How can management of uncertainty in sustainable diversion limits be advanced in the review of the Murray-Darling Basin Plan?

This paper explores how scientific uncertainty was addressed in the Australian Government's decision-making process leading to the establishment of the 'sustainable diversion limit' (SDL) for the Murray-Darling Basin Plan in 2012. Our research draws on a systematic document analysis to generate an argument map representing the reasoning presented in government reports and legislation, as well as interviews with current and former public servants and researchers who have knowledge of the decision-making process. Looking towards the review of the Basin Plan, this analysis provides additional evidence for a number of areas to be discussed to advance the management of uncertainty in the associated decision-making. First, there is a need to address the challenges to adaptive management, as adaptive management delegates much of the uncertainty to future changes in policy as improved knowledge is gained. Second, there is a need to generate and use new knowledge for the review since the legislative mandate to use the 'best available science' enabled the use of pre-existing models and historical climate data. Third, there is a need for dialogue on handling of trade-offs between objectives given that uncertainty creates space for political pressures from interest groups. Fourth, there should be wider transparency about uncertainty in decision-making processes.