(7) Risk and Resilient Decision-Making

There are multiple risks that need to be managed in the context of water and the MDB. First, and foremost, is the very large variation in precipitation across seasons and years that can result in both floods and extended droughts. This risk has been managed by building very large water storages and allocating water to irrigators via water entitlements that are a share of a consumptive pool [69]. Thus, in periods of low water storages and inflows, holders of water entitlements, and in particular, those with low-reliability water entitlements, receive less than they would in "normal" years. This allocation of water also places a priority on providing water volumes to water rights with subsidiary priority on discretionary environmental flows that are not managed as water entitlements [70].

Despite a median climate change scenario developed by CSIRO for 2030 and 2050 that has, respectively, an 11% and 17% reduction in the runoff for the southern MDB [71], there was no consideration of climate change in the setting of SDLs as part of the Basin Plan [72,73]. Equally relevant, no consideration was made for the effects of climate change on the economic returns associated with the A\$3.5 billion already spent, and billions to be spent, on upgraded irrigation infrastructure [73,74]. This is problematic because modeling suggests that a more resilient strategy, in relation to droughts, is to reduce water diversions rather than invest in water infrastructure [75].
