A review of salt mobilisation and management in irrigated areas of the Murray Darling Basin

Previous studies of salt mobilisation processes and management strategies in the irrigation areas of the Murray-Darling Basin are reviewed to facilitate the identification of effective options for reducing the impact of drainage from irrigation areas on river water salinity. The report concludes that salt mobilisation and export is highly variable between irrigation regions with rates ranging from 1t/ha/yr to over 10t/ha/yr. Processes contributing to high salt mobilisation are salt wash-off, groundwater seepage, engineered subsurface drainage and channel outfall. The relationships between these processes are influenced by hydrogeological, climatic and management factors specific to each region. The greatest potential for salt mobilisation occurs through groundwater seepage where highly saline groundwater systems are connected to surface water bodies. The suitability of management options depends on the spatial, hydrologic, climatic and management characteristics of the irrigated area, with thecost of diverting additional drainage water assessed against the improved water quality and possible implications of increased salt storage.