Processes of salinity

Salinity is a problem in Australia because most of our groundwater and surface water systems are poorly drained and enormous amounts of salt are stored in the landscape. As water moves through the landscape, salts stored in the soil and water are picked up and carried to different parts of the landscape.

Many saline areas in NSW are the result of entirely natural processes. However, salinisation is exacerbated as a result of changes in land use and land management. Increased salt in soils, rivers and groundwater reflects changes to the water cycle in different areas and the way in which groundwater moves through the subsurface.

The processes of salinity involve mechanisms of salt mobilisation and accumulation.

  • Salts are dissolved and mobilised by surface water and groundwater.
  • Rising groundwater remobilises salts previously stored at depth in the soil
  • Salts are concentrated at, or near, the earths surface by evaporation

There are several factors that influence the distribution and extent of salinity in the landscape. They include:

the water cycle (where the movement of water between the atmosphere, the land and the sea can cause a salinity problem when salt is redistributed by a change in the water balance

climatic factors such as rainfall and temperature and where there is a change in the amount of precipitation relative to evaporation and water use by plants

geology and geomorphology where some rock types are more likely to contribute to salinity problems, because their composition and texture and can influence the movement of water

understanding groundwater flow systems and how different salts are responsible for salinity and how soils are an important consideration for salinity management

how vegetation can reduce groundwater recharge by intercepting water before it reaches the groundwater system and how healthy, fully functioning ecosystems can help reduce the impacts of salinity

the changes in land use and how these have altered the way water moves through the landscape contributing to salinity problems

Page last updated: 11 October 2013