5335.2 Predicting the Future Extent of Dryland Salinity
Identifying areas that may be at risk from dryland salinity in future, and the rate of
salinisation, can help to prioritise efforts needed for its prevention or amelioration.
It is more expensive to reclaim salt-affected land than it is to prevent it from forming
in the first place.
Methods have been developed for assessment of salinity risk across areas of
varying extent, from the farm scale to national scale (Gilfedder and Walker 2001 ).
Generally, these have been developed to suit available data, which vary according to
the extent and site of study areas. Consequently, there was a lack of consistency
between the range of methods used to predict salinity risk across Australia, and the
methods varied widely in both methodology and reliability.
Where detailed land contours are available (as is increasing the case through
automated photogrammetry using digital aerial photography, LiDAR and available
satellites) it is possible to identify land that may be affected if groundwater levels
rose by some fixed amount (e.g. if they rose a further 1 or 2 m above existing known
saline areas). This is likely to be more effective in areas with existing saline out-
breaks. In cases where there are no surface expressions of salinity, the depth of the
watertable needs to be known from monitoring bores. Land-based geophysical sur-
veys that measure terrain conductivity at various depths are very good at identifying
local areas that have a high salt content and a hazard of becoming saline, however
as they do not measure soil-water (watertables) and account for micro-topographic
effects, cannot be used alone for risk assessment.
6 Management of Dryland Salinity
The management of dryland salinity can be conceptualised into three approaches:
(1) recovery – where a solution is implemented based on managing the causal agents
(water table/saline soil); (2) containment – modifying the causal processes to some
degree and in so doing limiting the full impacts; and (3) adaptation – accepting
saline soils and taking steps to enable the profitable use of saline land and water.
In the context of salinity management systems, revegetation using deep-rooted
perennial vegetation and engineering options are considered recovery and contain-
ment strategies, while implementation of integrated catchment options (e.g. higher
water use cropping, perennial pastures and salt land pasture systems) are primarily
for containment and adaptation.
Salinity in Dryland Agricultural Systems: Challenges and Opportunities