Building responsive bio-economic models to replicate complex farm management decisions for mixed irrigation farming systems in southern NSW

This paper is part of a broader study that uses AusFarm, a complex biophysical model, to model a mixed irrigation farming system in the Murray Irrigation Area and Districts (Murray Irrigation Limited (MIL) post 1995). The study is unique is that the biophysical model has been coupled to an economic module that includes an irrigation sequence model and pricing function. The study has enabled the examination of water market tools that irrigators have available to them in the MIL (‘temporary water’ and ‘carry over’), and the importance of these tool in managing future risk under changing climates.
This paper shows that a combination of water market tools will be an important component in managing risk under changing climate, at least under a mid-range emissions scenario with modest reductions in irrigation water availability. For example, the modelling in this paper shows that having both the ability to carry over water to the following water year, and access to temporary water markets increases the likelihood of sowing opportunities and yield gains for the summer irrigated crop for both historical and projected climate periods. Access to these tools will become crucial as irrigators manage future water supply and demand risk under the impact of climate change and changes to water policy.