The establishment of baseline conditions is critical for any management plan that seeks to manage environmental condition. By setting an effective baseline, management plans can more effectively compare future changes based on management interventions or other external drivers. In the river management space, this is becoming increasingly complicated as shifting baselines lead to confused target achievement and complexities with evaluating outcomes.
In South Australia, previous water resources management plans have used a modelled scenario with the impacts of water resource development removed (the ‘No Dams’ scenario). Evaluation of the outcomes of these plans highlighted a significant difference between hydrological evaluation of environmental outcomes (environmental water requirement metrics) and the observed condition of ecosystems. Flow assessment suggested environmental condition was critically low and failing all objectives while actual environmental data showed declining condition but not the catastrophic conditions. This difference is being driven by the increase in water available under the ‘No Dams’ scenario compared to a pre-European flow regimes due to land clearance.
Moving forward, setting of baseline condition needs to be more reflective of the needs of the species rather than an arbitrary flow scenario. We used multiple methods to identify historic periods of flow that could be used to describe a baseline scenario that reflects the needs of taxa present in the system. By using actual flow and ecological data we removed the common concern of landholders around the use of modelling and reduced uncertainty around the suitability if the flow regimes for the target species.