Types of salinity and their prevention

The NSW Government is working with the Australian Government, local government, farmers and the broader community to treat and prevent the different types of salinity.

The key to addressing dryland salinity is managing excess water in the landscape. This can be done by:

• maintaining adequate vegetation cover
• maximising water use by choosing an appropriate mix of pasture species
• minimising long fallows, using crop rotations and conservation farming methods in cropping areas
• maintaining soil health (fertility, pH and structure) to maximise plant growth.

Under appropriate conditions, salt-affected sites can be treated by:

• keeping stock off the area to allow regrowth
• applying mulch to reduce erosion
• planting salt tolerant grasses, herbs, shrubs and tree species
• adding gypsum and/or fertilisers to help plant growth
• preventing erosion by using contour banks to direct surface water away from the site
• reducing waterlogging by establishing banks and subsurface drains to intercept shallow subsurface water and direct it away from the site
• pumping groundwater to lower the water table.

The NSW Government also provides other detailed resources for land managers who need to assess and manage salinity on the Department of Primary Industries and Regional Development's salinity webpage.

Modelling dryland salinity allows us to:

• assess and compare different actions to manage salinity
• fill gaps where data is limited
• forecast additional data based on our current data in space and time
• predict future trends.

Models help us to understand salinity processes in a landscape. We need to know:

• where is the salt and how much is there
• how salt and water move
• how geology and landscapes influence movement
• what affects how fast salt and water are moving
• how changing something in one location affects the rest of the catchment or basin.

Several models have been used in New South Wales to help answer these questions.

PERFECT

Used at a property scale, this well-established tool estimates surface runoff, lateral flow, recharge and the impacts of vegetation changes on the water cycle. In 2015, this model was used to forecast the impacts of climate change on surface runoff and recharge.

CATSALT

This is a catchment scale model developed and applied to predict the effects of land use changes on stream flows, stream salinities and salt loads in the NSW Murray-Darling Basin.

2Csalt

Developed by the NSW, Victorian and Queensland governments and CSIRO, this tool was used for salt mobilisation modelling for state reporting under Murray-Darling Basin reporting arrangements. In New South Wales, it has been applied in:

• the 2008 Salinity Audit update
• the CERAT risk assessment tool to help identify and prioritise land use planning decisions to protect and preserve the health of coastal estuaries.

CATPLUS

This was developed by the Department of Primary Industries Victoria and the former Cooperative Research Centre for Plant-based Management of Dryland Salinity. The model predicts the impacts of various land use scenarios on catchment water yield and salinities to stream. In New South Wales, CATPLUS has been applied in the Tarcutta Creek catchment in the Murrumbidgee valley.

Management and engineering practices that might be used include:

• avoiding over-irrigation by monitoring soil moisture to work out water requirements
• practising good crop selection such as using deep-rooted plants to maximise water extraction
• minimising fallow periods using crop rotations and break crops
• avoiding deep ripping and overtillage to minimise infiltration of water
• maintaining satisfactory fertility levels, pH and structure of soils to encourage growth of high yielding crops
• using subsurface drainage systems to collect and control water seeping below the plant roots and water entering and/or leaving the irrigation site
• using large bores, or bore fields to draw down the regional water table and maintain it below the root zone and disposing of saline water in special evaporation basins, or in other approved ways.

The NSW Government provides resources on salinity to help irrigators.

Urban salinity needs to be addressed at the local level and across the relevant catchment. This is because groundwater is affected by actions at both levels.

At the catchment level, prevention involves managing the land as described under dryland salinity.

At the local level, councils and residents should:

• avoid overwatering public parks, sports fields, home gardens and lawns
• plant large native trees and shrubs in open spaces
• replace leaking channels and pipes with corrosion-resistant materials
• minimise groundwater recharge from dams, artificial lakes and drainage basins
• drain water away from infrastructure to avoid ponding
• connect septic tanks to piped sewerage systems where possible
• connect roof drainage to stormwater systems rather than sullage pits (a pit holding the used water from washing clothes and kitchen utensils)
• monitor changes to water table levels and groundwater quality
• establish gardens with low water requirements.

The Local Government Salinity Initiative (LGSI) published a series of booklets to support local government on urban salinity issues.