Optimisation of Agricultural Drainage to Manage Irrigation Salinity in Australia: An example from the Murray Irrigation Area, Australia

The environmentally sustainable productivity of irrigated Agriculture areas in the semi arid and arid regionsof the world is being challenged by the waterlogging and secondary salinisation of landscapes (Ghassemi et al.,1995). About one-third of the world's irrigated lands have reduced productivity as a consequence of poorlymanaged irrigation that has caused water logging and salinity (FAO, 1998). In a 1990 study (Gutteridge, etal., 1990) it was estimated that areas of high watertables (i.e. watertables within two meters of the landsurface) in the Murray Darling Basin of Australia would increase to 95 % of the total area irrigated within50 years if no actions were taken. This situation coupled with dry land and urban salinity and consequentrising salinity levels of rivers resulted in the development of a range of land and water management schemes(Blackmore, 1995) under a basin wide Salinity and Drainage Strategy. In order to achieve the salinity targetsa number of actions such as adoption of engineering options to manage irrigation salinity and bestmanagement practices, on-farm and regional management activities and education and extension endeavoursare being implemented. Wakool Tullakool Subsurface Drainage Scheme (WTSSDS) is an example ofengineering options to manage irrigation salinity in the Murray Irrigation Area of New South WalesAustralia.The Wakool Tullakool Subsurface Drainage Scheme (WTSSDS) is located in the Wakool and TullakoolIrrigation Districts of New South Wales, Australia. The total area of these irrigation districts is 2,080k m2(208,000 ha) which includes 357 holdings. Rice, winter pasture, summer pasture, dairying and wintercrops are the major irrigated enterprises. During 1981 WTSSDS was installed to drain shallow salinegroundwater into evaporation basins for 'disposal'.