Stream Salinisation
The role of groundwater processes in both dryland and irrigation-induced salinity has been long recognised. Across significant areas of Australia, land clearing and cropping has increased groundwater recharge, raised the watertable and driven increased discharge of saline groundwater into nearby streams. The Audit (NLWRA) estimated that about 25,000 km2 of salt-affected lands could potentially increase to 170,000 km2 by 2050. The current annual cost in terms of lost agricultural production and infrastructure damage has been estimated at $250m with degradation of ecological assets undefined (NLWRA, 2001). Of concern is increasing trends in stream salinity in the Murray-Darling Basin and the south-west of Western Australia. About a third of divertible surface water in streams in south-west Western Australia is classified as brackish and saline, with only half of streams classified as potable in terms of salinity (WA Government, 2000).
Land and stream salinisation has been a key motive for understanding how groundwater systems respond to changing land use, as well as processes of seepage flux and salt mobilisation to water bodies. Significant investments have been made in engineering solutions such as groundwater interception schemes to reduce salt loads to significant rivers such as the River Murray.
Further Information
References
NLWRA, 2001. Australian dryland salinity assessment 2000. National Land and Water Resources Audit, Canberra. WA Government, 2000. The salinity strategy. Natural resource management in Western Australia. WA State Salinity Council.