The worst drought in Australian history poses a serious threat to the sustainability of the irrigated agriculture in most irrigation systems across the Murray-Darling Basin (MDB). There is a need for pragmatic approaches to use available water resources more efficiently and to minimise losses in earthen irrigation supply channels. The new water policy of the Australian Government focuses on ensuring water security for all water users, through a suite of actions, including a new “Basin Plan”, and “Sustainable Rural Water Use and Infrastructure” under “Water for the Future” program that underpins saving water by reducing conveyance and seepage losses in irrigation supply systems. This paper presents a framework for identifying seepage hotspots and estimating seepage losses in open channel irrigation systems for targeting investments to minimise the water loss. The main elements of the framework are: field measurements, modelling, economic analysis to determine the cost per megaliter (1ML = 1,000 m3) of water saved; and to examine the potential options for financing the water saving investments. Using data from two irrigation systems in the Murrumbidgee catchment located in the southern MDB, a national case for reducing seepage water losses in irrigation channels is presented. It is proposed that increased level of security for investments on water saving programs is required as an incentive to achieve the targets on water savings. Giving a value to the water recovered from reducing seepage losses at irrigation system level, this study shows how just one component of the overall water losses in irrigation systems can benefit all stakeholders including the environment. Options for financing the infrastructure improvement program for water savings are proposed.

Keywords: Water security, geophysical techniques, groundwater flow model, low-cost technologies, economic analysis.