The Golden Gift of Groundwater in Australia’s MDB

Abstract

The Murray-Darling Basin (MDB) has the second-most variable surface flows in the world. The unreliable nature of MDB surface water supply is expected to increase under climate change. To partially address this future problem, Australia’s government released 927 gigalitres (GL = 1 billion litres) of groundwater rights to agricultural users in the basin under the Murray-Darling Basin Plan (2012-2026). A key argument for that action was the perception that groundwater resources in the basin are sustainable, and more reliable, than surface water resources. Access to more reliable water often transforms agricultural cropping choices. This chapter uses an optimization model of the MDB to explore how basin agriculture may transform in response to reliable water access—particularly in the northern part of the MDB. We find that traditional opportunistic cropping systems (i.e., annuals) shift towards high-value systems (e.g., perennials) and change irrigation practices when access to groundwater resources is increased. We also examine the change in value for those new groundwater rights as climate change impacts take hold.