Enhancing irrigation resilience through brackish groundwater desalination: a case study in Australia’s Murray-Darling Basin

The Murray-Darling Basin (MDB) is Australia’s largest and most critical agricultural region, but its water resources face significant pressure due to climate variability and rainfall and runoff reductions under climate change. To ensure the resilience of irrigated agriculture, there is a need to diversify water sources and integrate innovative water management solutions. Brackish groundwater represents a largely untapped alternative water resource that, when desalinated, could supplement traditional surface water and fresh groundwater supplies. However, its adoption in agriculture is hindered by factors such as high costs, environmental concerns regarding brine disposal, and regulatory complexities.

This study investigates the potential for brackish groundwater desalination to enhance the resilience of irrigated agriculture in the MDB under uncertain water availability. A demonstration site established in South Australia’s Riverland region showcases a containerised reverse osmosis (RO) system producing around 100 kL/day of freshwater to irrigate a section of almond orchard and disposing of brine via aquifer injection into a naturally saline surface aquifer. This novel approach has the potential to lower capital costs and minimise land use compared to conventional evaporation ponds. Insights from the project include the importance of hydrogeological assessments, the scalability of aquifer-based brine disposal, and the feasibility of low-recovery RO systems optimised for agricultural contexts. Ensuring safe surface water-groundwater interactions has been a key focus of the project.

The study is also developing a cost calculator to enable professional end users to examine the potential for desalination to be integrated into their irrigation systems. This analysis has also been extended to inform a number of future outlook scenarios, including the integration of desalination to help mitigate the impacts of drought, and to identify scenarios where desalination could enable transformations in productivity. Analysis of climate change scenarios forms part of this analysis.

Key findings emphasise the importance of site-specific design, industry collaboration, and policy frameworks to facilitate the adoption of desalination and other non-conventional alternative water sources in agriculture. By helping to address the barriers to implementation, this work contributes to enhancing the sustainability and resilience of irrigated agriculture in water-scarce regions like the MDB, offering valuable insights for broader global applications. The findings provide a pathway to tackle uncertainties in water resource availability and to support sustainable agricultural development.