Identifying opportunities for achieving water savings throughout the Murray–Darling Basin

Demand for water from the rivers of the Murray–Darling Basin (MDB) in Australia continues to increase, despite a Cap on diversions being in place since 1996. Previous and ongoing efforts to improve water use efficiency (WUE) within the Basin have focused primarily on engineering solutions, in particular through reducing losses from seepage, leakage and evaporation within the distribution system, by upgrading channels or replacing them with pipes. Water trading is enabling water to be moved from low value to high-value enterprises consistent with market demand. On many properties the installation of improved water reticulation and application systems, including replacing some of the flood and furrow systems with sprinkler, trickle and micro-drip systems, is also achieving significant savings allowing for significant improvements in productivity per unit of water used.A model was constructed to explore the potential for achieving further on-farm savings within the MDB through increased adoption of best management practices aided by low and high levels of investment. The approach was based on the only consistent Basin-wide statistics relating to irrigation (land use by irrigated crop or pasture for 1996) and is highly transparent and amenable to modification since it operates in Microsoft Excel™. The approach sidesteps connectivity issues between ground and surface water and focuses on water applied to crops.This model can be simply adapted for similar studies in other river systems. The value of investing in reducing the amount of water lost during its transmission to farms was also examined in a separate spreadsheet analysis. Despite significant limitations in the underlying data, it was shown that savings in excess of 900 GL per annum can be achieved on irrigated farms in the Basin, under reasonable time frames, and plausible scenarios for farm investment and the adoption of new technologies. Savings of this magnitude have the potential to provide a significant incentive to develop and implement policies that could bring them into being. Even greater savings are feasible through investing significantly in new irrigation technologies, in increasing adoption rates, and in reducing current losses incurred in bringing water from storages and river systems to the farm gate.