
to optimise environmental outcomes for enduring benefit. Most high-priority environmental watering objectives rely on ecosystem processes that operate beyond individual rivers or wetlands. Therefore, in prioritising sites for environmental watering, decision-makers are increasingly considering
the combination of waterways that need to be watered to optimise outcomes. Portfolios of waterways are being managed in a coordinated way to support high-value species, as well as critical ecosystem services.
For example, coordinated releases from Hume Reservoir, the Goulburn River and Campaspe River have been used to trigger the movement of young golden perch and silver perch throughout northern Victorian waterways. The VEWH and its program partners are also working together to identify the most important refuge habitats to water during critically dry periods.
Optimising environmental outcomes of operational water releases
The VEWH is working closely with storage managers and river operators to identify how operational releases —
water releases made from storages to enable the water distribution system to operate or make water available for consumptive uses — can be delivered in ways that meet customer needs and contribute to environmental outcomes. This also helps river operators meet their environmental obligations.
Planning for a range of climatic scenarios each year
Watering requirements can vary considerably between
wet and dry years. In drought and dry conditions, the
aim is to prevent catastrophic losses and maintain critical refuge habitats to prevent significant declines of native populations. In wet conditions, the aim shifts to boosting ecological productivity and environmental condition and to increasing populations of native plants and animals. Climatic conditions can change quickly within a year, and the VEWH and its program partners need to be able to respond accordingly. The seasonal watering plan identifies potential watering actions that may be delivered to each system under different climatic scenarios: this is explained in more detail in subsection 1.3.4.
1.1 The Victorian environmental watering program
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