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Processes of Salinity
Salt is a natural feature in many Australian landscapes including the Murray-Darling Basin. It has accumulated over the past 65 million years through invasions of the sea and the natural geological change eg erosion. The Basin being exceptionally flat terrain, low rainfall and high evaporation have combined to concentrate salt in the soil and groundwater.
The increasing salinisation of the rivers and landscape of the Murray-Darling Basin is being driven by rising groundwater levels. These are mobilising salt stored in sub soils and bringing it to the soil surface or carrying it sideways into streams. Rising groundwater tables do not automatically cause salinisation, but the wide distribution of salinised sub soils throughout the Basin means that in practice rising groundwater tables indicate a high likelihood of increased salt mobilisation.
When groundwater levels are close to the soil surface, capillary action carries salt upward to the plant root zone causing land to become saline. Streams and rivers become saline through salt being washed from the soil surface or where groundwater levels with high salt loads, begin to permanently intersect with the base of the stream or river. This process dramatically increases the water salinity levels.
Causes of increase groundwater levels and Salinity
Removal of deep rooted native vegetation
Replacement with shallow rooted annual crops and pastures
In efficient excess irrigation
River regulation Impacts of Salinity
Reduction in water resources
Reduction in agricultural land
Damage to urban infrastructure
Constraints and losses to industry
Reduction in biodiversity
Reduction of living and aesthetics of the landscape What is being done?
There are numerous projects being conducted with the aims to combat salinity. The Murray Darling Basin Commission has developed the Basin Salinity Management Strategy, which provides a framework for state salinity strategies and catchment management strategies. For more information on salinity projects visit the following links:
Links to Other Sites |
