Types of salinity
Primary salinity - Lake Wyara, western Queensland, a naturally occuring saline lake
Secondary salinity - Area of secondary salinity in the Lockyer Valley, South-East Queensland (photo copyright Jack Lynch)
There are two main types of salinity which can occur—primary and secondary—either naturally or resulting from human activities.
Primary salinity occurs naturally in soils and waters. Examples of naturally occurring saline areas include salt lakes, salt pans, salt marshes and salt flats.
Secondary salinity is salting that results from human activities, usually land development and agriculture. Common forms of secondary salinity are:
- irrigation—irrigated areas, either as a result of rising groundwater tables (from excessive irrigation) or the use of poor quality water
- dryland—non-irrigated landscapes, generally as a result of clearing vegetation and changes in land use
- sea water intrusion—coastal aquifer systems where sea water replaces groundwater that has been over-exploited
- point source—large levels of salt in effluent from intensive agriculture and industrial wastewater.
Fretting of brickwork
Salting of brickwork
Salinity is not restricted to rural areas. Urban salinity can develop in a variety of ways, is generally a combination of both dryland and irrigation salinity, and has the potential to damage many high-value assets.
There are two broad types of urban salinity including problems:
1) caused directly by urban development (e.g. leaking pipes, pools, septic tanks, over-watering of parks and gardens etc)
2) present prior to construction of an urban area (e.g. urban development in an area with existing shallow groundwater or seepage).
Signs of urban salinity
- Bare patches of ground often with a white salt crust on the surface.
- Waterlogged areas.
- Salting of brickwork or rising damp in buildings.
- Road, pavement or driveway crumbling or deterioration.
- Growth of salt tolerant species.
- Fretting of bricks and mortar.
Avoiding urban salinity
- Avoid over watering of gardens.
- Keep the area of lawn to a minimum.
- Plant deep rooted native vegetation and plant gardens with low water requirements.
- Try to avoid ponding of water.
The main thing to remember about avoiding urban salinity is to limit the amount of water that reaches the watertable.
External related links
- Department of Primary Industries—Victoria
- Deaprtment of Environment, Climate Change and Water—New South Wales
Last reviewed 10 April 2012
Last updated 24 February 2010