Assessment of the ability to meet environmental water requirements in the Upper South East of South Australia

Often there are a number of criteria that must be considered when evaluating water resource management options, for example both water quantity and quality issues. Each criterion generally requires a separate model to assess the outcomes from different possible scenarios. Each model will have its own uncertainties and limitations, and the combination of all of these considerations can make the identification of acceptable, let alone optimal, options difficult. In this work, a resources management problem to identify the optimal operation of a large drainage network to support ecosystems at a number of key wetlands has been considered. These ecological outcomes were assessed by the ability to deliver sufficient volumes of water below important salinity thresholds. It was found that even with an unknown volume of water available, the optimal operations of the drainage network were generally constant. For the majority of wetlands considered, the ability to supply sufficient water below a given salinity threshold was mostly insensitive to uncertainty in the contributing groundwater salinity. However, in some wetlands, water of desirable salinity levels was unlikely to be available for all scenarios at one target wetland, the variability in groundwater salinity considered had a large influence on the availability of water of suitable quality. This work highlights the importance of keeping the modelling objectives in mind when considering the outputs and uncertainties involved in integrated modelling assessment.