Dimensiones de la rentabilidad

Loss of flooding due to river regulation is the key degrading factor in the declining resilience of the Macquarie Marshes wetland ecosystem, driving both ecological and social systems beyond viable thresholds, significantly increasing susceptibility to the impacts of climate change. As summarised (3.2.3), climate change in the Macquarie Marshes will probably primarily drive reduction in flooding volumes and frequencies.

However, past impacts of water regulation on loss of flooding will likely continue to overshadow those projected through climate change. Given existing water entitlements to the Macquarie Marshes (146243ML general security and 3340ML supplementary), the likelihood of resilience to anticipated climate change is uncertain. The single primary adaptation for restoring the Macquarie Marshes ecosystem is the return of adequate environmental water needed to restore the short and moderate inter-flood intervals. This can be achieved through increased water entitlements for the environment or reductions in extractive share of flow through changes in legislation and policy. Achieving this within the next decade will likely buffer against existing 2030 climate change projections of increased temperature and reduced runoff. Intermediate adaptations through the removal of biophysical drivers such as buy-back, voluntary water sharing, and increased outlet capacity to increase environmental water volume aimed at eliminating inter floods interval larger than 2 to 4 years can have only a limited effect. True ecological restoration and resilience to long-term climate change can only come from changes of social institutions behaviours and amendments to the water sharing plans (Jenkins et al., 2011).

Presently, an explicit consideration of climate change adaptation strategies, within the developed objectives hierarchy, is lacking. Adaptation to climate change can be autonomous, physical, institutional/political, or through land management (Jenkins et al. (2011). Adaptations within the Macquarie Marshes Nature Reserve should aim to minimise the effects of climate change on the ecosystem through biophysical and behavioural adaptations.

Potential adaptations may include:

 Water Flows: obtaining adequate environmental water to restore the short and moderate inter flood intervals;

 On-ground Management: improving the management and use of existing water allocations as well as to maximise the effectiveness of treatment and abatement activities;

 Social values: promoting and increasing social understanding within the local and broader community of the value of the natural environment of the Macquarie Marshes;

 Water Sharing Plan: reviewing the water sharing plan to specify shorter durations for the inter flood intervals;

 Modelling Capacity: improving regional scale modelling capacity of climate change projections that enable maximising ecological returns on environmental flows; and

 Strategic Adaptive Management: implementing a strategic adaptive management with appropriate documentation that can be reviewed and used for decision-making.

Within the context of structured decision-making, climate change adaptation strategies

management of environmental water for key ecological objectives as well as to the enabling objectives aimed to effectively engage with water management policies, planning, and processes to support functioning ecosystems. Adaptation through amendments to the water-sharing plan should also be lined under similar enabling and water sharing objectives. Promoting social understanding should link under the high-level people’s objectives, focusing on building partnerships with local farmers and communities. Increasing modelling capacity can only be attained through the support of science under enabling objectives. Finally, the implementation of a strategic adaptive management plan falls naturally under the wetlands adaptive management strategy objectives within the high-level enabling objective.

Figure 17: Integration of climate change adaptation strategies within existing objectives hierarchy, presently developed by OEH.

Temporal hierarchy of adaptation

Interaction of existing challenges in the Macquarie Marshes nature reserve and Ramsar site along with projected climate change for the region suggest adaptation strategies are reliant on the time horizon for short and long-term management (Figure 18).

Under existing climatic conditions, the Macquarie Marshes have been severely impacted by river regulation, reducing flooding volumes, and extending the inter-flood intervals. Key ecological assets are experiencing extreme water duress leading to changes in the ecological character of the Ramsar site. Among the prominent and most chronicled changes, include observed degradation of semi-permanent vegetation and reduction in waterbirds breeding events. Ecosystem services have also diminished, namely in reduction of grazing productivity, affected areas reliant on livestock grazing.

Short-term strategies

Given projected climate change for the near future (i.e., 2030), the main challenges facing the Macquarie Marshes will centre on effective management of water allocations operating within a heavily regulated system. Relatively small changes in climate will likely be eclipsed by the natural variation of the environment. For now, short-term management strategies will inevitably focus on reducing the dominant obstacles standing in the way of desired restoration targets. Avoiding identified thresholds of concern of ecological assets during inter-flood periods will enable managers to sustain the ecosystem or as a minimum to delay degradation. Reducing the inter-flood interval stands as one of the foremost obstacles that may be eased through buying back sufficient volumes of water and increasing the outlet capacity.

Implementing a strategic adaptive management approach requires that managers learn from ecological responses during inter and intra flooding periods. Improving hydrological modelling capacity and testing ecological responses to increased allocations of environmental flows will enhance development of adaptation strategies.

This requires change in attitude towards ongoing quantitative monitoring, aimed at assessing the outcomes of taken management actions and continuously improving models of ecological cause-and-effect to future management scenarios.

Long-term strategies

Long term climate change projections (2070), imply increased changes to the floodplain, potentially surpassing those brought by river regulation. With no significant increase in water allocations, continued degradation of the Macquarie Marshes ecological indicators and social values is anticipated. Even with sophisticated adaptive water management strategies, developed in the short term, their success in achieving desired management objectives would be highly limited without changes to existing legislation and policy regarding water entitlements (Hannah et al. 2002; Scott et al.

2002; Moser and Ekstrom 2010). Changes in social institutional attitude and legislation that foster cooperation within and across jurisdictions, will ultimately be necessary to

Figure 18: Time horizon of adaptation strategies for the Macquarie Marshes.