ABSTRACT
The Murray Darling Basin covers more than 1,000,000 square kilometers, or one-seventh of the Australian continent, and is the catchment for the Murray and Darling rivers. The river system extends from Queensland, and includes threequarters of New South Wales and half of Victoria, through South Australia and drains out of a single exit of Lake Alexandriana to the sea. The Basin supports almost three-quarters of Australia’s irrigated agricultural production, an important export for Australia. While naturally saline, human activity has significantly changed the Basin’s natural water balance systems. The removal of (deeprooted) native vegetation and the replacement with (shallow rooted) European style annual crops and pastures has resulted in excess rain and irrigation water entering the groundwater systems. As groundwaters rise, the gradient between these saline groundwater mounds and the rivers decrease. In some regions groundwater salinity can reach 50,000 EC, i.e. electroconductivity, which is a measure of salt concentration: 600 EC is thought to be suitable for potable water.1 Saline water contained in the soils then percolates into the rivers, increasing water salinity. While estimates vary, costs reported by the Murray Darling Basin Commission place annual costs due to human-induced salt impacts at $130 million in agricultural costs, $100 million in infrastructure and $40 million in environmental costs across the Basin.2
