7.2.3. Dryland salinity

Dryland salinity occurs when groundwater discharges or seeps to the surface, bringing soil salts with it. It can occur naturally but is accelerated if catchment hydrology (water balance) is changed, such as when deep-rooted perennial vegetation is removed (see Diagram 1). USE DIAGRAM on p7 of LAYNA
Dryland salinity can cause vegetation loss and stream salinisation and can act as a precursor to soil erosion. Urban areas and infrastructure are also affected by dryland salinity.

Diagram 1: The effect of removing deep-rooted vegetation on groundwater discharge.
Source: D Slinger and K Tenison.

Box section:
Causes of dryland salinity
• Replacement of deep-rooted perennial vegetation with shallow-rooted pastures and crops that use less water, resulting in an elevation of the watertable,  which brings salt to the surface
• Over-irrigation of crops, lawns and recreation areas with similar effect to the above
• The breakdown of rock/sediments containing high levels of salt
• Salt in rainfall, depending on rainfall amount and distribution
• Landform and hydrogeology characteristics

Effects of dryland salinity
• Loss of desirable vegetation
• Growth of salt-tolerant species
• Reduced crop and pasture production and decreased enterprise flexibility
• Waterlogged soil
• Soil erosion on bare areas
• Increased salt loads in waterways
• Reduced surface and groundwater quality
• Declining soil structure
• Damage to buildings, roads, septic systems and pipes
End box section